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Anal perianal imaging part 2 perianal fistula CT MRI Dr Ahmed Esawy

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Anal perianal imaging part 2 perianal fistula ct mri dr ahmed esawy
Anal perianal imaging part 1 ct mri anatomy dr ahmed esawy
ANAL ,PERIANAL IMAGING
(endovaginal ultrasound endoanal ultrasound
perineal ultrasound
MRI)
FOR ANAL ,PERIANAL DISEASE3/ Image reconstruction and processing artifacts
• ANAL ANATOMY
• ANAL PERIANAL FISTULA
• ANAL TEARS (OBSTETRIC)
• FAECAL INCONTINENCE
• OTHER DISEASES
• NATOMY ANORECTAL ANATOMY :
• Anal Sphincter:
• internal sphincter
• external sphincter
• Puborectalis muscle and levator ani
• Sub cutaneous perianal fistula
• Sub mucous perianal fistula
• Low anal perianal fistula
• High anal perianal fistula
• Pelvi rectal perianal fistula
• Simple fistulography
• Perianal fistulography
• Endosonography Perianal fistula
• A. A superficial fistula.
• B. An intersphincteric fistula.
• C. A transsphincteric fistula.
• D. A suprasphincteric fistula.
• E. An extrasphincteric fistula.

Published in: Health & Medicine
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Anal perianal imaging part 2 perianal fistula CT MRI Dr Ahmed Esawy

  1. 1. Dr Ahmed Esawy ANAL PERIANAL IMAGING Dr. Ahmed Esawy MBBS M.Sc MD
  2. 2. Dr Ahmed Esawyyour name ANAL ,PERIANAL IMAGING (endovaginal ultrasound endoanal ultrasound perineal ultrasound MRI) FOR ANAL ,PERIANAL DISEASE
  3. 3. Dr Ahmed Esawy PERIANAL FISTULA IMAGING
  4. 4. Dr Ahmed Esawy FISTULA:  ABNORMAL communication between lumen of one viscus and lumen of another NTERNAL FISTULA) (or) between lumen of one hollow viscus to the exterior (EXTERNAL FISTULA) (or) between any two vessels
  5. 5. Dr Ahmed Esawy Latin : flute (or) a pipe (or) a tube.
  6. 6. Dr Ahmed Esawy • Anal fistula, is a single track with an external opening and an internal opening in the mucosa of the anal canal or rectum. • However the track usually has a complicated course. • Accurate assessment of the complete fistulous complex involves detection of internal & external openings as well the course of the main tract and its extensions. • Radiological imaging of the pelvis adds an important dimension to our understanding of rectal and perianal disease.
  7. 7. Dr Ahmed Esawy A perianal fistula is an abnormal connection between the epithilialised surface of the anal canal and the skin. The causes of perianal fistulas: Primary Obstruction of anal gland which leads to stasis and infection with abscess and fistula formation (most common cause). Secondary Iatrogenic (hemorrhoideal surgery) Inflammatory bowel diseases (Crohn's disease more common than colitis ulcerosa) Infections (viral, fungal or TB) Malignancy
  8. 8. Dr Ahmed Esawy AETIOLOGY OF ANAL FISTULA Anal gland theory: • The majority of anal fistulas are associated with an abscess caused by an infected anal gland. • The abscess is formed initially within the intersphincteric space and then spreads along adjacent potential spaces. • Common organisms include E. coli, enterococcus species, and bacteroides species.
  9. 9. Dr Ahmed Esawy Other Causes include: • I. pelvic sepsis. • II. Perineal Injuries. • III Anal disorders: Fissure. Hidradenitis. Hemorrhoids. • IV-Inflammatory bowel disease: Crohn‫׳‬s disease. Ulcerative Colitis. Actinomycosis. Venereal infections.
  10. 10. Dr Ahmed Esawy PATHOLOGY OF ANAL FISTULA • Infection usually affects anal glands at the level of dentate line. Spread of infection may occur: • Downward: → Perianal abscess and intersphincteric fistula. • Upward: → Pelvic abscess and suprasphincteric fistula. • Outward: → Ischiorectal abscess and transsphincteric fistula.
  11. 11. Dr Ahmed Esawy THE GOODSALL‫׳‬S RULE • If the external opening is anterior to a transverse anal line the internal opening will be in a direct straight line to the nearest crypt. • If the opening is posterior to the transverse line, the internal opening will be in a posterior midline crypt, and the tract will be curved.
  12. 12. Dr Ahmed Esawy RADIOLOGICAL ASSESSMENT • Simple fistula can be easily detected: internal opening, external opening, and a low tract. • However complex & recurrent fistulae require accurate assessment by radiological imaging. • Fistulography, MRI and EUS have been used with variable accuracy.
  13. 13. Dr Ahmed Esawy CLINICAL INTERPRETATION • Main Tract: radial or curvilinear. • Fistula level: the point in which the main tract of the fistula traverse the sphincters. • Internal opening: the point in which the tract traverses the mucosa- submucosa complex. • Secondary tract: The direction and the anatomic space were assessed. • Chronic fistula cavity: appear as a hypoechoic area thicker than the main tract, sometimes filled with hydrogen peroxide (bright hypoechoic).
  14. 14. Dr Ahmed Esawy Anal fistula and perianal suppurative conditions The primary tract is presented as a band of poor reflectivity within the longitudinal muscle (LM) which have external opening and internal opening, the last is usually difficult to detect on physical examination, but with EAUS the criteria of internal opening can be easily detected: The Intersphincteric tract contacts the internal sphincter A defect is present in the internal sphincter at point of contact with the intersphincteric tract There is an actual break in the subepethelial tissue . Moving the probe in and out within the canal and also circumferentially to detect the extent of the tract
  15. 15. Dr Ahmed Esawy Classification The most widely used classification is the Parks Classification which distinguishes four kinds of fistula: intersphincteric, transsphincteric, suprasphincteric and extrasphincteric. The most common fistulas are the intersphincteric and the transsphincteric. The extrasphincteric fistula is uncommon and only seen in patients who had multiple operations.In these cases the connection with the original fistula tract to the bowel is lost. A superficial fistula is a fistula that has no relation to the sphincter or the perianal glands and is not part of the Parks classification.These are more often due to Crohns disease or anorectal procedures such as haemorrhoidectomy or sphincterotomy.
