Abstract
Purpose
To evaluate the best non-contrast magnetic resonance imaging (MRI) sequence and role of intravenous contrast administration in preoperative characterization and classification of perianal fistulae, keeping surgery as gold standard.
Methods
This prospective study comprised of forty-five consecutive patients with actively draining external perianal opening. MRI was performed on a 1.5 T scanner using non-contrast and contrast enhanced sequences in multiple planes. St. James’s University Hospital MRI based classification system was used to classify the fistulae into five grades. Taking surgery as gold standard, association between surgical and MRI findings was statistically analysed.
Results
Of the 45 patients recruited, forty were deemed eligible for inclusion. Mean age was 39.7 ± 11.7 years with male preponderance (M: F = 8:1). Commonest type was Grade 1 (40%). The best sequences in terms of overall accuracy were axial & coronal planes of contrast enhanced fat suppressed (FS) T1W turbo spin echo (TSE) (95.7%) followed by FS T2W TSE (94.1%) while sagittal T2W TSE sequence with or without fat suppression had the lowest accuracy (90.13%). The difference in overall diagnostic accuracy of FS T2W TSE and contrast enhanced FS T1W TSE sequence for evaluating perianal fistula was not statistically significant (p = 0.52). However, contrast study had a better accuracy in detecting internal openings and secondary tract of recurrent/ post-operative cases.
Conclusion
Best non-contrast MRI sequence is FS T2W TSE (axial and coronal). Non-contrast MRI is equally efficient to contrast study while evaluating primary/previously unoperated cases thereby eliminating the role of contrast in such cases. However, intravenous contrast should be administered for evaluating post-operative cases with recurrence.
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Data availability
Patients referred from department of surgery, Silchar Medical College and Hospital, Assam, India for radiological evaluation of perianal fistula.
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Acknowledgements
Dr Pankaj Gupta, PGIMER, Chandigarh; Dr Debalok Chakraborty, SMCH, Silchar, Assam; Dr Angela Phukan, GNRC Medical, North Guwahati, Assam.
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Both authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by GCD under supervision of DKC. The first draft of the manuscript was written by GCD. Review and editing were done by GCD and DKC. Both authors read and approved the final manuscript.
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Approval was obtained from the institutional ethics committee of Silchar Medical College and Hospital, Assam, India for this prospective study. Study was done over a period of one year. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional ethics committee.
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Written informed consent was obtained from all individual participants included in the study.
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Das, G.C., Chakrabartty, D.K. Best non-contrast magnetic resonance imaging sequence and role of intravenous contrast administration in evaluation of perianal fistula with surgical correlation. Abdom Radiol 46, 469–475 (2021). https://doi.org/10.1007/s00261-020-02616-1
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DOI: https://doi.org/10.1007/s00261-020-02616-1