| Lesion | Per subject | Ilium R+L | Sacrum R+L |
---|
Kappa value (95% CI) | ER | 0.72 (0.57 to 0.84) | 0.67 (0.53 to 0.79) | 0.56 (0.42 to 0.70) |
| BME | 0.61 (0.47 to 0.74) | 0.64 (0.50 to 0.76) | 0.71 (0.57 to 0.82) |
| FI | 0.55 (0.41 to 0.68) | 0.45 (0.32 to 0.58) | 0.60 (0.46 to 0.72) |
| EEa | 0.73 (0.63 to 0.84) | 0.68 (0.58 to 0.79) | 0.45 (0.35 to 0.56) |
| BFa | 0.63 (0.53 to 0.73) | 0.60 (0.50 to 0.70) | 0.32 (0.22 to 0.42) |
ICC(3, 1)/ICC(2, 1) | ER | 0.79/0.75 | 0.78/0.74 | 0.71/0.67 |
| BME | 0.93/0.92 | 0.88/0.86 | 0.94/0.93 |
| FI | 0.71/0.63 | 0.54/0.46 | 0.75/0.70 |
| EEa | 0.72/0.71 | 0.65/0.63 | 0.55/0.55 |
| BFa | 0.55/0.55 | 0.59/0.59 | 0.35/0.35 |
- aEE and BF were assessed as score per four joint surfaces irrespective of the number of SIJ MRI slices affected. Kappa values: MRI lesion as binary variable per subject. Intraclass correlation coefficients: MRI lesion as sum score per subject. AS, ankylosing spondylitis; BF, backfill; BME, bone marrow edema; CI, confidence interval; EE, extended erosion; ER, erosion; FI, fat infiltration; ICC(3, 1), intraclass correlation coefficient (3, 1): Readers are considered not representative of a larger population of readers; ICC(2, 1), Intraclass correlation coefficient (2, 1): Readers are considered representative of a larger population of readers.