Multimodal evaluation of renal perfusional changes due to extracorporeal shock wave lithotripsy

To examine the effect of extracorporeal shock wave lithotripsy (ESWL) on renal perfusion before and after treatment, by assessing renal resistive index (RI) using colour Doppler ultrasonography (CDUS), magnetic resonance perfusion imaging (MRPI), radionuclide renography and big-endothelin-1 values (Big-ET-1).

In 69 normotensive patients the RI was measured before, 1, 3, 6 and 24 h after ESWL using CDUS. The RI values, measured in interlobar/arcuate arteries, were correlated with the findings on MRPI, done before and within 24 h after ESWL. In addition, renal plasma flow (RPF, assessed on radionuclide renography) and Big-ET-1 levels (a potent vasoconstrictor peptide), served as a control for evaluating renal perfusion. The patients were stratified in three age groups, i.e. or=60 years, with 23 patients in each group.

The mean (sd) RI increased significantly in the treated kidneys, from 0.64 (0.05) before to 0.72 (0.08) after ESWL (P = 0.001). Only in patients aged >or=60 years did the RI continue to increase over the 24 h. MRPI showed a decrease of renal blood flow (RBF) in all age groups, but most significantly in those aged >or=60 years. The radionuclide renography and big-ET-1 levels changed significantly only in the oldest group. The best correlation was between RI and RBF changes detected by MRPI.

ESWL obviously causes disturbances of renal perfusion, particularly in elderly patients (>or=60 years). Measurement of RI with Doppler techniques might provide useful information for the clinical diagnosis of renal damage.