Magnetic resonance imaging is the modality of choice to assess the small bowel. The loops of the small bowel need to be adequately distended for an accurate diagnostic assessment to be made, because if not, collapsed bowel segments may conceal large lesions and normal bowel walls may appear thickened. To achieve this, MR enteroclysis using a duodenal catheter guided by fluoroscopy is usually performed for administration of a distension agent. Oral solutions can also be used, but are they as effective?
Radiologists at the University Hospital of Ulm in Germany decided to find out. They conducted a retrospective analysis of MRI small bowel images acquired after patients had ingested one of two types of oral solutions or had a solution administered by catheter. Study findings published online in Acta Radiologica revealed that one of the orally-administered solutions – locust bean gum/mannitol (LBM) – performed as well and in some areas of the small bowel – better than catheter-administered solution.
The study consisted of an analysis of 45 patients who had a small bowel MRI exam performed using one of the three dissension agent methods during a 36 month time period, psyllium was orally administered to a total of 15 patients. Exams of the first 15 patients who had catheter-administered tylose solution and the most recent 15 patients who ingested locust bean gum and mannitol comprised the remainder. The patient cohort included 26 men and 19 women, who ranged in age from 12 to 71 years. Patients in each subgroup were similar in terms of age distribution, sex, confirmed Crohn’s disease, and segmental mural thickening. Sixty percent had diagnosed pathological thickening of the bowel wall.
Two experienced radiologists independently interpreted the 45 exams, ranking the diagnostic value for the different bowel segments on a 5 point scale. They also measured the diameter of the intestinal lumen for the duodenum and at the ligament of Treitz in the terminal ileum and in the cecum. Lead author Stefan A. Schmidt, M.D., of the department of diagnostic and interventional radiology, and colleagues, determined that highly significant differences concerning the diagnostic value for the duodenum and terminal ileum.
The catheter-administered tylose solution outperformed the oral agents in two major ways. It showed the best bowel distension in the duodenum, in the proximal jejunum and the ileum. The radiologists reported that it was superior in terms of subjective diagnostic value and in the achieved intraluminal diameter. However, the LBM agent produced the best bowel distension in the distal and terminal ileum. It also showed the best distension in the cecum.
Based on the researchers’ findings, the radiology department has changed its standard protocol from MR enteroclysis to oral administration of LBM for the majority of its patients. The authors stated that the LBM solution is now used with patients who have known or suspected lesions involving the more distal small bowel segments – the ileum and terminal ileum. This localization is common in patient with Crohn’s disease.
Performance of oral agents for bowel distension prior to MRI. Appl Radiol.