Color flow Doppler sonography for extracorporeal shock wave lithotripsy.

This report documents the usefulness of color Doppler sonography for early verification of urinary stone fragmentation during extracorporeal shock wave lithotripsy with ultrasonographic focusing. In the experimental study lithotripsy was performed on human urinary stones placed in pig kidneys. Increasing color flow within the stone mass created by movement of small fragments indicated fragmentation earlier than pixel movement on the standard gray scale sonogram. The success of treatment was demonstrated macroscopically. In the clinical study 25 patients with radiopaque kidney stones were treated by color Doppler guided shock wave lithotripsy and compared to a control group of 32 patients with similar stone characteristics in whom the end point of treatment was chosen based on B-mode sonography alone. The amount of color flow within the stone reflex determined the end point of treatment. The degree of fragmentation was confirmed by fluoroscopy immediately after treatment. Disintegration was successful in all cases and fragments passed spontaneously. Color Doppler imaging during shock wave lithotripsy provides reliable information on the spatial and temporal characteristics of stone fragmentation, and is superior to B-mode sonography by providing more immediate, objective information on stone fragmentation and allowing better evaluation of the focal zone. With the help of this technique, the number of applied shock waves could be reduced by 20% compared with the control group.