[Value of high resolution magnetic resonance imaging for preoperative evaluation of Denonvilliers fascia in patients with rectal cancer].

Objective: Total mesorectal excision (TME) is the gold standard for surgical treatment of mid-low rectal cancer, but the postoperative incidence of urination and sexual dysfunction is relatively high. Preserving the Denonvilliers fascia (DF) during TME can reduce the postoperative incidence of urination and sexual dysfunction. In this study, high resolution magnetic resonance imaging (MRI) was used to observe the imaging performance and display of DF, so as to determine the value of this technique in preoperative evaluation of the preservation of DF. Methods: A descriptive cohort study was carried out. Clinical data of patients with rectal cancer who underwent TME and received preoperative high-resolution MRI at department of Gastrointestinal Surgery, the Third Affiliated Hospital of Sun Yat-sen University from August 2015 to June 2017 were retrospectively analyzed. The characteristics of DF were examined, and the shortest distance (d) between the anterior edge of tumor and DF was measured on high-resolution MRI. The distance d was compared between patients with stage T1-T2 and those with stage T3. Receiver operating characteristic (ROC) analysis was used to determine the predictive value of d for stage T1-T2 disease. Results: Thirty-two patients were enrolled in the study, including 27 males and 5 females with mean age of (62.9±8.9) years. DF was visualized in 96.9% (31/32) of cases on the T2WI sequence. The mean distance d in patients with stage T1-T2 disease (n=23) was (6.73±2.65) mm, and in those with stage T3 disease (n=9) was (1.30±1.15) mm (t=5.893, P<0.001). A cutoff of d >3 mm yielded specificity and positive predictive value for diagnosing stage T1-T2 disease of both 100%, sensitivity of 95.7% and negative predictive value of 90%. The optimum threshold of d was >3.05 mm, and Youden index was 0.957. Conclusions: High-resolution MRI can show the DF and accurately evaluate the relationship of DF with tumor in rectal cancer patients. Analysis on d value can provide an objective basis for the safe preservation of DF.