Login to Access Video or Poster Abstract: MP62-01
Sources of Funding: None

Introduction

The mean stone density (MSD) and stone heterogeneity index (SHI), was defined as the mean of Hounsfield unit (HU) and the standard deviation of a HU on non-contrast computed tomography (NCCT), are already reported independent predictor of SWL outcomes. We investigated whether MSD-SHI ratio can be a significant predictor for SWL outcomes in patients with ureteral stones.

Methods

Medical records were obtained from a consecutive database of patients (n = 1,824) who had undergone the first session of SWL between November 2005 and December 2014 in the Severance Hospital, Seoul, Korea. Ultimately, 700 patients with ureter calculi were eligible for the current analyses. Stone related variables including mean stone length (MSL), MSD, skin-to-stone distance (SSD), and SHI were obtained on NCCT.

Results

The mean age of total patients was 52.55±13.88 years. The distribution of ureteral stone locations was comprised of 573 cases of upper ureter stones (81.9%), 48 cases of mid-ureter stones (6.9%), and 79 cases of lower ureter stones (11.2%). The MSL was 9.12±3.89 mm, and the mean MSD and SHI were 707.04±272.10 HU and 244.90±110.16 HU, respectively. The mean SSD was 110.81±18.98 mm. The one-session success and one-session stone-free rates were 69.6%. The univariate logistic regression models revealed the following predictive factors of one-session success following SWL for ureteral stones: shorter MSL, lower MSD, higher SHI, and lower MSD-SHI ratio. The multivariate analyses also demonstrated that a shorter MSL, lower MSD, higher SHI, and lower MSD-SHI were independent predictors of one-session success after SWL for ureteral calculi. For one-session success rates, the AUC of ROC curves in total cohort were 0.725 for MSD, 0.661 for MSL, and 0.749 for MSD-SHI ratio and there were no significant differences between MSD and MSD-SHI ratio (P = 0.348). In patients with upper 50% MSL, the AUC of ROC curves were 0.676 for MSD, 0.661 for MSL, and 0.764 for MSD-SHI ratio and there were significant differences between MSD and MSD-SHI ratio (P = 0.011) (Fig. 1).

Conclusions

MSL, MSD, SHI, and MSD-SHI were independent predictors of one-session success after SWL for ureteral calculi. MSD-SHI showed higher predictive value compared to MSD or MSL in patients with relatively large stone.

Funding

None