Evaluation of Acute Post-Shock Wave Lithotripsy Renal Changes by Dynamic Magnetic Resonance Imaging: A Prospective Clinical Study

Abstract

We studied acute renal morphological and hemodynamic changes aftershock wave lithotripsy of renal stones. A total of 60 adult patients with a single renal stone 25mm or less in a radiologically normal urinary tract were eligible for shock wave lithotripsy and included in analysis. Study exclusion criteria were hypertension, diabetes mellitus, previous recent stone management and other contraindications to shock wave lithotripsy. Renal perfusion and morphological changes were evaluated by dynamic magnetic resonance imaging before, and 2to4 hours and 1 week after lithotripsy. In all cases there was a statistically significant decrease in renal perfusion 1 week after shock wave lithotripsy compared to before and 2 to 4hours after lithotripsy (66% vs 71% and 72% of the aortic blood flow, respectively, p<0.05). At 1-week followup 39 unobstructed renal units (65%) showed no significant difference in renal perfusion at any time while 21 (35%) obstructed renal units showed a significant decrease in renal perfusion compared to before and 2 to 4 hours after lithotripsy (63% vs 76% and 75%, p = 0.003 and 0.005, respectively). Hematomas were observed in 7 cases (12%) 2 to 4 hours after lithotripsy, of which 5 were subcapsular and 2 were intrarenal. Three subcapsular hematomas resolved after 1 week. Localized loss of corticomedullary differentiation was observed in 2 patients (3.3%) with intrarenal hematoma 2 to 4hours after treatment. Generalized loss of corticomedullary differentiation wasobserved 1 week after lithotripsy in 5 cases (8.3%). Shock wave lithotripsy alone induces minimal, reversible acute renal morphological changes and does not induce significant changes in renal perfusion. Posttreatment obstruction has a major effect on renal perfusion on thetreated side and must be managed urgently.