PURPOSE This study aimed to assess the reliability of rectal villous tumors staging between rectal MRI and histological examination used as the Gold Standard and to investigate causes for discrepancies. METHODS The rectal 1.5 T MR scans of 40 patients followed for a histologically proven rectal villous adenoma were retrospectively included. Two independent experienced radiologists staged each tumor according to the TNM classification and described the occurrence of retraction of the rectal wall or spiculations within the associated mesorectum. A third radiologist collected tumor's morphological characteristics. RESULTS Among the 40 villous tumors studied, 25 (63%) were non-invasive and 15 (37%) were invasive. The mean volume of tumors with spiculations and retraction was significantly greater (p < 0.05) compared to tumors without these characteristics. Spiculations and retraction of the rectal wall were observed regardless of the definitive histological stage and did not represent a malignancy criterion. A weak interobserver reliability [Gwet's AC2: 0.31 (0.04-0.57)] in T-staging was observed between the two readers. Reader 1 showed a high reliability [Gwet's AC2: 0.90 (0.81-0.99)] in T-staging between Histopathological examination and preoperative MRI. In the opposite, reader 2 showed a weak reliability [Gwet's AC2: 0.31 (0.03-0.58)] in T-staging. He overstaged all tumors (100%) with spiculations (p < 0.05). CONCLUSION MRI understaged rectal villous adenoma and was unable to detect degenerative criteria, along with slight Interobserver agreement. The typical worrisome signs of rectal tumor, such as retractions and spiculations, occurred in all stages and were responsible for misstaging in most cases, in particular bulky tumors.

中文翻译：

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术前 MRI 和组织病理学检查之间绒毛状肿瘤分期的可靠性。

目的 本研究旨在评估直肠 MRI 和用作黄金标准的组织学检查之间直肠绒毛状肿瘤分期的可靠性，并调查差异的原因。方法 回顾性纳入了 40 名患者的直肠 1.5 T MR 扫描，这些患者随访了经组织学证实的直肠绒毛状腺瘤。两名独立的经验丰富的放射科医生根据 TNM 分类对每个肿瘤进行分期，并描述直肠壁回缩或相关直肠系膜内毛刺的发生。第三位放射科医生收集了肿瘤的形态特征。结果 在研究的 40 个绒毛状肿瘤中，25 个 (63%) 是非侵入性的，15 个 (37%) 是侵入性的。具有毛刺和回缩的肿瘤的平均体积显着更大（p < 0. 05) 与没有这些特征的肿瘤相比。无论最终的组织学阶段如何，都观察到直肠壁的毛刺和回缩，并且不代表恶性肿瘤标准。在两个读者之间观察到 T 分期的观察者间可靠性 [Gwet 的 AC2：0.31 (0.04-0.57)] 较弱。Reader 1 在组织病理学检查和术前 MRI 之间的 T 分期中显示出高可靠性 [Gwet's AC2：0.90 (0.81-0.99)]。相反，阅读器 2 在 T 分期中表现出较弱的可靠性 [Gwet 的 AC2：0.31 (0.03-0.58)]。他将所有肿瘤 (100%) 分期过度与毛刺 (p < 0.05)。结论 MRI 对直肠绒毛状腺瘤分期不足，无法检测到退行性标准，以及观察者间的轻微一致性。直肠肿瘤的典型令人担忧的迹象，