[Predicting renal stone fragility against ESWL]

The mineral content (MC) and mineral density (MD) of renal stones, measured by dual energy X-ray absorptiometry, were compared with the experimental and clinical results of stone disintegration by shock wave.

In the experimental study, the MC and MD values correlated significantly with the total shock wave energy used, with a correlation coefficient (r) for MC being 0.814 and for MD, 0.706 (n = 46). The mean MC and MD values were 0.521 +/- 0.387g and 0.317 +/- 0.121 g/cm2 (n = 14) respectively in patients undergoing clinically successful ESWL, while those were 4.27 +/- 6.19g and 0.626 +/- 0.302 g/cm2 (n = 6) respectively in patients undergoing clinically unsuccessful ESWL. Those values differed significantly between the two groups (p < 0.05, p < 0.01, respectively). The combination of MC, MD and area values of a stone was shown to be the best predictor of treatment outcome, with a predictive value of incorrect discrimination being 17% and that of correct discrimination, 85% using linear discriminant analysis.

The mineral content and mineral density, measured by dual energy X-ray absorptiometry, may provide the best prediction of outcome of patients undergoing ESWL treatment.