Morphological and functional features prognostic factor of magnetic resonance imaging in locally advanced rectal cancer

Background Although imaging can be suggestive of the diagnosis of rectal cancer, the primary imaging role is to assist in treatment triage of histologically diagnosed tumors. The possibility of a multimodal approach in the response to the treatment opens the way for the selection of criteria more personalized to the patient. Purpose To assess the prognostic factor of morphological and functional magnetic resonance imaging (MRI) in rectal cancer. Material and Methods Seventy-seven patients were enrolled and underwent MRI before treatment and 59 patients underwent MRI after treatment. Radiologists evaluated the presence of lesions using a 4-point confidence scale; they recorded anatomical side, extent, and distance from the anorectal junction and distance from the circumferential margin. Tumor location was classified according to the involvement of proximal rectal channel and/or distal rectal channel. Radiologists scored signal intensity on T2-weighted (T2W) images, diffusion-weighted images (DWI), and MRI dynamic enhancement pattern. Tumor regression grade (TRG) and pathological T (pT) were the gold standard. Results Lesion vascularization score before treatment showed a predictive value of complete pathological response (sensitivity 88%, specificity 50%) based on pT, while using TRG lymph node number before treatment (sensitivity 83%, specificity 57%) showed a predictive value for response treatment. T2W signal (sensitivity 78%, specificity 30%) and DWI signal after treatment (sensitivity 78%, specificity 61%) showed a good predictive value for local rectal recurrences. Conclusions Lesion vascularization and lymph node number had a predictive value for neoadjuvant treatment complete response in rectal cancer. T2W signal intensity and DWI signal showed a good predictive value for local rectal recurrences.