ARRT MRI Exam — Questions and Answers

Question 1: Magnetization transfer contrast (MTC) in MRI is based on the exchange of magnetization between which two proton pools?

Free water protons and bound macromolecular protons (Correct answer)
Fat protons and water protons
Arterial and venous blood
Intracellular and extracellular water

Correct answer: Free water protons and bound macromolecular protons

MTC involves saturation of bound macromolecular protons, which transfer their saturation to free water protons, reducing signal in tissues with high macromolecular content.

Question 2: Which labeling term indicates that an item has been tested and poses no known hazards in ALL MRI environments?

MR Conditional
MR Compatible
MR Approved
MR Safe (Correct answer)

Correct answer: MR Safe

The ASTM 'MR Safe' label means the item poses no known hazards in all MRI environments and is made of non-conductive, non-magnetic, non-RF-reactive materials.

Question 3: Bilateral symmetric T2 hyperintensity in the basal ganglia of a child is most associated with which condition?

Glioblastoma multiforme
Acute ischemic stroke
Wilson's disease or metabolic disorder (Correct answer)
Multiple sclerosis

Correct answer: Wilson's disease or metabolic disorder

Bilateral symmetric basal ganglia T2 signal abnormality in a child raises concern for metabolic disorders such as Wilson's disease, mitochondrial disease, or toxic encephalopathy.

Question 4: In MR angiography, time-of-flight (TOF) technique produces vascular signal by exploiting which physical principle?

Inflow enhancement: unsaturated blood entering a saturated imaging slab (Correct answer)
T2 prolongation of blood
T1 shortening by gadolinium contrast
Chemical shift between blood and surrounding fat

Correct answer: Inflow enhancement: unsaturated blood entering a saturated imaging slab

TOF MRA relies on flow-related enhancement: flowing unsaturated blood entering a slice that has saturated stationary tissue appears bright relative to background.

Question 5: Under ARRT policy, which of the following must a registered MRI technologist report within 30 days?

Purchasing new MRI accessories
Change of mailing address
Obtaining an additional college degree
A felony conviction or guilty plea (Correct answer)

Correct answer: A felony conviction or guilty plea

ARRT's Standards of Ethics require technologists to report criminal convictions or guilty pleas within 30 days.

Question 6: Which SAR limit (Specific Absorption Rate) is the FDA guideline for whole-body RF energy deposition in a 15-minute period for non-controlled conditions?

1.5 W/kg
3 W/kg
4 W/kg (Correct answer)
2 W/kg

Correct answer: 4 W/kg

The FDA guideline for whole-body average SAR under normal operating mode is 4 W/kg over any 15-minute period.

Question 7: A T1 hyperintense (bright) lesion in the brain is most consistent with which finding?

Subacute blood or fat-containing lesion (Correct answer)
Acute infarct
Pure fluid-filled cyst
Vasogenic edema

Correct answer: Subacute blood or fat-containing lesion

T1 hyperintensity in the brain is classically associated with subacute hemorrhage (methemoglobin), fat, protein-rich fluid, or melanin.

Question 8: Most superconducting magnets have a (horizontal or vertical) magnetiic field and are of the design type __.

Selenoid magnet (Correct answer)
Superconducting
Resistive magnet
Permanent magnet

Correct answer: Selenoid magnet

Most high-field superconducting MRI magnets are designed as solenoid magnets. In this configuration, the superconducting wire coils are arranged to create a strong, uniform magnetic field that runs horizontally through the bore of the scanner. This solenoid design is highly efficient for generating the powerful and homogeneous fields required for advanced MRI imaging.

Question 9: What document must candidates agree to when submitting an ARRT MRI registry application?

JRCERT Accreditation Standards
ACR Practice Parameter for MRI
ASRT Scope of Practice
ARRT Standards of Ethics (Correct answer)

Correct answer: ARRT Standards of Ethics

All ARRT applicants must attest to adhering to the ARRT Standards of Ethics as a condition of application.

Question 10: During an MRI exam, a patient begins experiencing intense burning sensations on their skin near monitoring cables. What is the most likely cause?

Gradient-induced peripheral nerve stimulation
RF-induced heating from looped or coiled cables (Correct answer)
Quench event beginning
SAR limit exceeded

Correct answer: RF-induced heating from looped or coiled cables

Looped or coiled cables act as antennas and can develop high RF-induced currents causing thermal burns on the skin.

Question 11: Which vital sign parameter is most critical to monitor during MRI in a sedated pediatric patient?

Temperature with a mercury thermometer
Heart rate via standard ECG only
Blood pressure only
Oxygen saturation via MR-compatible pulse oximetry (Correct answer)

Correct answer: Oxygen saturation via MR-compatible pulse oximetry

Continuous oxygen saturation monitoring via MR-compatible pulse oximetry is essential in sedated pediatric patients to detect respiratory compromise caused by sedation.

Question 12: What is contrast-to-noise ratio (CNR) in MRI and why is it important?

The number of phase encodes used to improve tissue differentiation
The difference in SNR between two adjacent tissues; it determines the ability to distinguish lesions from normal tissue (Correct answer)
The ratio of gadolinium dose to body weight
The ratio of TR to TE for optimal contrast

Correct answer: The difference in SNR between two adjacent tissues; it determines the ability to distinguish lesions from normal tissue

CNR is the SNR difference between adjacent tissues; high CNR is essential for detecting lesions because it reflects how well two tissues can be discriminated from each other.

Question 13: What sound pressure level (dB) can MRI gradient noise reach, necessitating hearing protection for patients?

99–115 dB (Correct answer)
130–140 dB
75–85 dB
60–70 dB

Correct answer: 99–115 dB

MRI gradient switching can generate noise levels of 99–115 dB SPL, exceeding safe hearing thresholds and requiring earplugs or headphones for patients.

Question 14: A small bandwidth makes _slices possible.

Dicker
Slimmer (Correct answer)

Correct answer: Slimmer

In MRI, the slice selection gradient, in conjunction with the radiofrequency (RF) pulse, determines the slice thickness. A smaller receiver bandwidth means that a narrower range of frequencies is sampled. This corresponds to a smaller range of magnetic field strengths along the slice selection gradient, resulting in the selection of a thinner, or 'slimmer,' slice.

Question 15: Which gradient is primarily responsible for frequency encoding in MRI?

Phase-encoding gradient
Spoiler gradient
Readout gradient (Correct answer)
Slice-select gradient

Correct answer: Readout gradient

The readout (frequency-encoding) gradient is applied during signal acquisition, causing spins at different positions to precess at different frequencies.

Question 16: Which type of aneurysm clip is considered MR Unsafe regardless of age or appearance?

Cobalt-chromium clips
Platinum clips
Ferromagnetic stainless steel clips (Correct answer)
Titanium clips

Correct answer: Ferromagnetic stainless steel clips

Ferromagnetic stainless steel aneurysm clips are MR Unsafe because the static field can exert significant torque on the clip, risking rupture of the aneurysm.

Question 17: What is the effect of reducing the number of phase-encoding steps while keeping FOV and frequency steps constant?

Through-plane resolution is affected
Frequency-direction resolution decreases
SNR improves and scan time increases
Scan time decreases and phase-direction spatial resolution decreases (Correct answer)

Correct answer: Scan time decreases and phase-direction spatial resolution decreases

Fewer phase-encoding steps means less time to fill k-space (shorter scan) but larger voxels in the phase direction, reducing spatial resolution in that dimension.

Question 18: MR Conditional implants are safe to scan only when:

The scan time is under 30 minutes
The radiologist approves verbally
Specific conditions of field strength, SAR, and gradient limits are met (Correct answer)
The patient gives verbal consent

Correct answer: Specific conditions of field strength, SAR, and gradient limits are met

MR Conditional devices are safe only when the defined conditions of use (field strength, SAR, gradient dB/dt, scan duration) are strictly followed.

Question 19: Echo planar imaging (EPI) is used in which MRI techniques due to its extremely fast acquisition speed?

Conventional T1 spin echo and MRCP
STIR and inversion recovery sequences
MR arthrography and spectroscopy
DWI, fMRI, and perfusion imaging (Correct answer)

Correct answer: DWI, fMRI, and perfusion imaging

EPI acquires an entire k-space in a single excitation, enabling the speed needed for diffusion-weighted imaging, fMRI BOLD imaging, and dynamic perfusion studies.

Question 20: The landmark for centering an MRI brain exam using a head coil is located at:

Nasion or bridge of the nose (Correct answer)
External auditory meatus
Top of the skull
Occiput

Correct answer: Nasion or bridge of the nose

The nasion (bridge of the nose) is the standard external landmark used to center the isocenter of the MRI system for brain imaging.

Question 21: On an axial MRI of the abdomen at the level of L1, which structure is seen as a round low-signal structure anterior to the aorta?

Portal vein
Inferior vena cava
Superior mesenteric artery (Correct answer)
Celiac axis

Correct answer: Superior mesenteric artery

The superior mesenteric artery (SMA) arises from the anterior aorta at approximately L1 and appears as a round flow-void structure surrounded by fat on axial images.

Question 22: In a spin echo (SE) sequence, increasing the repetition time (TR) while keeping TE short primarily results in:

Increased T1 weighting
Increased T2 weighting
Decreased T1 weighting (more proton density/T2-like contrast) (Correct answer)
Increased SNR only with no contrast change

Correct answer: Decreased T1 weighting (more proton density/T2-like contrast)

A long TR allows full T1 recovery of all tissues, reducing T1 contrast differences; combined with short TE, this produces proton density weighting.

Question 23: Which of the following is a documented risk of MRI during the first trimester of pregnancy?

Ionizing radiation exposure
Gadolinium retention in fetal tissue
All of the above except ionizing radiation (Correct answer)
Acoustic noise damage to fetal hearing

Correct answer: All of the above except ionizing radiation

MRI does not use ionizing radiation, but first-trimester risks include acoustic noise and potential gadolinium retention; non-contrast scanning is preferred.

Question 24: A candidate applying for the ARRT MRI registry via the post-primary pathway must hold a primary ARRT certification in which of the following disciplines?

Dental radiology
Radiography, nuclear medicine, radiation therapy, or sonography (Correct answer)
Medical assisting
Medical dosimetry

Correct answer: Radiography, nuclear medicine, radiation therapy, or sonography

The post-primary pathway requires a current, active ARRT primary credential in an approved imaging or therapy discipline.

Question 25: In MRI, what does the term 'bandwidth' typically refer to in clinical practice?

The range of flip angles used in a sequence
The RF pulse duration in milliseconds
The number of phase-encode steps acquired
The range of frequencies sampled during readout, affecting SNR and chemical shift (Correct answer)

Correct answer: The range of frequencies sampled during readout, affecting SNR and chemical shift

Receiver bandwidth is the range of frequencies digitized during readout; wider bandwidth reduces chemical shift and distortion but decreases SNR.

Question 26: Magnets that use liquid helium or cryogen to cool the wires after applying direct current to a coil of wire.

Resistive magnet
Selenoid magnet
Permanent magnet
Superconducting (Correct answer)

Correct answer: Superconducting

Superconducting magnets utilize special alloys that, when cooled to extremely low temperatures (near absolute zero) using cryogens like liquid helium, lose all electrical resistance. This allows a large current to flow indefinitely without power, creating very strong and stable magnetic fields. These magnets are essential for high-field MRI systems, typically operating at 1.5 Tesla and above.

Question 27: Which MRI sequence is best suited for evaluating articular cartilage because it provides excellent contrast between cartilage, fluid, and bone?

T1-weighted SE
Inversion recovery (STIR)
FLAIR
Proton density fat-saturated (PD FS) (Correct answer)

Correct answer: Proton density fat-saturated (PD FS)

PD fat-saturated sequences highlight cartilage defects as intermediate-signal cartilage contrasts sharply against bright joint fluid and suppressed fat.

Question 28: On a coronal MRI of the knee, which structure appears as a low-signal C-shaped band along the tibial plateau?

Medial meniscus (Correct answer)
Anterior cruciate ligament
Iliotibial band
Posterior cruciate ligament

Correct answer: Medial meniscus

The medial meniscus appears as a low-signal C-shaped (bow-tie) structure on coronal images along the medial tibial plateau.

Question 29: Which structure in the knee joint is best evaluated with MRI and appears as a low-signal-intensity triangular structure?

Articular cartilage
Patellar tendon
Anterior cruciate ligament
Medial meniscus (Correct answer)

Correct answer: Medial meniscus

The medial meniscus is best visualized on MRI as a low-signal-intensity fibrocartilaginous triangular structure on coronal and sagittal images.

Question 30: Inversion recovery sequences null a specific tissue when the readout pulse is applied at time TI equal to:

T1/2 of the tissue
2 × T1 of the tissue
0.5 × TE
0.693 × T1 of the tissue (T1 × ln2) (Correct answer)

Correct answer: 0.693 × T1 of the tissue (T1 × ln2)

The longitudinal magnetization of a tissue crosses zero at TI = T1 × ln(2) ≈ 0.693 × T1; applying the readout at this moment nulls that tissue's signal.

Question 31: Which MRI pulse sequence is most commonly used to perform MR angiography without contrast injection?

