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MR Imaging of fistula : Its inputs and implications for su MR Imaging of fistula : Its inputs and implications for su

MR Imaging of fistula : Its inputs and implications for su - PowerPoint Presentation

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MR Imaging of fistula : Its inputs and implications for su - PPT Presentation

HTayar i ADaghfou s FJabnoun KBouzaid i LRezgui Marhou l Radiology services Trauma center Tunisia Taher Maamouris Hospita l Nabeul GI27 INTRODUCTION ID: 284436

anal fistula axial weighted fistula anal weighted axial images disease results complex intersphincteric coronal track tract mri image abscess

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Slide1

MR Imaging of fistula : Its inputs and implications for surgical management

H.Tayar*i, A.Daghfou*s, F.Jabnoun**, K.Bouzaid**i, L.Rezgui Marhou*lRadiology servicesTrauma center*, TunisiaTaher Maamouri’s Hospita**l, Nabeul

GI27Slide2

INTRODUCTION

Anal fistula is a benign condition but may cause considerable distress to the patient and difficulty for the surgeon. Fistulae are

intimately

related

to the anal sphincter

complex

,

so

that

incision and drainage

may

damage

these

muscles to

avariable

degree

with

the

risk

of anal incontinence.

The correct balance

between

eradication

of infection and maintenance of continence

depends

upon

accurate

pre

-

operative

assessment

of

fistula

geography

,

namely

the site and

level

of

any

internal

opening

, the

anatomy

of the

primary

track

and the

presence

of

any

secondary

ramifications.

These

questions are best

answered

by MRI,

which

is

more

accurate

than

all

other

pre

-

operative

investigations. Slide3

OBJECTIVES

Illustrate the contribution of magnetic resonnance imaging in the diagnosis and assessement of anal fistulas for providing valuable

assisstance

in

conducting

surgical

.Slide4

MATERIALS AND METHODSRetrospective

study.The study population comprised teen adult patients complaining of anal fistula and whose

all

received

a

clinical

examination

by a surgeon and a

pelvic

MRI.

The

protocol

includes

T1 and T2

weighted

sequences

in

three

planes, a

sequence

of diffusion and T1 Fat

Sat

gadolinuim

injection in

three

planes.Slide5

resultsAverage

age: 38 years.Sex ratio: 6 men/4women.All patients were followed for crohn’s disease.

Pelvic

MRI has

objectified

6

complex

fistula

and 4 cases of simple

fistula

.

Collections

were

observed

in 5 cases.Slide6

Results : EXAMPLE 1

ab Simple linear

intersphincteric

fistula

.

Axial T2-weighted

(a)

and STIR images

(b)

show fistulous tracks in the

intersphincteric

plane ( ).

Coronal T1-weighted

postcontrast

image at the same level

(c) demonstrates hyperenhancement in the same region, representing inflammation ( ).

cSlide7

RESULTS: EXAMPLE 2:

Complex

intersphincteric

fistula

with

horseshoe

track

.

43-year-old man with complex

fistulating

Crohn’s disease. The intersphincteric fistulous track ( in axial T2 Weighter”

a”and

STIR”b” images)

crosses the midline in the anterior interhemispheric

space ( in coronal T2-Weighter images

“c”) forming a horse-shoe track.

a

b

cSlide8

RESULTS: EXAMPLE 2 :

defEnhancement

on

contrast

administration

is

noted

in the

three

plans axial

(d)

, coronal

(e)

et sagittal

(f)

T1-weighted postcontrast images ( ):ACTIVE FISTULASlide9

RESULTS: EXAMPLE 3 :

acbSimple

transphincteric

fistula

29-year-old woman with long-standing

Crohn’s

disease.

(a)

STIR image showing a

transsphincteric

fistula.

