System Architecture and Design Flashcards

In transesophageal echocardiography (TEE) probe design, the phased array is mounted on a flexible endoscope primarily to:

Answer: Allow higher ultrasound frequencies without chest-wall attenuation

Placing the transducer in the esophagus eliminates the lung and rib barriers, allowing higher frequencies that provide superior resolution compared to transthoracic windows.

Acoustic impedance mismatch at tissue interfaces results in:

Answer: Reflection of a portion of the acoustic energy back to the transducer

When ultrasound encounters a boundary between tissues with different acoustic impedances, some energy is reflected and some transmitted, generating the echoes used to form the image.

The purpose of a matching layer on an echocardiographic transducer face is to:

Answer: Reduce acoustic impedance mismatch between the piezoelectric element and tissue

The matching layer has an intermediate acoustic impedance that progressively bridges the large impedance gap between the piezoelectric crystal and soft tissue, maximizing energy transfer.

Continuous-wave (CW) Doppler differs architecturally from pulsed-wave (PW) Doppler in that CW systems:

Answer: Employ two separate elements—one continuously transmitting, one continuously receiving

CW Doppler uses dedicated transmit and receive elements operating simultaneously, allowing measurement of any velocity without aliasing but sacrificing range selectivity.

In color Doppler flow mapping, the system assigns color based on:

Answer: Mean Doppler frequency shift (velocity) and variance within each sample volume

Color Doppler encodes mean velocity (frequency shift) and variance (turbulence indicator) across a 2D map, typically displaying flow toward the transducer in red and away in blue.

Which system design feature is specifically incorporated into intracardiac echocardiography (ICE) catheters compared to TEE probes?

Answer: Very small phased array mounted on a steerable catheter shaft

ICE catheters house a miniaturized phased array on a steerable catheter that can be advanced into cardiac chambers for guidance during intracardiac procedures.

Strain rate imaging in modern echocardiographic platforms is derived architecturally from:

Answer: Spatial gradients of myocardial velocity data from tissue Doppler or speckle tracking

Strain rate is calculated as the spatial gradient of myocardial velocity (from tissue Doppler) or from frame-to-frame displacement of speckle patterns, reflecting regional deformation.