Which color control was adjusted in color bar A to produce color bar B?
Answer : B
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.
Which pulsed-wave Doppler adjustment would be appropriate to correct the aliasing seen in this image?
Answer : C
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.
What is the benefit of using a wall filter?
Answer : D
A wall filter in Doppler ultrasound is designed to remove low-frequency signals that are often caused by tissue motion, vessel wall movement, or other forms of motion artifact. These low-frequency signals can clutter the Doppler spectrum, making it difficult to accurately interpret blood flow velocities. By filtering out these unwanted low-frequency signals, the wall filter helps to enhance the clarity of the Doppler signal, allowing for more accurate measurements of blood flow velocities.
American Registry for Diagnostic Medical Sonography (ARDMS). Sonography Principles and Instrumentation (SPI) Examination Review Guide.
Which setting can be increased to correct for clutter artifact when using pulsed-wave Doppler?
Answer : C
The wall filter, also known as the high-pass filter, is used in Doppler ultrasound to remove low-frequency signals, which are typically associated with clutter artifacts. Clutter artifacts can be caused by tissue motion or vessel wall movement, and they appear as low-frequency signals that can obscure the desired blood flow signals. By increasing the wall filter setting, these low-frequency signals are filtered out, thus reducing the clutter artifact and providing a clearer depiction of the blood flow.
American Registry for Diagnostic Medical Sonography (ARDMS). Sonography Principles and Instrumentation (SPI) Examination Review Guide.
Which is a method to reduce noise?
Answer : D
Persistence is a form of temporal averaging where consecutive frames are averaged to reduce random noise, resulting in a smoother image. Increasing persistence effectively reduces noise by averaging out transient noise artifacts while preserving the true signal. This improves image quality, although it may also reduce the temporal resolution, making it less suitable for rapidly moving structures.
ARDMS Sonography Principles & Instrumentation Guidelines
Hedrick WR, Hykes DL, Starchman DE. Ultrasound Physics and Instrumentation. 4th ed. Philadelphia, PA: Elsevier Saunders; 2005.
In this image, what does the data below the baseline represent?
Answer : B
In the provided image, data below the baseline represents blood flow moving away from the transducer, which can indicate retrograde flow. When using spectral Doppler, the baseline separates flows towards and away from the transducer. Aliasing occurs when the velocity of blood flow exceeds the Nyquist limit, causing the display to wrap around and appear on the opposite side of the baseline. This phenomenon is common in high-velocity flow situations and results in part of the flow being displayed below the baseline. Retrograde flow further supports this, as it shows blood moving in the opposite direction to the expected flow.
ARDMS Sonography Principles & Instrumentation Guidelines
Kremkau FW. Sonography Principles and Instruments. 9th ed. Philadelphia, PA: Elsevier; 2016.
Which adjustment can maintain the same frame rate when the depth is increased?
Answer : B
When the depth of imaging is increased, the time it takes for the ultrasound pulses to travel to and from the deeper structures also increases, which can reduce the frame rate. To maintain the same frame rate, one effective adjustment is to decrease the image width. Narrowing the image width reduces the number of scan lines required to create each frame, allowing the system to maintain a higher frame rate despite the increased depth.
ARDMS Sonography Principles and Instrumentation guidelines
Kremkau, F. W. (2015). Diagnostic Ultrasound: Principles and Instruments.