Use of computerized tomography in the delineation of uric acid calculi.

Computerized tomography without injection of contrast material was used to detect the presence of uric acid stones within the kidney in 10 patients. In contrast to the lucent appearance on conventional urography the stones are dense on computerized tomography. The technique is useful to differentiate lucent stones from renal pelvic tumors. Additionally, stone dissolution can be monitored with sequential computerized tomography studies.