Utility of the MRI for diagnosis and classification of perianal fistulas

Transcription

1 Utility of the MRI for diagnosis and classification of perianal fistulas Poster No.: C-2400 Congress: ECR 2012 Type: Authors: Keywords: DOI: Scientific Exhibit C. SALAS LORENTE Pelvis, Gastrointestinal tract, MR, Diagnostic procedure, Education, Fistula, Inflammation /ecr2012/C-2400 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 11

2 Purpose To review the anatomy of the perianal region and to describe the Magnetic Resonance imaging findings of the perianal fistulas, their relationship with the sphincter complex and to classify them using the St. James's University Hospital classification. Methods and Materials We reviewed all the MR imaging studies made at our institution during the last five years, with the clinical diagnose of perianal fistula. MRI was performed with a 1.5 T (Philips NT Intera, Philips Medical Systems, Best, Netherlands), with a 4-channels phasedarray surface coil. Sequences were obtained on oblique transverse and coronal planes oriented orthogonal and parallel, respectively, to the anal sphincter, planned using a midline sagittal image. T2 weighted images (WI), fat suppressed T2 WI and T1 WI were obtained. After completion of these series, a paramagnetic contrast agent was intravenously injected and a 3D fat suppressed T1 weighted sequences were obtained. Images for this section: Page 2 of 11

3 Fig. 1: Fig. 1 - Axial and coronal MR imaging of the anal canal Page 3 of 11

4 Results We show the spectrum of perianal fistulas. They are described according to St. James's University Hospital classification in order to define their morphology and their relationship to the anal sphincter and the levator ani muscles. The complexity of the track is also showed (simple or branched). The internal opening of the primary tract was localized on axial images using the surgical "anal clock" where at 12 o'clock is the anterior perineum and at 6 o'clock the natal cleft; 3 o'clock refers to the left lateral aspect and 9 o'clock to the right of the anal canal. The external opening, if detectable, and any possible fistula's extension or associated abscess was reported. (Fig.2) St James's University Hospital Classification Grade I: Simple linear Intersphincteric Fistula, the fistulous track extends from the skin of the perineum or natal cleft to the anal canal, and the ischiorectal and ischioanal fossa are clear There is no ramification of the track within the sphincter complex. (Fig.3) Grade II: Intersphincteric Fistula with an Abscess or Secondary Track, the primary track and a secondary track or abscess are also bounded by the external sphincter. Secondary fistulous tracks may be of the horseshoe type, crossing the midline (Fig.4) Grade III: Transsphincteric Fistula, Instead of tracking down the intersphincteric plane to the skin, the trans-sphincteric fistula pierces through both layers of the sphincter complex and then arcs down to the skin through the ischiorectal and ischioanal fossa (Fig.5) Grade IV:Transsphincteric Fistula with an Abscess or Secondary Track in the Ischiorectal or Ischio-anal Fossa (Fig.6) Page 4 of 11

5 Grade V:Supralevator and translevator, perianal fistulous disease extends above the insertion of the levator ani muscle (Fig.7) Images for this section: Fig. 2: Drawing shows the normal anatomy of the anal canal in coronal and axial plane Page 5 of 11

6 Fig. 3: Axial T2WI, Coronal T2WI and axial FS T1WI with contrast MR image shows a intersphincteric fistula entering the anal canal in the midline posteriorly Page 6 of 11

7 Fig. 4: Coronal T2WI and FST1WI with contrast-enhanced MR image shows a right intersphincteric abscess cavity above the primary intersphincteric. Axial T2WI and axial FST1WI with contrast MR image shows an intersphincteric horseshoe fistula confined by the external sphincter. Page 7 of 11

8 Fig. 5: Axial T2WI and coronal FST1WI shows the right trassphinteric fistula, passing through the isquianal fossa and piercing both layers of the sphincter complex. Page 8 of 11

9 Fig. 6: coronal and axial T2WI, and coronal contrast-enhanced FST1WI, Show a transsphincteric fistula with an abscess in the ischiorectal fossa Page 9 of 11

10 Fig. 7: Coronal y axial T2 WI, fistulous track crossing the right isquiorretal fossa affects the levator muscle, with an abscess in supraellevador space and the anterior rectovaginal space Page 10 of 11

11 Conclusion MR imaging allow the localization of the fistula, the external and internal openings, the primary and secondary tracks, its relation to the pelvic floor structures and sphinter complex and provides a precise classification and treatment. References 1. Jaime de Miguel Cribado, et all. MR Imaging Evaluation of Perianal Fistulas: Spectrum of Imaging Features. Radiographics 2012;32: Morris J, Spencer JA, Ambrose NS. MR imaging classification of perianal fistulas and its implications for patient management. Radiographics.2000;20: Stoker J, Rociu E, Zwamborn AW, Schouten WR. Endoluminal MR imaging of the rectum and anus:technique, application and pitfalls.radiographics. 1999;19: Beets-tan R,Beets G, Kessels A, et al.preoperatve MR imaging of anal fistulas: does it really help the surgeon? Radiology. 2001;218: Sánchez F, Mendoza JL, Salueña I, García-Paredes J, Cruz-Santamaría DM, Cuenca F, et al. Historia natural de la enfermedad fistulosa perianal en pacientes con enfermedad de Crohn. Rev Esp Enferm Dig 2003; 95 (Supl. 1): 20. C Campo M, et al. Utilidad de la resonancia magnetica en la valoración de las fístulas perianales. Radiologia. 2003;45: Personal Information C.Salas Lorente, J. Díez García, A. García Sanchez, M.Gil García, R.Begué Gómez, C. Vicándi Galdos, J.C Canahuiri From the Department of Radiology. I.D.I. Hospital Arnau de Vilanova.LLeida.Spain Page 11 of 11