The Usefulness of Unenhanced Helical Computerized Tomography in Patients with Urinary Calculi

Kim, Hong Seok; Jang, Sang Woong; Jeong, Young Beom; Kim, Young Gon; Kim, Jong Soo

Abstract

PURPOSE: This study was performed to ascertain the usefulness of unenhanced helical computerized tomography(unenhanced CT) in patients with urinary calculi.
MATERIALS AND METHODS
Between June 2001 and August 2002, 72 patients with acute flank pain, suspected of having urinary calculi, underwent an unenhanced CT, followed by intravenous urography(IVU) within 24 hours. The unenhanced CT and IVU were compared for the presence and location of the urinary calculi and secondary signs of ureteral obstruction(hydroureter, hydronephrosis, strands of perinephric fat and strands of periureteric fat, tissue-rim sign).
RESULTS
65 of the 72 patients had 74 urinary calculi. Unenhanced CT diagnosed 72 urinary calculi with a sensitivity and specificity of 97.3 and 100%, respectively, with 2.7% false negative. IVU diagnosed 49 urinary calculi with a sensitivity and specificity of 63.5 and 80%, respectively, with 36.5% false negative. For the secondary signs of ureteral obstruction, unenhanced CT diagnosed 71.2% with hydronephrosis, 63.6% with hydroureterosis, 19.7% with tissue rim sign, 15.2% with strands of perinephric fat, and 12.1% with strands of periureteric fat; and IVU diagnosed 76.1% with hydronephrosis, 60.9% with hydroureterosis and 56.5% with delayed ureteral opacification. Besides the urinary calculi, gall bladder stones and renal simple cysts were diagnosed. The cost of the unenhanced CT was about four times higher than that of the IVU.
CONCLUSIONS
Unenhanced CT is an accurate, safe and rapid technique for the assessment of urinary stones, and would be a valuable diagnostic tool for urinary calculi.