Fig. 2

Pelvic MRI images from four patients with Crohn’s disease. A1, A2 Axial and coronal T2-weighted images of an 18-year-old male with linear high-signal fistula between the internal and external anal sphincters without branching or abscess formation (11 points, low activity group#); B Axial T2-weighted image of a 31-year-old female with a Y-shaped branching high-signal fistula (12 points, low activity group#); C Axial T2-weighted image of a 34-year-old male with multiple high-signal fistula (18 points, high activity group#); D1, D2 Axial and coronal T2-weighted images of a 28-year-old male with multiple perianal abscesses and lesions involving the levator ani muscle (22 points, high activity group#). #Scores were calculated according to the Van Assche’s classification, with 14 or less in the low activity group and the rest in the high activity group