比较直肠粘液腺癌（RMAC）与直肠经典腺癌（RCAC）治疗前分期的基线MR影像特征，探讨粘液癌亚型是否影响MRI评估标准和高危肿瘤的识别。 共306例该研究对接受直肠癌手术切除的患者进行了回顾性分析。比较两种亚型的原发肿瘤和淋巴结 (LN) 的 MR 成像参数。进行Logistic回归和接受者操作特征分析来分别测试RMAC和RCAC中LN成像参数与恶性LN状态之间的显着相关性。在pT3和pT4阶段，粘液性肿瘤的长度大于RCAC肿瘤。对于 pN0 患者，MRI 上最大 LN 的长径和短径在 RAC 中可能比 RMAC 更大。对于 pN 患者，RMAC 中表现出内部异质性的淋巴结比例明显大于 RAC 中。恶性淋巴结最大短径的最佳截止值为 RMAC 6.05 mm 和 RAC 8.05 mm。基于最大短直径预测 LN 转移的最高 AUC 对于使用 6 mm 尺寸截止的 RMAC 为 0.794，对于使用 8 mm 截止的 RAC 为 0.667。与 LN 转移相关的成像特征在 RMAC 之间是不同的和RCAC，并建议采用不同的淋巴结大小标准来区分高危肿瘤。临床医生应对 LN 状态保持警惕，并在分配临床策略之前考虑组织学亚型。版权所有 © 2023 大学放射科医生协会。由爱思唯尔公司出版。保留所有权利。

To compare baseline MR imaging features for pre-treatment staging between rectal mucinous adenocarcinoma (RMAC) and rectal classical adenocarcinoma (RCAC), and to investigate whether the subtype of mucinous carcinoma influences MRI evaluation criteria and high-risk tumors identifying.A total of 306 patients who underwent surgical rectal cancer resection were retrospectively reviewed in the study. MR imaging parameters of the primary tumor and lymph nodes (LNs) were compared between two subtypes. Logistic regression and receiver operating characteristic analyses were performed to test significant associations between LN imaging parameters and malignant LN status in RMAC and RCAC, respectively.The length of mucinous tumors was larger than RCAC tumors in pT3 and pT4 stage. For pN0 patients, the long and short diameters of the largest LN on MRI were more likely to be larger in RCAC than RMAC. For pN+ patients, the proportion of LNs exhibiting internal heterogeneity in RMAC was obviously greater than that in RCAC. The best cut-off value of the largest short diameter of malignant LNs was 6.05 mm for RMAC and 8.05 mm for RCAC. And the highest AUC for predicting LNs metastases based on the largest short diameter was 0.794 for RMAC using 6 mm size cut-off, and 0.667 for RCAC using 8 mm cut-off.The imaging features that were associated with LN metastases were different between RMAC and RCAC, and different size criteria of LNs was suggested to distinguish high-risk tumors. Clinicians should stay vigilant of LN status and take histologic subtypes into consideration before assigning clinical strategies.Copyright © 2023 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.