  16. 16. Dr Ahmed Esawy The providential piont is detection of internal opening
  17. 17. Dr Ahmed Esawy STANDARD CLASSIFICATION  Sub cutaneous  Sub mucous  Low anal  High anal  Pelvi rectal
  18. 18. Dr Ahmed Esawy  Can be low level fistula- open into anal canal below the internal ring. high level fistula- at/ above the internal ring.  Can be Simple- without any extensions Complex- with extensions  Can be single multiple- TB, ulcerative colitis, crohn’s, HIV, LGV
  19. 19. Dr Ahmed Esawy Imaging techniques • Fistulography • Endosonography • CT • MRI
  20. 20. Dr Ahmed Esawy Simple fistulography
  21. 21. Dr Ahmed Esawy LIMITATION : • extensions from the primary tract may fail to fill with contrast material if they are plugged with debris,are very remote, or there is excessive contrast material reflux from either the internal or external opening • the sphincter muscles themselves are not directly imaged, which means that the relationship between any tract and the sphincter must be guessed • difficult to decide whether an extension has a supra- or an infralevator location • the exact level of the internal opening in the anal canal is often impossible to determine with sufficient accuracy • Acute tracks may not have a patent lumen • Difficult to relate the track to the sphincter and levator ani • Shown to be accurate in only 16 % • cannot distinguish between the different types of fistula and its exact course through/in between anal sphincters and also fails to know the integrity of sphincters Simple fistulography
  22. 22. Dr Ahmed Esawy Pelvic floor (levator ani muscle ) can be approximately demarcated by the green line shown in AP supine view of the pelvis going through the bases of bilateral greater trochanters while on lateral view it it lies at the level of line connecting the tip of coccyx to inferior border of pubic symphysis. So any fistula going above this line has to be supralevator/high fistula and the one which is below this line will be low anal fistula.
  23. 23. Dr Ahmed Esawy
  24. 24. Dr Ahmed Esawy Fistulography in a male patient. Coronal image shows that it is obvious that there are several high extensions (arrows) surrounding the anorectal junction; however, the exact anatomic location of these is unclear because the pelvic floor (ie, levator ani in this case) cannot be directly visualized. Definition of extension location (supra- or infralevator) is central to surgical management. Useful if extra sphincteric fistula suspected.
  25. 25. Dr Ahmed Esawy Perianal fistulography
  26. 26. Dr Ahmed Esawy A 36 yrs old man with perianal pruritis and discharge since 3-4months. There was a skin opening in right posterior aspect around the anus CONTINUE Right perianal blind ending sinus tract with a small ramification
  27. 27. Dr Ahmed Esawy O mark denotes the external opening on the skin of the fistula/sinus tract. A small NG tube( 5F) is passed through the opening. So the direction of the tube is the direction of the tract. Contrast is injected and films are taken in AP and Lateral views. Right perianal blind ending sinus tract with a small ramification CONTINUE
  28. 28. Dr Ahmed Esawy There is a sinus tract in right perianal fossa and travels superiorly and posteriorly stopping short of the lumen of anal cannal in posterior midline. It shows a small ramification along the right anterolateral aspect. No obvious contrast is seen to flow into the anal canal suggesting lack of communication with the anal canal. END Right perianal blind ending sinus tract with a small ramification
  29. 29. Dr Ahmed Esawy  FISTULOGRAPHY/ SINUSOGRAPHY: • For knowing the exact extent/origin of sinus (or)fistula. • Water soluble or ultrafluid lipoidal iodine dye is used. • Lipoidal iodine is poppy seed oil containing 40% iodine.
  30. 30. Dr Ahmed Esawy Fistulography images of horseshoe track in antero-posterior fistulography (A) showing left gluteal external orifices left horseshoe track communicating left ischiorectal fossa track and hole, right horseshoe track next to levator ani, which communicates with the internal hole in anterior position, perianal ipsilateral external orifice and the superficial blindly branch in right large labia [6] that evolves into new external orifice, observed on admission; and its schematic superposition (B). MRI image showing the ischiopubic track and left perineal oval fistula extending to the gluteal region (C) and perianal track and vulvar compromise (D).
  31. 31. Dr Ahmed Esawy Endosonography Perianal fistula
  32. 32. Dr Ahmed Esawy Fistula classification based on ultrasound Submucosal Subcutaneous The tract is located between the internal sphincter and the skin, without muscular fibers. Intersphincteric The tract goes through the intersphincteric space with out traversing the external sphincter fibers. Low transsphincteric The tract traverses only the distal external sphincter third, which by ultrasonography correspond to the lower portion of the medium anal canal. Medium transsphincteric The tract traverses both sphincters, external and internal, in the lower part of the medium anal canal, this is in the half closest to the lower anal canal. High transsphincteric The tract traverses both sphincters, in the higher part of the medium anal canal, in the space below puborectalis. Suprasphincteric The tract goes above or through the puborectalis level. Extrasphincteric The tract affects structures above the sphincters, generally with the internal opening in the abdominal cavity or the high rectum, this type of fistula usually cannot be studied by ultrasound.
  33. 33. Dr Ahmed Esawy
  34. 34. Dr Ahmed Esawy Simple linear intersphincteric fistulas extend directly from the perianal skin into the anal canal, sparing both the ischiorectal and ischioanal spaces. These fistulas do not traverse the external anal sphincter but may traverse the distal most portion of the internal sphincter below the level of the dentate line.
  35. 35. Dr Ahmed Esawy CLASSIFICATION OF ANAL FISTULA A. A superficial fistula. B. An intersphincteric fistula. C. A transsphincteric fistula. D. A suprasphincteric fistula. E. An extrasphincteric fistula.
  36. 36. Dr Ahmed Esawy A superficial fistula tracks below both the internal anal sphincter and external anal sphincter complexes B. An intersphincteric fistula tracks between the internal anal sphincter and the external anal sphincter in the intersphincteric space. C. A transsphincteric fistula tracks from the intersphincteric space through the external anal sphincter. D. A suprasphincteric fistula leaves the intersphincteric space over the top of the puborectalis and penetrates the levator muscle before tracking down to the skin. E. An extrasphincteric fistula tracks outside of the external anal sphincter and penetrates the levator muscle into the rectum.
  37. 37. Dr Ahmed Esawy Diagram shows different types of fistulous . On left of image, cephalad line represents extrasphincteric tract running in suprasphincteric plane before descending to perineum. Middle line shows transsphincteric tract, and caudal line shows short extrasphincteric tract running directly from anal canal to external opening on perianal skin. On right of image are two intersphincteric tracts: Cephalad tract ascends in intersphincteric plane before running suprasphincteric to descend in extrasphincteric plane. More caudal tract on right descends in intersphincteric plane to skin.
