Guidelines on postoperative magnetic resonance imaging in patients operated for cryptoglandular anal fistula: Experience from 2404 scans

Figure 4 A 47-year-old male patient with a high transsphincteric fistula with supralevator extension. The fistula appeared to have ‘clinically’ healed as the external opening had closed with cessation of all pus. Magnetic resonance imaging (MRI) done after 26 wk post-surgery showed patent internal opening and active intersphincteric portion of the fistula tract [hyperintense on T2 and short-T1 inversion recovery (STIR)]. The patient was operated again. MRI done after 14 wk after 2^nd surgery showed fistula has healed completely. The hyperintense signal (white) in the preoperative images has turned hypointense (black). A: Axial section (schematic diagram); B: Coronal section (schematic diagram); C: Pre-operative T2-weighted MRI; D: Sketch of pre-operative axial MRI image highlighting internal opening and the intersphincteric portion of fistula tract (green color); E: Pre-operative STIR axial MRI; F: Postoperative (26 wk after 1^st surgery) T2-weighted axial MRI showing patent internal opening and persistent intersphincteric portion of fistula tract; G: Sketch highlighting patent internal opening and intersphincteric portion of fistula tract (green color); H: Postoperative (26 wk after 1^st surgery) STIR axial MRI showing patent internal opening and persistent intersphincteric portion of fistula tract; I: Postoperative (14 wk after 2^nd surgery) T2-weighted axial MRI showing completely healed fistula; J: Postoperative (14 wk after 2^nd surgery) STIR axial MRI showing completely healed fistula. STIR: Short-T1 inversion recovery.