Direct hydrogen peroxide MRI fistulography versus indirect (intravenous) MRI fistulography in patients with perianal fistula

Abstract

Background Perianal fistula is a rather common disease; its symptoms range from mild to severe, impairing anal continence; accurate preoperative evaluation avoids recurrence following surgical procedures. Aim of work Our study examined the diagnostic accuracy of magnetic resonance imaging with direct percutaneous instillation of hydrogen peroxide mixed with gadolinium (direct fistulography) in comparison to intravenous gadolinium contrast-enhanced study (indirect fistulography). Methods This prospective study was conducted on patients referred to Airforce hospital radiology department and were diagnosed with perianal fistula, Direct and indirect MR fistulography were performed using a 1.5T MRI scanner. The type of fistulae, internal openings, secondary branches, and abscesses were compared to surgical findings. Results Our study included 35 male patients. Both direct and indirect methods detected primary tracts with 97.1% sensitivity and accuracy rates of 91.9% and 89.2%, respectively. The direct method was superior in detecting secondary branches and internal openings with accuracy rates of 97.37% and 93.3%, respectively, compared to 86.8% and 86.6% for the indirect method, while the indirect method was superior in detecting abscess collections with 100% accuracy rate compared to 89.2% accuracy rate for the direct method. None of the patients reported fever or bleeding after the procedure. Conclusions Both direct and indirect fistulography showed comparable abilities in detecting primary fistulous tracts. However, the direct fistulography was superior in detecting internal openings and secondary tracts particularly in chronic cases, whereas indirect Fistulography was superior in detecting abscess collections. Incorporating both methods into our routine could thus improve the efficacy of surgical procedures.