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Dr. Ahmed Refaey, FRCR Consultant Radiologist Riyadh Military Hospital.

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Presentation on theme: "Dr. Ahmed Refaey, FRCR Consultant Radiologist Riyadh Military Hospital."— Presentation transcript:

1 Dr. Ahmed Refaey, FRCR Consultant Radiologist Riyadh Military Hospital

2 Format of the lecture  Anatomy  Pathogenesis  Imaging techniques  Scanning protocoles  Classification  Examples

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4 Anatomy  Anatomical canal : - extends from perineal skin to dentate line  Surgical canal : - extends from perineal skin to anorectal ring ( 1-1.5cm abov e dentate line ) - total length 4-5 cm

5 Anal sphincter comprised of 3 layers  Internal sphincter - continuance of circular smooth muscle of rectum, involuntary, contracts at rest & relaxes at defecation  Intersphincteric space  External sphincter - voluntary striated muscle, continuous cranially with puborectal muscle &levator ani

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7  Puborectal muscle has its origin on both sides of the symphysis pubis, forming a sling around the anorectum

8  The puborectal muscle is contracted at rest and accounts for the 8O0 angulation of the anorectal junction. It relaxes during defecation

9  On axial and coronal MR images, the different layers of anal sphincter and the surrounding structures can be displayed perfectly

10 AxialCoronal

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12 Perianal fistula  Abnormal connection between the epithilialised surface of the anal canal and the skin.

13 Causes  1ry - obstruction of anal gland which leads to stasis & infection with abscess & fistula formation ( most common cause )  2ry - iatrogenic ( post hemorrhoiedal surgury ) - inflammatory bowel dis. ( crohn’s disease ) - infections ( viral, fungal or TB ) - malignancy

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16 Imaging techniques  Fistulography  Endosonography  CT  MRI

17 Perianal fistulography

18 Anal endosonography

19 CT

20 MRI protocol  T1W &T2W fse axial and coronal  T2W with fat sat  T1W + CM  FOV 200

21  T2W  anatomy  T2W with fat sat ----  fistula

22 The anal clock P: anterior perineum n: natal cleft

23 The anal clock  The surgeon’s view of the perianal region when the patient is in the supine lithotomy position, corresponds to the orientation of axial MRI of the perianal region

24 Reporting  Position of the mucosal opening on axial images using anal clock  Distance of mucosal defect to perianal skin on coronal images  2ry fistulas or abscess

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26 Classification  Parks classification 1- intersphincteric 2- transsphincteric 3- extrasphincterisc 4-suprasphincteric Intersphincteric & transsphincteric are the most common Intersphincteric --> 70 % Transsphincteric -->20%

27 MR imaging Grading of perianal fistulas St. James university hospital classification

28 MRI Grading of perianal fistulas  Grade 1 : simple linear intersphincteric fistula  Grade 2 : intersphincteric fistula with abscess or 2ry track  Grade 3 : transsphincteric fistula  Grade 4: transsphinteric fistula with abscess or2ry track within ischeorectal fossa  Grade 5 : supralevator & translevator fistula

29 Grade 1 : simple linear intersphincteric fistula

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32  Intersphincteric fistula  Axial T2W with and without fat saturation  The intersphincteric fistula located at 6 o’clock

33 Intersphincteric fistula

34 Perianal fistula with an abscess

35 Grade 2 : intersphincteric fistula with abscess or 2ry track

36 Grade 3 : transspincteric fistula

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38 Transsphincteric fistula  The defect through internal & external sphincter at 6 o’clock is clearly visible

39  Transsphincteric fistula at 11 o’clock

40 Grade 4: transsphinteric fistula with abscess or2ry track within ischeorectal fossa

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43 Grade 5 : supralevator & translevator fistula

44 Suprasphincteric fistula  Two tracts in ischeorectal region  The right sided tract runs over the puborectal muscle (asterisc) & the mucosal opening lies at the level of dentate line (black arrow)

45 Extrasphincteric fistula  A small abscess in left ischeoanal fossa, the fistula runs through levator ani, it is therefore above the sphincter complex and extrasphincteric

46 Complex fistula  2 tracts in left buttock form single tract  The fistula breaks through the external sphincter  In intersphincteric space it divides again into 2 tracts  One ends blindly in the intersphincteric space  The other breaks through the internal sphincter with mucosal defect at 1 o’clock

47 Differential diagnosis

48 Pielonidal sinus  Small abscess just above the nates  No relation with sphincter complex

49 Proctitis  No fistula was seen  Diffuse thickening of rectal mucosa due to proctitis

50 Ischiorectal space abscess  An abscess in ischiorectal space with no connection to the sphincter complex

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52  Goodsall DH, Miles WE. Diseases of the anus and rectum. London, England: Longmans, Green,  ↵ Parks AG, Gordon PH, Hardcastle JD. A classification of fistula-in-ano. Br J Surg 1976; 63:1-12. ↵  ↵ Halligan S. Imaging fistula-in-ano. Clin Radiol 1998; 53: ↵  ↵ Kuijpers HC, Schulpen T. Fistulography for fistula-in-ano: is it useful? Dis Colon Rectum 1985; 28: ↵  ↵ Weisman RI, Orsay CP, Pearl RK, et al. The role of fistulography in fistula-in-ano: report of 5 cases. Dis Colon Rectum 1991; 34: ↵  ↵ Choen S, Burnett S, Bartram CI, Nicholls RJ. Comparison between anal endosonography and digital examination in the evaluation of anal fistulae. Br J Surg 1991; 78: ↵

53  ↵ Guillaumin E, Jeffrey RB, Shea WJ, et al. Perirectal inflammatory disease: CT findings. Radiology 1986; 161: ↵  ↵ Yousem DM, Fishman EK, Jones B. Crohn disease: perirectal and perianal findings at CT. Radiology 1988; 167: ↵  ↵ Barker PG, Lunniss PJ, Armstrong P, Reznek RH, Cottam K, Phillips RK. Magnetic resonance imaging of fistula-in-ano: technique, interpretation, and accuracy. Clin Radiol 1994; 49:7-13. ↵ ↵ ↵ Spencer JA, Ward J, Beckingham IJ, Adams C, Ambrose NS. Dynamic contrast-enhanced MR imaging of perianal fistulas. AJR Am J Roentgenol 1996; 167:  ↵ Haggett PJ, Moore NM, Shearman JD, Travis SPL, Jewell DP, Mortensen NJ. Pelvic and perianal complications of Crohn's disease: assessment using magnetic resonance imaging. Gut 1995; 36: ↵

54  Koelbel G, Schmeidl U, Majer MC, et al. Diagnosis of fistulae and sinus tracts in patients with Crohn's disease: value of MR imaging. AJR Am J Roentgenol 1989; 152:  Myhr GE, Myrvold HE, Nilsen G, Thoresen JE, Rinck PA. Perianal fistulas: use of MR imaging for diagnosis. Radiology 1994; 191:  ↵ Hussain SM, Stoker J, Schouten WR, Hop WCJ, Lameris JS. Fistula-in- ano: endoanal sonography versus endoanal MR imaging in classification. Radiology 1996; 200: ↵  ↵ Halligan S, Bartram CI. MR imaging of fistula-in-ano: are endoanal coils the gold standard? AJR Am J Roentgenol 1998; 171: ↵  ↵ Spencer JA, Chapple K, Wilson D, Ward J, Windsor ACJ, Ambrose NS. Outcome after surgery for perianal fistula: predictive value of MR imaging. AJR Am J Roentgenol 1998; ↵

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