磁共振弥散加权成像测定表观弥散系数值对肛瘘的诊断及其活动性的评估

The diagnosis of ADC value of MRI-DWI for anal fistula and the assessment of that for activity of anal fistula

目的:研究磁共振弥散加权成像(MRI-DWI)测定表观弥散系数(ADC)值对肛瘘的诊断及对肛瘘活动性的评估价值。方法:选取医院收治的86例肛瘘患者,依据肛周疾病活动性指数(PDAI)将其分为缓解期组(40例)和活动期组(46例)。两组患者均采用MRI-DWI进行诊断,以美国直结肠外科医师协会(ASCRS)的肛瘘诊断标准为“金标准”,对比两组患者的瘘道及脓肿位置;绘制受试者工作特征(ROC)曲线,计算ROC曲线下面积(AUC),分析MRI-DWI对肛瘘的诊断效能。结果:两组患者的瘘道位置(括约肌内、经括约肌、括约肌外以及高位肛提肌)及脓肿位置(高位、低位以及会阴脓肿)情况之间的差异均无统计学意义;在与ASCRS的肛瘘诊断“金标准”比较中,MRI-DWI诊断活动期肛瘘灵敏度为93.33%,特异度为6.67%,AUC为0.942。选择约登指数最大时对应的ADC数值作为两组的截断值,缓解组和活动组的ADC截断值分别为0.91和1.13。结论:MRI-DWI测定ADC值对肛瘘的诊断及对肛瘘活动性的评价具有重要意义。

Objective:To study the values of apparent diffusion coefficient(ADC)value that was measured by magnetic resonance imaging-diffusion weighted imaging(MRI-DWI)in the diagnosis of anal fistula and the assessment of anal fistula activity.Methods:86 patients with anal fistula who admitted to hospital were selected.And they were divided into“in remission group”(40 cases)and“active stage group”(46 cases)according to perianal disease activity index(PDAI).Both two groups were diagnosed by MRI-DWI.The fistula and abscess location of the two groups were compared with the diagnostic“gold standard”of anal fistula of American Society of Colon and Rectal Surgeons(ASCRS).The receiver operating characteristic(ROC)curve was drawn,and the area under curve(AUC)of ROC was further calculated,and then,the diagnostic efficiency of MRI-DWI for anal fistula was analyzed.Results:There were no significant difference between the two groups at the locations of anal fistula(inside of sphincter,via sphincter,outside of sphincter and levator ani at high position)and abscess(abscess at high position,low position and perineum).In the comparison with ASCRS“gold standard”of diagnosing anal fistula,the sensitivity,specificity and AUC of MRI-DWI were 93.33%,6.67%and 0.942 in diagnosing anal fistula at active stage,respectively.The ADC value corresponding to the maximum Yoden index was selected as the cut-off value of two groups.And the ADC cut-off values of“in remission group”and“active stage group”were 0.91 and 1.13,respectively.Conclusion:The ADC value that was measured by MRI-DWI is of great significance in the diagnosis of anal fistula and the evaluation of anal fistula activity.