Submit Manuscript | http://medc rav eonline.co m Introduction Colorectal adenocarcinoma is the third most common malignant neoplasia and the third leading cause of death from cancer in men and women in the United States. Current data show that the incidence of colorectal adenocarcinoma is decreasing in developed countries but increasing in developing countries. 1 The 2018 estimates of the Bra - zilian National Cancer Institute (Instituto Nacional do Câncer–INCA) were 17,380 new cases in men and 18,980 in women, making col - orectal adenocarcinoma the third most common neoplasia in men and the second most common in women in Brazil. 2 In the past 15 years, rectal cancer management has evolved in several aspects. Specifical - ly, a better understanding of the natural history of the disease, more precise radiological staging, multimodal therapeutic intervention, refined surgical techniques, and more detailed histopathological re - ports may have positively influenced patient survival. In this context, multidisciplinary management of colorectal cancer plays an important role and requires the coordinated teamwork of colorectal surgeons, oncologists, radiologists, and radiotherapists. 3 Total mesorectal exci - sion is still the basis of treatment in rectal cancer. However, neoadju - vant therapy and more conservative practices have been adopted in cases of clinical/pathological responses to radiochemotherapy. 4 Ra - diological evaluation of the response is of paramount importance for the selection of patients eligible for alternative treatment strategies, including ‘watch-and-wait’. Diffusion-weighted imaging is already being used routinely in the evaluation of the pathological response of rectal tumour patients submitted to neoadjuvant therapy. Some re - searchers have tried to estimate the tumour regression grade (TRG) using magnetic resonance imaging, as has been described for post-ra - diochemotherapy pathological evaluation, thus rendering it a valuable instrument. Considering the good results obtained with multimodal therapy in extraperitoneal rectal cancer, the evaluation of the pathological re - sponse post-neoadjuvant therapy must be considered as a factor for safe indication, both for the conservative option, in which the organ is preserved, and for radical surgical resection, influencing the choice between sphincter-preserving surgery and abdominoperineal excision. A precise evaluation, by comparing the results of post-neoadjuvant therapy magnetic resonance imaging with those obtained from his - Int J Radiol Radiat Ther. 2018;5(4):254 ‒ 258. 254 © 2018 Oliveira et al. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and build upon your work non-commercially. Magnetic resonance imaging is effective in assessing tumour regression after neoadjuvancy in rectal adenocarcinoma