If compression is set too high and transmit power is too low, what are the expected imaging consequences?

• A. Compression too high makes the image too bright; transmit power too low yields a weak signal and low SNR
• B. Compression too high makes the image too dark; transmit power too low yields strong signal
• C. Compression has no effect; transmit power too low yields high SNR
• D. Compression too low makes image too bright; transmit power too high improves SNR

Answer: (A)

Compression in ultrasound refers to how the display maps echo amplitudes into brightness levels, i.e., the dynamic range of the image. If compression is set too high, bright echoes saturate the display, causing those areas to appear overly bright and wash out finer details in regions of high intensity. At the same time, transmitting with too little power reduces the energy sent into the tissue, so the echoes are weaker. That lowers the signal strength relative to the noise, producing a weak image with poor signal-to-noise ratio. So you get a picture that looks too bright in saturated areas and overall has a diminished, noisier signal due to the low transmit power.