Fig. 2

Thirty-one-year-old woman with remitting mechanical back pain over several years. The sacral part of the left sacroiliac joint in the cartilaginous compartment demonstrates increased signal intensity compatible with bone marrow edema (curved white and black arrows on STIR), which is not visible on the transitional slice nor in the ligamentous compartment. See legend to Fig. 1 for details on the structure of the figure. STIR short tau inversion recovery, T1SE T1 spin echo