  38. 38. Dr Ahmed Esawy Classification of anal fistulas: perianal fistulas may appear as (1) superficial fistulas that do not traverse any sphincter muscle. (2) Fistulas are intersphincteric when they traverse the intersphincteric space or internal anal sphincter or Transesphincteric (3) when they extend through the external anal sphincter into the ischioanal space (4) Spread beyond the external sphincter results in extrasphincteric or suprasphincteric fistulas
  39. 39. Dr Ahmed Esawy Diagram of the coronal view shows perianal anatomic areas. A indicates anal canal; R, rectum, 1, submucosal space; 2, intersphincteric space; 3, ischioanal space; 4, supralevator space.
  40. 40. Dr Ahmed Esawy classification of fistulas consists of 5 grades... . A, Grade 1: simple linear intersphincteric fistula B, Grade 2: intersphincteric fistula with intersphincteric abscess or secondary fistulas C, Grade 3: transsphincteric fistula
  41. 41. Dr Ahmed Esawy E, Grade 5: supralevator and translevator disease. A indicates anal canal; and R, rectum. D, Grade 4: transsphincteric fistula with abscess or secondary track within the ischioanal or ischiorectal fossa
  42. 42. Dr Ahmed Esawy Congenital : Perianal fistula has been reported in early infancy. And in some cases the tracks are lined by columnar or transitional epithelium, suggesting that they might have a congenital or developmental origin
  43. 43. Dr Ahmed Esawy Illustration in coronal plane shows fistula extensions (secondary tracts): A extension into roof of ischioanal fossa, arising from apex of a transsphincteric fistula; B supralevator pararectal extension arising from apex of a transsphincteric fistula; C supralevator extension originating from intersphincteric plane, D intersphincteric horseshoe
  44. 44. Dr Ahmed Esawy TECHNIQUE OF EUS in AF with contrast • While the patient in the left lateral position a conventional EUS is performed. • The probe should be introduced at the higher, middle, and lower third of the anal canal. • Fistula appears as hypoechoic areas within the submucosa, internal or external sphincter, or perianal tissue. • A catheter is inserted into the external opening. • Hydrogen peroxide is first injected slowly to show the main tract, then, injection at a greater pressure was performed to detect secondary tracts.
  45. 45. Dr Ahmed Esawy THE PRACTICAL USES OF EUS WITH H2O2 • EUS is beneficial in detecting the course of the primary tract . Moreover, endosonography is cost-effective and superior in diagnosing trans-sphincteric fistula and exclude secondary tracts. • EUS can detect the site & number of the internal opening. • Identification of those high fistulae that will be subsequently treated with a sphincteric saving procedure. • Detection of chronic fistula complex or secondary tracts.
  46. 46. Dr Ahmed Esawy • Comparing MRI with endoanal ultrasound with H2O2, it seems that the latter has certain advantages: it is cheap, simple, quick (takes less than 10 minutes) and is portable (can be performed in the operating room). • Thus, EUS has a degree of reliability high enough to be considered the preferred examination technique in the study of complex anal fistulae.
  47. 47. Dr Ahmed Esawy Endoanal ultrasound Limitation • Operator dependent • Highly accurate at identifying the internal opening • Depicts fewer secondary extensions than MR • Difficulty differentiating active track from fibrosis
  48. 48. Dr Ahmed Esawy INTERSPHINCTERIC FISTULA • Intersphincteric fistula (yellow track) extending from the dentate line down to the skin through the intersphincteric plane.
  49. 49. Dr Ahmed Esawy After administration of peroxide, EUS scan shows immediate extension to the anal lumen, below the level of the internal anal sphincter (arrow).
  50. 50. Dr Ahmed Esawy The fistula tracks upward below the internal sphincter (arrowhead ), tracks posteriorly into the intersphincteric plane (arrow ). It forms a second track in the intersphincteric region (arrows ).
  51. 51. Dr Ahmed Esawy Simple transsphincteric fistula. After administration of peroxide, endoanal US scan shows a direct communication that extends from the skin immediately adjacent to the anal canal (small arrow) through the distal aspect of the posterior internal anal sphincter (arrowhead) to the anal canal (large arrow). Echogenic air is trapped in the anal mucosa anteriorly, which may falsely suggest communication at this location. After demonstration of this single superficial posterior fistula, the patient underwent an unroofing procedure only, with no loss of continence Simple transsphincteric fistula. Drawing in the coronal plane, with a horizontal line corresponding to the level of the US image, shows extent of the fistula depicted in a.
  52. 52. Dr Ahmed Esawy Intersphincteric fistula. Anal endosonogram in transverse plane at mid–anal canal level in a male patient shows fistula with hypoechoic tract located in intersphincteric plane between external (EAS) and internal (IAS) anal sphincters. Internal sphincter is markedly hypoechoic. At surgery, the internal opening was located at 6 o’clock posteriorly and was correctly predicted from anal endosonographic visualization because of the radial position of the fistula within the intersphincteric plane.
  53. 53. Dr Ahmed Esawy Complex intersphincteric fistulas are associated with abscesses or secondary tracks and are limited by the external anal sphincter Intersphincteric fistula. (a) After administration of peroxide, endoanal US scan shows immediate extension to the anal lumen, below the level of the internal anal sphincter (arrow). (b, c) The fistula also tracks upward below the internal sphincter (arrowhead in b), tracks posteriorly into the intersphincteric plane (arrow in b), and forms a second track in this intersphincteric region (arrows in c). (a) (b)
  54. 54. Dr Ahmed Esawy Intersphincteric fistula: Drawing in the coronal plane, with horizontal lines corresponding to the levels of the US images, shows extent of the intersphincteric fistula depicted in a-c
  55. 55. Dr Ahmed Esawy Line diagram of the coronal view shows a right intersphincteric fistula ( track) extending from the dentate line down to the skin through the intersphincteric plane
  56. 56. Dr Ahmed Esawy Vertical submucosal and intersphincteric extensions Vertical submucosal and intersphincteric extensions. (a) Despite an unremarkable initial endoanal US examination, US scan obtained after peroxide injection into a superficial posterior opening shows a fistula extending through both the markedly thinned internal (shortest arrow) and external anal sphincters, communicating with the anal lumen, and tracking in both the submucosal and intersphincteric spaces (long arrows). Vertical submucosal and intersphincteric extensions. (b) US scan shows that, in the middle of the anal canal, approximately 2 cm more cranial than image in a, additional tracks extend vertically in the submucosal (shortest arrow) and intersphincteric spaces (long arrows). (c) (c) Drawing in the coronal plane, with horizontal lines corresponding to the levels of the US images, shows extent of the fistula and additional tracks
  57. 57. Dr Ahmed Esawy TRANSSPHINCTERIC FISTULA • Trans-sphincteric fistula (yellow track) crossing the ischiorectal fossa and piercing both layers of the sphincter complex.
