Which technique averages individual frames together to improve the image?
Answer(s): C
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.
ARDMS Sonography Principles and Instrumentation guidelines"Ultrasound Physics and Technology: How, Why and When" by M. Evans, C. Archer, and K. Weston
What results from increasing the packet length when using color Doppler imaging?
Answer(s): D
Increasing the packet length in color Doppler imaging means increasing the number of pulses used to interrogate each scan line. This improves the accuracy of velocity measurements and sensitivity to low flow velocities but has the drawback of decreasing the frame rate. A longer packet length requires more time to acquire the necessary data, which reduces the number of frames that can be processed and displayed per second. Consequently, while color Doppler imaging becomes more precise, the temporal resolution (frame rate) decreases.
ARDMS Sonography Principles and Instrumentation guidelines"Color Doppler, Power Doppler, and Spectral Doppler" by Michael J. Riccabona
Which image demonstrates appropriate spectral Doppler gain?
Answer(s): B
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.
ARDMS Sonography Principles and Instrumentation guidelines"Understanding Ultrasound Physics" by Sidney K. Edelman
Which factor improves axial resolution?
Answer(s): A
Axial resolution refers to the ability to distinguish two structures that are close to each other along the direction of the sound beam. It is determined by the spatial pulse length (SPL), which is the product of the number of cycles in a pulse and the wavelength. Shorter SPL means shorter pulse duration, which leads to better axial resolution. This is because shorter pulses allow for better separation of echoes from closely spaced structures.
ARDMS Sonography Principles and Instrumentation guidelinesKremkau, F. W. (2015). Diagnostic Ultrasound: Principles and Instruments.
What reduces speckle and increases visualization of specular reflectors and attenuated structures?
Spatial compounding involves acquiring multiple frames from different angles and averaging them. This technique reduces speckle noise, which is a granular interference pattern, and enhances the visualization of specular reflectors (smooth surfaces that reflect sound in a single direction) and attenuated structures (structures that reduce the intensity of the sound beam). By averaging frames from different angles, spatial compounding improves image quality and contrast resolution.
ARDMS Sonography Principles and Instrumentation guidelinesHedrick, W. R., Hykes, D. L., & Starchman, D. E. (2005). Ultrasound Physics and Instrumentation.
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