Stage pT0-T1 rectal cancers: emphasis on submucosal high intensity on high-resolution T2-weighted imaging and other morphological features.

BackgroundIdentification and staging of rectal cancer are mainly based on the difference in signal intensity (SI) between the tumor and normal structures of the intestinal wall on T2-weighted imaging. However, differentiating stage pT0-T1 from pT2 rectal tumors is difficult using routine magnetic resonance imaging (MRI) sequences.PurposeTo summarize and explore whether MRI findings from routine imaging can help differentiate pT0-T1 from pT2 rectal tumors.Material and MethodsA total of 110 patients with pT0-T2 rectal cancer underwent preoperative pelvic MRI examinations and tumor resection without preoperative chemoradiotherapy. MRI findings of rectal lesions (including tumor location, shape, longitudinal length, maximum cross-section, submucosal high intensity [SHI], extramural fibrotic scarring, wall shrinkage, lesion-to-wall signal intensity ratio, and presence of lymph node with short axis over 3 mm) and clinical characteristics were analyzed by univariate and multivariate analyses to screen the independent factors associated with pathological results.ResultsOf all the lesions, 32 tumors were proved to be pT0-T1 and 78 tumors were pT2. Univariate and multivariate logistic regression analyses revealed that tumor shape (odds ratio [OR] = 24.607, P < 0.001), SHI (OR = 6.129, P = 0.002), and extramural fibrotic scarring (OR = 0.110, P = 0.007) were independent factors distinguishing pT0-T1 tumors from pT2 tumors. If the rectal lesion has a cauliflower-like shape with SHI and no extramural fibrotic scarring, it is more likely to be a pT0-T1 tumor.ConclusionThe imaging features obtained from the routine MRI sequence showed potential value for differentiating pT0-T1 from pT2 rectal tumors.