Objective: To explore the feasibility of CT attenuation value (CTvalue) to predict the composition of upper urinary calculi and the number of shock waves (NSW) and success rate (SR) of extracorporeal shock wave lithotripsy (ESWL).
Methods: A total of 146 patients with upper urinary calculi treated by ESWL were included. CT scan was performed before ESWL. Upper urinary calculi with the maximum diameters of less than or equal to 2 cm were included. Infrared spectroscopy was used to analyze the composition of calculi. The effect of ESWL was estimated at 1 month followup. The factors that influence NSW and SR of ESWL were analyzed by correlation analysis.
Results: The CTvalue of calcium calculi were larger than that of noncalcium calculi ( P<0.001). The differences of NSW,SR of ESWL and CTvalues of calculi between the patients with different ages,skintostone distances and genders were not statistically significant. The partial correlation analysis found that CTvalue and long diameter of calculi were positively correlated with the NSW ( P<0.05). This result was consistent in subgroup analysis (stone site: kidney or ureter). CTvalue and long diameter of calculi were negatively correlated with SR of ESWL ( P<0.05). However,the CTvalue of ureteral calculi was not correlated with SR of ESWL in subgroup analysis.
Conclusion: The power of CTvalue to predict upper urinary calculi composition is insufficient. Higher CTvalue suggests more NSW in ESWL,but CTvalue is not suitable to predict SR of ESWL.
Keywords: CT; Composition; Shock wave lithotripsy; Urinary calculi.