Table 2

Agreement between sacroiliitis on conventional radiographs (modified New York criteria) and a positive MRI-SI based on structural lesions

 Reader 1Reader 2
 X-SI (adjudicated score)
MRI-SI-sErosions: cut-off ≥3mNYmNY
PositiveNegativeTotalPositiveNegativeTotal
Positive221032Positive6863131
Negative105444549Negative59391450
Total127454581*Total127454581
Positive agreement: 16.1% κ: 0.21Positive agreement: 35.8% κ: 0.39
Fatty lesions: cut-off ≥3mNYmNY
PositiveNegativeTotalPositiveNegativeTotal
Positive533487Positive6147108
Negative74420494Negative66407473
Total127454581Total127454581
Positive agreement: 32.9% κ: 0.39Positive agreement: 35.1% κ: 0.40
Erosions/fatty lesions: cut-off ≥5mNYmNY
PositiveNegativeTotalPositiveNegativeTotal
Positive492675Positive7460134
Negative78428506Negative53394447
Total127454581Total127454581
Positive agreement: 32.0% κ: 0.39Positive agreement: 39.6% κ: 0.44
  • mNY modified New York criteria.

  • *Note: in this table 581 patients are included (total number of included patients in the study being 582) since the T1-sequence MRI was missing in one patient (STIR-sequence available).