Echo planar imaging (EPI)
Time-of-flight (TOF) angiography (Correct answer)
Spin echo with long TR/TE
Inversion recovery with fat suppression

Correct answer: Time-of-flight (TOF) angiography

TOF MRA relies on flow-related enhancement: unsaturated blood flowing into a saturated imaging slice produces high signal relative to stationary tissue.

Question 32: Which ARRT resource provides the official list of examination content categories, subcategories, and approximate percentage weighting for the MRI registry exam?

ACR MRI practice parameters
ASRT curriculum guide
JRCERT program outcomes report
ARRT Content Specifications document (Correct answer)

Correct answer: ARRT Content Specifications document

The ARRT Content Specifications document is the authoritative blueprint that outlines all tested domains and their weightings for the MRI registry exam.

Question 33: What is the Larmor frequency in MRI?

The bandwidth of the RF receiver coil
The frequency at which gradient coils switch polarity
The rate of T1 relaxation for water
The resonant frequency at which protons precess in a given magnetic field (Correct answer)

Correct answer: The resonant frequency at which protons precess in a given magnetic field

The Larmor frequency (ω₀ = γB₀) is the precise resonant frequency at which protons absorb and emit RF energy in the applied field.

Question 34: A patient reports having a cardiac pacemaker. What is the standard MRI safety classification for most older pacemakers?

MR Unsafe (Correct answer)
MR Compatible
MR Conditional
MR Safe

Correct answer: MR Unsafe

Most older pacemakers are classified MR Unsafe because the magnetic field can interfere with device function or cause heating.

Question 35: What does a high b-value in diffusion-weighted imaging (DWI) indicate?

Lower magnetic field strength required
Stronger diffusion-sensitizing gradients and greater sensitivity to restricted diffusion (Correct answer)
Faster acquisition with less motion sensitivity
Shorter echo time and less diffusion weighting

Correct answer: Stronger diffusion-sensitizing gradients and greater sensitivity to restricted diffusion

The b-value reflects the strength and duration of diffusion-sensitizing gradients; higher b-values increase diffusion contrast but also reduce SNR.

Question 36: Which k-space trajectory fills the center of k-space first, providing low-spatial-frequency (contrast) information early in the acquisition and reducing motion sensitivity?

Reverse linear ordering
EPI single-shot trajectory
Linear (sequential) k-space filling
Centric (elliptic centric) k-space ordering (Correct answer)

Correct answer: Centric (elliptic centric) k-space ordering

Centric k-space ordering acquires the low-frequency center of k-space at the beginning of the scan, capturing image contrast during peak enhancement and minimizing motion effects on image quality.

Question 37: On a T1-weighted MRI, which substance normally appears hyperintense (bright)?

Edema
Subacute blood (methemoglobin) (Correct answer)
Cortical bone
Cerebrospinal fluid

Correct answer: Subacute blood (methemoglobin)

Methemoglobin in subacute hemorrhage shortens T1 relaxation time, producing a bright signal on T1-weighted images.

Question 38: EPI (echo planar imaging) sequences are particularly prone to which artifact caused by off-resonance spins accumulating phase during the long readout?

Chemical shift (N/2 ghost or Nyquist ghost) and geometric distortion (Correct answer)
Susceptibility artifact only in GRE
Magic angle artifact
Truncation artifact

Correct answer: Chemical shift (N/2 ghost or Nyquist ghost) and geometric distortion

EPI's long readout makes it sensitive to field inhomogeneity, causing geometric distortion along the phase-encode direction and N/2 ghosting from alternating echo phase inconsistencies.

Question 39: Traditional GRE order

Reduce the impact of residual transverse magnetization by using spoiler gradients. (Correct answer)
To lessen the impact of residual transverse magnetization, use long TR.
Maintain transverse magnetization for additional attempts

Correct answer: Reduce the impact of residual transverse magnetization by using spoiler gradients.

In traditional (spoiled) Gradient Echo (GRE) sequences, spoiler gradients are applied at the end of each TR period. The primary purpose of these gradients is to intentionally dephase any residual transverse magnetization. This prevents the magnetization from contributing to the signal in subsequent TRs, ensuring that the signal primarily reflects T1 weighting and maintains consistent image contrast by avoiding contamination from previous excitations.

Question 40: Which breathing technique is recommended for upper abdominal MRI (liver, pancreas) to minimize respiratory motion artifact?

Continuous shallow breathing
Breath-hold acquisitions combined with respiratory-triggered sequences for longer scans (Correct answer)
Free breathing throughout all sequences
Hyperventilation before each sequence

Correct answer: Breath-hold acquisitions combined with respiratory-triggered sequences for longer scans

Breath-hold sequences minimize diaphragmatic motion for dynamic contrast imaging; respiratory triggering or navigator gating is used for longer acquisitions that cannot be completed in a single breath-hold.

Question 41: Fast spin-echo (FSE/TSE) sequences acquire multiple lines of k-space per TR using which approach?

A single 90° pulse followed by multiple 180° refocusing pulses (echo train) (Correct answer)
Multiple 90° pulses with a single 180° refocusing pulse
Using a series of partial flip-angle pulses
Rapidly toggling the frequency-encoding gradient

Correct answer: A single 90° pulse followed by multiple 180° refocusing pulses (echo train)

FSE uses an echo train (RARE principle): after a 90° excitation, a series of 180° pulses generates multiple spin echoes, each phase-encoded differently, filling multiple k-space lines per TR.

Question 42: In MRI of the breast, a finding described as a 'rim-enhancing mass' on dynamic contrast imaging is most suspicious for:

Simple cyst
Fat necrosis
Malignant lesion (Correct answer)
Fibroadenoma

Correct answer: Malignant lesion

Rim enhancement of a breast mass, indicating peripheral enhancement with central necrosis, is a suspicious finding associated with malignancy.

Question 43: Which of the following maneuvers most directly reduces chemical shift artifact of the first kind?

Increase receiver bandwidth (Correct answer)
Switch from spin echo to gradient echo
Apply fat suppression
Increase field of view

Correct answer: Increase receiver bandwidth

Increasing the receiver bandwidth reduces the chemical shift displacement (measured in pixels) between fat and water signals along the frequency-encode direction.

Question 44: How many CE credits are required per ARRT MRI biennium renewal cycle?

50
36
24 (Correct answer)
12

Correct answer: 24

ARRT mandates 24 continuing education credits every two years to renew the MRI registry credential.

Question 45: FLAIR (Fluid-Attenuated Inversion Recovery) suppresses which signal and is most useful for detecting:

Muscle signal; soft tissue tumors
Blood signal; hemorrhage
CSF signal; periventricular and cortical lesions (Correct answer)
Fat signal; bone marrow edema

Correct answer: CSF signal; periventricular and cortical lesions

FLAIR uses an inversion pulse timed to null CSF, making periventricular lesions and cortical pathology (MS plaques, subarachnoid hemorrhage) visible against suppressed fluid.

Question 46: Parallel imaging techniques such as GRAPPA and SENSE reduce scan time by:

Eliminating the need for radiofrequency pulses
Increasing the magnetic field strength
Using multiple receiver coil elements to partially fill k-space and reduce phase encoding steps (Correct answer)
Applying stronger gradient pulses

Correct answer: Using multiple receiver coil elements to partially fill k-space and reduce phase encoding steps

Parallel imaging exploits spatial sensitivity information from multiple coil elements to skip phase encoding lines, reconstructing the full image and reducing acquisition time.

Question 47: Which coil type provides the highest signal-to-noise ratio (SNR) for imaging small superficial structures such as the wrist?

Head coil
Phased-array spine coil
Dedicated extremity or surface coil (Correct answer)
Body coil

Correct answer: Dedicated extremity or surface coil

Dedicated extremity or surface coils placed close to the anatomy maximize SNR by minimizing the receive volume to the region of interest.

Question 48: The 'late gadolinium enhancement' (LGE) pattern of subendocardial distribution in cardiac MRI is most consistent with which diagnosis?

Myocarditis
Hypertrophic cardiomyopathy
Cardiac sarcoidosis
Ischemic scar (prior myocardial infarction) (Correct answer)

Correct answer: Ischemic scar (prior myocardial infarction)

Subendocardial LGE following a coronary territory distribution is the classic pattern of ischemic scar from prior myocardial infarction.

Question 49: Which MRI artifact is caused by periodic patient motion such as cardiac or respiratory movement?

Ghosting (motion) artifact (Correct answer)
Chemical shift artifact
Magnetic susceptibility artifact
Gibbs ringing artifact

Correct answer: Ghosting (motion) artifact

Ghosting artifacts appear as repeated copies of moving structures along the phase-encoding direction due to periodic physiologic motion.

Question 50: A pregnant MRI technologist should follow which guideline regarding working in the MRI suite?

Limit time in the scanner room primarily during the first trimester due to acoustic and gradient exposure (Correct answer)
Avoid all scanner rooms during pregnancy
Take a leave of absence immediately upon learning of pregnancy
Wear a lead apron to reduce MRI exposure

Correct answer: Limit time in the scanner room primarily during the first trimester due to acoustic and gradient exposure

Current guidelines suggest limiting time within the bore and active scanner room primarily in the first trimester; there is no requirement to cease work entirely.

Question 51: What is the mechanism of action of gadolinium-based contrast agents (GBCAs) in MRI?

They shorten T1 relaxation time of nearby water protons, increasing signal on T1-weighted images (Correct answer)
They directly emit radio waves that increase signal
They block radiofrequency pulses to create contrast
They increase T2 relaxation time, increasing signal on T2-weighted images

Correct answer: They shorten T1 relaxation time of nearby water protons, increasing signal on T1-weighted images

Gadolinium shortens the T1 relaxation time of surrounding water protons through dipole-dipole interactions, causing increased signal intensity on T1-weighted sequences.

Question 52: What does the term 'repetition time' (TR) refer to in MRI pulse sequences?

The total scan duration
The time between successive RF excitation pulses applied to the same slice (Correct answer)
The time for magnetization to return to equilibrium after T2 decay
The time between the RF pulse and the echo

Correct answer: The time between successive RF excitation pulses applied to the same slice

TR is the interval between the beginning of one RF excitation pulse and the beginning of the next for the same slice, controlling T1 contrast.

Question 53: A patient reports a prior allergic-like reaction to a GBCA. Which of the following is the recommended premedication protocol?

Aspirin 24 hours before
Antihistamine only, 1 hour before
No premedication is effective for GBCA reactions
Corticosteroid + antihistamine, with the first steroid dose 13 hours before injection (Correct answer)

Correct answer: Corticosteroid + antihistamine, with the first steroid dose 13 hours before injection

The ACR-recommended premedication protocol for prior GBCA reactions includes corticosteroids given 13, 7, and 1 hour before contrast, combined with an antihistamine 1 hour before.

Question 54: Which section of the ARRT MRI content specifications covers pulse sequence selection and acquisition parameter optimization?

Physics and Instrumentation
Procedures
Image Production (Correct answer)
Patient Care and Education

Correct answer: Image Production

Image Production covers acquisition parameters, pulse sequences, and image quality optimization.

Question 55: Which parameter, when increased, will most directly improve the signal-to-noise ratio (SNR) in an MRI image?

Decreasing the field of view (FOV)
Increasing the bandwidth
Increasing the number of excitations (NEX/NSA) (Correct answer)
Increasing the echo train length (ETL)

Correct answer: Increasing the number of excitations (NEX/NSA)

Increasing NEX/NSA averages more signal acquisitions, which reduces noise and improves SNR proportional to the square root of the number of averages.

Question 56: The magnetic field's intensity is varied from head to foot by this gradient coil.

X
Y
Z (Correct answer)

Correct answer: Z

In most MRI systems, the main magnetic field (B0) is oriented along the Z-axis, which typically runs from the patient's head to foot. The Z-gradient coil is specifically designed to create a linear variation in the magnetic field strength along this Z-axis. This allows for precise slice selection and spatial encoding in the head-to-foot dimension.

Question 57: Which type of MRI coil provides the best SNR for imaging a small, superficial structure?

Phased-array coil designed for the spine
Solenoid body coil at isocenter
Large volume (birdcage) coil surrounding the patient
Small surface coil placed directly over the region of interest (Correct answer)

Correct answer: Small surface coil placed directly over the region of interest

A small surface coil placed close to the target anatomy maximizes signal reception from that area while minimizing noise from surrounding regions.

Question 58: What is the primary trade-off when reducing the field of view (FOV) in MRI?

Decreased scan time and improved SNR
Increased slice coverage with same resolution
Improved spatial resolution but increased risk of aliasing artifacts (Correct answer)
Improved SNR with no change in resolution

Correct answer: Improved spatial resolution but increased risk of aliasing artifacts

Reducing FOV increases spatial resolution by making voxels smaller, but if anatomy extends beyond the reduced FOV, aliasing (wrap-around) artifacts occur.

Question 59: The standard dose of a non-specific extracellular GBCA for most MRI examinations is:

0.3 mmol/kg
0.1 mmol/kg (Correct answer)
0.01 mmol/kg
0.05 mmol/kg

Correct answer: 0.1 mmol/kg

The standard dose for most extracellular GBCAs is 0.1 mmol/kg body weight, which provides adequate contrast enhancement for most clinical applications.

