Fig. 1

The CBM scores to evaluate fatty lesions by MRI in the SIJs. The figure shows a T1w TSE sequence and a coronal slice of the SIJs. Each of the SIJs was divided into four quadrants by the joint space and a horizontal fictitious line passing below the first sacral neural foramina. The comprehensive Berlin scoring method quantifies fatty lesions on a 0–3 scale (0: no fatty lesions, 1: ≤ 33%, 2: 33–66%, 3: > 66% of the subchondral bone area in the respective quadrant), adding up to a total score of 0–24