Radiologic diagnosis of common bile duct stones.

Unenhanced spiral CT and, in the hands of the experienced, US are accurate noninvasive methods of imaging the common bile duct. This is particularly true when there is a low clinical and laboratory probability of a common bile duct stone being present. In the diagnosis of bile duct stones, CT and US are effective and readily available screening techniques and may aid in the selection of patients who require MRCP or treatment with ERCP. Avoiding ERCP and the associated expense and morbidity is a goal that is becoming attainable with optimized CT, US, and MRCP techniques and an awareness of subtle findings.