Increased Transmit Frequency: This would generally improve the resolution of the image but does not directly correlate to the changes seen in the provided image link.
Increased Scale: Adjusting the scale changes the velocity range displayed but does not directly affect the speckle or noise reduction.
Decreased Color Gain: Reducing the color gain can decrease the amount of color noise, making the blood flow regions more defined, which aligns with the change observed from image A to image B.
Decreased Acoustic Power: This reduces the overall intensity of the ultrasound beam, affecting penetration depth and overall brightness but is less likely to result in the specific improvements seen.
Reference:
"Understanding Ultrasound Physics" by Sidney K. Edelman
ARDMS Sonography Principles and Instrumentation study materials