Prediction of gallstone composition: synthesis of CT and radiographic features in vitro.

Abstract

To test a morphoradiographic algorithm designed to predict the composition of gallstones with use of computed tomography (CT) to define calcification patterns. Two reviewers retrospectively evaluated the radiographic features of 120 separate in vitro specimens (59 radiopaque and 61 radiolucent), then classified the stones into several categories of composition with the algorithm. The most useful features for prediction of cholesterol composition were, in order of decreasing importance, stone shape, absence of dense calcification on plain radiographs, overall CT attenuation not higher than that of water, presence of a second generation of smaller stones, and a peripheral cover of calcification detected on CT scans of aging cholesterol stones. The greatest error occurred in distinction between stones with mixed composition (50%-79% cholesterol) and older stones with higher cholesterol content (80%-95% cholesterol). The range of qualitative CT appearances advances the possibility of predicting gallstone composition and potential outcome of nonsurgical treatment.