Khalaf 1 Cine MRI assessment of motility in the unprepared small bowel in the fasting and fed state: Beyond the breath-hold Running head: Optimised analysis technique for the assessment of small bowel motility

Background: The symptoms of functional bowel disorders are common in postprandial but investigations are generally undertaken in the fasted state using invasive procedures. MRI provides a non-invasive tool to study the gastro-intestinal tract in an unperturbed, fed state. The aim of this study was to develop a technique to assess small bowel motility from cine MRI data in the unprepared bowel in fasting and fed states. Methods: Fifteen healthy volunteers underwent a baseline MRI scan after which they consumed a 400g soup. Subjects then underwent a postprandial scan followed by further scans at regular intervals. Small bowel motility was assessed using single-slice bTFE cine MRI. An optimised processing technique was used to generate motility data based on power spectrum analysis of voxel-signal changes with time. Inter-observer variability (n=15) and intra-observer (n=6) variability were assessed. Changes in the motility index were compared between fasted and immediate postprandial state. Results: Excellent agreement between observers was seen across the range of motility measurements acquired, with intraclass correlation coefficient (ICC) of 0.979 (p<0.0001) and Bland-Altman limits of agreement 95% CI: -28.9 to 45.9a.u. Intraobserver variability was low with ICC of 0.992 and 0.960 (2 observers, P<0.0001). Changes from the fasted to immediately postprandial state showed an average increase of 122.4±98.7% (n=15)