Gallstone Dissolution with Methyl Tertiary Butyl Ether: An Experimental Study on Selection of Gallstone by Plain Radiography and Ultrasonography

ABSTRACT

PURPOSE: The purpose of this study was to determine whether in vitro plain radiography and ultrasonography(US) could predict the outcome of gallstone dissolution with methyl tert-butyl ether(MTBE). METHODS AND MATERIALS The plain radiography and ultrasonography of 75 gallstones removed at surgery from 75 patients were obtained. The plaih radiographic findings were grouped by their calcification pattern as group llucent, group 2central, group 3diffuse and group 4 laminated. The ultrasonographic findings were grouped by their echo pattern as group 1arc shaped, clearly defined surface echo followed by distinct acoustic shadow, group 2strong surface echo with gradually attenuating, meniscus shaped inner echo, group 3strong surface echo with fill-in pattern of internal echo, group 4strong surface echo with irregular inner echo and group 5entirely discerning circumsference, homogeneous internal echotexture. After imaging, the gallstones underwent MTBE dissolution for 6 hours. The residual weight of each stone was measured every 2 hours. The correlation between imaging findings and dissolution rate was retrospectively analysed. RESULTS: The radiolucent and central calcification stones were dissolved rapidly as compared with the diffuse and laminated calcification stones(p<.05). There was no statistically significant difference among the groups based on ultrasonographic findings alone. However, after exclusion of the certain calcification groups that were resistent to dissolution-diffuse or laminated calcification stones-all US groups except one that shows wholly circumscribed margin and homogeneous fill-in pattern of internal echo dissolved well to average 20% or less of the original weight(p<.05). CONCLUSION: MTBE dissolution can be tried in stones that meet both ultrasonographic (not a stone with homogeneous fill-in pattern of internal echo) and plain radiographic (radiolucent or cental calcification stone) criteria.