BACKGROUND & AIMS Few data are available to guide the use of anal imaging for patients with Crohn's disease (CD) who are not suspected of having perianal fistulas. We aimed to evaluate the role of anal imaging supplementary to magnetic resonance enterography (MRE) in these patients. METHODS In a prospective study, we added a round of anal MR imaging (MRI), collecting axial images alone, to MRE evaluation of 451 consecutive adults who were diagnosed with or suspected of having CD but not believed to have perianal fistulas. Images were examined for perianal tracts; if present, colorectal surgeons reexamined patients to identify external openings or perianal inflammation or abscess. Patients were followed and data were collected on dedicated treatment for perianal fistulas or abscess. We calculated the diagnostic yield for anal MRI, associated factors, and outcomes of MRI-detected asymptomatic perianal tracts. RESULTS A total of 440 patients (mean age, 29.6±8.9 years) met the inclusion criteria. Anal MRI revealed perianal tracts in 53 patients (12%; 95% CI, 9.3%-15.4%). Surgeons however did not identify any lesions that required treatment. The asymptomatic tracts were mostly single unbranched (83%), inter-sphincteric (72%), or had a linear dark signal at the tract margin (79%). Younger age at MRE, female sex, and CD activity index scores of 220-450 were independently associated with detection of perianal tracts. MRI detection of asymptomatic tracts was independently associated with later development of perianal fistulas or abscess that required treatment: 17.8% cumulative incidence at 37 months and an adjusted hazard ratio of 3.06 (95% CI, 1.01-9.27; P = .048). CONCLUSIONS In a prospective study of patients with CD, we found that adding anal MRI evaluation to MRE resulted in early identification of patients at risk for perianal complications.

中文翻译：

---

不怀疑有肛周瘘的克罗恩病患者的磁共振肠造影辅助肛门成像。

背景和目的 很少有数据可用于指导未怀疑有肛周瘘的克罗恩病 (CD) 患者使用肛门成像。我们旨在评估肛门成像辅助磁共振肠造影 (MRE) 在这些患者中的作用。方法 在一项前瞻性研究中，我们在连续 451 名被诊断患有或怀疑患有 CD 但未被认为患有肛周瘘的成人的 MRE 评估中增加了一轮肛门 MR 成像 (MRI)，仅收集轴向图像。检查肛周图像；如果存在，结直肠外科医生会重新检查患者以识别外部开口或肛周炎症或脓肿。对患者进行随访并收集有关肛周瘘管或脓肿的专门治疗的数据。我们计算了肛门 MRI 的诊断率，MRI 检测到的无症状肛周的相关因素和结果。结果 共有 440 名患者（平均年龄，29.6±8.9 岁）符合纳入标准。肛门 MRI 显示 53 名患者存在肛周束（12%；95% CI，9.3%-15.4%）。然而，外科医生没有发现任何需要治疗的病变。无症状的纤维束大多为单条不分支（83%）、括约肌间（72%），或在纤维束边缘有线性暗信号（79%）。MRE 年龄较小、女性和 CD 活动指数评分为 220-450 与肛周检测独立相关。MRI 对无症状束的检测与需要治疗的肛周瘘或脓肿的后期发展独立相关：37 个月的累积发生率为 17.8%，调整后的风险比为 3.06（95% CI，1.01-9.27；P = .048）。