Axial Spondyloarthritis, an inflammatory arthritis condition of spine and pelvic joints, causes severe pain and muscle stiffness. To decrease severe pain and unnecessary therapeutic procedures, early diagnosis and therapeutic interventions are very important. This early diagnosis can be achieved by means of MRI studies. In radiographs, inflammation of spine and structural lesions of sacroiliac joints can visible before starting of structural damage.

Therefore, to serve the case, a study has been conducted to check the reliability of structural lesions seen on MRI for classification of patients in accordance with (ASAS) axial SpondyloArthritis (axSpA) criteria in DESIR cohort.

A total of 582 patients were participating in the study. The patients who were under the age of 50 and showed symptoms that last for 3 months to 3 years were selected for the study. The diagnostic studies such as MRI T1-w images (structural lesions, MRI-SI-s) MRI STIR (inflammation, MRI-SI) and sacroiliac joints radiographs (X-SI) were scored by two well – calibrated readers. Further, the MRI-SI and X-SI difference was adjudged by a third reader. For the study, formerly proposed cut-offs of positive MRI-SI-s with more than 5 erosions & fatty lesions (E/FL ≥5) were taken.            

The analysis was done and out of 582 patients, only 418 fulfilled the ASAS axSpA criteria. Out of which 127 patients were evaluated as modified New York (mNY) positive and 134 (according to reader 1) & 75 (according to reader 2) were as MRI-SI-s positive. The mNY and MRI-SI-s agreement was in the balance with each other (reader1,k:0.39; reader2,k:0.44). Therefore, if E/FL≥5 cut-off was used rather than mNY, no change in classification was seen in 478 patients of reader 1 and 469 of reader 2. Furthermore, in condition of mNY replacement, where only MRI-SI-s was performed, 12 patients of reader 1 & 10 of reader 2 might not classify as axial SpondyloArthritis. On the other hand, in both scenarios, 3 patients of reader 1 & 6 of reader 2 might be additionally classified as axial SpondyloArthritis. The same kind of results was noticed for E≥3 and FL≥3 cut-offs.

The whole analysis reach to a conclusion that the structural lesions of sacroiliac joints on MRI are reliable for axSpA diagnosis either as additionally or as a substitute for radiographs in the ASAS axSpA classification.