Conclusion
The inter- and intra-observer agreement for the evaluation of spondyloarthritis-related and degenerative MRI changes in the spine and spondyloarthritis-related changes in the sacroiliac joints were investigated in this study. In the spine, substantial to almost perfect observer agreement was found for the evaluation of the location and the size of vertebral signal changes and for disc degeneration and disc contour. In the sacroiliac joints substantial to almost perfect observer agreement was found for the grading of bone marrow oedema and fatty marrow deposition, the depth of bone marrow oedema and for subchondral sclerosis. Also, 'Global assessment' regarding the spondyloarthritis diagnosis had substantial or almost perfect observer agreements.