Department of Radiology, Massachusetts General Hospital, 55 Fruit Street, White 270, Boston, MA, 02114, USA.
Department of Radiology, Prince of Songkla University, Hat Yai, Songkhla, Thailand.
Abdom Radiol (NY). 2019 Feb;44(2):438-445. doi: 10.1007/s00261-018-1759-x.
To evaluate the role of pelvic MR imaging in differentiating between low rectal and anal cancers using the pathological results as the gold standard.
In this study, retrospective analysis of 100 patients with a history of low rectal (n = 50) or anal (n = 50) cancers who underwent staging pelvic MR imaging before treatment was performed. The following parameters were analyzed: distance from the anal verge to the tumor, percentage of tumor above puborectalis muscle, tumor size, T2W signal intensity, sphincter/levator muscles invasion, organ invasion, and MRI diagnosis. Multivariable logistic regression was performed to determine factors associated with low rectal and anal cancers. Distances from the anal verge to the tumor were compared using receiver-operating characteristic (ROC) curves.
From the ROC curves, the cut-off value for the distance from the anal verge to the tumor in differentiating between low rectal and anal cancers was 2.1 cm and the area under the ROC curve was 0.90 (95% CI 0.84-0.97). Multivariate logistic regression revealed three significant factors in differentiating between low rectal and anal cancers, including T2 mixed hyper- and hyposignal intensity (OR 66.00, 95% CI 4.66-934.81), distance cut-off value (OR 34.72, 95% CI 5.73-210.27), and absence of sphincter invasion (OR 18.75, 95% CI 1.91-183.96), with sensitivity, specificity, PPV, and NPV of 98%, 88%, 89%, and 97%, respectively, and diagnostic accuracy increased from 79% (reader 1) and 82% (reader 2) to 93%.
MR imaging can be useful to differentiating between low rectal and anal cancers which benefits staging and treatment planning.
以病理结果为金标准，评估盆腔磁共振成像在区分低位直肠和肛门癌中的作用。
本研究回顾性分析了 100 例接受治疗前分期盆腔磁共振成像的低位直肠（n=50）或肛门（n=50）癌患者。分析了以下参数：肿瘤距肛缘的距离、肛提肌上方肿瘤的百分比、肿瘤大小、T2W 信号强度、内外括约肌侵犯、器官侵犯和 MRI 诊断。采用多变量逻辑回归确定与低位直肠和肛门癌相关的因素。使用受试者工作特征（ROC）曲线比较肿瘤距肛缘的距离。
ROC 曲线显示，肿瘤距肛缘的距离区分低位直肠和肛门癌的截断值为 2.1cm，ROC 曲线下面积为 0.90（95%CI 0.84-0.97）。多变量逻辑回归显示，区分低位直肠和肛门癌有三个显著因素，包括 T2 混合高和低信号强度（OR 66.00，95%CI 4.66-934.81）、距离截断值（OR 34.72，95%CI 5.73-210.27）和无括约肌侵犯（OR 18.75，95%CI 1.91-183.96），其敏感性、特异性、PPV 和 NPV 分别为 98%、88%、89%和 97%，诊断准确性从读者 1 的 79%和读者 2 的 82%提高到 93%。
磁共振成像有助于区分低位直肠和肛门癌，有利于分期和治疗计划。
