Renal stone shadowing: an investigation of contributing factors.

A series of in vitro experiments evaluated the effects of intervening tissue, B-mode processing algorithms, stone chemical composition, stone size, and reverberation artifacts on the acoustic shadows of renal stones. Stone size was found to be the most important variable; intervening tissue and focal zone placement also affected imaging. Reverberation artifacts may fill in an acoustic shadow, but can still provide information. The survey algorithm produced slightly clearer shadows than the static storage algorithm. Gray-scale map changes, increased power, and chemical composition of calculi did not affect shadowing.