Question 60: The corpus callosum is best evaluated on which MRI plane for assessing callosal agenesis?

Sagittal (Correct answer)
Axial
Coronal
Oblique

Correct answer: Sagittal

The sagittal midline plane provides the best single view of the entire corpus callosum from genu to splenium for assessing agenesis or dysgenesis.

Question 61: On the ARRT MRI registry exam, which content area covers patient care, contrast agents, and MRI safety screening?

Image Production
Procedures
Patient Care and Education (Correct answer)
Physics and Instrumentation

Correct answer: Patient Care and Education

Patient Care and Education encompasses screening, safety, contrast administration, and patient communication topics.

Question 62: In a spin-echo sequence, what is the role of the 180° refocusing pulse?

It reverses phase dispersion caused by static field inhomogeneities to form an echo (Correct answer)
It suppresses fat signal by inverting its magnetization
It encodes spatial information along the frequency direction
It excites protons from equilibrium into the transverse plane

Correct answer: It reverses phase dispersion caused by static field inhomogeneities to form an echo

The 180° pulse flips the transverse magnetization so that faster and slower precessing spins rephase, forming a spin echo and eliminating fixed inhomogeneity effects.

Question 63: What causes the 'zipper' artifact that appears as a line of noise across the MRI image?

Eddy currents induced by gradient switching
External RF interference entering the scan room through a breach in shielding (Correct answer)
Incomplete fat suppression
Patient motion during phase encoding

Correct answer: External RF interference entering the scan room through a breach in shielding

A zipper artifact is caused by external RF noise at a specific frequency leaking into the Faraday-shielded room, appearing as a bright line at that frequency position.

Question 64: What is the primary consequence of using a high acceleration factor in parallel imaging?

Increased spatial resolution
Reduced SNR due to the g-factor penalty (Correct answer)
Improved T1 contrast
Reduced scan time with no image quality loss

Correct answer: Reduced SNR due to the g-factor penalty

High acceleration factors in parallel imaging introduce a geometry (g-factor) penalty that reduces SNR, especially in the center of the image where coil sensitivity overlap is less distinct.

Question 65: Susceptibility-weighted imaging (SWI) exploits differences in which magnetic property between tissues?

T1 relaxation time
Magnetic susceptibility (Correct answer)
Chemical shift
Proton density

Correct answer: Magnetic susceptibility

SWI uses the phase and magnitude information from a long-TE GRE sequence to detect subtle differences in magnetic susceptibility (e.g., deoxyhemoglobin, iron, calcium).

Question 66: What differentiates T2 from T2* is

T2* is the product of changing molecular magnetic field inhomogeneity and static magnetic field inhomogeneity, which is represented by T2.
The combination of changing molecular magnetic field inhomogeneity and static magnetic field inhomogeneity, or T2*, is represented by T2.
The combination of changing molecular magnetic field inhomogeneity and static magnetic field inhomogeneity is represented by T2*, which equals T2. (Correct answer)
The combination of changing molecular magnetic field inhomogeneity and static magnetic field inhomogeneity is represented by T2*, or T2*.

Correct answer: The combination of changing molecular magnetic field inhomogeneity and static magnetic field inhomogeneity is represented by T2*, which equals T2.

T2 relaxation describes the decay of transverse magnetization due to intrinsic molecular interactions and microscopic magnetic field inhomogeneities. T2* relaxation, however, encompasses both these intrinsic T2 effects and additional macroscopic static magnetic field inhomogeneities inherent to the scanner and patient. Therefore, T2* is always shorter than or equal to T2, as it accounts for more dephasing factors.

Question 67: In MRI, what does the term 'k-space' represent?

The final reconstructed image space
The physical space inside the MRI bore
The raw frequency-domain data before Fourier transformation into an image (Correct answer)
A map of gradient field inhomogeneities

Correct answer: The raw frequency-domain data before Fourier transformation into an image

K-space is the mathematical frequency domain where raw MRI data is stored; a Fourier transform converts k-space data into the final spatial image.

Question 68: For temporomandibular joint (TMJ) MRI, images are obtained with the jaw in which two positions?

Right lateral and left lateral
Supine and prone
Clenched and relaxed
Open and closed mouth (Correct answer)

Correct answer: Open and closed mouth

TMJ MRI is performed with the mouth both open and closed to evaluate articular disc position and movement through the full range of condylar motion.

Question 69: Which coil type generally provides the highest SNR for imaging a small superficial structure?

Quadrature head coil
Surface coil (Correct answer)
Volume coil
Body coil

Correct answer: Surface coil

Surface coils placed close to the target anatomy have superior SNR for small or superficial structures because they detect signal from a limited volume with less noise.

Question 70: Which artifact appears as parallel bright and dark bands in the phase-encoding direction when the FOV is too small and the patient extends beyond it?

Aliasing (wraparound) (Correct answer)
Gibbs ringing
Chemical shift type 2
Susceptibility artifact

Correct answer: Aliasing (wraparound)

When anatomy outside the FOV is phase-encoded, it aliases (wraps around) and appears as a superimposed copy on the opposite edge of the image, sometimes appearing as bands.

Question 71: Iron oxide nanoparticles (e.g., USPIO) used as MRI contrast agents primarily shorten which relaxation time?

Neither T1 nor T2
T1 only
T2 only with no T2* effect
T2 and T2* (susceptibility effect) (Correct answer)

Correct answer: T2 and T2* (susceptibility effect)

Iron oxide particles create local magnetic field inhomogeneities that predominantly shorten T2 and T2*, causing signal loss (darkening) on T2-weighted and gradient echo images.

Question 72: What is the Specific Absorption Rate (SAR) a measure of in MRI?

Rate of image data acquisition in k-space
Contrast agent uptake rate in tissue
Rate at which radiofrequency energy is absorbed by the patient's tissue per unit mass (Correct answer)
Speed of gradient switching in Tesla per meter per second

Correct answer: Rate at which radiofrequency energy is absorbed by the patient's tissue per unit mass

SAR (W/kg) quantifies RF energy deposition in tissue and is a primary safety limit to prevent excessive tissue heating during MRI.

Question 73: Which of the following best describes the purpose of the ARRT MRI 'didactic' requirement in the post-primary pathway?

Attending at least one MRI conference per year
Passing a vendor-specific MRI operations test
Completion of a formal coursework curriculum covering MRI physics, procedures, and patient care (Correct answer)
Shadowing a radiologist for 40 hours

Correct answer: Completion of a formal coursework curriculum covering MRI physics, procedures, and patient care

The didactic requirement ensures candidates have formal academic instruction in MRI-specific knowledge areas before sitting for the registry.

Question 74: Gibbs (truncation) artifact is caused by:

Undersampling of k-space — insufficient high-frequency data to represent sharp tissue interfaces (Correct answer)
Field inhomogeneity near air-tissue interfaces
Aliasing from a FOV smaller than the patient
Patient motion during scanning

Correct answer: Undersampling of k-space — insufficient high-frequency data to represent sharp tissue interfaces

Gibbs artifact arises from the Fourier series representation of sharp edges when high spatial-frequency k-space data is truncated, producing ringing lines parallel to the interface.

Question 75: Spin echo sequence is modified by rapid spin echo sequence by

progressively adding gradients encoded with frequencies
Gradient additions for spoilers
Adding repeated pulses of 90 degrees
Adding 180-degree pulses in succession (Correct answer)

Correct answer: Adding 180-degree pulses in succession

The rapid spin echo (also known as Fast Spin Echo or Turbo Spin Echo) sequence modifies the conventional spin echo by applying a train of multiple 180-degree refocusing pulses after a single 90-degree excitation pulse. Each 180-degree pulse generates a separate echo, allowing multiple lines of k-space to be acquired within a single TR period. This significantly shortens scan times compared to conventional spin echo sequences.

Question 76: In contrast to the spin echo sequence (SE), the gradient echo sequence (GRE)

possesses a 180-degree pulse and T2 dephasing
possesses a 180-degree pulse and T2* dephasing.
has T2* dephasing and lacks a 180-degree pulse. (Correct answer)
has a T2 dephasing pattern and no 180-degree pulse.

Correct answer: has T2* dephasing and lacks a 180-degree pulse.

Gradient Echo (GRE) sequences fundamentally differ from Spin Echo (SE) sequences because they do not use a 180-degree radiofrequency refocusing pulse. Instead, GRE sequences employ a gradient reversal to rephase the spins and create an echo. Since there is no 180-degree pulse to correct for static magnetic field inhomogeneities, GRE sequences are sensitive to T2* dephasing, making them more prone to susceptibility artifacts than SE sequences.

Question 77: The 'ABER' position used in shoulder MRI arthrography stands for:

Abduction and Elbow Rest
Adduction and External Rotation
Abduction and External Rotation (Correct answer)
Abduction and Endorotation

Correct answer: Abduction and External Rotation

ABER (Abduction and External Rotation) positions the arm to tension the inferior glenohumeral ligament and improve detection of partial-thickness undersurface rotator cuff tears.

Question 78: For MRI of the breast, the patient should be positioned in which orientation?

Upright sitting position
Prone with breasts hanging freely in a dedicated bilateral breast coil (Correct answer)
Lateral decubitus on the affected side
Supine with arms at sides

Correct answer: Prone with breasts hanging freely in a dedicated bilateral breast coil

Prone positioning with the breasts hanging freely in dedicated bilateral surface coils minimizes motion and maximizes coil coupling for optimal breast MRI.

Question 79: Which breast MRI positioning protocol is standard for screening and diagnostic evaluation?

Upright in a dedicated open MRI
Supine with arms overhead
Lateral decubitus with the ipsilateral breast dependent
Prone with the breasts in a dedicated bilateral breast coil (Correct answer)

Correct answer: Prone with the breasts in a dedicated bilateral breast coil

Prone positioning with bilateral dedicated breast coils provides optimal tissue separation, bilateral coverage, and reproducible enhancement kinetics.

Question 80: In a gradient echo sequence, what replaces the 180° refocusing pulse used in spin echo?

A slice-select gradient reversal
A phase-encoding rewinder gradient
A second 90° RF pulse
A reversed readout gradient (Correct answer)

Correct answer: A reversed readout gradient

Gradient echo sequences use a reversed readout gradient to rephase spins, making them sensitive to T2* rather than T2.

Question 81: Which of the following is a mandatory competency category that must be documented before a student can sit for the ARRT MRI registry?

MRI-guided biopsy procedures
MRI-compatible pacemaker implantation
Head MRI without contrast (Correct answer)
Cardiac MRI stress testing

Correct answer: Head MRI without contrast

Head MRI without contrast is among the required clinical competencies students must document as part of ARRT's clinical requirements.

Question 82: Which of the following best describes the 'magic angle' artifact and at what angle it occurs?

Susceptibility dropout at 45° to B0
Chemical shift banding in fat at 55°
T2 darkening of tendons at 45° to B0
Artifactual T1/PD signal increase in ordered collagen structures at ~55° to B0 (Correct answer)

Correct answer: Artifactual T1/PD signal increase in ordered collagen structures at ~55° to B0

When ordered collagen fibers (tendons, ligaments) are oriented at ~55° to B0, dipole-dipole interactions average to zero, artifactually increasing signal on short TE sequences.

Question 83: In the context of the ARRT MRI registry, 'structured education' refers to which requirement?

Completion of an accredited primary radiologic technology program (Correct answer)
Attending MRI vendor training only
Online CE modules totaling 50 hours
Hospital orientation programs

Correct answer: Completion of an accredited primary radiologic technology program

Structured education means graduating from a formal, ARRT-recognized educational program as the foundation for registry eligibility.

Question 84: How does increasing the echo train length (ETL) in a fast spin echo (FSE) sequence affect image quality?

SNR improves proportional to ETL
T1 contrast increases significantly
Spatial resolution improves in all directions
Scan time decreases but T2 blurring may increase (Correct answer)

Correct answer: Scan time decreases but T2 blurring may increase

Longer ETL fills k-space faster (reducing scan time) but each echo has progressively more T2 decay, causing blurring particularly of edges and fine detail.

Question 85: What is the effect of increasing the echo time (TE) on T2-weighted images?

Increases T2 weighting by allowing more transverse relaxation (Correct answer)
Increases T1 weighting
Decreases T2 weighting by increasing signal
Has no effect on tissue contrast

Correct answer: Increases T2 weighting by allowing more transverse relaxation

A longer TE allows more time for T2 decay, so tissues with short T2 lose more signal, increasing contrast between tissues with different T2 values.

Question 86: On MRI of the prostate using PI-RADS scoring, which sequence is the most dominant sequence for peripheral zone lesions?

MR spectroscopy
Dynamic contrast-enhanced (DCE)
T1-weighted
Diffusion-weighted imaging (DWI) (Correct answer)

Correct answer: Diffusion-weighted imaging (DWI)

DWI is the dominant sequence for peripheral zone lesion characterization in the PI-RADS v2.1 scoring system for prostate MRI.

Question 87: What does 'isotropic voxel' mean in MRI acquisition?

