Feasibility of small bowel flow rate measurement with MRI

Objective: To evaluate whether it is feasible to measure the segmental flux of small bowel content using MR phase‐contrast (PC) pulse sequences. Materials and methods: Using a phantom the accuracy of flux measurements was validated. Afterwards, 10 volunteers were included in a prospective clinical trial. To provide standardized small bowel distension, all volunteers ingested four equal portions of 400 mL of water doped with 5 mL gadoterate and 5.8 g Metamucil mite. The MR protocol covering the sagittal cross‐sections of the small bowel included several two‐dimensional (2D) PC sequences with a velocity encoding of 7 cm/second at a temporal resolution of 0.55 second. As proof of concept time‐dependent flux was measured after intravenous (i.v.) administration of a spasmolytic agent in one volunteer. Results: Phantom measurements resulted in an excellent correlation between pump and PC measured flow rates (R = 0.999). Time‐resolved small bowel flux was successfully measured in distended small bowel loops of all volunteers. A mean flow rate of 0.188 mL/second (standard deviation ± 0.144 mL/second) was documented. The flux plots presented a sinus wave‐like shape with regular aboral and oral flow. A spasmolytic effect both on flux and motility could be shown with residual flux despite complete arrest of small bowel motility. Conclusion: PC MRI allows time‐resolved in vivo measurement of small bowel flux in single well‐distended bowel loops filled with gadolinium‐doped aqueous solution. J. Magn. Reson. Imaging 2010;32:345–351. © 2010 Wiley‐Liss, Inc.