How spiral computed tomography can be helpful in the evaluation of urinary stones composition?

determining its most appropriate management. Helical computed tomography (CT) can provide helpful information on stone size and stone composition. Objectives: We sought to determine the urinary stone composition by CT characteristics. Materials and Methods: Since March 2008 till August 2009, 120 renal stones were obtained from patients who had undergone pyelolithotomy or nephrolithotomy at the Imam-Ali hospital, Zahedan, Iran. Stones with the largest diameter more than or equal to 5 mm were studied. Each calculus was placed inside the chicken lean meat. The radiologist was unaware of the exact chemical composition of the stones. We used independent sample t test for comparison of the absolute Hounsfield unit (HU) values of the different types of calculi. Results: Of total 120 participated patients, 67 (55.8%) were male and 53 of them (44.2%) were female. The mean age of cases was 35.8 ± 12.4 years. According to HU in CT scan and final confirmation with chemical analysis, the calculi were classified into several groups. Of 120 stones, 112 were chemically pure and 8 were mixed. There were 59 calcium oxalate, 27 calcium phosphate, 17 uric acid, 5 struvite, 4 cysteine and 8 mixed stones with variable ratios. In the analysis of the stones, overall difference between densities of the stones was statistically significant (P < 0.001). Conclusion: According to the result of our study, we concluded t