MR FISTULOGRAPHY: OUR EXPERIENCE WITH PERCUTANEOUS INSTILLATION OF AQUEOUS

JELLY INTO THE TRACTS TO DELINEATE PERIANAL FISTULA

Author: Joish Upendra Kumar

Co Authors: Abimanyu S, Satyendra Raghuwanshi, Tukaram Rathod

Institution: Command Hospital Air Force, Bangalore

Perianal fistula

Chronic, potentially disabling, problem – for the patientRecurrence - commonInadequate surgery – leading cause of recurrenceOver excision may lead to Anal incontinenceMR Fistulography

Provide adequate anatomical delineation of fistula preoperativelyAid surgeon to plan the appropriate approachReduced risk of recurrence

Park’s classification of perianal fistula

Pathophysiology- Cryptoglandular concept – 90% of cases•Infection of anal glands and crypts within the intersphincteric plane•Inflammatory blockade of their outlets

•Abscess formation•Rupture into the anal canal and skin

•Fistula formation•Recurrent infections

Role of MRIBetter soft tissue anatomy and delineation of tracts3 dimensional assessment - possibleAccurate lengths, types of tracts, openings, subsidiary tracts can be

identifiedEndorectal coils and/or body coils – can be used

Aim of study

Study the role of Instillation of aqueous jelly into the tracts prior to MR Fistulography

Study Design

Prospective study – January to September 201415 cases included3 females and 12 malesAge range : 25 -54 years

Average age of cases - 35 years

Protocol

External opening of fistula- cannulated with a IV cannula or a hypodermic needle

5-7 ml of aqueous jelly instilled prior to the MRI examination.

Jelly used - 2 percent lignocaine jelly.

Siemens Magnetom Avanto – 1.5 Tesla – MR System for scanning

MR Protocol

Parameters T2 Axial T2

coronal

T2 Axial

FS

T2 Coronal

FS

T1 Axial

TR in ms 7070 5930 4400 6810 725

TE in ms 85 90 85 90 21

Slice thickness 2 mm 2 mm 2 mm 2 mm 2 mm

Resolution 320/75 256/70 320/70 256/70 320/70

No of Averages 2 2 3 2 2

4

10

1

Types of fistulous tracts

TranssphinctericIntersphinctericExtrasphincteric

T2 weighted axial image showing a intersphincteric type (red solid arrow) of fistulous tract.

T2 weighted coronal image showing a fistulous tract in intersphincteric plane (red solid arrow).

Other parameters studied

3 cases showed lateral ramifications. 1 case had Supralevator extension. 2 cases had ischioanal abscesses

T2 weighted coronal image showing a collection underneath the left levator ani muscle (red solid arrow).

T2 weighted axial mage showing a anterolateral ramification (red solid arrow).

T2 weighted coronal mage showing a supralevator extension (blue solid arrow).

T2 weighted coronal mage showing extrasphincteric tract (blue solid arrow).

Discussion – MR Fistulography

Various techniques used for better delineation of anatomy of complex fistulae

Post IV contrast (GAD) MRI Pickup wall enhancementChronic cases – usually do not enhanceNo tract distensionSmaller tracts – difficult to identify

Other techniques used in the past – MR Fistulography

Distension of tracts usingNormal salineDiluted GAD

Temporary and inadequate distension

Smaller tracts and internal openings – may not be detected

Conclusion

Instillation of aqueous jelly into the tracts prior to MR Fistulography has the following benefitsSemisolid/Jelly in consistencyCheap and readily availableAdequate and persistent distension of tractsHarmless and painless - Safe for use

References

1. Buchanan GN, Williams AB, Bartram CI, Halligan S,  Nicholls RJ, Cohen CR. Potential clinical

implications of direction of a trans-sphincteric anal fistula track. Br J Surg , 2003; 90 (10) 1250 -

1255.

2. Akhtar, M. Fistula in Ano-An Overview.JIMSA. 2012; 25(1): 53-55

3. Parks AG, Gordon PH, Hardcastle JD. A classification of fistula-in-ano. Br J Surg, 1976;63:1–12.

4. Manar T Alaat El Essawy. Magnetic Resonance Imaging in Assessment of Anorectal Fistulae

and its role in management, J Gastroint Dig Syst 2013, 3:3

5. Khera PS, Badawi HA, Afifi AH. MRI in perianal fistulae. Indian J Radiol Imaging 2010;20:53-7

6. Myhr GE, Myrvold HE, Nilsen G, et al. Peri-anal fistulas: use of MR imaging for diagnosis.

Radiology 1994;191:545–554.

7. Dariusz Waniczek, Tomasz Adamczyk, Jerzy Arendt, Ewa Kluczewska, Ewa Kozińska-Marek.

Usefulness assessment of preoperative MRI fistulography in patients with perianal fistulas. Pol J

Radiol, 2011; 76(4): 40-44