PREDICTION OF GALLSTONE COMPOSITION - SYNTHESIS OF CT AND RADIOGRAPHIC FEATURES IN-VITRO

PURPOSE: To test a morphoradiographic algorithm designed to predict th e composition of gallstones with use of computed tomography (CT) to de fine calcification patterns. MATERIALS AND METHODS: Two reviewers retr ospectively evaluated the radiographic features of 120 separate in vit ro specimens (59 radiopaque and 61 radiolucent), then classified the s tones into several categories of composition with the algorithm. RESUL TS: The most useful features for prediction of cholesterol composition were, in order of decreasing importance, stone shape, absence of dens e calcification on plain radiographs, overall CT attenuation not highe r than that of water, presence of a second generation of smaller stone s, and a peripheral cover of calcification detected on CT scans of agi ng cholesterol stones. The greatest error occurred in distinction betw een stones with mixed composition (50%-79% cholesterol) and older ston es with higher cholesterol content (80%-95% cholesterol). CONCLUSION: The range of qualitative CT appearances advances the possibility of pr edicting gallstone composition and potential outcome of nonsurgical tr eatment.