( )

(b)

Axial and

( c)

coronal

Sagittal T1-weighted postcontrast images in the same patient demonstrates hyperenhancement along fistulous tract. ( )Slide10

RESULTS : EXAMPLE 4:

abc

Trans

-

sphincteric

complex

fistula

with

abscess

There are axial T2-Weighted images:

The trans-

sphincteric

track is seen entering the anal canal at 6 o’ clock ( ).In addition, an abscess in the left ischioanal

fossa

is seen

( ).Slide11

RESULTS : EXAMPLE 4:

defAxial T1-weighted

postcontrast

image

(d)

in the same patient demonstrates

hyperenhancement

along a contiguous fistulous tract to the skin ( ).

Axial and coronal T1-weighted

postcontrast

images

(e-f)

shows partial enhancement of rim ( ), indicating presence of fluid in center with rim of inflammatory tissue:

abcesses

.Slide12

RESULTS : EXAMPLE 5:

Complex fistula and voluminous abcesses(a) Axial T2-weighted image shows large abscess extending into right gluteus and levator ani muscles.( )(b) Axial fat-saturated T2-weighted image shows abscess (a) more clearly because bright signal of fat, in which abscess is located, is suppressed. ( ) (c ) T1-weighted image after administration of IV contrast medium clearly shows rim enhancement of lesions on right ( ), indicating presence of large amount of pus.

a

b

cSlide13

RESULTS : EXAMPLE 5:(d)

Coronal sequence shows the course of the fistula ( )from the canal anal to the left levator ani muscle .dSlide14

dISCUSSION

Anal fistula is a common disease that has long challenged surgeons’ skills. Perianal fistula, if not treated properly will result in one of two terrible complications, recurrence or incontinence. The key to successful management of fistula-in-ano lies in correctly identifying the full extent of disease and its relationship to the sphincter complex. It’s the role of Magnetic Resonnance Imaging.This exam is more sensitive than even surgical exploration of the tract. Slide15

dISCUSSIONMRI imaging of

perianal fistulae relies on the inherent high soft tissue contrast resolution and the multiplanar display of anatomy by this modality.It’s especially useful in patients with fistulae associated with Crohn’s disease and those with reccurent fistulae, as these entities are associated with branching fistulous tracts.Missed extensions are the commonest cause of recurrence. Slide16

dISCUSSIONT2W images (TSE and fat-suppressed) provide good contrast between the

hyperintense fluid in the tract and the hypointense fibrous wall of the fistula, while providing good delineation of the layers of the anal sphincter.Gadolinuim-enhanced T1W images are useful to differentiate a fluid-filled tract from an area of inflammation.The tract wall enhances, whereas the central portion is hypointense.Abscesses are also very well depicted on post-gadolinuim images.Slide17

dISCUSSIONThe exact location of the primary tract (

ischioanal or intersphincteric) is most easily visualized on axial images.The presence of disruption of the external anal sphincter differenciates a transsphincteric fistula from an intersphincteric one.The internal opening of the fistula is also best seen in this plane.Coronal images depict the levator plane, thereby allowing differentiation of supralevator

from

infralevator

infection.

A combination of an axial and a longitudinal series (coronal,

sagittal

or radial) will provide all the necessary details. Slide18

dISCUSSIONMRI also allows to classify anal fistulas in five grades according to:

JAMES’S UNIVERSITY HOSPITAL MR IMAGING CLASSIFICATION OF PERIANAL FISTULAS Grade Description 0 Normal appearance 1 Simple linear intersphincteric fistula2 Intersphincteric fistula with intersphincteric abscess or secondary fistulous track 3 Trans-sphincteric fistula 4 Trans-sphincteric fistula with abscess or secondary track within the ischioanal or ischiorectal fossa5 Supralevator and translevator diseaseSlide19

CONCLUSION

Magnetic resonance imaging has become a powerful tool in the evaluation of anal anatomy. In patients with complex disease, MRI is an important adjunct in delineating disease location and extent, its relationship to sphincter muscles, and in planning management. MRI also plays an important role in evaluating the response to medical and surgical therapies.