The value of negative oral contrast material in MR cholangiopancreatography

Purpose: Evaluation of the use of a negative oral contrast material in MR cholangiopancreatography (MRCP). Material and methods: We performed MRCP in single-shot technique (TSE, RT=2800 ms, TE=1100 ms, ETL=64) in 38 patients before and 20-30 min after oral administration of 300-600 ml of a negative oral contrast material. The visualization ducts and details important for the diagnosis was evaluated in a blinded manner. Ductal diameters were measured. Both sets of images were evaluated qualitatively. Results: The ductal diameters did not change after administration of oral contrast material. In 1/3 of all cases the ductal structures were superimposed by a high signal intensity of fluid in the gastrointestinal tract, especially in the tail of the pancreas. After administration of oral contrast material only in 3 patients could a complete visualisation of the ducts not be achieved. In 5 cases, details relevant for the diagnostic decision could be seen only on post-contrast images. The anatomic orientation was not compromised by the absence of signal in the gastrointestinal tract. Conclusion: Negative oral contrast material should be given before performing a MRCP to provide non-superimposed visualization of the bile and pancreatic ducts. There is no negative influence of the oral contrast material on the diameter of the ducts. (orig.)