Post on 27-May-2015
MRI Imaging of Peri-anal Fistula.
Dr. Abd Allah Nazeer. MD.
Normal MR anatomy of the anal canal
Grade 1 Simple Inter-sphincteric Fistula
Grade 2 Inter-sphincteric track with secondary track or abscess
Grade 3 Trans-sphincteric Fistula
Grade 4 Trans-sphincteric Fistula With Abscess or Secondary Track
Grade 5 Supralevator and Translevator Disease
Majority (50%) of patients with idiopathic peri-anal fistulation have uncomplicated disease25% have trans-sphincteric fistulae complicated by secondary tracks or ischiorectal abscess Supra-levator or trans-levator disease is relatively rare in this patient group (8%).
Grade 1- Intersphincteric fistula.
Grade 1- Intersphincteric fistula.
Axial T2-weighted images with fat suppression (STIR) at two different levels (a, b). The dotted arrows demonstrate the inter-sphincteric fistula and its extension to the skin (solid arrow)
Grade 1- Intersphincteric fistula.
Grade 1- Intersphincteric fistula.
Grade 2- Inter-sphincteric fistula with collection or secondary tract.
Grade 3- Trans-sphincteric fistula.
Grade 3- Trans-sphincteric fistula.
Grade 3- Trans-sphincteric fistula.
Grade 3- Trans-sphincteric fistula.
Grade 3- Trans-sphincteric fistula.
Grade 3- Trans-sphincteric fistula.
Grade 4- Trans-sphincteric fistula with secondary track or abscess formation.
Grade 4- Trans-sphincteric fistula.
Trans-sphenteric fistula with abscess formation.
Trans-sphenteric fistula with abscess formation.
Grade 5- Translevator disease.
Grade 5- Translevator disease.
Grade 5 :supralevator & translevator fistula
Left supra-levator abscess with inflammatory changes at the left obturator muscle and extension to the ischiorectal fossa.
Complex fistula
Horseshoe fistula with abscess formation at ischio-rectal and ischio-anal fossa.
Differential diagnosis
Sinus pilonidalisOn the left an example of a sinus pilonidalis.There is a small abscess just above the nates.There is no relation with the sphincter complex.
ProctitisOn the left images of a patient who presented with anal complaints.No fistula was seen.There is, however, a diffuse thickening of the rectal mucosa due to a proctitis.
Abscess in the Ischioanal spaceAn abscess in the ischioanal space with no connection to the sphincter complex