Benefits & pitfalls of administration of rectal gel enema in MRI assessment of rectal cancer

Objectives

To assess diagnostic benefits of filling of the rectum with ultrasound gel during MR assessment of rectal cancer and the pitfalls that occurs due to rectal distention.

Materials/methods

40 patients presented with rectal cancer for either initial MR staging or for assessment after neoadjuvent chemoradiotherapy using ultrasound transmission gel as a contrast for rectal filling.

Results

MR with gel rectal filling showed better depiction in all patients with small tumors than in non filling of the rectum. The filling of rectum with gel increased the distance of the lower tumor border from the anal verge however it showed better assessment of the site of the fixed tumor lower edge in all cases of pedunculated tumor masses. Also rectal filling decreases the distance from the perirectal fascia which may affect the CRM.

Conclusions

MR with rectal gel filling is useful in assessment of cases with rectal cancer and by combining empty rectum & distended rectum in the same study we can get the benefits & avoid the pitfalls by correlating the images in both techniques.Clinical Relevance/Application This study helped in assessment of patients with rectal cancer either referred for initial MR staging or for assessment after neoadjuvent chemoradiotherapy.