Evaluation of Urinary Stones Ex Vivo With Micro-Computed Tomography: Preliminary Results of an Investigational Technique

Abstract

Purpose: To evaluate the ultrastructural features of the urinary stonesremoved with endoscopic stone surgery, using micro computed tomography(micro-CT).Materials and Methods: Patients who had endoscopic surgery for renalor ureteral stones removal were included in this study. After surgery, thestones were classified into three groups and investigated with Skyscan 1174micro-CT. Group I underwent percutaneous nephrolithotomy (PNL) withultrasonic lithotripsy; group II had ureteroscopic stone surgery (USS) withpneumatic lithotripsy; and group III (the control group) had stone removalwith USS or PNL without lithotripsy. Stone homogeneity, voids, and theinternal structure of the stones were evaluated. Chi-square test was used toevaluate the difference statistically. P values less than .05 were consideredstatistically significant.Results: A total of 24 “calcium oxalate monohydrate” stones from 24patients were scanned with micro-CT. Stones treated with ultrasoniclithotripsy (group I) were more fragile, fragmented, and cracked than thosetreated with the pneumatic lithotripsy (group II; P = .01). Stones in groupII were more homogeneous and smooth than those in group I and resembled those of the control group (P = .02). Homogeneous, non-fragile stones andheterogeneous, fragile calculi were seen in all groups.Conclusion: The stone fragility could be confirmed by micro-CTinvestigation. Ultrasonic lithotripters increase the stone fragility, which isdemonstrated with increased heterogeneity by micro-CT.

Keywords

• urinary calculi
• micro- CT scan
• radiographic image interpretation
• calcium oxalate