SPI ARDMS Sonography Principles and Instrumentation Free Practice Exam Questions (2025 Updated)

Comprehensive and Detailed Explanation From Exact Extract:

Cross talk (spectral mirror artifact) appears as a duplication of the spectral waveform above and below the baseline. One primary cause is excessive Doppler gain, which amplifies weak signals and noise symmetrically. Reducing gain minimizes this artifact.

Principles and Instrumentation state:

"Cross talk in spectral Doppler may result from high gain settings. Lowering the gain can reduce or eliminate this artifact."

PRF adjustments affect aliasing, not cross talk.

Baseline shifts affect waveform positioning.

Wall filter affects low-frequency signals but not cross talk.

Therefore, the correct answer is A: By decreasing the Doppler gain.

QUESTION NO28

Which artifact is demonstrated by the arrow in this image?

A close-up of an ultrasound Description automatically generated

A. Mirroring

B. Noise

C. Shadowing

D. Enhancement

Answer: C

Comprehensive and Detailed Explanation From Exact Extract:

The image shows an area of signal dropout directly deep to the strongly reflecting structure (likely a vessel wall or calcification), indicated by the arrow. This is a classic example of shadowing artifact.

According to sonography Principles and Instrumentation:

"Shadowing occurs when a highly attenuating or reflective structure blocks the ultrasound beam, resulting in absence of signal distal to the object."

Mirroring (A) produces duplicated structures.

Noise (B) appears as random speckles.

Enhancement (D) produces increased echogenicity distal to an anechoic structure.

Therefore, the correct answer is C: Shadowing.

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Comprehensive and Detailed Explanation From Exact Extract:

The primary purpose of compression is to reduce the dynamic range of received echoes, making the image more visually interpretable by adjusting contrast without losing diagnostic information.

According to sonography instrumentation reference:

“Compression reduces the dynamic range of the signal amplitudes to fit within the display range of the monitor while preserving important differences in tissue echogenicity.”

Therefore, the correct answer is D: Reduce the dynamic range.

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Changing the displayed depth control directly affects the pulse repetition frequency (PRF). When the depth setting is increased, the ultrasound system needs more time to send and receive echoes from deeper structures, resulting in a lower PRF. Conversely, decreasing the depth allows for a higher PRF since the time required for the sound waves to travel to and from the structures is shorter. PRF is crucial for determining the maximum detectable velocity in Doppler ultrasound without aliasing.References:

ARDMS Sonography Principles and Instrumentation guidelines

"Understanding Ultrasound Physics" by Sidney K. Edelman

Persistence is a technique used in ultrasound imaging that averages individual frames together to improve the overall image quality. This process helps to reduce noise and improve the signal-to-noise ratio, leading to clearer and more stable images. By averaging multiple frames, transient artifacts are minimized, and the continuity of structures is better visualized. Persistence is particularly useful in imaging static or slow-moving structures.References:

ARDMS Sonography Principles and Instrumentation guidelines

"Ultrasound Physics and Technology: How, Why and When" by M. Evans, C. Archer, and K. Weston

Comprehensive and Detailed Explanation From Exact Extract:

Compression reduces the dynamic range of the returning echoes, which alters how many shades of gray are displayed. It compresses the range of signal amplitudes to fit into the grayscale display range.

According to sonography instrumentation reference:

“Compression alters the dynamic range, adjusting how many shades of gray are displayed to optimize image contrast.”

Therefore, the correct answer is B: The shades of gray displayed.

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Aliasing in pulsed-wave Doppler occurs when the sampled Doppler frequency exceeds the Nyquist limit, which is half of the pulse repetition frequency (PRF). This results in an incorrect representation of the blood flow velocities, causing the waveform to wrap around and appear on the opposite side of the baseline. To correct aliasing, the PRF should be increased, which raises the Nyquist limit and allows for accurate measurement of higher velocities without aliasing. Increasing the PRF effectively reduces the likelihood of aliasing artifacts in the Doppler signal.

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

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.

A string phantom is designed to evaluate the accuracy of Doppler ultrasound systems, specifically in measuring flow velocity. It consists of a moving string or filament that mimics blood flow within a vessel. By using this phantom, sonographers can assess how accurately the ultrasound system can detect and measure the speed of the moving target. This helps in calibrating and verifying the performance of Doppler systems, ensuring they provide accurate flow velocity readings in clinical practice.

American Registry for Diagnostic Medical Sonography (ARDMS) Sonography Principles and Instrumentation study materials.

Textbook of Diagnostic Sonography by Hagen-Ansert, S. L. (latest edition).

Comprehensive and Detailed Explanation From Exact Extract:

In color Doppler, frequency shifts can be displayed either above or below the baseline in spectral Doppler. In spectral Doppler, a positive shift is displayed above the baseline by default (unless inverted). In color Doppler, red/blue assignments depend on color map orientation.

Principles and Instrumentation state:

"A positive Doppler shift (flow toward the transducer) is displayed above the baseline in spectral Doppler."

Red color (B) does not always correspond to positive shift; it depends on color map.

Negative shift (C) does not always indicate venous flow.

Wall filter settings (D) affect low-velocity signals, not shift direction.

