OBJECTIVE: The aim of this prospective study was to investigate the feasibility of using a negative oral contrast agent to null the bowel signal during magnetic resonance cholangiopancreatography. MATERIAL AND METHOD: Fifteen healthy volunteers with no previous history of pancreaticobiliary disease or surgery were imaged with a single-shot fast spin-echo pulse sequence, using a magnetic resonance imaging system operating at 1.0 T. Data acquisition was started before and after administration of oral contrast agent. Using the magnetic resonance images obtained before and after administration of oral contrast agent, the common bile duct, pancreatic duct and papilla were assessed and graded by two radiologists. The frequency of adverse effects and the tolerance of the contrast were also evaluated. RESULTS: All patients that found negative oral contrast agent unpleasant (73% of the cases) tolerated well the oral contrast agent. Adverse effects as abdominal pain and diarrhea were noted in 30% of the patients. In all patients the high signal intensity from the intestinal fluid was completely suppressed. The depictions of the common hepatic duct were slightly improved, whereas the depictions of the choledochus, papilla and pancreatic duct were markedly improved by the negative oral contrast agent administration. CONCLUSION: Negative oral magnetic resonance contrast agent can be an effective and safe contrast media in eliminating signal intensity of the gastrointestinal tract, thus improving the depiction of the biliary system in magnetic resonance cholangiopancreatography.

Keywords: Magnetic resonance imaging, Biliary system, Pancreatic duct, Contrast media

PURPOSE: To evaluate the carotid and vertebral arteries by magnetic resonance angiography, using different contrast volumes and dilution techniques. SUBJECTS AND METHODS: Prospective study of 15 patients, which included the evaluation of 30 common carotid arteries, 30 internal carotid arteries, 30 external carotid arteries and 30 vertebral arteries, using different gadolinium (Gd-DTPA) volumes and dilutions: group I - single-dose (14 ml of Gd-DTPA); group II - double-dose (28 ml of Gd-DTPA); group III - single-dose, dilution at 50%. Gd-DTPA was administered using a power injector at 2 ml/sec (group I) and 3 ml/sec (groups II and III). A qualitative assessment was performed for each arterial segment. Three radiologists, who judged the quality of depiction of the arteries, vascular signal intensity and contours delineation, performed a consensus analysis. RESULTS: All evaluated features showed better performance in group II (complete depiction of the arteries, good vascular signal intensity and well defined contours). In group I, there was adequate depiction of the arteries, but inadequate vascular signal intensity and contours delineation. Group III showed the poorest results, with inadequate parameters for all evaluated features. CONCLUSION: Among the tested Gd-DTPA dilutions and volumes, double-dose contrast injection allowed better evaluation of the carotid and vertebral arteries. The studies with dilution of Gd-DTPA showed the poorest results.

Keywords: MR angiography. Gadolinium (Gd-DTPA). Carotid arteries.