The Effectiveness of Non-contrast Computerized Tomography (CT) in Evaluation Ofresidual Stones after Percutaneous Nephrolithotomy / 대한비뇨기과학회지

ABSTRACT

PURPOSE: The sensitivity of antegrade pyelogram (AGP), plain film radiography (KUB) and non-contrast, thin cut abdomen computerized tomography (CT) were prospectively compared for the detection of residual stones following a percutaneous nephrolithotomy. MATERIALS AND METHODS: Fifty patients (53 renal units), who had undergone a percutaneous nephrolithotomy for radiopaque renal pelvis stone, as well as a non-contrast abdomen CT 1 month postoperatively, were prospectively evaluated. The number and size of residual fragments, as determined by immediate postoperative AGP, postoperative 1 month KUB and abdomen CT, were compared. RESULTS: The stone-free rates according to the AGP, KUB and non-contrast CT were 73.6 (39/53), 62.3 (33/53) and 20.8% (11/53), respectively. In terms of clinically insignificant residual fragments (CIRFs), the success rates were 84.9 (45/53), 83.0 (44/53) and 41.5% (22/53), respectively. With respect to the residual stones (22 cases), which were detected by CT, but not by KUB, 45.5% (10 cases) were more than 4mm in size on CT, with a mean size of 7.4mm. The sensitivity for the detection of residual fragments was 47.6% for KUB compared to 100% for non-contrast CT. Seven patients received additional extracorporeal shock wave lithotripsy (ESWL) for residual stones following CT. CONCLUSIONS: Non-contrast, thin cut abdomen CT is the most accurate imaging modality for determination of the stone-free rate following a PCNL. Non-contrast abdomen CT gives accurate information for the selection of patients who may benefit from additional ESWL treatment and for follow-up planning.