Objective To observe the value of high-resolution direct MRI using hydrogen peroxide for diagnosing complex or recurrent anal fistulas.Methods Data of preoperative specialized physical examination,transperineal ultrasound(TPUS),pelvic cavity low-resolution plain MRI and fistula high-resolution direct MRI of 27 patients with complex or recurrent anal fistulas confirmed by surgery were retrospectively analyzed.The receiver operating characteristic(ROC)curves were constructed,and the area under the curves(AUC)were calculated to assess the diagnostic performance of the above 4 methods for identifying internal openings,tracts of fistulas and perianal abscesses.Results Among 27 cases,totally 51 internal openings,54 fistula tracts(including 30 intersphincteric,18 transsphincteric,3 extrasphincteric and 3 suprasphincteric fistulas)and 18 perianal abscesses were found.The efficacy of high-resolution direct MRI for diagnosing internal opening of complex or recurrent anal fistula(AUC=0.880)was higher than that of specialized physical examination,TPUS and low-resolution plain MRI(AUC=0.553,0.687,0.687,all P＜0.05),and the efficacy of high-resolution direct MRI for diagnosing tract of complex or recurrent anal fistula(AUC=0.889)was higher than that of specialized physical examination and TPUS(AUC=0.556,0.694,both P＜0.05),but not significantly different with low-resolution plain MRI(AUC=0.833,P＞0.05).The efficacy of high-resolution direct MRI for diagnosing perianal abscesses of complex or recurrent anal fistula(AUC=0.971)was higher than that of specialized physical examination(AUC=0.549,P＜0.05)and comparable to TPUS and low-resolution plain MRI(AUC=0.745,0.858,both P＞0.05).Conclusion High-resolution direct MRI using hydrogen peroxide was helpful for diagnosing complex or recurrent anal fistulas.

Objective To observe the value of high-resolution direct MRI using hydrogen peroxide for diagnosing complex or recurrent anal fistulas.Methods Data of preoperative specialized physical examination,transperineal ultrasound(TPUS),pelvic cavity low-resolution plain MRI and fistula high-resolution direct MRI of 27 patients with complex or recurrent anal fistulas confirmed by surgery were retrospectively analyzed.The receiver operating characteristic(ROC)curves were constructed,and the area under the curves(AUC)were calculated to assess the diagnostic performance of the above 4 methods for identifying internal openings,tracts of fistulas and perianal abscesses.Results Among 27 cases,totally 51 internal openings,54 fistula tracts(including 30 intersphincteric,18 transsphincteric,3 extrasphincteric and 3 suprasphincteric fistulas)and 18 perianal abscesses were found.The efficacy of high-resolution direct MRI for diagnosing internal opening of complex or recurrent anal fistula(AUC=0.880)was higher than that of specialized physical examination,TPUS and low-resolution plain MRI(AUC=0.553,0.687,0.687,all P＜0.05),and the efficacy of high-resolution direct MRI for diagnosing tract of complex or recurrent anal fistula(AUC=0.889)was higher than that of specialized physical examination and TPUS(AUC=0.556,0.694,both P＜0.05),but not significantly different with low-resolution plain MRI(AUC=0.833,P＞0.05).The efficacy of high-resolution direct MRI for diagnosing perianal abscesses of complex or recurrent anal fistula(AUC=0.971)was higher than that of specialized physical examination(AUC=0.549,P＜0.05)and comparable to TPUS and low-resolution plain MRI(AUC=0.745,0.858,both P＞0.05).Conclusion High-resolution direct MRI using hydrogen peroxide was helpful for diagnosing complex or recurrent anal fistulas.