Imaging in perianal fistulising Crohn’s disease: A practical guide for the gastroenterologist

Figure 1 Magnetic resonance imaging of the pelvis demonstrating an intersphincteric fistula with an associated collection. A: Axial T2 fat-saturated image: Intersphincteric collection (“a” sign) with T2 hyperintense content; B: Axial T1 fat-saturated post-gadolinium image: This collection demonstrates rim enhancement surrounding a central low-signal area, consistent with pus; C: Axial T2 fat-saturated image: Intersphincteric tract (arrow) demonstrates a central hyperintense signal with a hypointense rim; D: Axial T1 fat-saturated post-gadolinium image: The tract contents show enhancement without rim enhancement, consistent with granulation tissue within the tract and a fibrous tract wall.