Free Practice Questions for ARDMS SPI Exam

Comprehensive and Detailed Explanation From Exact Extract:

Temporal resolution reflects how quickly frames are updated (frame rate). Reducing the number of scan lines per frame (low line density) decreases acquisition time, thus increasing frame rate and improving temporal resolution.

According to sonography instrumentation reference:

“Lower line density allows for faster frame rates, improving temporal resolution at the expense of spatial resolution.”

Therefore, the correct answer is D: Low line density.

Enhancement is an artifact that results from decreased attenuation. When an ultrasound wave travels through a medium with lower attenuation compared to surrounding tissues, it loses less energy. Consequently, the structures located deeper than the low-attenuation medium appear brighter on the ultrasound image. This artifact is commonly observed behind fluid-filled structures, such as cysts or the urinary bladder, where the sound waves encounter minimal resistance and thus less attenuation.References:

ARDMS Sonography Principles and Instrumentation guidelines

"Diagnostic Ultrasound: Principles and Instruments" by Frederick W. Kremkau

Increasing the pulse repetition frequency (PRF) helps to optimize the color Doppler imaging by reducing aliasing.

Aliasing occurs when the PRF is too low to accurately sample the rapid blood flow velocities, leading to incorrect color representation.

By increasing the PRF, the system can more accurately measure higher velocities without distortion, improving the overall quality of the color Doppler image.References:

ARDMS Sonography Principles and Instrumentation guidelines on Doppler imaging and techniques to reduce aliasing.

M-mode (Motion mode) is used in ultrasound to measure and display the movement of structures over time.

This mode is particularly useful in cardiac imaging to assess the motion of heart walls and valves.

M-mode provides a one-dimensional view of the motion of tissues and is often used in conjunction with 2D imaging for a comprehensive assessment.

It is essential in evaluating the dynamic function of organs, especially in cardiology, where precise measurements of cardiac structures' movement are crucial.References:

ARDMS Sonography Principles and Instrumentation guidelines on modes of ultrasound imaging and their clinical applications.

Comprehensive and Detailed Explanation From Exact Extract:

Axial resolution is primarily determined by the spatial pulse length (SPL), which depends on both wavelength and the number of cycles per pulse. A shorter pulse length provides better axial resolution. The Principles and Instrumentation documents state:

"Axial resolution = SPL/2. To improve axial resolution, the pulse duration must be shortened — achieved by decreasing the pulse length."

Note: While increasing frequency also improves axial resolution (because it shortens wavelength), in this question, decreasing pulse length directly targets SPL, making it the most precise answer.

Therefore, the correct answer is C: Pulse length.

QUESTION NO6

In this image, which artifact is demonstrated?

A close-up of a sound wave Description automatically generated

A. Mirroring

B. Aliasing

C. Range ambiguity

D. Spectral broadening

Answer: A

Comprehensive and Detailed Explanation From Exact Extract:

The provided image shows a pulsed-wave Doppler spectral display. There are two identical Doppler spectra present — one on the top and an inverted one on the bottom — a classic appearance of the mirroring artifact.

Mirroring occurs when the strong Doppler signal reflects off a highly reflective interface and produces a duplicate signal on the opposite side of the baseline. The mirrored signal mimics the original spectral waveform but appears as a reversed, symmetric version.

According to official sonography Principles and Instrumentation references:

"Mirror image artifact in Doppler (also called cross-talk) occurs when a strong signal is incorrectly displayed on both sides of the baseline, producing a duplicated waveform."

Aliasing would show wrap-around of velocities beyond the Nyquist limit, typically producing a cutoff and color reversal — not seen here.

Range ambiguity produces overlapping signals from different depths — also not applicable here.

Spectral broadening would result in widening of the Doppler spectral trace — which is not evident here.

Therefore, the correct answer is A: Mirroring.

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Comprehensive and Detailed Explanation From Exact Extract:

In phased arrays, transmit focus is electronically controlled by varying the timing (delays) of the activation of elements.

Principles and Instrumentation state:

"Electronic focusing is achieved by introducing varying time delays to individual elements, allowing beam focusing at different depths."

Mechanical rotation (A) applies to older mechanical probes.

Matching layers (B) and acoustic lens impedance (C) do not control focusing electronically.

Therefore, the correct answer is D: Adjusting relative delay times of the array elements.

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The color bar on a Doppler ultrasound display indicates the range of velocities that the system can detect and display. In color bar A, the scale is set to a higher maximum velocity (64 cm/s), while in color bar B, the scale is set to a lower maximum velocity (16 cm/s). Adjusting the scale (or velocity range) changes the upper and lower limits of the velocities displayed, which affects the sensitivity of the Doppler system to detect flow velocities. Lowering the scale allows for better visualization of lower velocities, but it may also increase the likelihood of aliasing for higher velocities.

American Registry for Diagnostic Medical Sonography (ARDMS). Sonography Principles and Instrumentation (SPI) Examination Review Guide.

Comprehensive and Detailed Explanation From Exact Extract:

The matching layer is placed between the transducer’s piezoelectric element and the patient’s skin. Its primary function is to improve the transmission of sound energy into the body by reducing the acoustic impedance mismatch between the crystal and tissue, minimizing reflection at the transducer surface.

According to sonography instrumentation reference:

“The matching layer improves transmission of ultrasound energy by reducing impedance mismatch between the transducer and soft tissue, thus increasing the efficiency of sound energy transfer.”

Therefore, the correct answer is D: Increase sound transmission.

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Comprehensive and Detailed Explanation From Exact Extract:

Reflection is maximized when the ultrasound beam strikes a tissue interface at 90 degrees (perpendicular). This angle provides optimal return of echoes for imaging.

According to sonography instrumentation reference:

“Maximal reflection occurs when the sound beam strikes a boundary at 90 degrees.”

Therefore, the correct answer is D: Reflection.

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The aperture of a transducer is the active area that emits and receives the ultrasound waves. In a linear array transducer, increasing the aperture (using more elements for transmission and reception) results in a deeper focus because the beam is more tightly focused over a longer distance. This improves lateral resolution at greater depths, as the ultrasound beam maintains a narrower width for a longer distance. It allows for better imaging of deeper structures without sacrificing resolution.

American Registry for Diagnostic Medical Sonography (ARDMS). Sonography Principles and Instrumentation (SPI) Examination Review Guide.