Bisacodyl micro-enema before MRI of rectal tumors: effects on rectum, image quality and patient acceptance

To assess the effects of a bisacodyl micro-enema on rectal physio-morphology, image quality, and patient acceptance when used as preparation before MRI of rectal tumors.

In this prospective single-center study, we made an intra-individual comparison of patients with suspected early rectal cancer who all completed MRI without (MRex) and with (MRin) a bisacodyl micro-enema. The width and the anal-oral extension of the submucosal edema in the healthy rectal wall, anal-oral extension of luminal fluid, and rectal distension were registered. Image artifacts were recorded with a figurative visual analog scale (fVAS), and patient acceptance with questionnaires at baseline, after MRex, and MRin. Significance levels were calculated with a t-test, the Wilcoxon signed-rank test, or McNemar's test for paired samples and inter-reader agreement with Gwets AC1 statistics.

Consecutively, 50 patients (mean age, 65 years ± 10, 26 men) were included. The median (iqr) summed width of submucosa (MRex, 26 (12) mm, MRin 39 (13) mm, p < 0.01) and anal-oral fluid extension (MRex 0 (0) mm, MRin 134 (91) mm, p < 0.001) increased. Susceptibility artifacts on diffusion weighted imaging (axial plane p ≤ 0.04 and parallel plane p < 0.001) were reduced. No increase in rectal distension, motion artifacts, or side effects was registered, and the patient-reported acceptance remained unchanged.

Bisacodyl significantly increased the submucosal width and extension of intraluminal fluid, did not lead to distension of the rectum, improved image quality, and was well tolerated by the patients.

Question Bisacodyl micro-enema can improve MRI of early stage-rectal tumors, but the impact on rectal physio-morphology, image quality, and patient acceptance is unknown. Result Bisacodyl micro-enema increased the submucosal width and intraluminal fluid, did not distend the rectum, improved image quality, and was well tolerated by the patients. Clinical relevance Bisacodyl micro-enema represents a reliable preparation before MRI of rectal tumors and can improve imaging of early-stage cancer. This is increasingly important because of the shift toward earlier stages due to screening programs and the growing use of organ-saving treatment.