Voxel with equal dimensions in all three spatial directions (Correct answer)
Voxel that produces equal signal in T1 and T2 sequences
Voxel with equal field strength in all dimensions
Voxel aligned with the main magnetic field

Correct answer: Voxel with equal dimensions in all three spatial directions

An isotropic voxel has identical length, width, and height, allowing high-quality multiplanar reformats without resolution loss.

Question 88: Under ARRT policy, which scenario would trigger an automatic ethics review before an MRI registry application is processed?

Candidate holds a second radiography credential
Candidate previously worked as a radiography aide
Candidate has exceeded the CE deadline by one week
Candidate has a prior misdemeanor conviction on record (Correct answer)

Correct answer: Candidate has a prior misdemeanor conviction on record

ARRT requires candidates with prior criminal history to undergo an ethics review to determine eligibility before the application proceeds.

Question 89: Which MRI screening form section is most critical for identifying implanted devices that may be MR Unsafe?

Implants and devices section (Correct answer)
Medication list section
Allergies section
Surgical history section

Correct answer: Implants and devices section

The implants and devices section identifies items such as pacemakers, cochlear implants, and aneurysm clips that may be MR Unsafe.

Question 90: What is a 'quench' in MRI terminology?

A sudden loss of superconductivity causing helium boil-off (Correct answer)
A gradient coil failure
A patient motion artifact
A rapid increase in field strength

Correct answer: A sudden loss of superconductivity causing helium boil-off

A quench occurs when the superconducting magnet loses its superconducting state, causing liquid helium to vaporize rapidly and potentially displacing oxygen in the room.

Question 91: Which of the following is NOT an acceptable primary pathway for ARRT MRI registry eligibility?

Hold an associate degree only with no primary ARRT credential (Correct answer)
Hold a primary ARRT certification in radiation therapy
Hold a primary ARRT certification in radiography
Hold a primary ARRT certification in nuclear medicine technology

Correct answer: Hold an associate degree only with no primary ARRT credential

Candidates must hold a current primary ARRT certification in an approved discipline; an associate degree alone does not satisfy eligibility.

Question 92: What is the effect of increasing receiver bandwidth on MRI image quality?

Spatial resolution decreases
Image contrast improves significantly
SNR increases and scan time decreases
SNR decreases but chemical shift artifact is reduced (Correct answer)

Correct answer: SNR decreases but chemical shift artifact is reduced

Increasing bandwidth reduces chemical shift artifact and allows shorter TE/TR, but more noise is accepted per unit time, lowering SNR.

Question 93: Require the employment of solenoid coils because of the B0's orientation; these coils are more effective than linear coils and can be electrically combined with other coils to enhance signal homogeneity across an area of interest.

Quadrature
Phased array
Vertical (Correct answer)
Helmholtz pair

Correct answer: Vertical

Vertical coils are specifically designed for MRI systems where the main magnetic field (B0) is oriented vertically, often found in open or permanent magnet systems. These coils are more effective than linear coils in this orientation and can be electrically combined with other coils to enhance signal homogeneity across the area of interest, optimizing signal reception for vertical field systems.

Question 94: Which ARRT ethics requirement must be fulfilled as part of the MRI registry application process?

Pre-application ethics review if applicable (Correct answer)
Advanced cardiac life support (ACLS)
Magnetic field safety officer training
CPR certification

Correct answer: Pre-application ethics review if applicable

Applicants with certain violations must complete a pre-application review, and all applicants must attest to meeting ARRT's Standards of Ethics.

Question 95: The echo time (TE) in gradient-echo sequences affects which type of contrast?

Proton density contrast only
TR governs all contrast in GRE sequences
T1 contrast only
T2* contrast — longer TE increases T2* weighting and susceptibility effects (Correct answer)

Correct answer: T2* contrast — longer TE increases T2* weighting and susceptibility effects

In gradient-echo sequences, TE controls T2* contrast; longer TE allows greater T2* dephasing, increasing susceptibility effects from blood products, iron, and air-tissue interfaces.

Question 96: Which MRI sequence is most sensitive for detecting early bone marrow edema in stress fractures?

T1-weighted SE
GRE in-phase
Proton density without fat saturation
STIR or fat-saturated T2 (Correct answer)

Correct answer: STIR or fat-saturated T2

STIR and fat-saturated T2 sequences suppress the bright fat signal of normal marrow, making the high-signal edema of stress fractures conspicuous.

Question 97: Which MRI technique uses magnetically labeled water protons as an endogenous tracer to measure cerebral blood flow without contrast injection?

Blood Oxygen Level Dependent (BOLD) fMRI
Dynamic Contrast Enhanced (DCE) MRI
Arterial Spin Labeling (ASL) (Correct answer)
Dynamic Susceptibility Contrast (DSC) MRI

Correct answer: Arterial Spin Labeling (ASL)

ASL uses RF inversion of arterial water protons proximal to the imaging plane as a flow tracer, enabling non-invasive perfusion measurement.

Question 98: Which MRI sequence is most sensitive for detecting acute subarachnoid hemorrhage?

Gradient Echo (GRE)
FLAIR (Fluid Attenuated Inversion Recovery) (Correct answer)
T2-weighted FSE
Diffusion-Weighted Imaging (DWI)

Correct answer: FLAIR (Fluid Attenuated Inversion Recovery)

FLAIR suppresses CSF signal, making subarachnoid blood appear hyperintense against a dark CSF background.

Question 99: In MRI, the term 'flip angle' refers to:

The phase angle accumulated during readout
The angle of the gradient coils relative to the main magnet
The angle by which the net magnetization is rotated from B0 by the RF pulse (Correct answer)
The angular difference between excitation and reception coils

Correct answer: The angle by which the net magnetization is rotated from B0 by the RF pulse

The flip angle is the degree of rotation of the net magnetization vector away from the longitudinal axis produced by an RF pulse.

Question 100: Which ligament of the knee is best seen on sagittal MRI images and connects the posterior femur to the anterior tibia?

Anterior cruciate ligament (Correct answer)
Medial collateral ligament
Posterior cruciate ligament
Arcuate ligament

Correct answer: Anterior cruciate ligament

The anterior cruciate ligament (ACL) runs from the posterior lateral femoral condyle to the anterior tibial spine and is best evaluated on sagittal MRI.

Question 101: Nephrogenic Systemic Fibrosis (NSF) is a serious complication associated with GBCA administration in patients with:

Active infection
Liver failure
Severe renal impairment (GFR <30 mL/min/1.73m²) (Correct answer)
Allergy to iodine

Correct answer: Severe renal impairment (GFR <30 mL/min/1.73m²)

NSF occurs almost exclusively in patients with severe kidney disease (GFR <30) because impaired renal clearance prolongs gadolinium exposure, allowing transmetallation and tissue deposition.

Question 102: Diffusion tensor imaging (DTI) and tractography are primarily used to evaluate which brain structure?

Metabolite concentrations
Gray matter cortical thickness
Cerebral blood flow
White matter fiber tracts and connectivity (Correct answer)

Correct answer: White matter fiber tracts and connectivity

DTI measures the directional diffusion of water in white matter to map axonal fiber tracts, enabling tractography of major pathways such as the corticospinal tract.

Question 103: The quantity of determines the receiver bandwidth.

Frequency samples in the matrix (Correct answer)
Phase changes within the matrix

Correct answer: Frequency samples in the matrix

The receiver bandwidth in MRI is directly determined by the number of frequency samples (pixels) in the frequency encoding direction. A higher number of samples requires a wider bandwidth to accurately capture the range of frequencies present in the signal within the acquisition time. This ensures proper spatial resolution and minimizes aliasing artifacts in the resulting image.

Question 104: The ARRT MRI registry exam content specification places approximately what percentage of questions in the 'Procedures' domain?

50%
20%
35% (Correct answer)
10%

Correct answer: 35%

Approximately 35% of the MRI registry exam covers Procedures, making it one of the largest content areas.

Question 105: Which MRI technique encodes functional brain activity by detecting changes in blood oxygenation level?

Blood oxygen level-dependent (BOLD) fMRI (Correct answer)
Diffusion tensor imaging (DTI)
Arterial spin labeling (ASL)
MR spectroscopy (MRS)

Correct answer: Blood oxygen level-dependent (BOLD) fMRI

BOLD fMRI detects regional neural activity via the magnetic susceptibility difference between oxyhemoglobin and deoxyhemoglobin, providing maps of brain activation.

Question 106: Fast spin echo sequences, in contrast to spin echo, have

T2 weighting increased but susceptibility decreased (Correct answer)
T2 weighting decreased but susceptibility rose
Diminished susceptibility and T2 weighting
elevated susceptibility and elevated T2 weighting

Correct answer: T2 weighting increased but susceptibility decreased

Fast Spin Echo (FSE) sequences utilize multiple 180-degree refocusing pulses, which effectively reduce the impact of magnetic susceptibility artifacts by repeatedly rephasing spins. This leads to decreased susceptibility artifacts compared to conventional spin echo. Additionally, FSE sequences can achieve stronger T2 weighting due to the extended echo train and multiple echoes contributing to the signal, often resulting in increased T2 weighting.

Question 107: On MRI of the liver, a simple hepatic cyst is expected to show which signal characteristics?

T1 low, T2 low
T1 high, T2 high, with peripheral enhancement
T1 high, T2 low
T1 low, T2 high, no enhancement (Correct answer)

Correct answer: T1 low, T2 high, no enhancement

Simple hepatic cysts have low T1 signal, very high T2 signal due to pure fluid content, and show no contrast enhancement.

Question 108: Which artifact arises when signal from outside the FOV wraps around to the opposite side of the image?

Gibbs ringing artifact
Susceptibility artifact
Aliasing (wrap-around) artifact (Correct answer)
Chemical shift artifact

Correct answer: Aliasing (wrap-around) artifact

Aliasing occurs in the phase-encode direction when anatomy outside the FOV is undersampled, causing it to appear on the opposite side.

Question 109: Which safety zone in an MRI facility is defined as the area that requires screening and controlled access due to the fringe magnetic field?

Zone I
Zone III (Correct answer)
Zone IV
Zone II

Correct answer: Zone III

Zone III is the area where the fringe field poses risk and requires restricted access; only screened individuals may enter.

Question 110: Diffusion-weighted imaging (DWI) measures the random Brownian motion of water molecules. Restricted diffusion (e.g., in acute stroke) appears as:

Low signal on DWI, high ADC
High signal on DWI, high ADC
Low signal on DWI, low ADC
High signal on DWI, low ADC (Correct answer)

Correct answer: High signal on DWI, low ADC

In acute ischemia, cytotoxic edema restricts water movement; restricted diffusion shows high signal on DWI (b=1000) and low signal on ADC map (low diffusivity).

Question 111: Which phase-encoding direction choice can help reduce motion artifact from breathing in abdominal MRI?

Increase the number of slices
Orient phase encoding in the right-left direction so respiratory motion projects away from the anatomy of interest (Correct answer)
Orient phase encoding in the anterior-posterior direction to capture all motion
Use a larger FOV in the frequency direction

Correct answer: Orient phase encoding in the right-left direction so respiratory motion projects away from the anatomy of interest

Placing phase encoding in the right-left direction directs respiratory ghosting away from critical abdominal structures, reducing diagnostic interference.

Question 112: In k-space, what does the center of k-space primarily determine?

Image contrast (Correct answer)
Image resolution
Slice position
Echo time

Correct answer: Image contrast

The center of k-space contains low spatial frequencies that carry the bulk of image contrast and overall signal intensity.

Question 113: Substances in the presence of an applied magnetic field that show a modest rise in magnetic field. They exhibit both positive and low susceptibility.

Ferromagnetic
Paramagnetic (Correct answer)
Diamagnetic
Superpapmagnetic

Correct answer: Paramagnetic

Paramagnetic materials exhibit a weak, positive susceptibility to an external magnetic field. Their unpaired electrons align with the field, causing a modest increase in the local magnetic field, but this effect is lost once the external field is removed. Gadolinium, a common MRI contrast agent, is a well-known paramagnetic substance.

Question 114: When imaging the lumbar spine, which position best opens the intervertebral foramina and reduces lumbar lordosis for improved visualization?

Lateral decubitus
Prone with pillow under abdomen
Supine with legs elevated on a cushion (knees and hips flexed) (Correct answer)
Prone with legs extended

Correct answer: Supine with legs elevated on a cushion (knees and hips flexed)

Flexing the hips and knees while supine flattens lumbar lordosis, opens intervertebral foramina, and improves disc and nerve root visualization.

Question 115: What is the primary source of acoustic noise in an MRI scanner?

The radiofrequency transmitter coil vibrating
Rapid switching of gradient coils within the static magnetic field (Correct answer)
Cryogenic helium boil-off
The rotating fan of the RF amplifier

Correct answer: Rapid switching of gradient coils within the static magnetic field

Lorentz forces act on gradient coil conductors carrying rapidly switched currents within B0, causing coil vibration and the characteristic loud knocking noise.

Question 116: A candidate who fails the ARRT MRI registry exam may retest after what mandatory waiting period?

30 days
60 days
6 months
90 days (Correct answer)

Correct answer: 90 days

ARRT requires a 90-day waiting period between examination attempts for registry candidates.

Question 117: Which gradient-echo sequence uses a very short TR and a spoiler gradient to eliminate residual transverse magnetization before the next RF pulse?

