Perianal fistula protocol (MRI)
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At the time the article was created Yuranga Weerakkody had no recorded disclosures.View Yuranga Weerakkody's current disclosures
At the time the article was last revised Andrew Murphy had no financial relationships to ineligible companies to disclose.View Andrew Murphy's current disclosures
MRI protocol for the assessment of perianal fistulas is a group of MRI sequences put together to asses the extension and anatomic relationships of inflammatory fistulas to the anal sphincters, helping to plan surgical management and monitor treatment response.
NB: This article is intended to outline some general principles of protocol design. The specifics will vary depending on MRI hardware and software, radiologist's and referrer's preferences, institutional protocols, patient factors (e.g. allergy) and time constraints.
A good protocol for this purpose would include:
- fine 3 mm slices
- axial and coronal T2 FS or STIR
- axial and coronal T2 are helpful in the delineation of sphincter anatomy
- axial and coronal T1 FS with gadolinium-based intravenous contrast material
- axial T1
Some authors recommend 1:
- short-inversion-time inversion recovery (STIR)
- gradient-echo T1-weighted with or without gadolinium-based intravenous contrast material
- spin-echo T1-weighted
- spin-echo T2-weighted with saline instillation (MR fistulography)
A novel method is the use of volume MRI sequences (more routinely used in neuro and musculoskeletal MRI). The benefits are reduced imaging times and isotropic data allowing multiplanar reformatting while maintaining comparable contrast resolution.
- 1. Morris J, Spencer JA, Ambrose NS. MR imaging classification of perianal fistulas and its implications for patient management. Radiographics. 20 (3): 623-35. Radiographics (full text) - Pubmed citation
- 2. de Miguel Criado J, del Salto LG, Rivas PF et-al. MR imaging evaluation of perianal fistulas: spectrum of imaging features. Radiographics. 2012;32 (1): 175-94. doi:10.1148/rg.321115040 - Pubmed citation