Magnetic resonance fistulography with percutaneous jelly: A novel and cost-effective technique

Abstract

Background: Magnetic resonance fistulography (MRF) is a key non-invasive imaging technique for mapping perianal fistulas before surgery. The instillation of aqueous jelly, like ultrasound gel, enhances the signal-to-noise ratio, improving image quality and MRF accuracy. This low-cost approach improves accessibility, especially in resource-limited settings, while ensuring patient comfort and safety.

Objectives: To determine the impact of aqueous jelly on the accuracy of MRF in identifying fistulous tracts, internal openings, secondary ramifications and abscesses and the quality of visualisation of MRF with and without jelly instillation.

Method: A cross-sectional study at Krishna Rajendra and Cheluvamba Hospitals, Mysore (October 2024–March 2025), included 40 patients with perianal fistulas. Magnetic resonance fistulography was performed using a 1.5 Tesla uMR 570 system, without and with 5 mL – 7 mL of sterile aqueous jelly instilled percutaneously. MRI findings were compared with intraoperative results. Data were analysed using Statistical Package for the Social Sciences (SPSS) to assess sensitivity, specificity and accuracy.

Results: Magnetic resonance fistulography with gel improved visualisation, identifying internal openings in 92.5% of cases (vs. 24% without gel) and secondary tracts in 40% (vs. 17.5%). The accuracy compared to surgery was 97.5% for internal openings, 95% for secondary tracts, 97.5% for abscesses and 100% for supralevator extension.

Conclusion: Aqueous jelly instillation enhances MRF accuracy, improving fistula visualisation and aiding in preoperative planning. This technique reduces recurrence and incontinence risk and supports more accurate surgical interventions.

Contribution: This study re-emphasises the value of aqueous jelly in improving diagnostic accuracy and accessibility, especially in resource-limited settings.