  58. 58. Dr Ahmed Esawy Transsphincteric fistula extending through the internal anal sphincter. Prior to injection of peroxide, endoanal US scan shows a hypoechoic soft-tissue abnormality (large arrow) superficial to the anterior part of the internal anal sphincter (small arrow). Transsphincteric fistula extending through the internal anal sphincter. (b) After cannulation of the fistula and injection of peroxide, prompt visualization of the peroxide was noted in this fistula, which extends through the internal anal sphincter into a small superficial submucosal abscess cavity (arrow). (c) Drawing in the coronal plane, with a horizontal line corresponding to the level of b, shows the extent of the transsphincteric fistula and abscess
  59. 59. Dr Ahmed Esawy Transsphincteric fistula extending through the external anal sphincter and communicating with an intersphincteric abscess. (a) Peroxide- enhanced endoanal US scan reveals a transsphincteric fistula communicating with a small yet high posterior intersphincteric abscess cavity (arrow). No peroxide traverses the internal sphincter, and no communication with the anal lumen was identified (b) Drawing in the coronal plane, with a horizontal line corresponding to the level of a, shows the extent of the fistula and abscess
  60. 60. Dr Ahmed Esawy Transsphincteric fistula extending through the internal and external anal sphincters. (a) Peroxide-enhanced endoanal US scan shows extension of the fistula through the external anal sphincter into a small abscess within the posterior aspect of the internal anal sphincter (arrow). No communication with the anal canal was identified at subsequent surgery. (b) Drawing in the coronal plane, with a horizontal line corresponding to the level of a, shows extent of the fistula and abscess.
  61. 61. Dr Ahmed Esawy Transsphincteric fistula. (a) Preliminary ultrasound scan reveals a hypoechoic soft- tissue mass in the left lateral intersphincteric plane (large arrow) with marked deficiency of the internal sphincter posteriorly (small arrow). Transsphincteric fistula. (b) After peroxide injection, the US scan shows immediate communication with this abscess (large arrow), with the fistula extending through the thickened and irregular internal anal sphincter antrolaterally into the anal canal (small arrow). (c) Drawing in the coronal plane, with a horizontal line corresponding to the level of b, shows extent of the fistula and abscess
  62. 62. Dr Ahmed Esawy Transsphincteric fistula shown on anal endosonogram in the transverse plane at the mid–anal canal level in a female patient. In contrast to Figure before, the fistula () has penetrated the external anal sphincter (EAS). The internal opening was correctly predicted at 7-o’clock position. Note that the internal sphincter is relatively thinned here, which is a clue to the site of the internal opening, but there is no tract extending to the anal mucosa.
  63. 63. Dr Ahmed Esawy • EUS shows a direct communication that extends from the skin immediately adjacent to the anal canal (small arrow) through the posterior internal sphincter (arrowhead) &to the anal canal (large arrow).
  64. 64. Dr Ahmed Esawy • Trans-sphincteric fistula with an ischiorectal abscess (a).
  65. 65. Dr Ahmed Esawy • Transsphincteric fistula extending through the internal anal sphincter. Prior to injection of peroxide, EUS scan shows a hypoechoic soft-tissue abnormality (large arrow) superficial to the internal sphincter (small arrow).
  66. 66. Dr Ahmed Esawy • After injection of peroxide, contrast is seen extending through the internal sphincter into a small superficial submucosal abscess cavity (arrow).
  67. 67. Dr Ahmed Esawy • Transsphincteric fistula. EUS reveals a hypoechoic soft-tissue mass in the lateral intersphincteric plane (large arrow) with marked deficiency of the internal sphincter posteriorly (small arrow).
  68. 68. Dr Ahmed Esawy • Transsphincteric fistula. After peroxide injection, EUS shows immediate communication with this abscess (large arrow), with the fistula extending through the thickened and irregular internal anal sphincter antrolaterally into the anal canal (small arrow).
  69. 69. Dr Ahmed Esawy Grade 4 transsphincteric fistula with abscess. A, Axial (left) and sagittal (right) endoanal sonograms show a transsphincteric fistula with an abscess within ischioanal fossa at the 2-o’clock position. B and C, Axial and sagittal magnified endoanal sonograms show the intersphincteric component of the abscess (a) at the 12-o’clock position. In C, the IAS is shown between black arrows,and the EAS is shown between white arrows. D, Diagram of the coronal plane shows the extent of the transsphincteric fistula depicted in A–C. A indicates anal canal; and R, rectum.
  70. 70. Dr Ahmed Esawy HORSESHOE FISTULAS • Horseshoe fistulas. Drawing in the coronal plane, shows extent of the fistulas and abscess.
  71. 71. Dr Ahmed Esawy Horseshoe fistulas Horseshoe fistulas. (a) Preliminary endoanal US scan reveals irregular thickening with a soft-tissue mass (arrow) at the 11-o’clock position in the internal anal sphincter and the intersphincteric plane Horseshoe fistulas. (b, c) After peroxide injection, the US scans show immediate communication (arrow in b), with fistulas extending posteriorly in the external anal sphincter (large arrow in c) and through the internal anal sphincter into the anal lumen (small arrow in c). Horseshoe fistulas. (d) Drawing in the coronal plane, with horizontal lines corresponding to the levels of b and c, shows extent of the fistulas and abscess
  72. 72. Dr Ahmed Esawy Anal endosonogram at upper anal canal level in a male patient shows extensive hypoechoic horseshoe extension (). Because endosonography is limited to the transverse plane, it is difficult to determine whether this extension is infra- or supralevator.
  73. 73. Dr Ahmed Esawy Transverse anal endosonogram at upper anal canal level in a female patient shows intersphincteric horseshoe extenstion (arrows). Gas in the fistula causes acoustic shadowing (stars), which could be mistaken for transsphincteric tracts.
  74. 74. Dr Ahmed Esawy • Horseshoe fistulas. EUS scan reveals irregular thickening with a soft-tissue mass (arrow) at the 11- o’clock position in the internal sphincter and the intersphincteric plane.
  75. 75. Dr Ahmed Esawy Suprasphincteric fistula • Suprasphincteric fistula. After injection of peroxide, a US scan shows an intersphincteric abscess posteriorly (large arrow) immediately external to the internal anal sphincter (small arrow).
  76. 76. Dr Ahmed Esawy Suprasphincteric fistula : It appears as hypoechoic tract extending up to a level above puborectalis and then extend down through the levator ani muscle to reach skin (Jonathan et al., 2000). Suprasphincteric fistula: (a) after injection of peroxide, US scan shows an intersphincteric abscess posteriorly (large arrow) immediately external to the internal anal sphincter (small arrow). (b, c) Subsequent scans show secondary fistulas extending from this abscess through the right side of the internal anal sphincter into the anal lumen at the level of the puborectal muscle (arrow in b) and through the levator ani muscle superiorly (arrows in c). (d) Drawing in the coronal plane, with horizontal lines corresponding to the levels of the US images, shows extent of the abscess and fistulas (Quoted from Jonathan et al., 2000).
