MR imaging of normal extrahepatic bile ducts.

Abdominal scans of 48 patients without evidence of biliary tree or pancreatic head pathology were retrospectively evaluated to determine how often the normal common bile duct (CBD) could be visualized, as well as to determine which projections and pulse sequences optimized its visualization. Axial sequences with long repetition time (TR) and for echo time (TE) intervals (2,000-2,500 and 60-80 ms, respectively) were the most useful, identifying the normal CBD in 15 of 30 diagnostic studies. Axial sequences using short TR/TE intervals (300-800 and 20-25 ms, respectively) were less informative, identifying the CBD in only eight of 30 studies. Coronal studies were not useful, identifying the CBD in only one of 10 long TR/TE pulse sequences.