ARDMS Sonography Principles and Instrumentation ARDMS SPI Exam Practice Test

Answer : A

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.

Answer : A

Noise in the Doppler waveform can often be attributed to excessive gain settings. Decreasing the Doppler gain reduces the amplification of both the signal and the noise, thus providing a clearer and more accurate Doppler waveform. Excessive gain can cause speckling and clutter, which obscure the true Doppler signals. By reducing the gain, the noise level is minimized, resulting in a cleaner Doppler signal representation.

ARDMS Sonography Principles & Instrumentation Guidelines

Hagen-Ansert SL. Textbook of Diagnostic Ultrasonography. 8th ed. St. Louis, MO: Mosby; 2017.

Answer : D

The placement of an echo on an ultrasound image is dependent on the assumption that the speed of sound in soft tissue is 1540 m/s. If the speed of sound in the medium is less than this assumed speed, the ultrasound system will interpret the returning echo as taking longer to return than it actually does. This causes the system to place the echo deeper in the image than its actual position. Therefore, the echo will be displayed 'too deep' in the image.

ARDMS Sonography Principles & Instrumentation Guidelines

Kremkau FW. Sonography Principles and Instruments. 9th ed. Philadelphia, PA: Elsevier; 2016.

Answer : B

Write magnification, or pre-processing zoom, involves rescanning the region of interest (ROI) with more scan lines, thus acquiring new data for that specific area. This process increases the spatial resolution of the image in the magnified area because it gathers more detailed data by adjusting the scan parameters, resulting in improved image quality. This is different from read magnification (post-processing zoom), which simply enlarges the existing image data without increasing resolution.

ARDMS Sonography Principles & Instrumentation Guidelines

Hedrick WR, Hykes DL, Starchman DE. Ultrasound Physics and Instrumentation. 4th ed. Philadelphia, PA: Elsevier Saunders; 2005.

Answer : B

The color Doppler image shows an artifact where high-velocity blood flow exceeds the Nyquist limit, resulting in color wrap-around or aliasing. This artifact is visualized as a mosaic pattern of colors that abruptly change, indicating that the velocity exceeds the color Doppler scale's maximum. Aliasing occurs when the sampling rate (pulse repetition frequency) is insufficient to accurately capture the high velocities, causing the display to cycle back to lower velocities.

ARDMS Sonography Principles & Instrumentation Guidelines

Hagen-Ansert SL. Textbook of Diagnostic Ultrasonography. 8th ed. St. Louis, MO: Mosby; 2017.

Answer : C

The Mechanical Index (MI) is related to the likelihood of cavitation, which is the formation of gas bubbles in a liquid due to the low-pressure regions of the ultrasound wave. MI is a parameter that predicts the potential for mechanical bioeffects, including cavitation. A higher MI indicates a greater likelihood of cavitation occurring. It is calculated based on the peak negative pressure and the frequency of the ultrasound wave.

ARDMS Sonography Principles and Instrumentation guidelines

Kremkau, F. W. (2015). Diagnostic Ultrasound: Principles and Instruments.

Answer : B

The primary difference between Image A and Image B is the overall gain setting. Gain controls the amplification of the received echoes. A lower gain setting results in a darker image with less overall brightness, which is evident in Image A compared to Image B. Image B appears brighter, indicating a higher gain setting that amplifies the echoes more, making the structures appear more prominently.

ARDMS Sonography Principles and Instrumentation guidelines

Hedrick, W. R., Hykes, D. L., & Starchman, D. E. (2005). Ultrasound Physics and Instrumentation.