MR FISTULOGRAPHY: OUR EXPERIENCE WITH PERCUTANEOUS INSTILLATION OF AQUEOUS JELLY INTO THE TRACTS TO DELINEATE PERIANAL FISTULA Abstract No : IRIA - 1152

Perianal fistula Chronic, potentially disabling, problem – for the patient Recurrence - common Inadequate surgery – leading cause of recurrence Over excision may lead to Anal incontinence MR Fistulography Provide adequate anatomical delineation of fistula preoperatively Aid surgeon to plan the appropriate approach Reduced 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 MRI Better soft tissue anatomy and delineation of tracts 3 dimensional assessment - possible Accurate lengths, types of tracts, openings, subsidiary tracts can be identified Endorectal 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 2014 15 cases included 3 females and 12 males Age 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 TR in ms 7070 5930 4400 6810 725 TE in ms 85 90 21 Slice thickness 2 mm Resolution 320/75 256/70 320/70 No of Averages 2 3

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

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

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

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

Discussion – MR Fistulography Various techniques used for better delineation of anatomy of complex fistulae Post IV contrast (GAD) MRI Pickup wall enhancement Chronic cases – usually do not enhance No tract distension Smaller tracts – difficult to identify

Other techniques used in the past – MR Fistulography Distension of tracts using Normal saline Diluted 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 benefits Viscous Cheap and readily available Adequate and persistent distension of tracts Inherent contrast Harmless and painless - Safe for use

References 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. Akhtar, M. Fistula in Ano-An Overview.JIMSA. 2012; 25(1): 53-55 Parks AG, Gordon PH, Hardcastle JD. A classification of fistula-in-ano. Br J Surg, 1976;63:1–12. 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 Khera PS, Badawi HA, Afifi AH. MRI in perianal fistulae. Indian J Radiol Imaging 2010;20:53-7 Myhr GE, Myrvold HE, Nilsen G, et al. Peri-anal fistulas: use of MR imaging for diagnosis. Radiology 1994;191:545–554. 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