Overall gain controls the amplification of all the received ultrasound signals uniformly. This adjustment affects the brightness of the entire image by increasing or decreasing the amplification of the echoes returning from all depths. It is a primary control for adjusting image brightness. The overall gain should be set to an appropriate level to ensure that the ultrasound image is neither too bright (over-gained) nor too dark (under-gained), allowing for optimal visualization of the anatomical structures.
Reference:
American Registry for Diagnostic Medical Sonography (ARDMS). Sonography Principles and Instrumentation (SPI) Examination Review Guide.

Comprehensive and Detailed Explanation From Exact Extract:
The primary advantage of pulsed-wave Doppler is its ability to provide range resolution. This means the operator can select a specific depth (sample volume) from which Doppler signals are acquired, allowing precise localization of blood flow velocities.
According to sonography instrumentation reference:
"Pulsed-wave Doppler allows for range resolution, enabling velocity measurements at a specific depth along the ultrasound beam path." Continuous-wave Doppler does not have range resolution, as it measures velocities along the entire beam path.
Therefore, the correct answer is C: Range resolution.

Low persistence is best used for visualizing dynamic structures. Persistence is a setting that controls the averaging of successive frames to reduce noise and improve image quality. While high persistence can be beneficial for imaging static structures by providing a smoother image, it can blur or smear moving structures, making it difficult to visualize motion accurately. Low persistence settings allow for better temporal resolution and are therefore ideal for observing dynamic or moving structures such as the heart or blood flow.
Reference:
ARDMS Sonography Principles and Instrumentation (SPI) Exam Study Guide
"Diagnostic Ultrasound: Principles and Instruments" by Frederick W. Kremkau

* 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.

Aliasing occurs in Doppler ultrasound when the pulse repetition frequency (PRF) is less than twice the Doppler shift frequency (Nyquist limit). When this condition is met, the Doppler signals are not sampled frequently enough to accurately measure the frequency shifts, resulting in the misrepresentation of the flow velocities. This causes the aliasing artifact, where high-velocity flows are displayed incorrectly as wrapping around the baseline, leading to potential diagnostic errors.
Reference: ARDMS Sonography Principles and Instrumentation (SPI) Review, Doppler Artifacts section.