Ct-Based Stone Density as a Predictor of Treatment Modality Selection in Urolithiasis

Abstract

Objective: To assess the effectiveness of non-contrast computed tomography (NCCT) of stone density (Hounsfield Units, HU) as a predictive variable in the selection of a treatment modality and prognosis of patients with urolithiasis with a particular focus on the success rates of Shock Wave Lithotripsy (SWL).

Materials and Methods: The study is a retrospective cohort study in a sample size of 450 patients, who have undergone treatment of renal and proximal ureteral calculi between January 2024 and June 2025. Stratification of the patients was done according to treatment modality i.e., SWL (Group A) and Ureteroscopy with Laser Lithotripsy (URS) (Group B). Mean stone density was measured by the use of preoperative NCCT. The main results were stone-free rate (SFR) after 3 months, the number of SWL sessions and complication rates. Statistical analysis involved Chi-square and independent t-tests, and Receiver Operating Characteristic (ROC) curve.

Results: The average density of the stones was significantly greater in patients who needed secondary intervention after SWL than in those who were stone free (1150 +- 210 HU vs. 780 +- 190 HU; p<0.001). The ROC analysis was able to determine an optimum HU cutoff of 950 to predict SWL failure (Sensitivity 88% Specificity 82%). Multivariate analysis proved that stone density was an independent predictor of treatment failure OR=3.45; p=0.002). SWL versus URS Patients with stone density greater than 1000 HU had a much lower SFR than those in the URS (62%62% vs.94%; p<0.001).

Conclusion: NCCT stone density is a non-invasive, powerful predictor of stone vulnerability and treatment result. Stones that have a density of more than 950-1000 HU have a much lower SWL success. The inclusion of HU measurement into preoperative planning contributes to the optimal choice of the treatment modality decreasing the rates of retreatment and healthcare expenses.