  77. 77. Dr Ahmed Esawy Grade 5 suprasphincteric fistula and abscesses. A, Endoanal sonogram shows an ischioanal abscess at the 3- to 6-o’clock position (black arrows) and its transsphincteric extension through both the markedly thinned EAS and IAS (white arrows) at the level of the middle anal canal. B, After cannulation of the fistula and injection of peroxide, on a subsequent endoanal sonogram through the high anal canal level, prompt visualization of the peroxide was noted in the abscess (black arrows) and fistula extending through both the markedly thinned IAS and puborectalis muscle (PRM), which extends into a small superficial submucosal abscess cavity (white arrows) CONTINUE
  78. 78. Dr Ahmed Esawy C, Endoanal sonogram through the supralevatoric level obtained before administration of peroxide reveals a horseshoe supralevatoric abscess cavity (black arrows) and a deficiency area in the rectal wall at the 6-o’clock position (white arrow). A, After peroxide injection, an endoanal sonogram clearly depicts the suprasphincteric abscess cavity (black arrows) communicating with the anal lumen (white arrow) at the same location as in C. The internal opening is shown as a subepithelial breach connecting with the intersphincteric tract through an internal sphincteric defect. E, Diagram in the coronal plane shows the extent of the suprasphincteric fistula depicted in A–D. A indicates anal canal; and R, rectum C E Grade 5 suprasphincteric fistula and abscesses
  79. 79. Dr Ahmed Esawy EXTRASPHINCTERIC FISTULA • Extrasphincteric fistula. EUS scan shows a single hypoechoic mass (large arrow) outside the internal (small arrow) and external sphincters prior to peroxide injection.
  80. 80. Dr Ahmed Esawy • Exrtrasphincteric fistula. US scans obtained after injection show immediate communication with this small abscess cavity (arrow), with a fistula (arrow) tracking up the antrolateral rectal wall to the base of the prostate gland.
  81. 81. Dr Ahmed Esawy Extrasphincteric fistula. (a) Endoanal US scan shows a single hypoechoic mass (large arrow) outside the internal (small arrow) and external anal sphincters prior to peroxide injection Extrasphincteric fistula. (b, c) US scans obtained after injection show immediate communication with this small abscess cavity (arrow in b), with a fistula (arrow in c) tracking up the antrolateral rectal wall to the base of the prostate gland (P in c). Extrasphincteric fistula. (d) Drawing in the coronal plane, with horizontal lines corresponding to the levels of b and c, shows extent of the fistula and abscesses
  82. 82. Dr Ahmed Esawy Extrasphincteric and suprasphincteric fistulas Suprasphincteric fistula. (a) After injection of peroxide, a US scan shows an intersphincteric abscess posteriorly (large arrow) immediately external to the internal anal sphincter (small arrow). Suprasphincteric fistula. (b, c) Subsequent scans show secondary fistulas extending from this abscess through the right side of the internal anal sphincter into the anal lumen at the level of the puborectal muscle (arrow in b) and through the levator ani muscle superiorly (arrows in c). Suprasphincteric fistula. (d) Drawing in the coronal plane, with horizontal lines corresponding to the levels of the US images, shows extent of the abscess and fistulas.
  83. 83. Dr Ahmed Esawy PERIANAL FISTULA Use of peroxide-enhanced anal endosongraphy allows visualization of entire course of the echogenic fistula, including its relation to the internal and external sphincters and the levator ani muscle
  84. 84. Dr Ahmed Esawy Sometimes it is difficult to differentiate between a tract and small collection at one level ,but this can be overcome by moving and angling the probe ,as both tend to be hypoechoic, but tracts often have hyperechoic shadows in the middle which represent gas within the tract
  85. 85. Dr Ahmed Esawy anorectal abscesses
  86. 86. Dr Ahmed Esawy • Pelvic abscess (a) with a translevator fistula traversing the ischiorectal fossa.
  87. 87. Dr Ahmed Esawy INTERSPHINCTERIC ABSCESS • Intersphincteric abscess (a).
  88. 88. Dr Ahmed Esawy • Posterior intersphincteric abscess. A hypoechoic soft- tissue mass containing air immediately posterior to the anal canal in the intersphincteric zone (arrow).
  89. 89. Dr Ahmed Esawy Posterior intersphincteric abscess. (a) Endoanal US scan obtained before administration of peroxide reveals marked deficiencies of numerous areas of the internal anal sphincter, with a hypoechoic soft-tissue mass containing air immediately posterior to the anal canal in the intersphincteric zone (arrow). Posterior intersphincteric abscess (b) Scan obtained after peroxide injection shows prompt communication with this intersphincteric abscess (arrow).
  90. 90. Dr Ahmed Esawy Posterior intersphincteric abscess: (a) Endoanal US scan obtained before administration of peroxide reveals marked deficiencies of numerous areas of the internal anal sphincter, with a hypoechoic soft-tissue mass containing air immediately posterior to the anal canal in the intersphincteric zone (arrow). (b) Scan obtained after peroxide injection shows prompt communication with this intersphincteric abscess (arrow)
  91. 91. Dr Ahmed Esawy PERIANAL ABSCESS
  92. 92. Dr Ahmed Esawy Transperineal US demonstrating anal fistula
  93. 93. Dr Ahmed Esawy MRI IN FISTULA
  94. 94. Dr Ahmed Esawy Magnetic Resonance • Most accurate technique for evaluation of the primary track and any extensions. • More accurate predictor of patient outcome than surgical findings at EUA].
  95. 95. Dr Ahmed Esawy Endoanal coil • Endocoils give superior anatomical resolution of fistula disease within the sphincter • Resolution falls off rapidly outside the sphincter • Complex tracks outside the sphincter are not well seen
  96. 96. Dr Ahmed Esawy Correct orientation for MR imaging of anal canal. Sagittal T2-weighted scout image through patient’s midline is used to plan images that are truly transverse with respect to anal canal,as shown by white lines. Coronal imaging is then performed at 90° to the transverse plane.
  97. 97. Dr Ahmed Esawy MRI protocol • T1W &T2W fse axial and coronal • T2W with fat sat • T1W + CM • FOV 200 • IV gadolinium rarely administered
  98. 98. Dr Ahmed Esawy • T2W ----- anatomy • T2W with fat sat ---- fistula
  99. 99. Dr Ahmed Esawy The anal clock P: anterior perineum n: natal cleft
  100. 100. Dr Ahmed Esawy 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
  101. 101. Dr Ahmed Esawy T2W images without fat sat better display the anatomy, while the fat sat images better depict the fistulas. Perianal fistula: axial T2WI without fatsat (left) and with fatsat (right)
  102. 102. Dr Ahmed Esawy Reporting When you describe a fistula, it is important to mention the following characteristics: Position of the mucosal opening on axial images (using the anal clock). Distance of the mucosal defect to the perianal skin on coronal images. Secondary fistulas or abscesses.
