Stone Heterogeneity Index as a New Parameter for Prediction of Shockwave Lithotripsy Outcomes

Abstract

Background Renal stones are a major public health concern with continuously increasing prevalence. Extracorporeal shock wave lithotripsy (ESWL) which was introduced more than three decades ago as an authentic modality for the treatment of urinary stone disease is considered first choice of treatment for nearly all kind of urinary tract calculi. The outcome of ESWL for renal and ureteral stones depends on many factors, including stone size, Hounsfield Unit (HU), Skin Stone Distance (SSD) and Body Mass Index (BMI). Objective To introduce the concept of Stone Heterogeneity Index (SHI) as a single factor or in combination with other factors that predict the outcome of extracorporeal shock wave lithotripsy for adult patients with renal or ureteral stones. Methods This is a prospective study conducted on 60 Patients with renal and ureteral stones planned to have ESWL sessions attending urology outpatient clinic in Ain shams university and Misr University for Science and Technology hospitals. Results The radiologic heterogeneity of a urinary stone or SHI was independently associated with SWL success in patients with renal and ureteral calculi. SHI in the success group was 246.49 ± 82.13 while in the failure group was 159.20 ± 47.59 with Cutoff point < 183 predicting failure of ESWL outcome. SHI between success and failure groups was statistically significant being higher in success group. (p = 0.000). Conclusion SHI will play a promising role when determining a treatment modality in patients with a urinary stone, and especially when selecting the proper SWL candidates from the patients with a stone of large size or high Mean Stone Density (MSD).