Computed Tomographic Analysis of Gallbladder Stones: Correlation with Chemical Composition and In Vitro Shock-wave Lithotripsy

The recent advent of nonsurgical treatment for gallstones requires accurate in vivo analysis of their chemical composition in order to select the best candidates. As a preliminary work, we undertook an in vitro CT examination of 53 surgically removed gallstones and compared their CT patterns with their chemical composition. Those results were correlated with in vitro lithotripsy of the gallstones. The CT appearances were classified as follows: laminated (43%), dense (32%), rimmed (11%), isodense (8%) and faint (6%). The dense pattern contained a high calcium content. As the CT density increased, the calcium content increased, but the cholesterol content decreased proportionally. The number of shock waves needed to break down a gallstone less than 2 mm in size increased with stone volume and the cholesterol content increased but did not have any correlation with the calcium content level. As a result we found the CT examination to be a very sensitive method in detecting small amounts of calcium content in gallstones and the CT pattern and density of the gallstones were well correlated with their chemical composition, therefore in vivo CT examinations for ESWL candidates are desirable.