The value of negative oral contrast material in MR cholangiopancreatography

Purpose: Evaluation of the use of a negative oral contrast material in MR c holangiopancreatography (MRCP). Material and methods: We performed MRCP in single-shot technique (TSE, TR = 2800 ms, TE = 1100 ms, ETL = 64) in 38 pat ients before and 20-30 min after oral administration of 300-600 mi of a neg ative 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 d uctal diameters did not change after administration of oral contrast materi al. In 1/3 of all cases the ductal structures were superimposed by a high s ignal intensity of fluid in the gastrointestinal tract, especially in the t ail 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 o n 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 ne gative influence of the oral contrast material on the diameter of the ducts .