Variable | Sensitivity | Specificity | Positive LR | Negative LR |
---|---|---|---|---|
FI per se | ||||
FI in ≥ 1 SIJ quadrant | 0.70 (0.70)/0.80 | 0.72 (0.74)/0.77 | 2.48 (2.71)/3.51 | 0.42 (0.40)/0.26 |
FI in ≥ 2 SIJ quadrants1 | 0.70 (0.70)/0.80 | 0.73 (0.77)/0.78 | 2.60 (3.06)/3.63 | 0.41 (0.39)/0.26 |
FI with additional MRI lesions | ||||
FI w/o BME or erosion | 0.03 (0.03)/0.07 | 0.82 (0.84)/0.92 | 0.14 (0.16)/0.88 | 1.19 (1.16)/1.01 |
FI w/BME | 0.58 (0.58)/0.61 | 0.91 (0.91)/0.86 | 6.41 (6.46)/4.22 | 0.47 (0.47)/0.46 |
FI w/erosion | 0.68 (0.68)/0.67 | 0.98 (0.99)/0.89 | 35.10 (53.10)/6.31 | 0.33 (0.33)/0.37 |
Morphological features of FI | ||||
FI w/distinct border | 0.53 (0.53)/0.49 | 0.97 (0.98)/0.90 | 20.47 (30.98)/5.02 | 0.49 (0.48)/0.56 |
FI w/distinct border + BME | 0.40 (0.40)/0.36 | 0.99 (0.99)/0.91 | 31.20 (47.20)/3.92 | 0.61 (0.61)/0.71 |
FI w/distinct border + erosion | 0.50 (0.50)/0.40 | 1.00 (1.00)/0.95 | NC (NC)/7.61 | 0.50 (0.50)/0.63 |
Homogeneous FI | 0.58 (0.58)/0.58 | 0.97 (0.97)/0.93 | 17.94 (22.62)/8.48 | 0.44 (0.44)/0.45 |
Homogeneous FI + BME | 0.45 (0.45)/0.42 | 0.99 (0.99)/0.93 | 35.10 (35.40)/6.14 | 0.56 (0.56)/0.62 |
Homogeneous FI + erosion | 0.55 (0.55)/0.46 | 1.00 (1.00)/0.95 | NC (NC)/8.75 | 0.45 (0.45)/0.57 |
Subchondral FI | 0.70 (0.70)/0.75 | 0.85 (0.86)/0.83 | 4.55 (5.01)/4.33 | 0.35 (0.35)/0.30 |
Subchondral FI + BME | 0.58 (0.58)/0.58 | 0.94 (0.94)/0.86 | 8.97 (9.69)/4.22 | 0.45 (0.45)/0.49 |
Subchondral FI + erosion | 0.68 (0.68)/0.64 | 0.99 (0.99)/0.89 | 52.65 (79.65)/6.01 | 0.33 (0.33)/0.41 |
FI with ≥ 1 feature2 | 0.73 (0.73)/0.75 | 0.83 (0.84)/0.81 | 4.19 (4.62)/3.99 | 0.33 (0.33)/0.30 |
FI with ≥ 1 feature + BME | 0.60 (0.60)/0.58 | 0.93 (0.93)/0.86 | 8.51 (8.85)/4.00 | 0.43 (0.43)/0.50 |
FI with ≥ 1 feature + erosion | 0.70 (0.70)/0.64 | 0.99 (0.99)/0.89 | 54.60 (82.60)/6.01 | 0.30 (0.30)/0.41 |
FI with ≥ 2 features2 | 0.58 (0.58)/0.59 | 0.97 (0.98)/0.92 | 22.42 (33.93)/7.06 | 0.44 (0.43)/0.45 |
FI with ≥ 2 features + BME | 0.45 (0.45)/0.43 | 0.99 (0.99)/0.92 | 35.10 (53.10)/5.15 | 0.56 (0.55)/0.62 |
FI with ≥ 2 features + erosion | 0.55 (0.55)/0.47 | 1.00 (1.00)/0.95 | NC (NC)/8.94 | 0.45 (0.45)/0.56 |
Anatomical distribution of FI | ||||
≥ 1 FI in all 4 sacral quadrants | 0.45 (0.45)/0.58 | 0.90 (0.91)/0.92 | 4.39 (4.83)/6.91 | 0.61 (0.61)/0.46 |
≥ 1 FI in all 4 iliac quadrants | 0.35 (0.35)/0.42 | 0.95 (0.96)/0.95 | 6.82 (9.18)/7.89 | 0.69 (0.68)/0.61 |
≥ 1 FI in all 4 upper SIJ quadrants | 0.43 (0.43)/0.42 | 0.94 (0.95)/0.96 | 7.37 (9.12)/11.04 | 0.61 (0.60)/0.60 |
≥ 1 FI in all 4 lower SIJ quadrants | 0.43 (0.43)/0.57 | 0.93 (0.95)/0.94 | 6.03 (8.36)/9.33 | 0.62 (0.61)/0.46 |
Differences in positive or negative LR despite identical mean sensitivity and specificity data result from rounding differences.
↵1 FI in ≥ 2 SIJ quadrants on the same slice or in ≥ 1 SIJ quadrant on ≥ 2 adjacent slices.
↵2 Morphological features of FI: FI with distinct border, homogeneous FI, subchondral FI. AS: ankylosing spondylitis; BME: bone marrow edema; FI: fat infiltration; HC: healthy control; LR: likelihood ratio; MRI: magnetic resonance imaging; NC: not calculable; NSBP: nonspecific back pain; SIJ: sacroiliac joint; SpA: spondyloarthritis.