Can I do an MRI with focus on the sacroiliac joints?

MRI of the Sacroiliac Joints for Suspected Axial Spondyloarthritis

Yes, an MRI focused on the sacroiliac joints is appropriate and recommended, particularly if you have inflammatory back pain symptoms and negative or equivocal radiographs. 1

Imaging Protocol Recommendations

First-Line Imaging:

• Radiographs of the pelvis/sacroiliac joints should be performed as the initial imaging modality 1, 2
• If radiographs are negative or equivocal but clinical suspicion remains high, proceed to MRI

MRI Protocol for Sacroiliac Joints:

• MRI without IV contrast is rated highly appropriate (8/9) by the American College of Radiology 1, 2
• MRI without and with IV contrast is also rated highly (8/9), with contrast potentially helpful for initial evaluation of inflammatory changes 1

Key MRI Sequences:

• Para-axial proton density with fat suppression (paPD-FS) sequence is superior for detecting both acute and chronic lesions 3
• T1-weighted sequences are excellent for structural lesions (erosions, joint space changes) with significantly better sensitivity than radiographs (79% vs 42% for erosions) 4
• High-resolution intermediate-weighted (proton density) sequences can detect subchondral resorption, which may be an early sign of sacroiliitis 5

Clinical Relevance

Benefits of MRI for Sacroiliac Joints:

• Can detect inflammatory changes 3-7 years before they appear on radiographs 1
• Superior sensitivity for early disease detection compared to radiographs 1, 4
• Can identify both active inflammation (bone marrow edema, synovitis, capsulitis) and structural damage (erosions, sclerosis, ankylosis) 6
• Provides better assessment of disease activity and treatment response 1

When MRI is Particularly Indicated:

• Short duration of symptoms 1
• Negative or equivocal radiographs with persistent clinical suspicion 1
• Cases where disease activity is unclear 1
• When clinical or laboratory data are conflicting 1
• When MRI findings would alter treatment decisions 1

Important Considerations

• Non-contrast MRI is generally sufficient, though contrast may help identify subtle inflammatory changes in initial evaluation 1
• CT of the sacroiliac joints (7/9 rating) may be considered if MRI is contraindicated 1
• The Spondyloarthritis Research Consortium of Canada method can be used for quantification and follow-up of lesions 1
• MRI has demonstrated superior sensitivity with significantly more correct imaging findings compared to radiography for erosions (79% vs 42%), joint space changes (75% vs 41%), and overall detection (85% vs 48%) 4

In summary, MRI focused on the sacroiliac joints is highly appropriate for evaluating suspected axial spondyloarthritis, especially when radiographs are negative or equivocal but clinical suspicion remains high.