Role of oral cholecystography, real-time ultrasound, and CT in evaluation of gallstones and gallbladder function

The capacity of oral cholecystography (OCG), real-time ultrasound (RUS), and computed tomography (CT) to detect gallstones and to analyze their size, number, and composition was tested preoperatively in 37 patients undergoing elective cholecystectomy. Gallbladder response to a standard meal was also evaluated by OCG and RUS. Gallstones were analyzed chemically for calcium, cholesterol, and bilirubin content. The results show that RUS is the most valuable test for detecting gallstones and is similar to OCG in measuring their size and number, whereas CT underestimates the stone size. Gallbladder function in terms of contractability can be evaluated by RUS and OCG, but RUS provides useful information even if the gallbladder is not opacified at OCG. CT is more accurate than OCG in detecting the presence of calcium, and CT attenuation numbers are positively correlated with calcium content of the stone (r=0.87,p<0.01).