Background MRI plays a crucial role in restaging locally advanced rectal cancer treated with total neoadjuvant therapy (TNT); however, prospective studies have not evaluated its ability to accurately select patients for nonoperative management. Purpose To evaluate the ability of restaging MRI to predict oncologic outcomes and identify imaging features associated with residual disease (RD) after TNT. Materials and Methods This was a secondary analysis of the Organ Preservation in Rectal Adenocarcinoma (OPRA) trial, which randomized participants from April 2014 to March 2020 with stages II or III rectal adenocarcinoma to undergo either induction or consolidation TNT. Participants enrolled in the OPRA trial who underwent restaging MRI were eligible for inclusion in the present study. Radiologists classified participants as having clinical complete response (cCR), near-complete clinical response (nCR), or incomplete clinical response (iCR) based on restaging MRI at a mean of 8 weeks ± 4 (SD) after treatment. Oncologic outcomes according to MRI response category were assessed using Kaplan-Meier curves. Logistic regression analysis was performed to identify imaging characteristics associated with RD. Results A total of 277 participants (median age, 58 years [IQR, 17 years]; 179 male) who were randomized in the OPRA trial had restaging MRI forms completed. The median follow-up duration was 4.1 years. Participants with cCR had higher rates of organ preservation compared with those with nCR (65.3% vs 41.6%, log-rank P < .001). Five-year disease-free survival for participants with cCR, nCR, and iCR was 81.8%, 67.6%, and 49.6%, respectively (log-rank P < .001). The MRI response category also predicted overall survival (log-rank P < .001), distant recurrence-free survival (log-rank P = .005), and local regrowth (log-rank P = .02). Among the 266 participants with at least 2 years of follow-up, 129 (48.5%) had RD. At multivariable analysis, the presence of restricted diffusion (odds ratio, 2.50; 95% CI: 1.22, 5.24) and abnormal nodal morphologic features (odds ratio, 5.04; 95% CI: 1.43, 23.9) remained independently associated with RD. Conclusion The MRI response category was predictive of organ preservation and survival. Restricted diffusion and abnormal nodal morphologic features on restaging MRI scans were associated with increased likelihood of residual tumor. ClinicalTrials.gov identifier: NCT02008656 © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Milot in this issue.

中文翻译：

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MRI 可预测直肠癌观察等待患者的残留疾病和结果。


背景 MRI 在接受全新辅助治疗 (TNT) 治疗的局部晚期直肠癌重新分期中发挥着至关重要的作用；然而，前瞻性研究尚未评估其准确选择患者进行非手术治疗的能力。目的 评估 MRI 重新分期预测肿瘤结果并识别与 TNT 后残留病灶 (RD) 相关的影像学特征的能力。材料和方法这是对直肠腺癌器官保存 (OPRA) 试验的二次分析，该试验将 2014 年 4 月至 2020 年 3 月期间患有 II 期或 III 期直肠腺癌的参与者随机分组，接受诱导或巩固 TNT。参加 OPRA 试验并接受 MRI 重新分期的参与者有资格纳入本研究。放射科医生根据治疗后平均 8 周±4 (SD) 的 MRI 重新分期，将参与者分为临床完全缓解 (cCR)、接近完全临床缓解 (nCR) 或不完全临床缓解 (iCR)。使用 Kaplan-Meier 曲线评估根据 MRI 反应类别的肿瘤学结果。进行逻辑回归分析以确定与 RD 相关的成像特征。结果 OPRA 试验中随机分配的总共 277 名参与者（中位年龄 58 岁 [IQR，17 岁]；179 名男性）已完成重新分期 MRI 表格。中位随访时间为 4.1 年。与 nCR 参与者相比，cCR 参与者的器官保存率更高（65.3% vs 41.6%，对数秩 P < .001）。 cCR、nCR 和 iCR 参与者的五年无病生存率分别为 81.8%、67.6% 和 49.6%（对数秩 P < .001）。 MRI 反应类别还预测总体生存率（对数秩 P < .001）、远处无复发生存（对数秩 P = .005）和局部再生（对数秩 P = .02）。在至少进行了 2 年随访的 266 名参与者中，129 名（48.5%）患有 RD。在多变量分析中，扩散受限（比值比，2.50；95% CI：1.22，5.24）和异常的淋巴结形态特征（比值比，5.04；95% CI：1.43，23.9）仍然与 RD 独立相关。结论 MRI 反应类别可预测器官保存和存活。重新分期 MRI 扫描中的扩散受限和异常淋巴结形态特征与残留肿瘤的可能性增加相关。 ClinicalTrials.gov 标识符：NCT02008656 © RSNA，2024 本文提供了补充材料。另请参阅本期 Milot 的社论。