History A 20-year old woman living in Turkey presented with a 3-month history of lower back pain. She had no medical history of note and was taking no medications. Complete blood count, C-reactive protein level, sedimentation rate, and creatinine, alanine aminotransferase, and aspartate aminotransferase levels were within normal limits. Anteroposterior pelvic radiography and unenhanced pelvic CT were performed to rule out sacroiliitis. The imaging findings were abnormal, and the patient underwent contrast-enhanced sacroiliac MRI. A few days later, she underwent contrast-enhanced (100 mL iohexol, Omnipaque; GE Healthcare, Cork, Ireland) abdominal CT because of right upper quadrant pain. Figure 1: Anteroposterior pelvic radiograph. Figure 2: Axial unenhanced pelvic CT image. Figure 3a: (a) Coronal T2-weighted fat-saturated fast spin-echo (repetition time msec/echo time msec, 2220/57; section thickness, 4 mm), (b) axial unenhanced T1-weighted fat-saturated, and (c) axial contrast-enhanced (20 mL gadoteric acid, Dotarem; Guerbet, Roissy, France) T1-weighted fat-saturated (400/20; section thickness, 4 mm) sacroiliac images from MRI. Figure 3b: (a) Coronal T2-weighted fat-saturated fast spin-echo (repetition time msec/echo time msec, 2220/57; section thickness, 4 mm), (b) axial unenhanced T1-weighted fat-saturated, and (c) axial contrast-enhanced (20 mL gadoteric acid, Dotarem; Guerbet, Roissy, France) T1-weighted fat-saturated (400/20; section thickness, 4 mm) sacroiliac images from MRI. Figure 3c: (a) Coronal T2-weighted fat-saturated fast spin-echo (repetition time msec/echo time msec, 2220/57; section thickness, 4 mm), (b) axial unenhanced T1-weighted fat-saturated, and (c) axial contrast-enhanced (20 mL gadoteric acid, Dotarem; Guerbet, Roissy, France) T1-weighted fat-saturated (400/20; section thickness, 4 mm) sacroiliac images from MRI. Figure 4: Axial contrast-enhanced CT image of the abdomen.