Bile-tagged 3D magnetic resonance colonography after exclusive intravenousadministration of gadobenate dimeglumine, a contrast agent with partial hepatobiliary excretion

RATIONALE AND OBJECTIVES. Imaging of the colon is an important diagnostic p rocedure. Endoscopic colonoscopy and x-ray barium enemas are currently the standard diagnostic procedures. Magnetic resonance (MR) and computed tomogr aphic colonography have been recently introduced with true three-dimensiona l (3D) cross-sectional imaging. Up to now, all imaging techniques have requ ired the use of oral and/or aboral contrast agents for luminal enhancement and commonly, a relaxation medication (glucagon or N-butylseopolamine). Whi le performing several phase I, II, and III studies with a new partially hep atobiliary excreted gadolinium-based MR contrast agent, we noted substantia l intraluminal enhancement within the colon and investigated its potential for imaging. METHODS. Three-dimensional MR angiographic techniques enable imaging of lar ge volumes. We have used these sequences to detect contrast enhancement wit hin the hepatobiliary and gastrointestinal systems. A 3D volume of 40 x 32 x 12 cm with 42 images was acquired under breath-hold. Six volunteers were studied according to the protocol. No bowel preparation was performed and n o medication given. Subsequent follow-ups of the abdomen were performed at 1, 12, 24, 36, 48, 70, and 105 hours postinjection. Gadobenate dimeglumine at 0.1 mmol/kg body weight was given intravenously. Images were assessed qu antitatively and by blinded reader analysis. RESULTS. Intense intraluminal contrast enhancement within the colon was see n within 24 hours in all subjects. The homogeneous enhancement was of suffi cient intensity to enable 3D visualization and virtual endoscopy. The optim al time window for imaging was determined to be 16 to 50 hours postinjectio n. CONCLUSIONS. We report for the first time the feasibility of exclusively bi le-tagged MR colonography with the use of only an intravenous MR contrast t hat exhibits partial hepatobiliary excretion. This new diagnostic procedure will enable not only morphological assessment of the colon but also functi onal and pathophysiological studies on the transport kinetics of bile and s tool without any preparation of the patient.