Spoiled gradient echo (SPGR/FLASH) (Correct answer)
GRASS
Steady-state free precession (SSFP/TrueFISP)
FIESTA

Correct answer: Spoiled gradient echo (SPGR/FLASH)

Spoiled GRE sequences (SPGR, FLASH) use RF or gradient spoiling to destroy residual transverse magnetization between pulses, producing T1-weighted images with high SNR efficiency.

Question 118: Which of the following best describes the concept of signal-to-noise ratio (SNR) in MRI?

The difference in signal between two adjacent tissues
The ratio of TE to TR
The ratio of mean signal intensity in a region of interest to the standard deviation of background noise (Correct answer)
The number of signal averages divided by scan time

Correct answer: The ratio of mean signal intensity in a region of interest to the standard deviation of background noise

SNR is quantitatively defined as the mean signal from a region of interest divided by the standard deviation of noise measured in a background air region.

Question 119: Following an RF burst, protons will

As instructed by T1, recover along B0, and then dephase as instructed by T2*.
Dephase in accordance with T2*, then recover in accordance with T1 along B0. (Correct answer)
As per T2*, recover along B0, and thereafter dephase in accordance with T1.
As per T2*, dephase in accordance with T1 and then recover along B0.

Correct answer: Dephase in accordance with T2*, then recover in accordance with T1 along B0.

Immediately following an RF burst, the excited protons begin to lose their phase coherence, causing the transverse magnetization to decay. This dephasing is governed by T2* relaxation, which includes both intrinsic molecular interactions and static magnetic field inhomogeneities. Simultaneously, the longitudinal magnetization, which was tipped away from B0, begins to recover along the B0 field, a process governed by T1 relaxation.

Question 120: What is the primary purpose of fat saturation techniques in MRI?

To suppress the fat signal so adjacent structures are more conspicuous (Correct answer)
To eliminate chemical shift artifact entirely
To reduce T1 relaxation time of fat
To increase the signal from fat-containing tissues

Correct answer: To suppress the fat signal so adjacent structures are more conspicuous

Fat saturation applies a frequency-selective RF pulse to null the fat signal, improving visibility of adjacent enhancing or edematous tissue.

Question 121: Which MRI phenomenon occurs when protons at the boundary of fat and water tissues experience a frequency offset, causing a dark or bright band?

Magnetic susceptibility artifact
Wraparound (aliasing) artifact
Gibbs ringing
Chemical shift artifact (Correct answer)

Correct answer: Chemical shift artifact

Chemical shift artifact results from the ~3.5 ppm frequency difference between fat and water protons, causing spatial misregistration along the frequency-encode direction.

Question 122: What is the primary advantage of using a higher-relaxivity GBCA (e.g., gadobenate dimeglumine) compared to a standard-relaxivity agent?

It is completely renally safe at any dose
It crosses the blood-brain barrier more readily
It can be used at a lower dose to achieve comparable enhancement (Correct answer)
It eliminates the need for dynamic imaging

Correct answer: It can be used at a lower dose to achieve comparable enhancement

Higher relaxivity means greater T1 shortening per unit concentration, so a lower molar dose can produce equivalent or superior enhancement compared to standard agents.

Question 123: The term 'T1 mapping' in cardiac MRI using gadolinium is used to quantify which clinically important tissue property?

Extracellular volume fraction (ECV) as a marker of fibrosis (Correct answer)
Myocardial perfusion rate
Coronary artery stenosis grade
Ejection fraction

Correct answer: Extracellular volume fraction (ECV) as a marker of fibrosis

Pre- and post-contrast T1 mapping allows calculation of the extracellular volume (ECV), which is an established quantitative biomarker of diffuse myocardial fibrosis.

Question 124: What is the main advantage of parallel imaging techniques (e.g., GRAPPA, SENSE) in MRI?

Elimination of susceptibility artifacts
Reduced acquisition time by undersampling k-space using multiple coil elements (Correct answer)
Increased spatial resolution without penalty
Improved SNR by adding signals from multiple coils

Correct answer: Reduced acquisition time by undersampling k-space using multiple coil elements

Parallel imaging uses the spatial sensitivity profiles of phased-array coils to reconstruct missing k-space lines, allowing faster acquisitions at the cost of some SNR.

Question 125: In which direction does the chemical shift type 2 (India ink) artifact appear at fat-water interfaces, and on which sequence type is it seen?

Phase direction on gradient-echo sequences (Correct answer)
In-phase direction on STIR sequences
Frequency direction on spin-echo sequences
Both directions on EPI

Correct answer: Phase direction on gradient-echo sequences

Chemical shift type 2 (India ink or black boundary artifact) occurs in gradient-echo sequences at fat-water voxel boundaries and appears as a dark rim at these interfaces.

Question 126: What is the preferred patient position and coil for imaging the rotator cuff of the shoulder?

Prone, body coil
Supine, arm at side in neutral rotation, dedicated shoulder coil (Correct answer)
Supine, arm abducted 90°, flex coil
Sitting upright, surface coil

Correct answer: Supine, arm at side in neutral rotation, dedicated shoulder coil

Supine positioning with the arm at the side in neutral rotation and a dedicated shoulder coil provides optimal SNR and comfort for rotator cuff imaging.

Question 127: Which gradient is responsible for determining slice position in a 2D MRI acquisition?

Frequency-encoding gradient
Spoiler gradient
Slice-selection gradient (Correct answer)
Phase-encoding gradient

Correct answer: Slice-selection gradient

The slice-selection gradient is applied simultaneously with the RF pulse to excite only protons in the desired anatomical plane.

Question 128: A patient with a cochlear implant is scheduled for MRI. What is the primary concern?

Acoustic noise damage
Device displacement or demagnetization by the static field and RF heating (Correct answer)
Claustrophobia from the device signal
Heating of the cochlear fluid

Correct answer: Device displacement or demagnetization by the static field and RF heating

Cochlear implants contain magnets that can torque, displace, or demagnetize in the MRI field, posing significant safety risks.

Question 129: In MR imaging, the signal-to-noise ratio (SNR) improves with increasing field strength approximately as:

As the square root of B0
As the square of B0 (B0²)
Linearly (proportional to B0) (Correct answer)
SNR is independent of field strength

Correct answer: Linearly (proportional to B0)

SNR scales approximately linearly with B0 because both the equilibrium magnetization and the Larmor frequency (and thus the induced EMF) increase linearly with field strength.

Question 130: A technologist wants to reduce scan time while maintaining similar SNR. Which strategy is most effective?

Increase slice thickness
Use parallel imaging (SENSE/GRAPPA) (Correct answer)
Decrease the matrix size
Increase the repetition time (TR)

Correct answer: Use parallel imaging (SENSE/GRAPPA)

Parallel imaging techniques use multiple coil elements to under-sample k-space, reducing scan time while maintaining acceptable SNR through reconstruction algorithms.

Question 131: Cardiac MRI uses which technique to synchronize data acquisition with the cardiac cycle and minimize cardiac motion artifact?

ECG gating or cardiac triggering (Correct answer)
Real-time imaging without synchronization
Respiratory gating only
Breath-hold sequences only

Correct answer: ECG gating or cardiac triggering

ECG gating (prospective triggering or retrospective gating) synchronizes k-space acquisition to specific phases of the cardiac cycle, minimizing motion artifact from myocardial contraction.

Question 132: To form a magnet field, wires are arranged side by side.

Selenoid magnet (Correct answer)
Superconducting
Permanent magnet
Resistive magnet

Correct answer: Selenoid magnet

A solenoid magnet is formed by coiling a wire into a cylindrical shape. When an electric current passes through this coiled wire, it generates a uniform magnetic field along the axis of the cylinder. This design is fundamental to many types of MRI magnets, particularly superconducting systems, where the solenoid configuration efficiently produces a strong, homogeneous field.

Question 133: Gadolinium retention in the brain has been observed particularly in which structure on unenhanced T1-weighted images in patients receiving multiple GBCA doses?

Dentate nucleus of the cerebellum (Correct answer)
Hippocampus
Thalamus
Caudate nucleus

Correct answer: Dentate nucleus of the cerebellum

Gadolinium deposition in the dentate nucleus and globus pallidus manifests as T1 hyperintensity on unenhanced brain MRI after multiple GBCA administrations.

Question 134: Which MRI zone is defined as the area containing the MRI scanner itself where the static magnetic field is always present?

Zone III
Zone IV (Correct answer)
Zone II
Zone I

Correct answer: Zone IV

Zone IV is the MRI scanner room where the magnet is always on and unrestricted ferromagnetic items pose immediate danger.

Question 135: What is the purpose of the radiofrequency (RF) pulse in an MRI sequence?

To suppress gradient coil noise
To increase static magnetic field strength
To align hydrogen nuclei with each other
To tip net magnetization away from B0 (Correct answer)

Correct answer: To tip net magnetization away from B0

The RF pulse at the Larmor frequency tips the net magnetization vector away from the longitudinal axis to induce signal.

Question 136: Which MRI sequence is most commonly used for evaluating liver lesions using T2 contrast with heavy T2 weighting for the bile ducts?

DWI b1000
STIR of the abdomen
MRCP (heavily T2-weighted 3D or thick-slab) (Correct answer)
T1 in-phase/opposed-phase

Correct answer: MRCP (heavily T2-weighted 3D or thick-slab)

MRCP uses heavily T2-weighted sequences to make bile and pancreatic fluid appear bright, providing a non-invasive map of the biliary and pancreatic ductal system.

Question 137: The ARRT MRI exam content category 'Procedures' would most likely include a question about which topic?

Cryogen quench valve operation
Patient screening form design standards
Brain MRI protocol selection for stroke evaluation (Correct answer)
Larmor frequency calculations

Correct answer: Brain MRI protocol selection for stroke evaluation

Procedures covers clinical protocols such as selecting the appropriate MRI protocol for specific pathologies.

Question 138: Susceptibility-weighted imaging (SWI) is particularly sensitive to which types of tissue or substances?

Fat and water interfaces
Blood products (hemosiderin, deoxyhemoglobin), calcium, and iron-containing structures (Correct answer)
Myelinated white matter
Gadolinium-enhanced tissue

Correct answer: Blood products (hemosiderin, deoxyhemoglobin), calcium, and iron-containing structures

SWI exploits magnetic susceptibility differences between tissues; hemosiderin, deoxyhemoglobin, calcium, and iron create local field distortions that appear as marked hypointensity on SWI images.

Question 139: Chemical shift artifact of the first kind occurs at interfaces between fat and water and manifests as:

A bright band and a dark band at the fat-water interface in the frequency-encoding direction (Correct answer)
Signal voids around metallic implants
Image wrap-around from the opposite side
Zebra-stripe banding artifact

Correct answer: A bright band and a dark band at the fat-water interface in the frequency-encoding direction

First-kind chemical shift artifact creates a bright rim on one side and a dark void on the other side at fat-water interfaces in the frequency-encoding direction due to the 3.5 ppm resonance frequency difference.

Question 140: Which MRI finding is characteristic of a benign rotator cuff tear involving a full-thickness supraspinatus tendon rupture?

Low signal on all sequences through the tendon
Low T2 signal with thickening of the tendon
Fluid signal gap (T2 bright) extending through the full thickness of the tendon (Correct answer)
T1 bright signal in the tendon

Correct answer: Fluid signal gap (T2 bright) extending through the full thickness of the tendon

A full-thickness tear shows fluid (T2 hyperintense) extending completely through the tendon from bursal to articular surface.

Question 141: On brain MRI, the hippocampus is best evaluated for atrophy (as in Alzheimer's disease) on which plane?

Oblique axial
Sagittal only
Coronal, especially perpendicular to the long axis of the hippocampus (Correct answer)
Axial only

Correct answer: Coronal, especially perpendicular to the long axis of the hippocampus

Coronal T1-weighted images perpendicular to the long axis of the hippocampus provide the best visualization of hippocampal volume and atrophy.

Question 142: These materials are employed as T2 contrast agents because they show positive susceptibility, are stronger than paramagnetic materials but weaker than ferromagnetic materials.

Diamagnetic
Paramagnetic
Superpapmagnetic (Correct answer)
Ferromagnetic

Correct answer: Superpapmagnetic

Superparamagnetic materials possess magnetic properties stronger than paramagnetic substances but, unlike ferromagnetic materials, they do not retain magnetism once the external field is removed. They are often used as T2 contrast agents in MRI because their large magnetic moments create significant local field inhomogeneities, leading to rapid T2 decay and signal loss, which enhances contrast in certain tissues.

Question 143: What is the primary reason gadolinium-based contrast agents should not be used in patients undergoing hemodialysis without a specific clinical indication?

Risk of NSF remains even after hemodialysis removes gadolinium (Correct answer)
Dialysis filters destroy the contrast agent before it reaches the target tissue
Risk of anaphylaxis is higher in dialysis patients
Gadolinium is not effectively removed by standard hemodialysis

Correct answer: Risk of NSF remains even after hemodialysis removes gadolinium

While hemodialysis can remove most gadolinium, some residual free gadolinium remains after each session, and repeated exposure can still cause NSF in high-risk patients.

