ACCURACY OF DETECTION AND MEASUREMENT OF RENAL CALCULI - IN-VITRO COMPARISON OF 3-DIMENSIONAL SPIRAL CT, RADIOGRAPHY, AND NEPHROTOMOGRAPHY

PURPOSE: To compare accuracy of three-dimensional (3D) spiral computed tomography (CT) performed without administration of contrast material with that of radiography and linear nephrotomography in detection and measurement of renal calculi. MATERIALS AND METHODS: Fifty renal calc uli within an abdominal phantom were imaged with 3D spiral CT, radiogr aphy, and linear nephrotomography. Spiral CT data were analyzed with w orkstation-based 3D imaging software, with a thresholding procedure ba sed on the maximally attenuating voxel within each calculus during mea surement. Measurement accuracy and detection rates were compared accor ding to modality. Conventional and magnification corrected measurement s from radiography and linear nephrotomography were included. RESULTS: Spiral CT depicted calculi and allowed determination of the collectiv e two-dimensional and 3D linear measurements statistically significant ly more accurately than the other techniques; the mean linear measurem ent errors along individual axes did not exceed 3.6%. With 3D spiral C T, calculus volumes were determined with a mean error of -4.8%. CONCLU SION: 3D spiral CT enabled highly accurate determination of the volume s and all three linear dimensions of renal calculi. In addition, 3D sp iral CT depicted calculi more sensitively than traditional techniques and provided new information and improved accuracy in the evaluation o f nephrolithiasis.