Motility index measured by magnetic resonance enterography is associated with sex and mural thickness.

Background: Recently, a technique has been developed to use magnetic resonance enterography (MRE) for the evaluation of small bowel motility. The hypothesis was that assessment of the motility index (MI) should reflect differences in motility between clinical conditions.

Aim: To aim of the present observational, cross-sectional study was to evaluate the use of the MI in daily clinical practice.

Methods: All consecutive patients aged 18-70 years who were referred for MRE at the Department of Radiology during a 2-year period were asked to participate. Healthy volunteers were included as controls. MRE was prepared and conducted in accordance with clinical routines. On the day of examination, all the participants had to complete the visual analog scale for irritable bowel syndrome (IBS) and IBS-symptom severity scale. Maps of MI were calculated from dynamic MR images. ANOVA was used to evaluate differences in MI between groups, classified as healthy, Crohn's disease, ulcerative colitis, IBS, other assorted disorders and dysmotility. Logistic and linear regression were applied to the MI values. All medical records were scrutinized for medical history.

Results: In all, 224 examinations were included (inclusion prevalence 76.3%), with 22 controls and 202 patients. There was a significant difference in the MI of the jejunum ( 0.021) and terminal ileum ( 0.007) between the different groups. The MI was inversely associated with the mural thickness of the terminal ileum in men ( 0.001) and women ( 0.063) after adjustments, and tended to be lower in men than in women ( 0.056). Subjectively observed reduction of motility on MRI was accomplished by reduced MI of terminal ileum in men ( 0.001) and women ( 0.030). In women, diarrhea was inversely associated with the MI of the jejunum ( 0.029), and constipation was positively associated with the MI of the terminal ileum ( 0.039).

Conclusion: Although MIs differ across diseases, a lower MI of the terminal ileum is mainly associated with male sex and an increased mural thickness. Symptoms are weakly associated with the MI.