In vivo analysis of gallstone composition by computed tomography.

In vivo computed tomography (CT) of the gallbladder was performed in 39 patients with known cholelithiasis and subsequently correlated with the chemical composition of the retrieved gallstones. Six CT patterns were identified: pattern 1, negative defect within the bile; pattern 2, nonvisualization of calculi; pattern 3, faint homogeneous central calcification; pattern 4A, thin rim of calcification; pattern 4B, thick rim of calcification; pattern 5, dense homogeneous central calcification. These CT patterns correlated well with cholesterol (p = 0.05) and calcium bilirubinate (p = 0.01) contents and CT attenuation values (p less than 0.001). The most common pattern was CT pattern 2 (56.5%). The authors conclude that there is good correlation of the CT pattern with gallstone composition. This simple approach can be used to help identify patients for therapy with chemical dissolution and/or lithotripsy.