  103. 103. Dr Ahmed Esawy Classification Parks classification 1- intersphincteric 2- transsphincteric 3- extrasphincterisc 4-suprasphincteric Intersphincteric & transsphincteric are the most common Intersphincteric --> 70 % Transsphincteric -->20%
  104. 104. Dr Ahmed Esawy
  105. 105. Dr Ahmed Esawy 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
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  108. 108. Dr Ahmed Esawy Grade 1 simple linear intersphincteric fistula. (a) Line diagram of the coronal view shows a right intersphincteric fistula (yellow track) extending from the dentate line down to the skin through the intersphincteric plane.
  109. 109. Dr Ahmed Esawy Intersphincteric fistula On the left axial T2W images with and without fat saturation. An intersphincteric fistula is located at 6 o'clock. Continue with coronal images. On the coronal image the fistula runs caudally towards the skin. There is no connection with the external sphincter.
  110. 110. Dr Ahmed Esawy coronal images of another patient with an intersphincteric fistula.
  111. 111. Dr Ahmed Esawy Grade 1 Intersphincteric fistula perianal fistula. Coronal dynamic contrast- enhanced MR image shows a right intersphincteric fistula entering the anal canal in the midline posteriorly (arrow). Grade 1 perianal fistula. Axial T2- weighted MR image shows a posterior midline intersphincteric fistula (arrowhead).
  112. 112. Dr Ahmed Esawy Intersphincteric fistula: are usually simple hypoechoic tract in intersphincteric space but may be associated with secondary tracts Intersphincteric fistula: (a) after administration of peroxide, endoanal US scan shows immediate extension to the anal lumen, below the level of the internal anal sphincter (arrow). (b, c) The fistula also tracks upward below the internal sphincter (arrowhead in b), tracks posteriorly into the intersphincteric plane (arrow in b), and forms a second track in this intersphincteric region (arrows in c). (d) Drawing in the coronal plane, with horizontal lines corresponding to the levels of the US images, shows extent of the intersphincteric fistula depicted in a-c
  113. 113. Dr Ahmed Esawy Intersphincteric fistula in a male patient. Transverse STIR MR image shows that lateral margin of external sphincter (long arrow) contrasts against fat in the ischioanal fossa (star). Fistula (short arrow) is in the intersphincteric space posteriorly at 6 o’clock and is contained by the external sphincter. There is no tract in the ischioanal fossa.
  114. 114. Dr Ahmed Esawy Perianal fistula with an abscess
  115. 115. Dr Ahmed Esawy Grade 1- Intersphincteric fistula
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  124. 124. Dr Ahmed Esawy Grade 2 horseshoe perianal fistula. Line diagram of the axial view shows an intersphincteric horseshoe fistula (yellow track, arrow) confined by the external sphincter. Grade 2 horseshoe perianal fistula. Axial T2-weighted image shows an intersphincteric horseshoe fistula (arrow). Grade 2 : horseshoe intersphincteric fistula with abscess or 2ry track
  125. 125. Dr Ahmed Esawy Horseshoe extension (arrows) arising from intersphincteric fistula in a male patient Transverse STIR MR image shows that, in this case, the horseshoe practically encircles the anal canal.
  126. 126. Dr Ahmed Esawy Horseshoe fistula where the internal opening is seldom clearly defined which may fuse with IAS and it is rare to see any actual defect in the submucosa (Jonathan et al., 2000). Horseshoe fistulas: (a) Preliminary endoanal US scan reveals irregular thickening with a soft-tissue mass (arrow) at the 11-o’clock position in the internal anal sphincter and the intersphincteric plane. (b, c) After peroxide injection, the US scans show immediate communication (arrow in b), with fistulas extending posteriorly in the external anal sphincter (large arrow in c) and through the internal anal sphincter into the anal lumen (small arrow in c). (d) Drawing in the coronal plane, with horizontal lines corresponding to the levels of b and c, shows extent of the fistulas and abscess (Quoted from Jonathan et al., 2000).
  127. 127. Dr Ahmed Esawy Grade 2 perianal fistula with an abscess. Coronal dynamic contrast- enhanced MR image shows a left intersphincteric abscess cavity (arrowhead) above the primary intersphincteric track (curved arrow). The enteric entry point is suggested by a medial track (straight arrow). Grade 2 perianal fistula with an abscess. Line diagram of the coronal view shows a left intersphincteric abscess (a).
  128. 128. Dr Ahmed Esawy Grade 2 horseshoe perianal fistula with an abscess. (a)coronal, (b) axial, dynamic contrast-enhanced MR images show an intersphincteric abscess, which is peripherally enhanced (curved arrow) and contains a central focus of nonenhancing pus (straight arrow). As viewed in all three planes, the fistula is confined by the external sphincter and the ischiorectal fossa is unaffected
  129. 129. Dr Ahmed Esawy Grade 2 perianal fistula with an abscess. dynamic contrast-enhanced MR images show an intersphincteric abscess, which is peripherally enhanced (curved arrow) and contains a central focus of nonenhancing pus (straight arrow). As viewed in all three planes, the fistula is confined by the external sphincter and the ischiorectal fossa is unaffected.
  130. 130. Dr Ahmed Esawy Grade 2- Intersphincteric fistula with collection
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  132. 132. Dr Ahmed Esawy Grade 3 perianal fistula. Line diagram of the coronal view shows a right trans- sphincteric fistula (yellow track) crossing the ischiorectal fossa and piercing both layers of the sphincter complex Grade 3 : transsphincteric fistula
  133. 133. Dr Ahmed Esawy Grade 3 Trans-sphincteric fistula perianal fistula. Coronal dynamic contrast- enhanced MR image shows a right trans- sphincteric fistula (arrow) and inflammatory change in the right ischiorectal fossa. Note the entry site in the middle third of the anal canal Grade 3 perianal fistula. Axial dynamic contrast-enhanced MR image shows a left trans-sphincteric fistula within the ischiorectal fossa and piercing the external sphincter (arrow).
