Value of MRI morphologic features with pT1-2 rectal cancer in determining lymph node metastasis.

Abstract

To investigate the different features between metastatic lymph node and nonmetastatic lymph node on magnetic resonance imaging (MRI) and the relationship between the rectal lesion and lymph node metastasis (LNM). Eighty-two patients with retrospectively consecutive pT1-2 stage rectal cancer in 2016 were divided into lymph node metastasis (LNM+) and lymph node nonmetastasis (LNM-) group based on their histopathologic examinations. We evaluated the following features of lymph nodes: number, shape, signal heterogeneity, border, and diameter of the largest lymph node on T2-weight images. We also calculated tumor apparent diffusion coefficient ratio and tumor percent enhancement. Fisher's exact test was applied for inspecting lymph node numbers on MRI and logistic regression analysis in examining risk factors for LNM. The MR-LN number was significantly different between the LNM+ and LNM- group (median: 4 vs 1, P = 0.001). Multivariate logistic regression analysis exhibited that the diameter of the largest lymph node and the tumor percent enhancement of the arterial phase were independent risk factors of LNM (P = 0.005 vs 0.021, respectively). The largest lymph node's diameter and the tumor percent enhancement of arterial phase on MRI were helpful in determining LNM in pT1-2 rectal cancer.