MRI in the diagnosis of small bowel disease: use of positive and negative oral contrast media in combination with enteroclysis

The aim of the study was to evaluate the additional findings of MRI followi ng small bowel enteroclysis and to compare the efficacy of negative Lna pos itive intraluminal contrast agents. Fifty patients with inflammatory or tum orous small bowel disease were investigated by small bower enteroclysis and consecutive MRI using breathhold protocol (T1-weighted fast low-angle shot , T2-weighted turbo spin echo). Patients were randomly assigned to either r eg a positive oral (Magnevist, Schering, Berlin, Germany) or a negative ora l MR contrast media (Abdoscan, Nycomed, Oslo, Norway). The pattern of contr ast distribution, the contrast effect, presence artifacts, as well as bowel wall and extraluminal changes, were determined and compared between the co ntrast type using Fischer's exact test. Sensitivity, specificity, and diagn ostic accuracy for MRI and enteroclysis were calculated. Twenty-seven patie nts had clinically proven Crohn's disease and two patients surgically prove n small bowel tumours. Magnetic resonance imaging had important additional findings as abscesses and fistulae in 20 patients. Surgically compared sens itivities were 100 and 0% for MRI and enteroclysis, for the detection of ab scesses, and 83.3 and 17% for the diagnosis of fistulae, respectively. Bowe l wall thickening was more reliably detected with use of positive oral cont rast media without intravenous enhancement (p < 0.001), whereas postcontras t negative oral contrast media allow for a superior detection (p < 0.001). T2-weighted sequences were necessary with use of negative oral contrast med ia, because loop abscesses may be ed. Magnetic resonance imaging should be performed in all patients with suspicion of extraintestinal complications, because the complications are ore reliably detected by MRI. Negative oral c ontrast media show advantages with the: use of intravenous contrast but can mask loop abscesses using only T1-weighted imaging.