Table 1 Scoring system used to evaluate six consecutive semi-coronal magnetic resonance imaging slices (total score range 0–72)

Bone marrow edema

Hyperintense signal on short-tau inversion recovery

Score 4 quadrants in each sacroiliac joint 0/1, range per slice is 0–8

48

Bone marrow intensity

Hyperintensity of marrow edema using the presacral veins as reference

Score each sacroiliac joint 0/1, range per slice is 0–2

12

Bone marrow depth

Homogeneous increase of marrow signal ≥1 cm from the articular surface within either sacroiliac joint

Score each sacroiliac joint 0/1, range per slice is 0–2

12