CT-calculometry (CT-CM): advanced NCCT post-processing to investigate urinary calculi.

PURPOSE: This study aimed at evaluating the potential of CT-calculometry (CT-CM) as a novel method to determine mineralisation, composition, homogeneity and volume of urinary calculi based on preoperative non-contrast-enhanced computed tomography (NCCT) scans. MATERIALS AND METHODS: CT-CM was performed in preoperative NCCTs of 25 patients treated for upper tract urinary calculi by ureterorenoscopy or percutaneous nephrolithotomy. Absolute mineralisation values were achieved by use of quantitative CT-osteoabsorptiometry and compared to Fourier infrared spectroscopy as a reference for stone composition. Homogeneity was assessed by advanced software-based NCCT post-processing and visualised by using a maximum intensity projection algorithm. Volumetric measurement was performed by software-based three-dimensional reconstruction. RESULTS: CT-CM was feasible in all of the 25 NCCTs. Absolute mineralisation values calculated by quantitative CT-OAM might be used to identify the most frequent stone types. High levels of inhomogeneity could be detected even in pure component stones. Volumetric measurement could be performed with minimal effort. CONCLUSIONS: CT-CM is based on advanced NCCT post-processing software and represents a novel and promising approach to determine mineralisation, composition, homogeneity and volume of urinary calculi based on preoperative NCCT. CT-CM could provide valuable information to predict outcome of different stone treatment methods.