Role of dual-source dual-energy computed tomography versus X-ray crystallography in prediction of the stone composition: a retrospective non-randomized pilot study

Purpose: We aimed to evaluate the accuracy of determining stone composition with dual-source (DS) dual-energy (DE) computed tomography (CT). Methods: A total of 142 patients, diagnosed with urolithiasis and had complete medical records, were included in the study. The number, dimensions, location and CT density of the stones, and dose-length products and effective radiation dose were recorded for every patient. Stone compositions determined with DECT by two radiologists separately were compared with crystallography method. Results: Among 138 stones with a crystallographic result out of 187 stones evaluated, 58 calcium oxalate, 42 hydroxyapatite, 24 uric acid and 10 cystine stones were detected. DECT showed a sensitivity and negative predictive value of 68.67 and 67.5 % for calcium oxalate. Moreover, DECT was found to be very useful in predicting hydroxyapatite and cystine stones with a 100 % sensitivity and negative predictive value. Cohen kappa correlation test showed a substantial agreement (κ = 0.682) between crystallographic analysis and prediction with DECT-analysis, which was statistically significant (p < 0.001). Conclusion: In this retrospective study, an unenhanced DECT was found to be accurate for in vivo determination of stone type, and thus it can be used easily without any extra burden to the patient or cost while providing additional information.