Detecting composition of urolithiasis by Raman spectroscopy after minimal invasive urological management

Urolithiasis is a common, disturbing disease with high recurrent rate (60% in five years). Accurate diagnosis of urinary stone composition is important in preventing stone recurrence. With the improvement in minimal invasive urological surgery, such as ureteroscopic lithotripsy, and extracorporeal shock wave lithotripsy, stone management becomes not so suffering and effective than before. However, the new problem arises in that less and less stone fragments could be collected because of tiny expelled stone powder after MIUS. The goal of this study is to use Raman spectroscopy (RS) to analyze small stone fragments collected from urine of patients with urolithiasis after MIUS. First, data from five main urinary stones [Calcium oxalate monohydrate (COM), Dicalcium phosphate dehydrate (DCPD), Calcium phosphate hydroxide (hydroxyl apatite, or HAP), Calcium oxalate dehydrate (COD), and uric acid] were established in RS database. Second, we used RS and clinical Fourier Transform Infrared Spectroscopy (FTIR) to analyze stone fragments collected from patients with urolithiasis. Seventeen patients were enrolled in the study and all had comparable results between RS detection and clinical analysis by FTIR. RS approach has successfully detected tiny stone powders with or without fluorescence photobleaching. We successfully measured COM, DCPD, HAP, COD, and uric acid stones. This study demonstrated the feasibility of using RS for conducting the clinical stone analysis from the tiny urinary stone sample. It provided satisfying results and could be applied on clinical practice.