MO118ROLE OF DUAL ENERGY COMPUTED TOMOGRAPHY IN PREDICTING THE CHEMICAL COMPOSITION OF STONES

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Abstract Background and Aims Dual-energy CT (DECT) has shown excellent outcomes in differentiating the chemical composition of the urinary stones with a great accuracy. A reliable determination of the chemical type of the stone help the clinician to better satisfy treatment options for the patient- medical versus surgery We used the DECT in our study to assess the accuracy of non-invasive differentiation of renal stones using the 3rd generation dual-source computed tomography (CT) scanner in determining the chemical composition of renal stones and to determine appropriate management based on DECT determined chemical composition of stones. Method This prospective study was conducted in the Department of surgery and radiodiagnosis and Imaging, Era Medical College and RML institute of Medical Sciences , Lucknow over the study period, i.e., November 2016 to May 2018 . The patients were those referred for non-contrast/contrast CT for the diagnosis/evaluation of urolithiasis from the department of Surgery admitted for PCNL/ESWL/therapeutic ureterorenoscopy. DECT ratios of the various stones were noted and compared with the post extraction analysis of stones for composition. A total of 100 patients were included in the study, and their DECT results were compared with the post-extraction analysis (by infrared spectroscopy as the standard comparative method). Results Mean age of patients was 41.15+/- 10.08 years with 64% being males. DECT was highly sensitive and specific in the diagnosis of various types of calculi based on their dual-energy ratio. It was found to be 100% sensitivity and 97.2% specificity for differentiating UA stones with level of agreement between chemical and DECT was almost perfect (k= .951) .However for hydroxyapatite stones was substantial (k=.889). Most of the stones belonged to non-UA category (72%), and only 28% were UA calculi. The sensitivity and specificity in differentiating a calcium oxalate from non-calcium oxalate calculus was 94.1% and 95.5%, respectively. Conclusion DECT highly sensitive and effective in characterizing chemical composition of the urinary stones and can help in determining the management plan and reduce the unnecessary burden of surgical interventions.