Therefore, the correct answer is A: A positive shift is always above the baseline.

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Comprehensive and Detailed Explanation From Exact Extract:

Ideal imaging transducers have broad bandwidths (allowing multiple frequencies for better axial resolution and flexibility) and a low quality factor (which indicates efficient damping, leading to short pulses and better image quality).

According to sonography instrumentation reference:

“Imaging transducers operate with broad bandwidth and low quality factor to achieve short pulse duration and optimal axial resolution.”

Therefore, the correct answer is B: Broad bandwidth; low quality factor.

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Comprehensive and Detailed Explanation From Exact Extract:

The thermal index (TI) indicates the potential for tissue heating due to ultrasound energy absorption. Increasing acoustic power increases the amount of energy transmitted into the body, which raises the thermal index.

According to sonography instrumentation reference:

“An increase in acoustic output power results in a corresponding increase in the thermal index, reflecting higher potential for tissue heating.”

Therefore, the correct answer is C: Thermal Index.

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Edge enhancement is a processing technique used in ultrasound imaging to improve the visibility of the edges of structures.

In image A, the borders of the cystic lesion might appear less defined due to a lack of edge enhancement.

By turning on edge enhancement, the ultrasound system processes the image to accentuate the boundaries, leading to a clearer and more distinct outline of the cystic lesion as seen in image B.

This adjustment reduces the artifact within the cystic lesion by emphasizing the differences in the adjacent tissue interfaces, thus improving the overall image quality.References:

American Registry for Diagnostic Medical Sonography (ARDMS) Sonography Principles and Instrumentation guidelines on image optimization techniques.

Comprehensive and Detailed Explanation From Exact Extract:

In color Doppler imaging, the default color map assigns red and blue to represent flow direction relative to the transducer (usually red toward, blue away). The color invert control reverses this assignment.

According to sonography Principles and Instrumentation:

"The color invert control reverses the baseline of the color map, swapping red and blue assignments for flow direction."

Color priority adjusts the overlay of color vs grayscale.

Color gain controls amplification of the Doppler signal.

Color threshold sets minimum amplitude to display color.

Therefore, the correct answer is D: Color invert.

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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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Comprehensive and Detailed Explanation From Exact Extract:

Each additional focal zone requires extra transmissions per scan line, which slows down frame acquisition, thereby reducing the frame rate.

Principles and Instrumentation state:

"Increasing the number of focal zones lowers frame rate because multiple pulses are needed per scan line for each focal depth."

Increasing PRF (B) allows faster data acquisition.

Decreasing depth (C) shortens round-trip time, increasing frame rate.

Decreasing sector width (D) reduces scan lines, increasing frame rate.

Acoustic Shadowing: This artifact occurs when a structure absorbs or reflects most of the ultrasound waves, causing a shadow behind the structure. It does not cause improper positioning of a reflector on the display.

Speckle: This is a form of noise in ultrasound imaging that appears as granular texture. It can affect image quality but does not lead to improper positioning of reflectors.

Enhancement: This artifact occurs when the area behind a weakly attenuating structure appears brighter. It affects the brightness of the image but does not affect the position of reflectors.

Range Ambiguity: This occurs when an echo is received after the next pulse has been sent out, causing the reflector to be placed at an incorrect depth on the display. This is because the system assumes the echo came from the most recent pulse.

Comprehensive and Detailed Explanation From Exact Extract:

The wall filter in Doppler ultrasound is designed to eliminate low-frequency signals, typically associated with motion artifacts such as vessel wall or tissue motion. These low-frequency signals are not part of the desired blood flow signal and can interfere with accurate Doppler display.

When the wall filter setting is increased, it removes these low-frequency signals from the Doppler spectrum. However, increasing the wall filter too much can also eliminate true low-velocity flow information, leading to a loss of clinically relevant data.

This principle is described in official sonography Principles and Instrumentation references:

"Increasing the wall filter will reduce the display of low-frequency Doppler shifts, which are typically associated with slow-moving structures. These low-frequency signals can represent either slow blood flow or tissue motion artifacts."

Therefore, the correct answer isD: Reduced display of low-frequency shifts.

Option B demonstrates appropriate spectral Doppler gain. Appropriate gain settings ensure that the Doppler signal is adequately amplified without introducing excessive noise or artifacts. In Option B, the spectral waveform is clearly visible with distinct borders, and the background noise is minimal. In contrast, other options might show either under-gained (too little signal) or over-gained (excessive noise and signal) images, making it difficult to accurately interpret the spectral Doppler information.References:

ARDMS Sonography Principles and Instrumentation guidelines

"Understanding Ultrasound Physics" by Sidney K. Edelman

Temporal resolution refers to the ability to accurately depict moving structures over time.

A narrow sector width reduces the area being scanned, which increases the frame rate because fewer scan lines are required per frame.

Higher frame rates improve temporal resolution, allowing for better visualization of fast-moving structures.

Other factors like scan depth and the number of focal zones also affect frame rate but typically reduce it when increased, thereby decreasing temporal resolution.References:

ARDMS Sonography Principles and Instrumentation guidelines on factors affecting temporal resolution and frame rate.