B-0625 Features on MRI after transanal endoscopic microsurgery in patients with rectal cancer

L.A. Heijnen, M. Maas, M.H. Martens, D.M.J. Lambregts, J.W.A. Leijtens, W. Deserno, G.L. Beets, R.G.H. Beets-Tan | Sunday, March 10, 10:30 – 12:00 / Room A

Purpose: Transanal endoscopic microsurgery (TEM) is a minimal invasive technique for local resection of T1 and selected T2 tumours and is also an emerging option for good-responders after chemoradiation. In most centres follow-up includes regular MRI. This study aimed to describe the MR morphology of the rectal wall during follow-up in patients that received TEM.
Methods and Materials: Forty-nine patients underwent a post-TEM MRI in our centre. For 21 patients only one post-operative MRI was available. For 28 patients >1 MRIs were available. The MR morphology of the TEM-site was studied on the consecutive MR examinations. 32 patients were primary treated with TEM, 17 patients underwent chemoradiation followed by TEM.
Results: We identified three morphological patterns: (1) rectal wall thickening with or without fibrosis, (2) a notch at the TEM-location, and (3) irregular delineation of the rectal wall. Multiple patterns could occur within one patient. 32 patients (65%) had rectal wall thickening, 17 patients (35%) a notch, and 28 patients (57%) irregular delineation of the rectal wall. In addition to these patterns, oedema (due to chemoradiation) persisted in post-chemoradiation TEM-patients. Ten patients had dehiscence after TEM post-chemoradiation (n=58%). Six luminal recurrences occurred; 3 had rectal wall thickening, 3 a notch, and 5 an irregular rectal wall.
Conclusion: Three patterns were identified on MRI after TEM. This enables radiologists to monitor this group of patients more accurately. Since minimal invasive techniques are gaining, it is very important for radiologists and surgeons to have knowledge about the normal follow-up findings after TEM.