Low pretreatment gallbladder stone densities at computed tomography predict rapid stone clearance following extracorporeal shock wave lithotripsy.

The importance of routine computer tomographic (CT) stone analysis in optimizing the therapeutic outcome after extracorporeal shock wave lithotripsy (ESWL) remains controversial. The aim of the present prospective study was to seek a correlation between CT findings and stone clearance rates after ESWL in 159 patients. One hundred fifty-nine symptomatic patients (116 females, 43 males) with solitary radiolucent gallbladder stones underwent CT for stone analysis before lithotripsy. In Group I (<50 HU, n=104), stone clearance was achieved in 55.8% of patients within 6.11+/- 6.95 months; in Group II (51-100 HU, n = 28), in 50.0% of patients within 11.2 +/- 10.3 months; in Group III (>100 HU, n = 27) in 29.7% of patients within 9.60 +/- 6.96 months. The mean follow-up period was 17.9 +/- 10.0 months. Patients in Group I showed a significantly higher rate of stone clearance than those in Groups II and III (p < 0.001) as well as a significantly shorter time for the achievement of total stone clearance than either of the other groups (p < 0.001). The authors conclude that CT stone analysis provides a more accurate method of selecting patients suitable for ESWL and may be of importance in predicting the expected length of time for achieving complete stone clearance.