1. MRI Imaging of Peri-anal Fistula.
Dr. Abd Allah Nazeer. MD.

7. Normal MR anatomy of the anal canal

15. Grade 1 Simple Inter-sphincteric Fistula

16. Grade 2 Inter-sphincteric track with
secondary track or abscess

17. Grade 3 Trans-sphincteric Fistula

18. Grade 4 Trans-sphincteric Fistula With
Abscess or Secondary Track

19. Grade 5 Supralevator and Translevator Disease

24. Majority (50%) of patients with
idiopathic peri-anal fistulation have
uncomplicated disease
25% 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%).

25. Grade 1- Intersphincteric fistula.

26. Grade 1- Intersphincteric fistula.

27. 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)

30. Grade 1- Intersphincteric fistula.

31. Grade 1- Intersphincteric fistula.

32. Grade 2- Inter-sphincteric fistula with
collection or secondary tract.

38. Grade 3- Trans-sphincteric fistula.

39. Grade 3- Trans-
sphincteric
fistula.

40. Grade 3-
Trans-
sphincteric
fistula.

41. Grade 3-
Trans-
sphincteric
fistula.

42. Grade 3-
Trans-
sphincteric
fistula.

43. Grade 3- Trans-sphincteric fistula.

46. Grade 4- Trans-sphincteric fistula with secondary
track or abscess formation.

47. Grade 4- Trans-sphincteric fistula.

48. Trans-sphenteric fistula with abscess formation.

49. Trans-sphenteric fistula with abscess formation.

52. Grade 5- Translevator disease.

53. Grade 5- Translevator disease.

54. Grade 5 :
supralevator & translevator fistula

56. Left supra-levator abscess with inflammatory changes
at the left obturator muscle and extension to the
ischiorectal fossa.

62. Complex fistula

63. Horseshoe
fistula with
abscess
formation at
ischio-rectal
and ischio-anal
fossa.

65. Differential diagnosis
Sinus pilonidalis
On 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.

66. Proctitis
On 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.

67. Abscess in the Ischioanal space
An abscess in the ischioanal space with
no connection to the sphincter complex