Department of Radiology, Silchar Medical College & Hospital, Silchar, Assam, 788014, India.
Department of Radiodiagnosis, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, Chandigarh, 160012, India.
Abdom Radiol (NY). 2021 Feb;46(2):469-475. doi: 10.1007/s00261-020-02616-1.
To evaluate the best non-contrast magnetic resonance imaging (MRI) sequence and role of intravenous contrast administration in preoperative characterization and classification of perianal fistulae, keeping surgery as gold standard.
This prospective study comprised of forty-five consecutive patients with actively draining external perianal opening. MRI was performed on a 1.5 T scanner using non-contrast and contrast enhanced sequences in multiple planes. St. James's University Hospital MRI based classification system was used to classify the fistulae into five grades. Taking surgery as gold standard, association between surgical and MRI findings was statistically analysed.
Of the 45 patients recruited, forty were deemed eligible for inclusion. Mean age was 39.7 ± 11.7 years with male preponderance (M: F = 8:1). Commonest type was Grade 1 (40%). The best sequences in terms of overall accuracy were axial & coronal planes of contrast enhanced fat suppressed (FS) T1W turbo spin echo (TSE) (95.7%) followed by FS T2W TSE (94.1%) while sagittal T2W TSE sequence with or without fat suppression had the lowest accuracy (90.13%). The difference in overall diagnostic accuracy of FS T2W TSE and contrast enhanced FS T1W TSE sequence for evaluating perianal fistula was not statistically significant (p = 0.52). However, contrast study had a better accuracy in detecting internal openings and secondary tract of recurrent/ post-operative cases.
Best non-contrast MRI sequence is FS T2W TSE (axial and coronal). Non-contrast MRI is equally efficient to contrast study while evaluating primary/previously unoperated cases thereby eliminating the role of contrast in such cases. However, intravenous contrast should be administered for evaluating post-operative cases with recurrence.
以手术为金标准，评估最佳的非对比磁共振成像（MRI）序列及静脉对比剂给药在肛周瘘术前特征及分类中的作用。
本前瞻性研究纳入了 45 例有活动性外肛周外口引流的连续患者。MRI 检查在 1.5T 扫描仪上进行，采用多平面非对比增强和对比增强序列。采用圣詹姆斯大学医院 MRI 分类系统将瘘管分为五型。以手术为金标准，统计分析手术与 MRI 结果之间的相关性。
在纳入的 45 例患者中，40 例被认为符合纳入标准。平均年龄为 39.7±11.7 岁，男性优势（M：F=8：1）。最常见的类型是 1 级（40%）。整体准确性最佳的序列是轴位和冠状位对比增强脂肪抑制（FS）T1W 涡轮自旋回波（TSE）（95.7%），其次是 FS T2W TSE（94.1%），而矢状位 T2W TSE 序列加或不加脂肪抑制的准确性最低（90.13%）。FS T2W TSE 和对比增强 FS T1W TSE 序列评估肛周瘘的整体诊断准确性差异无统计学意义（p=0.52）。然而，对比研究在检测复发/术后病例的内口和二级管道方面具有更高的准确性。
最佳的非对比 MRI 序列是 FS T2W TSE（轴位和冠状位）。非对比 MRI 在评估原发性/未手术的病例时与对比研究同样有效，因此在这些病例中无需使用对比剂。然而，对于有复发的术后病例，应给予静脉内对比剂。
