Oddi sphincter and common channel: evaluation with pharmacodynamic MR cholangiopancreatography using fatty meal and secretin stimulation.

PURPOSE: This study was performed to assess the usefulness of pharmacodynamic MR cholangiopancreatography (MRCP) in depicting the segment covered by the Oddi sphincter.

MATERIALS AND

METHODS

Twelve volunteers were studied by pharmacodynamic MRCP. After stimulation by the oral intake of a fatty meal and an intravenous injection of secretin, a single-shot rapid acquisition relaxation enhancement (RARE) sequence was used to obtain consecutive images of the segment covered by the Oddi sphincter. The contraction range of the Oddi sphincter and the lengths of the common channel were measured on the MR console by comparing the most contracted image of the sphincter with the most relaxed image.

RESULTS

Pharmacodynamic MRCP showed periodic contraction of the Oddi sphincter in all cases. The range of sphincteric contraction over the biliary duct was 8-19 mm (11.8+/-3.2 mm, mean +/- standard deviation) and over the pancreatic duct 8-23 mm (10.0+/-1.5 mm). In 11 of the 12 cases, the common channel was depicted and its length ranged from 3-8 mm (5.2+/-1.3 mm).

CONCLUSION

Pharmacodynamic MRCP clearly depicted the range of contraction of the Oddi sphincter and the common channel, which are not usually revealed by conventional MRCP.