Question 144: The placement of the slice is established by the

The RF pulse's transmit frequency (Correct answer)
Radiofrequency coil's transmit frequency
phase difference
frequency of the RF pulse received

Correct answer: The RF pulse's transmit frequency

The placement of the slice in MRI is precisely established by the transmit frequency of the RF pulse. When a magnetic field gradient is applied, protons at different locations precess at different frequencies. By selecting a specific RF transmit frequency, only protons resonating at that exact frequency within the gradient field will be excited, thereby defining the slice's position.

Question 145: What is the main biological risk associated with rapidly switching gradient magnetic fields during an MRI scan?

Hypothermia
Acoustic damage
Peripheral nerve stimulation (Correct answer)
Radiofrequency burns

Correct answer: Peripheral nerve stimulation

Rapidly switching gradients can induce electrical currents in body tissue, causing peripheral nerve stimulation (PNS).

Question 146: What is the minimum number of clinical MRI hours required by ARRT before a candidate can sit for the MRI registry examination?

200 hours
1,000 hours
1,500 hours
500 hours (Correct answer)

Correct answer: 500 hours

ARRT requires candidates to document at least 500 hours of clinical MRI experience as part of eligibility requirements.

Question 147: The difference between the hydrogen's periodic frequency in fat and water is known as

CHEMICAL SHIFT (Correct answer)
SPIN DENSITY
FID
FOURIER TRANSFORM

Correct answer: CHEMICAL SHIFT

Chemical shift refers to the slight difference in the resonant frequency of protons when they are in different chemical environments, such as those found in fat versus water molecules. This frequency difference arises because electron shielding around protons varies with their molecular bonds, causing them to experience slightly different effective magnetic fields. This phenomenon is exploited in MRI to differentiate tissues but can also lead to artifacts if not properly accounted for.

Question 148: Which positioning aid is used to maintain the ankle in a 90° neutral position during MRI to optimally visualize the Achilles tendon?

Compression bandage
Ankle positioning block or foam wedge (Correct answer)
Vacuum immobilization device
Sand bag

Correct answer: Ankle positioning block or foam wedge

A foam wedge or ankle block holds the foot perpendicular to the leg, minimizing magic angle artifact and providing consistent Achilles tendon orientation.

Question 149: Which MRI protocol modification is used to evaluate the acetabular labrum of the hip with maximum sensitivity for tears?

MR arthrography with intra-articular gadolinium dilution (Correct answer)
Standard T2 FSE without contrast
T1 fat-saturated without contrast
Diffusion-weighted imaging of the hip

Correct answer: MR arthrography with intra-articular gadolinium dilution

MR arthrography with intra-articular dilute gadolinium distends the joint capsule, separating the labrum from the femoral head and maximizing sensitivity for labral tears.

Question 150: Magnets formed of ferrous material found naturally or from blocks or slabs.

Reistive
Selenoid
Permanent (Correct answer)
Superconducting

Correct answer: Permanent

Permanent magnets are created from naturally occurring ferromagnetic materials or specially treated blocks of ferrous material. These magnets retain their magnetism without requiring an external power source. They produce a constant magnetic field and are typically utilized in low-field MRI systems, offering a simpler and less costly design.

Question 151: Which MRI technique is used to assess brain perfusion by tracking the first pass of a gadolinium bolus?

Magnetic Resonance Spectroscopy (MRS)
Diffusion Tensor Imaging (DTI)
Dynamic Susceptibility Contrast (DSC) perfusion (Correct answer)
Arterial Spin Labeling (ASL)

Correct answer: Dynamic Susceptibility Contrast (DSC) perfusion

DSC perfusion MRI uses rapid T2*-weighted sequences to measure signal drop as gadolinium transits through the brain capillaries.

Question 152: What happens to image contrast when the echo time (TE) is increased in a T2-weighted sequence?

SNR improves due to longer signal collection
Tissues appear uniformly bright
T1 contrast increases
T2 contrast increases as tissues with short T2 decay faster (Correct answer)

Correct answer: T2 contrast increases as tissues with short T2 decay faster

Longer TE allows more T2 decay to occur, so tissues with short T2 lose signal faster and appear darker, enhancing T2 contrast between tissues.

Question 153: Which organization accredits MRI education programs whose graduates may be eligible to sit for the ARRT MRI registry?

The Joint Commission (TJC)
Joint Review Committee on Education in Radiologic Technology (JRCERT) (Correct answer)
American College of Radiology (ACR)
American Society of Radiologic Technologists (ASRT)

Correct answer: Joint Review Committee on Education in Radiologic Technology (JRCERT)

JRCERT accredits radiologic technology education programs, and graduation from an accredited program satisfies ARRT educational requirements.

Question 154: Which MRI sequence is the standard for evaluating the internal structure of bone marrow and is most sensitive to marrow infiltration or edema?

T1-weighted spin-echo
Proton density without fat suppression
STIR or fat-suppressed T2-weighted FSE (Correct answer)
T2*-weighted gradient echo

Correct answer: STIR or fat-suppressed T2-weighted FSE

STIR and fat-suppressed T2 sequences null normal fatty marrow signal, making pathological edema, infiltration, or tumor stand out as high signal against the nulled fat background.

Question 155: What score does ARRT use to determine passing on the MRI registry examination?

A norm-referenced score based on the current testing cohort
A raw score of 75%
A criterion-referenced passing standard set by content experts (Correct answer)
A scaled score of 75 out of 99

Correct answer: A criterion-referenced passing standard set by content experts

ARRT uses a criterion-referenced passing standard established by a panel of content experts, not a simple percentage or norm-based cut score.

Question 156: A technologist increases slice thickness from 3 mm to 6 mm. What is the expected change in image quality?

SNR improves but through-plane resolution decreases (Correct answer)
No change occurs because FOV is unchanged
Both SNR and spatial resolution improve
SNR decreases and spatial resolution improves

Correct answer: SNR improves but through-plane resolution decreases

Thicker slices contain more protons and generate more signal, improving SNR, but fine anatomical detail in the through-plane direction is reduced.

Question 157: Which of the following changes will increase spatial resolution without changing the FOV?

Increasing the matrix size (Correct answer)
Increasing slice thickness
Increasing NEX
Decreasing the matrix size

Correct answer: Increasing the matrix size

Increasing matrix size means more phase and frequency encoding steps, reducing voxel size and improving spatial resolution within the same FOV.

Question 158: What is the relationship between voxel size and SNR in MRI?

Larger voxels produce higher SNR (Correct answer)
SNR decreases as voxel volume doubles
Voxel size has no effect on SNR
Smaller voxels produce higher SNR

Correct answer: Larger voxels produce higher SNR

Larger voxels contain more protons contributing signal, increasing SNR, though at the cost of spatial resolution.

Question 159: When is a candidate's ARRT MRI registry exam score report typically available?

After 30 days by postal mail only
Immediately on screen at the testing center
Six weeks after the exam window closes
Within 3–5 business days via the ARRT website (Correct answer)

Correct answer: Within 3–5 business days via the ARRT website

ARRT posts official score reports to the candidate's online account within approximately 3–5 business days after testing.

Question 160: A patient with a metallic foreign body in the eye should be evaluated with which imaging modality BEFORE entering the MRI suite?

Bone scan
CT scan (Correct answer)
Ultrasound
PET scan

Correct answer: CT scan

A CT scan of the orbits is used to detect metallic ocular foreign bodies before MRI because ferromagnetic metal near the eye is a contraindication.

Question 161: What is the maximum number of times a candidate may attempt the ARRT MRI registry examination?

6 times total (Correct answer)
Unlimited attempts
3 times total
5 times within 5 years

Correct answer: 6 times total

ARRT limits candidates to 6 total examination attempts for any given credential.

Question 162: Which of the following best describes a blood-pool GBCA used in MR angiography?

It crosses the blood-brain barrier
It remains exclusively in the arterial system
It distributes only in hepatic tissue
It binds reversibly to albumin, prolonging intravascular residence time (Correct answer)

Correct answer: It binds reversibly to albumin, prolonging intravascular residence time

Blood-pool agents (e.g., gadofosveset) bind reversibly to albumin, extending their half-life in the vascular space and allowing steady-state MRA over a longer acquisition window.

Question 163: Which of the following best explains why a phased-array coil improves SNR compared to a body coil?

Multiple smaller coil elements are positioned close to the anatomy, maximizing signal pickup while limiting noise volume (Correct answer)
They increase the repetition time automatically
Phased-array coils use higher magnetic field strength
They apply stronger RF pulses to excite more protons

Correct answer: Multiple smaller coil elements are positioned close to the anatomy, maximizing signal pickup while limiting noise volume

Each element of a phased-array coil is small and close to the anatomy, providing high sensitivity to local signal with limited noise, and their combined data significantly improves overall SNR.

Question 164: The magnetic field's intensity is changed by this gradient coil from right to left.

Y
Z
X (Correct answer)

Correct answer: X

In a standard MRI coordinate system, the X-axis typically corresponds to the right-to-left (or left-to-right) direction across the patient. The X-gradient coil is engineered to produce a linear change in the magnetic field strength along this X-axis. This gradient is primarily used for spatial encoding, particularly for frequency encoding, in the right-to-left dimension.

Question 165: For MRI of the shoulder, the patient should be positioned with the arm in which orientation to best center the glenohumeral joint?

Arm crossed over the chest
Arm elevated above the head
Arm in full internal rotation only
Arm at the side in neutral or slight external rotation, shoulder centered in the coil (Correct answer)

Correct answer: Arm at the side in neutral or slight external rotation, shoulder centered in the coil

Positioning the shoulder with the arm at the side in neutral or slight external rotation and centering the glenohumeral joint within the dedicated shoulder coil optimizes image quality.

Question 166: One forms a spin echo through

changing the path of a proton using a radiofrequency pulse (Correct answer)
Turning B0 in the opposite direction
Using a gradient of a negative magnetic field

Correct answer: changing the path of a proton using a radiofrequency pulse

A spin echo is formed by applying a 180-degree radiofrequency (RF) pulse after an initial 90-degree RF excitation pulse. This 180-degree pulse effectively 'flips' the spins, causing them to rephase and produce a detectable echo signal. By reversing the effects of static magnetic field inhomogeneities, the 180-degree pulse allows for the recovery of signal that would otherwise be lost due to T2* dephasing.

Question 167: What is the purpose of applying a saturation band in MRI?

To suppress signal from specified tissue or flowing blood to reduce artifacts (Correct answer)
To improve spatial resolution in the phase direction
To increase SNR from the target anatomy
To shorten the overall scan time

Correct answer: To suppress signal from specified tissue or flowing blood to reduce artifacts

Saturation bands apply an RF pulse to a defined region, nulling its magnetization so it contributes no signal, which suppresses motion or flow-related artifacts.

Question 168: Gadolinium contrast extravasation at the IV injection site is classified as which type of adverse event?

Allergic-like reaction
Non-allergic physiologic reaction
Vascular reaction
Local injection site reaction (extravasation) (Correct answer)

Correct answer: Local injection site reaction (extravasation)

Extravasation occurs when contrast leaks from the vein into surrounding tissue; it is a local injection site reaction, not a systemic allergic event.

Question 169: This magnet has a strength of up to 0.3 T, can be switched off, and can be used in both horizontal and vertical field systems.

Permanent magnet
Selenoid magnet
Resistive magnet (Correct answer)
Superconducting

Correct answer: Resistive magnet

Resistive magnets consist of coils of wire through which a large electric current is continuously passed to generate a magnetic field. They can be switched off, offer field strengths typically up to 0.3 Tesla, and can be designed for both horizontal and vertical field orientations. However, they require significant continuous power and generate substantial heat, limiting their use in high-field MRI.

Question 170: Which ARRT exam content domain addresses gradient performance, field homogeneity, and RF coil function?

Procedures
Physics and Instrumentation (Correct answer)
Image Production
Patient Care and Education

Correct answer: Physics and Instrumentation

Physics and Instrumentation covers hardware components including gradients, RF coils, and magnet systems.

Question 171: Which classification of GBCAs carries the LOWEST risk for NSF based on ACR guidance?

Group III (macrocyclic) (Correct answer)
Group I (linear ionic)
Group II (linear non-ionic)
All GBCAs carry equal NSF risk

Correct answer: Group III (macrocyclic)

Macrocyclic GBCAs (Group III) have a more stable cage-like structure that resists transmetallation and are associated with the lowest NSF risk.

Question 172: When a constant magnetic field is present, hydrogen protons

Align yourself along the field and revolve around its center.
do not experience any magnetic field effects
Ascend the field and rotate around its center.
Stay basically orientated randomly while rotating around the field axis. (Correct answer)

Correct answer: Stay basically orientated randomly while rotating around the field axis.

When hydrogen protons are placed in a strong constant magnetic field (B0), they align either parallel or anti-parallel to the field, creating a slight net magnetization. However, individual protons do not simply align; they also precess (rotate) around the axis of the main magnetic field at their characteristic Larmor frequency. While there's a net alignment, their individual spin orientations remain somewhat random relative to each other as they precess.

Question 173: Magnetization transfer (MT) contrast in MRI works by selectively saturating which proton pool?