  134. 134. Dr Ahmed Esawy Trans-sphincteric fistula: appears as extension through the EAS is most important to recognize, and is clearly shown as an irregular poorly reflective finger like extensions from the primary tract running through the EAS, and disrupting its normal architecture (Jonathan et al., 2000) Transesphincteric fistula: extending through the internal and external anal sphincters. (a) Peroxide-enhanced endoanal US scan shows extension of the fistula through the external anal sphincter into a small abscess within the posterior aspect of the internal anal sphincter (arrow). (b) Drawing in the coronal plane, with a horizontal line corresponding to the level of a, shows extent of the fistula and abscess
  135. 135. Dr Ahmed Esawy Transsphincteric fistula axial T2WI and T2WI + fatsat of a transsphincteric fistula. The defect through the internal and external sphincter at 6 o'clock is clearly visible and more apparent on the fat sat images.
  136. 136. Dr Ahmed Esawy axial T2W-fatsat images of a transsphincteric fistula with the mucosal opening at 11 o'clock.
  137. 137. Dr Ahmed Esawy Coronal (a) T2-weighted fast spin-echotion thickness, 4 mm; gap, 0.4 mm) and (b) coronal STIR (4000/42, inversion time of 150 msec; echo train length, 16; matrix, 224256; section thickness, 4 mm; gap 0.4 mm; two signals acquired) MRimages acquired with external phased-array coil show complex transsphincteric fistula with tract (short straight arrows) in left ischioanal fossa that extends below ischial bone (I) toward the upper leg (not shown). At the ischial tuberosity, bone marrow edema (long straight arrow) is visible on b. Arrowheadexternal opening, curved arrowsmall abscess, AS anal sphincter
  138. 138. Dr Ahmed Esawy Transsphincteric fistula in a male patient. Transverse STIR MR image shows primary tract (vertical arrow) in right ischioanal fossa, where it can be clearly seen to penetrate external sphincter (star) to reach the intersphincteric space. Internal opening is posterior at 6 o’clock (horizontal arrow), at dentate line level.
  139. 139. Dr Ahmed Esawy Transsphincteric fistula in a male patient. Transverse STIR MR image at level of the internal opening shows primary tract (vertical arrow) at 4 –5 o’clock. Unlike image before, the tract cannot be traced right to the anal mucosa, and the adjacent internal sphincter (horizontal arrow) appears intact. However, an internal opening at 4 –5 o’clock was reported because this position indicated site of maximal infection in the intersphincteric plane.The internal opening was confirmed at this site during subsequent EUA. Intersphincteric plane is well seen in this patient between hyperintense internal sphincter and the external sphincter.
  140. 140. Dr Ahmed Esawy Left-sided transsphincteric tract (short arrow) in a female patient. Coronal STIRMR image shows large extension (long arrow) from apex of tract into roof of ipsilateral ischioanal fossa.
  141. 141. Dr Ahmed Esawy Left-sided transsphincteric fistula (short straight arrows) with internal opening at 6 o’clock (long straight arrow) in a female patient. Transverse STIR MR image shows remote extension (curved arrow) into ipsilateral buttock that was unsuspected at clinical examination but is well demonstrated atMRimaging. The extension was found at surgery guided byMRfindings.
  142. 142. Dr Ahmed Esawy Transsphincteric primary tract (short arrow) in the right posterior quadrant of a female patient. Transverse STIRMRimage shows two left-sided contralateral extensions (long arrows) that were undetected at EUA until results of patient’s MR examination were revealed to the surgeon in the operating theater.
  143. 143. Dr Ahmed Esawy Grade 3- Trans-sphincteric fistula
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  179. 179. Dr Ahmed Esawy Grade 4 perianal fistula with an ischiorectal fossa abscess. Line diagram of the coronal view shows a left trans-sphincteric fistula with a left ischiorectal fossa abscess (a). coronal dynamic contrast- enhanced MR image shows a left trans-sphincteric fistula (arrow) with a left ischiorectal fossa abscess (arrowheads) containing nonenhancing pus Grade 4: transsphinteric fistula with abscess or 2ry track within ischeorectal fossa
  180. 180. Dr Ahmed Esawy Grade 4 perianal fistula with an ischiorectal fossa abscess. Axial dynamic contrast- enhanced MR image shows a left trans-sphincteric fistula (arrow) with a left ischiorectal fossa abscess (arrowheads) containing nonenhancing pus. Grade 4: Trans-sphincteric Fistula with Abscess or Secondary Track within the Ischiorectal Fossa Grade 4 perianal fistula with an abscess. Line diagram of the axial view shows a left trans-sphincteric fistula and left ischioanal fossa abscess (a).
  181. 181. Dr Ahmed Esawy . Grade 4 perianal fistula with an abscess. Line diagram of the axial view shows intersphincteric and ischioanal fossa components of the abscess (a). Grade 4 perianal fistula with an abscess. Axial T2-weighted MR image shows a left trans-sphincteric fistula (straight arrow) with intersphincteric and left ischioanal fossa components of the abscess (curved arrows).
  182. 182. Dr Ahmed Esawy Grade 4- Trans-sphincteric fistula with secondary track
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  187. 187. Dr Ahmed Esawy Grade 5 perianal fistula. Coronal dynamic contrast-enhanced MR image shows a right translevator fistula (straight arrow) with extensive supralevator horseshoe ramification (curved arrows). Grade 5: Supralevator and Translevator Disease: Grade 5 perianal fistula with an abscess. Line diagram of the coronal view shows a pelvic abscess (a) with a translevator fistula traversing the ischiorectal fossa.
  188. 188. Dr Ahmed Esawy Bilateral supralevator extensions (long arrows) in a female patient. Coronal STIR MRimage clearly show levator plates (short arrows) bilaterally, so that it is easy for the radiologist to be confident that infection extends above them.
  189. 189. Dr Ahmed Esawy Grade 5- Translevator disease
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  194. 194. Dr Ahmed Esawy suprasphincteric fistula. There are two tracts in the ischioanal region. The right sided tract runs over the puborectal muscle (asterisk) and the mucosal opening lies at the level of the linea dentata (black arrow).
  195. 195. Dr Ahmed Esawy coronal T2W-images of a small abscess in the left ischioanal fossa, the fistula runs through the levator ani. It is therefore above the sphincter complex and extrasphincteric.
  196. 196. Dr Ahmed Esawy Fistula classified as extrasphincteric in a female patient on coronal T2- weighted MR image. Fistula tract (horizontal white arrows) is seen in left ischioanal fossa. Levator plates (vertical white arrows) are well depicted bilaterally. Tract penetrates the left levator plate, and the internal opening (top horizontal white arrow) is into the rectum, above the level of the puborectalis muscle () and well above the dentate line (black arrow).
  197. 197. Dr Ahmed Esawy complex fistula. Two tracts in the left buttock form a single tract (no. 1-2). This fistula breaks through the external sphincter (no. 4). In the intersphincteric space it divides again into two tracts (no. 5). One ends blindly in the intersphincteric space (no. 6). The other breaks through the internal sphincter with the mucosal defect at 1 o'clock.
