Abstract: Objective:To summarize the magnetic resonance imaging (MRI) features of the persistent perineal sinus (PPS).
Methods:The retrospective and descriptive study was conducted. The clinical data of 7 patients with PPS who were admitted to the Nanjing University of Traditional Chinese Medicine between July 2010 and January 2017 were collected. Patients received horizontal, anteroposterior axes and coronal scanning of MRI after abdominoperineal resection (APR) of rectal cancer. Two physicians read collectively films and then achieved consistent results if there was a disputed result. Observation indicators: (1) MRI features; (2) treatment and follow-up situations. Patients underwent resection of PPS according to results of MRI examination, and then regular pathological examination. Follow-up using telephone interview was performed to detect sinus recurrence and reoperation up to April 2017.
Results:(1) MRI features: ① Lesion location: lesions of PPS in 7 patients were located at the presacral areas, top side was up to the third sacral plane, and lower side extended down to the pubic area. ② Morphology and signal: sinus tract of 7 patients showed irregular flaky and tubular abnormal signals; fibrotic sinus tract wall showed low signals in T1 weighted imaging (T1WI) and T2WI; contents of sinus tract in 7 patients showed low signal in T1WI and high signals in T2WI and T2WI-fat suppression (T2WI-FS).Of 7 patients, uniform signal and mixed signal were respectively detected in 2 and 5 patients. ③ Branches and cystic spaces: 1 patient had a branch at the tip of the coccyx, extending to the rear of the sacral vertebra. The top of sinus tract in 4 patients enlarged to form a cavity. ④ Signs of infection: signs of infection in 3 patients included blurred and exuded fat gaps around the sinus tract, unclear and partially adhesion with pelvic organ; the pelvic floor muscles in 1 patient were thickened and swollen, with a high signal in T2WI-FS; flaky fluid shadows in 2 patients were seen in the posterior sinus, with a high signal in T2WI-FS, showing a tissue edema of anterior sacrum. ⑤ Enhancement features: result of MRI examination of 1 patient showed mild and heterogeneous enhancement of sinus. (2) Treatment and follow-up situations: among 7 patients undergoing sinus resection, 2 received curettage of superior sinus due to high location, and 5 received successfully operation. All patients underwent postoperatively regular antibiotic therapy. The healing time was 14-78 days, with an average time of 42 days. The postoperative pathological examination showed different degrees of inflammatory cell infiltration. Seven patients were followed up for 2-74 months, with an average time of 40 months. Of 7 patients, sinus in 6 patients was healed, 1 had recurrence of sinus and didn′t receive therapy. Seven patients didn′t undergo debridement or transposition of skin flap again.
Conclusion:The MRI imaging features of PPS includes flaky and tubular abnormal signal in the the anterior sacrum, low signal in T1WI, high signals in T2WI and T2WI-FS, and the enhanced scanning of sinus duct shows mild and heterogeneous enhancement.