Free water protons in tissue
Bound protons in macromolecules (semisolid pool), which transfers saturation to free water (Correct answer)
Fat protons at 3.5 ppm
Intracellular sodium protons

Correct answer: Bound protons in macromolecules (semisolid pool), which transfers saturation to free water

An off-resonance RF pulse saturates the restricted macromolecular proton pool; saturation is transferred to free water through magnetization exchange, reducing the water signal proportional to MT ratio.

Question 174: Magnetization of hydrogen using MRI

perpendicular to the primary magnetic field (Correct answer)
In the primary magnetic field path

Correct answer: perpendicular to the primary magnetic field

In MRI, the detectable signal is generated from transverse magnetization, which is created when an RF pulse tips the net magnetization of hydrogen protons away from the primary magnetic field (B0). This transverse magnetization precesses perpendicular to B0, inducing a current in the receiver coil. Therefore, the magnetization used for signal detection is perpendicular to the primary magnetic field.

Question 175: Which MRI contrast agent class is associated with the highest risk of nephrogenic systemic fibrosis (NSF)?

Macrocyclic ionic agents
Blood pool agents
Linear non-ionic agents (Correct answer)
Manganese-based agents

Correct answer: Linear non-ionic agents

Linear non-ionic (and some linear ionic) gadolinium agents release free Gd³⁺ more readily and carry the highest NSF risk in patients with severe renal impairment.

Question 176: On MRI, cortical bone appears as which signal intensity on both T1 and T2 weighted images?

Intermediate signal
Low signal (signal void) (Correct answer)
Variable signal
High signal

Correct answer: Low signal (signal void)

Cortical bone has very few mobile protons and produces a signal void (low signal) on both T1 and T2 weighted MRI sequences.

Question 177: In diffusion-weighted imaging (DWI), a high b-value results in:

Increased signal from rapidly diffusing molecules
Reduced T2 contribution to signal
Greater diffusion weighting and lower overall signal (Correct answer)
Less diffusion weighting and higher signal

Correct answer: Greater diffusion weighting and lower overall signal

Higher b-values apply stronger diffusion-sensitizing gradients, so freely diffusing water loses more signal, increasing lesion conspicuity for restricted diffusion.

Question 178: Which GBCA is approved by the FDA as a liver-specific agent taken up by hepatocytes?

Gadobenate dimeglumine (MultiHance)
Gadobutrol (Gadavist)
Gadoxetate disodium (Eovist/Primovist) (Correct answer)
Gadopentetate dimeglumine (Magnevist)

Correct answer: Gadoxetate disodium (Eovist/Primovist)

Gadoxetate disodium (Eovist in the US, Primovist in Europe) is taken up by functioning hepatocytes via OATP transporters, providing hepatobiliary phase imaging for liver lesion characterization.

Question 179: What is the Ernst angle in MRI?

The phase angle at which fat and water are in phase
The gradient angle that minimizes eddy currents
The angle at which the slice becomes isotropic
The flip angle that maximizes signal for a given TR and T1 (Correct answer)

Correct answer: The flip angle that maximizes signal for a given TR and T1

The Ernst angle (cos θ = e^(−TR/T1)) is the optimal flip angle for steady-state gradient echo imaging that maximizes SNR efficiency.

Question 180: Phase contrast MRI (PC-MRI) is primarily used to measure:

Velocity and flow of fluids such as blood and CSF (Correct answer)
Myelin content
Tissue T1 values
Chemical metabolite concentrations

Correct answer: Velocity and flow of fluids such as blood and CSF

PC-MRI encodes velocity as phase shifts of moving spins, allowing quantitative measurement of blood flow velocity and volume, and CSF pulsation.

Question 181: A patient is claustrophobic and anxious before their MRI. Which non-pharmacological intervention is most appropriate first?

Use a stronger magnetic field to shorten scan time
Refuse the exam and reschedule
Immediately administer IV sedation
Explain the procedure, offer a patient communication system, and consider feet-first entry (Correct answer)

Correct answer: Explain the procedure, offer a patient communication system, and consider feet-first entry

Thorough patient education, reassurance, mirror/prism glasses, music headphones, and entering the bore feet-first can significantly reduce claustrophobia before pharmacological intervention.

Question 182: What is the function of the shim coils in an MRI system?

Generate the main static magnetic field
Compensate for inhomogeneities in the B0 field to improve field uniformity (Correct answer)
Amplify the RF signal received from the patient
Produce the rapidly switching gradients for slice selection

Correct answer: Compensate for inhomogeneities in the B0 field to improve field uniformity

Shim coils generate small corrective magnetic fields that counteract spatial variations in B0, improving homogeneity and image quality.

Question 183: Which technique is most effective for reducing susceptibility artifact from a metallic implant in MRI?

Increase the slice thickness
Use a gradient-echo sequence
Use a spin-echo or fast spin-echo (FSE) sequence with narrow bandwidth (Correct answer)
Increase TE

Correct answer: Use a spin-echo or fast spin-echo (FSE) sequence with narrow bandwidth

Spin-echo and FSE sequences use 180° refocusing pulses that compensate for susceptibility-induced dephasing, and a narrow bandwidth reduces chemical shift but a wide bandwidth reduces susceptibility — MARS protocols use high bandwidth FSE.

Question 184: The anterior and posterior horns of the lateral ventricles are best evaluated for periventricular leukomalacia (PVL) on which MRI plane?

Coronal only
Axial and coronal (Correct answer)
Oblique
Sagittal only

Correct answer: Axial and coronal

Axial and coronal planes together best demonstrate periventricular T2 signal changes and volume loss around the lateral ventricular horns in PVL.

Question 185: A 'DC offset' or 'center dot' artifact seen as a bright spot in the center of the image is related to:

Patient positioning off-isocenter
Excessive TR causing saturation effects
A small DC current offset in the receiver causing a spike in the center of k-space (Correct answer)
B1 field inhomogeneity

Correct answer: A small DC current offset in the receiver causing a spike in the center of k-space

A DC offset artifact occurs when a constant voltage offset in the MR receiver chain introduces a spike at the origin of k-space (DC component), appearing as a bright dot at image center.

Question 186: Wraparound (aliasing) artifact in MRI is caused by:

Phase errors from pulsatile flow
Gradient non-linearity at the edges of the bore
T2* dephasing from metallic objects
Structures outside the FOV contributing signal that is folded back into the image (Correct answer)

Correct answer: Structures outside the FOV contributing signal that is folded back into the image

When anatomy extends beyond the selected FOV in the phase-encode direction, it is aliased and appears superimposed on the opposite side of the image.

Question 187: On diffusion-weighted MRI (DWI), an acute ischemic infarct typically shows:

High signal on DWI and low ADC values (Correct answer)
High signal on DWI and high ADC values
Low signal on both DWI and ADC maps
Low signal on DWI and high ADC values

Correct answer: High signal on DWI and low ADC values

Cytotoxic edema in acute infarction restricts water diffusion, producing high signal on DWI and low apparent diffusion coefficient (ADC) values.

Question 188: What is the primary advantage of parallel imaging techniques (e.g., GRAPPA, SENSE) in MRI?

They reduce scan time or allow higher spatial resolution by using multiple coil elements to under-sample k-space (Correct answer)
They eliminate the need for gradient coils
They improve T1 contrast
They increase SNR at the same scan time

Correct answer: They reduce scan time or allow higher spatial resolution by using multiple coil elements to under-sample k-space

Parallel imaging exploits spatial sensitivity differences among phased-array coil elements to reconstruct fully sampled images from under-sampled k-space, reducing scan time by the acceleration factor (R).

Question 189: For MRI of the knee, the standard patient position is:

Knee flexed 45°, patient supine without coil
Knee flexed 90°, patient prone
Knee hyperflexed, patient lateral
Knee extended in slight external rotation (5–15°), patient supine in dedicated knee coil (Correct answer)

Correct answer: Knee extended in slight external rotation (5–15°), patient supine in dedicated knee coil

The knee is imaged supine with slight external rotation (5–15°) to align the ACL parallel to the sagittal plane for optimal visualization within a dedicated knee coil.

Question 190: What is the primary reason gradient coils produce loud acoustic noise during MRI scanning?

RF pulses vibrate the RF coil housing
Lorentz forces cause the gradient coil windings to physically vibrate as current rapidly switches (Correct answer)
The patient table motor produces noise as it moves into position
Cryogen boiling creates mechanical vibration in the magnet bore

Correct answer: Lorentz forces cause the gradient coil windings to physically vibrate as current rapidly switches

Rapidly switching electrical current in gradient coils within the strong static field produces Lorentz forces that physically deflect the coils, generating loud knocking sounds.

Question 191: In MRI, what is k-space?

A unit of measurement for gradient strength
The physical space inside the magnet bore
The region of the brain studied in neuroimaging
The raw data space containing spatial frequency information used to reconstruct images (Correct answer)

Correct answer: The raw data space containing spatial frequency information used to reconstruct images

K-space is the mathematical domain that stores the raw MRI signal as spatial frequencies; a Fourier transform converts it into an image.

Question 192: Which MRI-specific safety topic is explicitly listed under the ARRT exam content specifications within Patient Care and Education?

Screening for implants and metallic foreign bodies (Correct answer)
Radiofrequency power amplifier maintenance
Gradient coil winding techniques
Cryogen manufacturing standards

Correct answer: Screening for implants and metallic foreign bodies

Screening patients for implants and metallic foreign bodies is a core patient safety responsibility explicitly included in the content specifications.

Question 193: MR spectroscopy (MRS) of the brain identifies metabolites by their distinct chemical shifts. Which metabolite is elevated in tumors with high cell density and membrane turnover?

Lactate
Creatine (Cr)
Choline (Cho) (Correct answer)
N-acetylaspartate (NAA)

Correct answer: Choline (Cho)

Choline is a marker of membrane synthesis and cellular turnover; elevated choline is characteristic of tumors, demyelination, and other high-proliferation states.

Question 194: In a spin-echo sequence, which combination of TR and TE produces a T2-weighted image?

Short TR, long TE
Long TR, short TE
Long TR, long TE (Correct answer)
Short TR, short TE

Correct answer: Long TR, long TE

T2-weighting requires long TR (to minimize T1 contrast by allowing full recovery) and long TE (to allow T2 differences between tissues to accumulate).

Question 195: Which of the following is the most effective method to reduce motion artifact from bowel peristalsis in abdominal MRI?

Use a larger FOV
Increase TR
Administer an antiperistaltic agent such as glucagon (Correct answer)
Apply saturation bands inferior to the FOV

Correct answer: Administer an antiperistaltic agent such as glucagon

IV or IM glucagon inhibits smooth muscle contraction (antiperistaltic effect), reducing bowel motion artifact during abdominal MRI acquisitions.

Question 196: A technologist wants to reduce chemical shift artifact at the fat-water interface. Which parameter change is most appropriate?

Decrease the number of slices
Increase the FOV
Increase the receiver bandwidth (Correct answer)
Decrease the receiver bandwidth

Correct answer: Increase the receiver bandwidth

Increasing receiver bandwidth reduces the frequency difference between fat and water in pixel units, shrinking the spatial shift of fat signal relative to water signal.

Question 197: Which MRI technique uses the difference in signal between in-phase and opposed-phase images to detect intravoxel fat within a lesion?

Chemical shift imaging (Dixon technique) (Correct answer)
Diffusion-weighted imaging
STIR fat suppression
MR spectroscopy

Correct answer: Chemical shift imaging (Dixon technique)

Chemical shift imaging exploits the precession frequency difference between fat and water; signal drop on opposed-phase images indicates intravoxel fat content.

Question 198: The normal intervertebral disc nucleus pulposus appears as which signal on T2-weighted MRI in a healthy young adult?

High signal (bright) (Correct answer)
Low signal
Signal void
Intermediate signal

Correct answer: High signal (bright)

The healthy nucleus pulposus is rich in water-containing proteoglycans and appears bright (high signal) on T2-weighted sequences.

Question 199: What does k-space represent in MRI?

The gradient amplitude map
The raw data space containing spatial frequency information from which the MR image is reconstructed by Fourier transform (Correct answer)
The physical space inside the magnet bore
The frequency range of the RF pulse

Correct answer: The raw data space containing spatial frequency information from which the MR image is reconstructed by Fourier transform

K-space is the mathematical data domain where raw MRI signal is stored as spatial frequencies; a Fourier transform converts k-space data into the final diagnostic image.

Question 200: Zipper artifact on an MRI image appears as a line of alternating bright and dark pixels across the image, most often caused by:

External RF interference from inadequate shielding or open RF cage door (Correct answer)
Patient movement
Coil coupling artifact
Gradient switching noise

Correct answer: External RF interference from inadequate shielding or open RF cage door

Zipper artifact is caused by external radiofrequency interference entering the scan room, typically due to an open waveguide, broken shielding, or improperly closed scanner room door.

Question 201: What is the term for the MRI safety classification that indicates a device has been tested and found safe under specified conditions?

MR Unsafe
MR Safe
MR Compatible
MR Conditional (Correct answer)

Correct answer: MR Conditional

MR Conditional means the device poses no known hazards when used within the specific conditions (field strength, SAR, gradient limits) stated by the manufacturer.

