对比增强MRI与T2加权MRI对直肠癌直肠系膜淋巴结分期的比较
该回顾性单中心研究纳入120例直肠癌患者，比较对比增强MRI征象「牛油果征」与T2加权形态学标准预测直肠系膜淋巴结转移的诊断性能。牛油果征AUC为0.91，敏感度94.6%、特异度87.5%，显著优于ESGAR共识标准（AUC 0.72）及队列优化的T2参数组合（交叉验证AUC 0.79）。结论支持将脂肪抑制对比增强T1加权序列常规纳入直肠癌分期方案。
要点
- 牛油果征在脂肪抑制对比增强T1加权图像上评估，诊断直肠系膜淋巴结转移AUC达0.91。
- 牛油果征敏感度94.6%、特异度87.5%，显著优于ESGAR共识T2标准（AUC 0.72）。
- 建议直肠癌MRI分期方案常规加入脂肪抑制对比增强T1加权序列。
关键影像表现/征象
- 牛油果征在脂肪抑制对比增强T1加权图像上评估，表现为直肠系膜淋巴结的对比增强特征。
- T2加权形态学特征分别依据ESGAR共识标准、文献衍生标准及队列优化参数组合进行评估。
诊断标准与关键数值
- 牛油果征预测直肠系膜淋巴结转移的AUC为0.91（95%CI 0.86-0.96），敏感度94.6%（53/56），特异度87.5%（56/64）。
- ESGAR共识标准AUC为0.72（95%CI 0.64-0.81），牛油果征显著优于其（p<0.001）。
- 队列优化T2参数组合表观AUC 0.81、交叉验证AUC 0.79，牛油果征显著优于其（p=0.02）。
- 所有文献衍生T2标准AUC范围为0.58-0.78，性能均较低。
临床应用与阅片要点
- 阅片时应在脂肪抑制对比增强T1加权序列上评估直肠系膜淋巴结的牛油果征，辅助判断转移。
- 牛油果征可提高淋巴结分期准确性，支持新辅助治疗及器官保留策略的精细化选择。
局限性
- 回顾性单中心设计，样本量120例，结论需多中心前瞻性验证。
以上解读依据论文摘要（全文未开放获取或许可不允许翻译转载）。
英文原文（摘要）· 点击展开
OBJECTIVES: To compare the diagnostic performance of the "Avocado Sign", a contrast-enhanced MRI feature, with T2-weighted morphological criteria for predicting mesorectal lymph node involvement in rectal cancer.
MATERIALS AND METHODS: This retrospective single-centre study included 120 consecutive patients with histopathologically confirmed rectal cancer who underwent 3-T pelvic MRI between January 2020 and May 2025. Two blinded abdominal radiologists independently assessed the Avocado Sign on fat-suppressed contrast-enhanced T1-weighted images and, in a separate session, T2-weighted morphological features for all mesorectal lymph nodes. The reference standard was total mesorectal excision histopathology. Performance was evaluated against European Society of Gastrointestinal and Abdominal Radiology (ESGAR) consensus criteria, literature-derived criteria, and a cross-validated cohort-optimised T2 parameter combination. Areas under the receiver operating characteristic curve (AUC) were compared using DeLong tests.
RESULTS: In total, 120 patients (89 men, 31 women; median age 65 years [IQR 58-73]) were evaluated. Mesorectal nodal metastases were confirmed in 56 (46.7%) patients. The Avocado Sign achieved an AUC of 0.91 (95% confidence interval [CI]: 0.86-0.96), with sensitivity of 94.6% (53/56) and specificity of 87.5% (56/64). It significantly outperformed the ESGAR consensus criteria (AUC 0.72; 95% CI: 0.64-0.81; p < 0.001) and the cohort-optimised T2 parameter combination (apparent AUC 0.81, cross-validated AUC 0.79; p = 0.02). All literature-derived T2 criteria demonstrated lower performance (AUC 0.58-0.78).
CONCLUSION: The contrast-enhanced Avocado Sign provided superior discrimination of mesorectal nodal status compared with comprehensive T2-weighted MRI criteria, supporting routine inclusion of fat-suppressed contrast-enhanced T1-weighted sequences in rectal cancer staging protocols.
KEY POINTS: QuestionCan contrast-enhanced MRI improve mesorectal lymph node staging accuracy compared with established T2-weighted morphological criteria in patients with rectal cancer? FindingsThe Avocado Sign demonstrated significantly superior diagnostic performance (area under the curve 0.91) compared with European consensus criteria (0.72) and all tested T2-weighted approaches. Clinical relevanceIncorporating contrast-enhanced sequences into rectal MRI protocols substantially improves nodal staging accuracy, supporting refined treatment selection for neoadjuvant therapy and organ-preservation strategies.
引用
- Lurz M, Schäfer AO. Contrast-enhanced vs T2-weighted MRI for mesorectal nodal staging in rectal cancer. Eur Radiol. 2026. PMID: 41999401. doi:10.1007/s00330-026-12516-5
供执业医师工作参考，不替代临床判断；数值与分级以指南原文为准。