  198. 198. Dr Ahmed Esawy perianal fistula who has Crohn's disease. Continue with the coronal images. On the coronal images the thickening of the bowel wall is demonstrated. Axial fatsat images depict the transmural inflammation with infiltration of the mesenteric fat. Crohn's disease
  199. 199. Dr Ahmed Esawy Transsphincteric fistula in a man with Crohn disease. (a, b) Transverse T2-weighted fast spin-echo MR images two signals acquired) obtained (a) without and (b) with fat saturation and (c) transverse fat-saturated contrast-enhanced T1-weighted fast spin- echo image (see Table for parameters) show two separate fistula tracts (straight and curved arrows) in left posterior ischioanal space, close to the anal sphincter (A). Both tracts show confluent high signal intensity centrally, which represents pus in the tract lumen. On a and b,the surrounding inflammatory tissue (arrowheads) is of low signal intensity (a), which increases with fat-saturation (b) and especially with contrast enhancement (c).Anterior tract (curved arrow) demonstrates more adjacent inflammation (arrowheads) than does posterior tract (straight arrow).
  200. 200. Dr Ahmed Esawy Intrapelvic disease in with Crohn perianal fistulas. Sagittal T2-weighted two- dimensional turbo MR image shows a presacral fluid collection (arrow) with connection to the bladder (not shown) and sigmoid colon (arrowhead) that was correctly diagnosed as a presacral abscess that drained to the bladder and sigmoid colon.
  201. 201. Dr Ahmed Esawy CT FISTULOGRAPHY
  202. 202. Dr Ahmed Esawy 21-year-old male with perianal complex fistulas. CT fistulography images clearly show complex perianal fistula tracts in subcutaneous shallow area, in rear of coccyx. Three anomalous fistula tracts with external opening were successfully identified. Extent of disease and complicated spatial information are better seen on volume rendering image. Minute fistula was not clearly seen
  203. 203. Dr Ahmed Esawy show complicated spatial information of two separate fistula tracts (short white arrows) with irregularly shaped abscess (* in C), which closes to mid-anal canal. Internal tiny ramifications (long white arrows in C) are not exactly confirmed at corresponding position on MR image. Fistula cavities are surrounded by inflammatory tissue (fistula wall, + in A, B). Irregular shape of abscess (* in B). 44-year-old female with recurrent fistulas after two operations. CT fistulography (A, C) and MR imaging (contrast-enhanced T1-weighted with fat suppression in B): reconstructed images clearly
  204. 204. Dr Ahmed Esawy 64-year-old male with perianal complex fistulas. CT fistulography (B, C) and MR imaging (contrast-enhanced T1- weighted with fat suppression in A): reconstructed images clearly show complicated spatial information of fistula tract (short white arrows). Latent secondary extensions (long white arrows in B, C) are clearly confirmed on CT but not corresponding MR image (long white arrow in A).
  205. 205. Dr Ahmed Esawy 64-year-old male with extrasphincteric fistula. MR imaging (T2-weighted with fat suppression in A) and CT fistulography (B): internal opening (short white arrow in A, B) of fistula (+ in A, B) is well identified in corresponding MR and CT images; confirmation of internal opening is major surgical aim.
  206. 206. Dr Ahmed Esawy 64-year-old male with perianal complex fistulas. MR imaging (contrast-enhanced T1-weighted with fat suppression in A) and CT fistulography (B): internal opening (short white arrow in A, B) of fistula (+ in A, B) is well identified in corresponding MR, CT images.
  207. 207. Dr Ahmed Esawy 38-year-old male with semi- horseshoe fistula. CT fistulography (D-G) and MR imaging (T2-weighted with fat suppression in A-C): transverse, coronal images clearly show circumferential spread of fistula (short white arrows in A-G). Extent of disease and complicated spatial information are better seen on volume rendering image (short arrows in G). External opening (long white arrow in B, E, G), internal opening (short black arrow in D), and secondary ramification (long black arrow in C, F) are seen.
  208. 208. Dr Ahmed Esawy 26-year-old male with fistula. MR imaging (T1-weighted with fat suppression in A, T2-weighted with fat suppression in C) and CT fistulography (B): fistula (short white arrow in A, B) spreads backward to skin’s surface with evident external opening. Tenuous internal opening (long white arrow in C) was successfully identified on MR image. Internal opening is confirmed clearly on MR image but not corresponding CT image, owing to lack of contrast agent filling.
  209. 209. Dr Ahmed Esawy 25-year-old female with fistula. MR imaging (T2-weighted with fat suppression in A, contrast-enhanced liver acquisition with volume acceleration in C) and CT fistulography (B). Fistula (short white arrows in C) perforating backward toward anal sphincter, spreads (short white arrow in A) backward to skin’s surface with evident external opening (long white arrow in A, B). Fistula is confirmed clearly on MR image but not corresponding CT image, owing to lack of contrast agent filling.
  210. 210. Dr Ahmed Esawy 54-year-old female with fistula caused by ruptured teratoma in pelvic cavity. MR imaging (contrast enhanced T1-weighted with fat suppression in A, C; T2- weighted without fat suppression image in B), and CT fistulography (D-F): mass (teratoma, short white arrows in A-F) perforates levator ani muscle downward, entering perianal spaces. Images (A-F) provide excellent imaging of fistula (long white arrow in C, F), teratoma, and their relationship to adjacent organ organization. Calcification (short black arrow in F) and gas (long black arrow in F) in teratoma can be seen.
  211. 211. Dr Ahmed Esawy Differential diagnosis
  212. 212. Dr Ahmed Esawy DEFINITION SINUS:  Blind track lined by granulation tissue leading from epithelial surface down into the tissues.  Latin: Hollow (or) a bay
  213. 213. Dr Ahmed Esawy .A) sinus and (b) a fistula . Both usually arise from a preceding abscess . A) this shows that is a blind track , in this case a pilonidal sinus with its hairs b) this shows that a fistula is a track connecting two (epithelial) lined surfaces .in this case colocutaneous fistula
  214. 214. Dr Ahmed Esawy 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.
  215. 215. Dr Ahmed Esawy 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.
  216. 216. Dr Ahmed Esawy Abscess in the Ischioanal space An abscess in the ischioanal space with no connection to the sphincter complex Ischiorectal space abscess
  217. 217. Dr Ahmed Esawy Hidradenitis suppurativa in a male patient. Transverse STIRMRimage (same parameters shows extensive superficial infection (arrows). Absence of any infection related to anal canal and intersphincteric space meant that diagnosis could be confidently made preoperatively by using imaging.

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