Question 202: Cross-excitation (cross-talk) artifact in multislice MRI occurs because of:

Patient breathing between slice acquisitions
Gradient switching between adjacent slices
Imperfect slice profiles causing RF excitation of adjacent slices (Correct answer)
Coil sensitivity overlap between two adjacent coil elements

Correct answer: Imperfect slice profiles causing RF excitation of adjacent slices

Real RF pulses have imperfect rectangular profiles; the tails of adjacent slice profiles overlap, causing partial saturation of neighboring slices — reduced by interleaved acquisition or adding gaps.

Question 203: In the ACR zone system, who is responsible for controlling access to Zone III?

Level 2 MR personnel (Correct answer)
Radiology technologists only
Any hospital staff with ID badge
MR-trained non-MR personnel

Correct answer: Level 2 MR personnel

Zone III access must be controlled by Level 2 MR personnel (those with full MR safety training) to prevent non-screened individuals from entering.

Question 204: A patient with a GFR of 45 mL/min/1.73m² requires a contrast-enhanced MRI. According to ACR guidelines, which GBCA group is preferred?

Contrast should be completely avoided
Group III macrocyclic agents (Correct answer)
Group II linear non-ionic agents
Group I linear ionic agents

Correct answer: Group III macrocyclic agents

The ACR recommends macrocyclic GBCAs (Group III) for patients with reduced renal function (GFR 30–60) due to their superior thermodynamic and kinetic stability.

Question 205: In dynamic contrast-enhanced (DCE) MRI of the breast, which kinetic enhancement curve pattern is most concerning for malignancy?

Persistent (type I)
Plateau (type II)
No enhancement
Washout (type III) (Correct answer)

Correct answer: Washout (type III)

A washout (type III) kinetic curve — rapid initial enhancement followed by signal decrease — is most suspicious for malignancy due to arteriovenous shunting in tumor neovasculature.

Question 206: When positioning a patient for a lumbar spine MRI, the technologist should place the patient in which position to reduce lumbar lordosis and improve image quality?

Seated upright
Supine with knees flexed and supported by a foam wedge (Correct answer)
Lateral decubitus position
Prone with legs flat

Correct answer: Supine with knees flexed and supported by a foam wedge

Flexing the knees with a foam wedge support flattens lumbar lordosis, reducing the curvature and aligning disc spaces parallel to axial slices for optimal visualization.

Question 207: Which inversion recovery technique is used to suppress fat signal in musculoskeletal MRI?

STIR (Short TI Inversion Recovery) (Correct answer)
VIBE
MPRAGE
FLAIR

Correct answer: STIR (Short TI Inversion Recovery)

STIR uses a short inversion time timed to null the longitudinal magnetization of fat, suppressing fat signal uniformly regardless of field inhomogeneity.

Question 208: Fast spin echo (FSE/TSE) sequences reduce scan time compared to conventional spin echo by:

Using a shorter repetition time
Acquiring multiple phase-encoding lines after each 90° excitation (echo train) (Correct answer)
Reducing the number of slices acquired
Increasing the voxel size to reduce k-space lines needed

Correct answer: Acquiring multiple phase-encoding lines after each 90° excitation (echo train)

FSE uses a train of 180° pulses after each excitation to fill multiple k-space lines per TR, reducing total scan time by a factor equal to the echo train length.

Question 209: What term describes an object becoming a high-speed projectile when brought near a strong MRI magnetic field?

Missile effect (Correct answer)
Quenching effect
Susceptibility effect
Gradient artifact

Correct answer: Missile effect

The missile effect (or projectile effect) occurs when ferromagnetic objects are rapidly accelerated toward the bore by the strong static magnetic field.

Question 210: On a sagittal MRI of the cervical spine, the posterior longitudinal ligament appears as a thin structure along which surface of the vertebral bodies?

Posterior (Correct answer)
Superior
Anterior
Lateral

Correct answer: Posterior

The posterior longitudinal ligament runs along the posterior surfaces of the vertebral bodies inside the spinal canal, anterior to the thecal sac.

Question 211: Which MRI sequence is most sensitive to hemorrhage detection because of its sensitivity to blood products?

Gradient echo (GRE) (Correct answer)
Fast spin echo (FSE)
Inversion recovery (IR)
Diffusion-weighted imaging (DWI)

Correct answer: Gradient echo (GRE)

Gradient echo sequences are sensitive to magnetic susceptibility differences caused by hemosiderin and deoxyhemoglobin, making them ideal for detecting hemorrhage.

Question 212: Multiple sclerosis (MS) plaques in the brain are classically found in which location on MRI?

Cerebellum exclusively
Gray matter of the cortex only
Periventricular white matter, corpus callosum, and juxtacortical regions (Correct answer)
Basal ganglia bilaterally

Correct answer: Periventricular white matter, corpus callosum, and juxtacortical regions

MS demyelinating plaques characteristically occur in periventricular white matter, corpus callosum (Dawson fingers), juxtacortical, and infratentorial regions.

Question 213: Gibbs ringing artifact is caused by:

Chemical shift between fat and water
Truncation of k-space data at high spatial frequencies (Correct answer)
Motion during phase encoding
RF pulse imperfections

Correct answer: Truncation of k-space data at high spatial frequencies

Gibbs ringing (truncation artifact) occurs when k-space is sampled with insufficient high-frequency data, causing oscillating bands near sharp tissue interfaces.

Question 214: Continuing education (CE) requirements for ARRT MRI credential renewal are completed over what cycle length?

1 year
5 years
3 years
2 years (Correct answer)

Correct answer: 2 years

ARRT requires 24 CE credits completed within a 2-year renewal cycle to maintain the MRI credential.

Question 215: What determines the slice thickness in a standard 2D MRI acquisition?

The number of phase-encoding steps
The repetition time and echo time
The field of view and matrix size
The bandwidth of the RF pulse and the slope of the slice-select gradient (Correct answer)

Correct answer: The bandwidth of the RF pulse and the slope of the slice-select gradient

Slice thickness = RF bandwidth / (gyromagnetic ratio × gradient strength); a wider RF bandwidth or shallower gradient yields a thicker slice.

Question 216: When performing MRI on a patient with an insulin pump, which step is essential before beginning the exam?

Tape the pump to the patient's leg during the scan
Increase the insulin dose before scanning
Leave the pump in place since insulin is not ferromagnetic
Remove the pump (if removable) or verify the pump is MR-conditional with the manufacturer before scanning (Correct answer)

Correct answer: Remove the pump (if removable) or verify the pump is MR-conditional with the manufacturer before scanning

Insulin pumps may malfunction, heat, or be damaged in the MRI environment; removal or manufacturer verification of MR-conditional status is mandatory.

Question 217: Which type of question format is exclusively used on the ARRT MRI registry computer-based examination?

Fill-in-the-blank
True/False
Multiple choice with one best answer (Correct answer)
Matching

Correct answer: Multiple choice with one best answer

The ARRT MRI exam uses only multiple-choice questions with four options and one best answer.

Question 218: The signal-to-noise ratio (SNR) in MRI is proportional to which of the following?

Voxel volume × √(NEX) × √(scan time factors) (Correct answer)
1 / (TR × TE)
Flip angle / repetition time
Field of view / matrix size only

Correct answer: Voxel volume × √(NEX) × √(scan time factors)

SNR increases with larger voxel volume, more signal averages (NEX), and longer acquisition times that allow more k-space sampling.

Question 219: When should a technologist notify the supervising radiologist or radiologist immediately during an MRI exam?

When the scan takes longer than expected
When the patient completes the screening form
When any adverse reaction to contrast, change in patient condition, or safety concern arises (Correct answer)
When the patient requests a blanket

Correct answer: When any adverse reaction to contrast, change in patient condition, or safety concern arises

Any adverse reaction to contrast agent, unexpected change in patient condition (loss of consciousness, seizure, cardiac event), or safety concern requires immediate radiologist notification.

Question 220: What minimum distance from the MRI magnet bore is generally recommended to keep unsecured ferromagnetic oxygen cylinders?

1 meter
3 meters
Distance depends on field strength and cylinder size (Correct answer)
5 meters

Correct answer: Distance depends on field strength and cylinder size

The safe exclusion zone for ferromagnetic oxygen cylinders depends on both the scanner's field strength and the cylinder size, so no single fixed distance applies universally.

Question 221: Which coil type provides the best signal-to-noise ratio (SNR) for a specific small anatomy because it is placed closest to the structure?

Head coil
Volume coil
Body coil
Surface coil (Correct answer)

Correct answer: Surface coil

Surface coils are placed directly over the anatomy of interest; their proximity maximizes SNR for superficial or small structures compared to larger volume coils.

Question 222: This kind of magnetic shielding confines the main magnet's field by using other magnets and their corresponding magnetic fields.

Passive
Active (Correct answer)

Correct answer: Active

Active magnetic shielding uses additional superconducting coils, placed around the main magnet, that generate opposing magnetic fields. These opposing fields effectively cancel out the main magnet's fringe field at a certain distance. This method significantly reduces the extent of the stray magnetic field outside the scanner, making it a more complex but often more effective and lighter shielding solution than passive methods.

Question 223: What is the recommended action when a patient with an unknown metallic implant cannot be identified before a clinically urgent MRI?

Consult the radiologist and ordering physician to assess risk vs. benefit (Correct answer)
Perform the scan with a 0.5T open system only
Proceed with the scan at lowest SAR
Cancel the exam without exception

Correct answer: Consult the radiologist and ordering physician to assess risk vs. benefit

The radiologist and referring physician must jointly assess whether clinical urgency outweighs the unquantified risk of scanning with an unknown implant.

Question 224: Which MRI-compatible monitoring device is used to detect heart rate and trigger cardiac-gated sequences?

Blood pressure cuff inflation timing
MR-conditional ECG with carbon or fiber-optic leads free of conductive loops (Correct answer)
Standard hospital ECG with adhesive electrodes
Finger-clip optical pulse oximeter (used for cardiac gating)

Correct answer: MR-conditional ECG with carbon or fiber-optic leads free of conductive loops

MR-conditional ECG systems with non-conductive or carbon fiber leads detect the R-wave for cardiac gating without creating conductive loops that could cause burns.

Question 225: Which sequence parameter directly controls the slice thickness in a 2D spin-echo acquisition?

TR duration
Bandwidth of the RF pulse divided by the slice-select gradient amplitude (Correct answer)
Bandwidth of the readout gradient
TE duration

Correct answer: Bandwidth of the RF pulse divided by the slice-select gradient amplitude

Slice thickness = RF pulse bandwidth ÷ slice-select gradient amplitude; thicker slices can be produced by widening the RF bandwidth or reducing the gradient strength.

Question 226: A 'blooming' artifact on gradient echo (GRE) MRI is caused by which substance?

Hemosiderin or calcification (Correct answer)
Fat
Cerebrospinal fluid
Gadolinium contrast

Correct answer: Hemosiderin or calcification

Hemosiderin, calcium, and other susceptibility-inducing substances cause local field inhomogeneities that appear as signal loss blooming on GRE sequences.

Question 227: MR spectroscopy (MRS) of the brain measures metabolite concentrations. Which metabolite, reduced in neuronal loss and gliosis, is considered a marker of neuronal integrity?

Choline (Cho)
Lactate (Lac)
Creatine (Cr)
N-acetylaspartate (NAA) (Correct answer)

Correct answer: N-acetylaspartate (NAA)

NAA (N-acetylaspartate) is located predominantly in neurons; its reduction indicates neuronal loss or dysfunction, making it a key spectroscopic marker of neuronal integrity.

Question 228: Which of the following best describes the purpose of placing the frequency-encoding gradient in the anterior-posterior direction for spine MRI?

To increase SNR
To reduce phase wrap (aliasing) from anterior abdominal structures (Correct answer)
To shorten scan time
To reduce susceptibility artifact

Correct answer: To reduce phase wrap (aliasing) from anterior abdominal structures

Placing frequency encoding AP moves phase wrap artifact (aliasing) to the AP direction, preventing anterior abdominal fat from wrapping onto the spine.

Question 229: Which phenomenon causes the chemical shift artifact in MRI, and in which direction does it occur?

Susceptibility differences between tissues; phase-encode direction
Resonance frequency difference between fat and water; frequency-encode direction (Correct answer)
T1 differences between tissues; readout direction
B1 field inhomogeneity; slice-select direction

Correct answer: Resonance frequency difference between fat and water; frequency-encode direction

Fat protons resonate at ~3.5 ppm lower frequency than water, causing spatial misregistration along the frequency-encoding direction.

Question 230: What is the effect of increasing the number of signal averages (NSA/NEX) on MRI image quality?

Spatial resolution increases
Scan time decreases
SNR decreases proportionally
SNR improves proportionally to the square root of NSA (Correct answer)

Correct answer: SNR improves proportionally to the square root of NSA

Averaging multiple acquisitions improves SNR by a factor of √NSA, though it linearly increases scan time.

ARRT MRI Exam

The ARRT Magnetic Resonance Imaging examination certifies technologists in MRI, assessing competency in patient care, MRI safety, image production physics and sequences, and clinical imaging procedures.

230

Questions

240 min

Time Limit

75%

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