对于局部晚期直肠癌 (LARC) 患者，新辅助放化疗 (nCRT) 后淋巴结状态阴性可能会考虑保留直肠方案，而不是完全直肠系膜切除；然而，目前的 MRI 淋巴结分期标准的准确性并不理想。本研究的目的是比较 LARC 患者 nCRT 后不同 MRI 维度标准对淋巴结分期的诊断准确性。 回顾性纳入 LARC nCRT 后接受 MRI 并随后进行手术的患者，并将其分为训练组和验证组。分别有 100 名和 39 名患者。根据欧洲胃肠放射学会共识指南（即 ESGAR 方法），由两名放射科医生独立评估最大直肠系膜淋巴结的短轴、长轴和头尾轴以及体积和淋巴结状态。在培训队列中评估读者间的一致性。组织病理学是参考标准。计算 ROC 曲线和最佳截止值，并与 McNemar 检验进行比较。研究人群包括 139 名患者（中位年龄 62 岁 [IQR 55-72]，94 名男性）。长轴 (κ = 0.81)、体积 (κ = 0.85) 和 ESGAR 方法 (κ = 0.88) 的读者间一致性较高，而短轴 (κ = 0.11) 的读者间一致性较低。长轴、体积和 ESGAR 方法在训练（分别为 71%、74% 和 65%）和验证（分别为 83%、78% 和 75%）中的准确度相似 (p > 0.05) ）队列。最大淋巴结长轴和体积测量的准确性不低于LARC nCRT后淋巴结分期的ESGAR方法。在直肠癌MRI再分期中，最大直肠系膜淋巴结长轴或体积的测量术前放化疗后的淋巴结分期是 ESGAR 淋巴结分期标准的更快、更可靠的替代方案。• 目前局部晚期直肠癌放化疗后淋巴结分期的 MRI 标准准确性欠佳且耗时。 • MRI 测量最大直肠系膜淋巴结的长轴或体积显示，对于评估局部晚期直肠癌的局部区域淋巴结状态具有良好的准确性。 • 放化疗后对最大直肠系膜淋巴结的长轴和体积进行 MRI 测量可能是 ESGAR 淋巴结分期标准的更快、更可靠的替代方案。© 2023。作者获得欧洲放射学会的独家许可。

In patients with locally advanced rectal carcinoma (LARC), negative nodal status after neoadjuvant chemoradiotherapy (nCRT) may allow for rectum-sparing protocols rather than total mesorectal excision; however, current MRI criteria for nodal staging have suboptimal accuracy. The aim of this study was to compare the diagnostic accuracy of different MRI dimensional criteria for nodal staging after nCRT in patients with LARC.Patients who underwent MRI after nCRT for LARC followed by surgery were retrospectively included and divided into a training and a validation cohort of 100 and 39 patients, respectively. Short-, long-, and cranial-caudal axes and volume of the largest mesorectal node and nodal status based on European Society of Gastrointestinal Radiology consensus guidelines (i.e., ESGAR method) were assessed by two radiologists independently. Inter-reader agreement was assessed in the training cohort. Histopathology was the reference standard. ROC curves and the best cut-off were calculated, and accuracies compared with the McNemar test.The study population included 139 patients (median age 62 years [IQR 55-72], 94 men). Inter-reader agreement was high for long axis (κ = 0.81), volume (κ = 0.85), and ESGAR method (κ = 0.88) and low for short axis (κ = 0.11). Accuracy was similar (p > 0.05) for long axis, volume, and ESGAR method both in the training (71%, 74%, and 65%, respectively) and in the validation (83%, 78%, and 75%, respectively) cohorts.Accuracy of the measurement of long axis and volume of the largest lymph node is not inferior to the ESGAR method for nodal staging after nCRT in LARC.In MRI restaging of rectal cancer, measurement of the long axis or volume of largest mesorectal lymph node after preoperative chemoradiotherapy is a faster and reliable alternative to ESGAR criteria for nodal staging.• Current MRI criteria for nodal staging in locally advanced rectal cancer after chemo-radiotherapy have suboptimal accuracy and are time-consuming. • Measurement of long axis or volume of the largest mesorectal lymph node on MRI showed good accuracy for assessment of loco-regional nodal status in locally advanced rectal cancer. • MRI measurement of the long axis and volume of largest mesorectal lymph node after chemo-radiotherapy could be a faster and reliable alternative to ESGAR criteria for nodal staging.© 2023. The Author(s), under exclusive licence to European Society of Radiology.