The rule of nuclear imaging in evaluating cholestasis - An update

The demonstration of ductal obstruction with or without dilatation is crucial in distinguishing medical from surgical jaundice. Ultrasonography is an extremely sensitive modality for detecting ductal dilatation and, in many cases, may also identify the underlying cause of obstruction. The advent of (99m)Tc-IDA cholescintigraphy has added an important new dimension to hepatobiliary imaging, supplying needed functional information concerning bile flow that is not available from the morphologically based ultrasound studies. This information is obtainable in patients whose bilirubin level is as high as 30 mg/100 ml. Thus, the two procedures frequently are complementary. In addition, in some clinical situations, cholescintigraphy may substitute for, or even be preferable to, ultrasonography. When the biliary tract is acutely obstructed, the functional abnormality frequently is immediately detectable, days before anatomic dilatation is detectable by ultrasound. Other situations where cholescintigraphy can add extremely important information include cases of localized intrahepatic obstruction and postoperative cases where ductal ectasia may be a 'normal' finding. In addition, the nuclear medicine procedure offers definite technical advantages over ultrasonography.