MRI in spondyloarthritis: when and how?

PURPOSE OF REVIEW: To summarize recent advances and challenges of using MRI toward early recognition of axial spondyloarthritis (SpA). RECENT FINDINGS: Low-grade bone marrow edema (BME) on sacroiliac joint (SIJ) MRI is nonspecific and may be misleading in recognition of axial SpA. Structural features on SIJ MRI along with BME may not only facilitate recognition of early disease, but also enhance specificity. Structural lesions on MRI and low-dose computed tomography are highly concordant, adding to criterion validity of SIJ MRI. There is accumulating evidence that SIJ MRI due to superior reliability of structural lesions may supplant the traditional imaging approach by pelvic radiographs in healthcare settings in which MRI is readily available. Pilot initiatives exploring the bone remodeling cascade in SIJs showed early reparative response upon biological treatment. Methodological challenges regarding evaluation and data processing of imaging examinations need to be addressed to enhance reproducibility and specificity of imaging in SpA. SUMMARY: Evaluation of SIJ MRI is contextual incorporating structural lesions and BME. MRI is but one element in pattern recognition toward diagnosis. An unmet need is dissemination of advances in imaging in SpA to the broad community of rheumatologists and radiologists.

Canada-Denmark MRI scoring system of the spine in patients with axial spondyloarthritis: updated definitions, scoring rules and inter-reader reliability in a multiple reader setting.

Objective: To validate the Canada-Denmark (CANDEN) MRI scoring system for the spine in axial spondyloarthritis with updated lesion definitions. Methods: Lesion definitions in the CANDEN system were updated and illustrated by a consensus set of reference images. Sagittal spine MRIs of 40 patients with axial spondyloarthritis obtained at baseline and at week 52 after initiation of treatment with the tumour necrosis factor inhibitor golimumab were evaluated in unknown chronology by seven readers blinded to all other data. Results: CANDEN MRI spine inflammation score had very good reliability for status scores (single-measure intraclass correlation coefficient (ICC) of 21 reader pairs median of 0.91 (IQR 0.88-0.92)) and change scores (ICC 0.88 (0.86-0.92)). CANDEN MRI spine fat score had good to very good reliability for status scores (ICC 0.79 (0.75-0.86)) and moderate to good reliability for detecting change (ICC 0.59 (0.46-0.73)). CANDEN MRI spine bone erosion score and CANDEN MRI spine new bone formation score had slight to moderate reliability for status scores (ICC 0.38 (0.32-0.52) and 0.39 (0.27-0.49), respectively). Conclusion: The CANDEN MRI spine scoring system allows a comprehensive evaluation of inflammation, fat, bone erosion and new bone formation of the spine in patients with axial spondyloarthritis. It demonstrated very good reliability for detecting change in inflammation, moderate to good reliability for detecting change in fat, and slight to moderate reliability for detecting bone erosions and new bone formation. Studies with longer follow-up or patients with more advanced spinal involvement may be needed to reliably detect change in bone erosion and new bone formation scores. Trial registration number: NCT02011386.