The Value of Non-Enhanced Spiral CT in the Diagnosis of Suspected Urolithiasis

Ahn, Sang Seog; Lee, Seong Ho; Kang, Il Mo

Abstract

PURPOSE: We prospectively determined the value of a non-enhanced spiral CT (NESCT) in the diagnosis of suspected urolithiasis by a comparison with excretory urography (EU).
MATERIALS AND METHODS
After giving informed consents, 114 and 103 patients, with suspected urolithiasis, underwent either NESCT or EU, respectively. All the NESCT and EU films were assessed by 2 urologists and 1 radiologist with no knowledge of the clinical histories. The sensitivity, specificity, positive and negative predictive value, diagnostic accuracy and other valuable diagnostics in each group were compared.
RESULTS
The sensitivity, specificity and accuracy of NESCT in diagnosing urinary calculi were 96.8, 95.2 and 96.5%, and for EU, were 75.3, 90.9 and 78.6%, respectively. The examinations were performed with an average of less than 5 minutes for the NESCT versus 113+/-31 minutes for the EU, and the times taken to a definitive diagnosis in the two groups were 2.4+/-0.3 and 59+/-5.2 hours, respectively. In the EU group, 24 patients (23.3%) had revisited and 11 (10.6%) were admitted for pain control, prior to the imaging evaluation, only 2 patients (1.7%) revisited, and none were admitted in the NESCT group. In our institution, the cost of a NESCT was more expensive than that of an EU (140,000 vs. 35,790 Won), however the cost-effectiveness is enhanced by the accuracy of NESCT, which lead to fewer ancillary studies.
CONCLUSIONS
NESCT is accurate, reliable and safe, and has many advantages over EU, and therefore could be recommended as a first diagnostic modality for the evaluation of patients with suspected urolithiasis.