MRI Contrast Use in Chronic Knee Pain
For most patients with chronic knee pain, start with MRI without contrast, reserving contrast-enhanced MRI for specific inflammatory and synovial pathologies that remain diagnostically unclear on non-contrast imaging. 1
Standard Approach: Non-Contrast MRI First
MRI without IV contrast is not usually indicated when initial radiograph is negative or demonstrates a joint effusion for routine evaluation of chronic knee pain. 1 Non-contrast MRI effectively identifies:
- Bone marrow lesions (BMLs) that correlate with knee pain, particularly in males or patients with family history of osteoarthritis 1
- Meniscal tears, though these are often incidental findings in older patients 1
- Subchondral insufficiency fractures earlier than radiographs, especially in middle-aged to elderly females 1
- Cartilage abnormalities using quantitative imaging techniques like T2 mapping 1
- Patellofemoral cartilage loss and associated BMLs in patients with anterior knee pain 1
- Loose bodies and osseous fragments without need for contrast enhancement 2
When to Add Contrast: Specific Inflammatory Conditions
Contrast-enhanced MRI may be more accurate in diagnosing specific causes of chronic knee pain that involve synovial or inflammatory pathology. 1 Add IV contrast when you suspect:
Inflammatory/Synovial Pathologies
- Hoffa's disease - enhancing synovitis thicker than 2 mm in Hoffa's fat correlates with peripatellar pain 1
- Deep infrapatellar bursitis 1, 3
- Patellofemoral friction syndrome 1, 3
- Adhesive capsulitis 1, 3
- Pigmented villonodular synovitis - contrast is useful for both diagnosis and quantifying disease extent 1, 3
Synovitis Quantification
- Contrast-enhanced MRI enables more accurate evaluation of synovitis than non-contrast MRI and is useful in quantifying the degree of synovial inflammation 1, 4
- Both BMLs and synovitis/effusion may indicate the origin of knee pain in patients with osteoarthritis 1
Common Pitfalls to Avoid
Do not order MRI without recent radiographs (within the past year), as approximately 20% of patients receive MRI without prior radiographs, which is inappropriate. 3
MRI should only be considered when:
- Surgery is being considered, OR
- Pain persists despite adequate conservative treatment, OR
- Initial radiographs are normal but symptoms persist 5
MRI without and with IV contrast is not usually indicated when initial radiograph demonstrates osteochondritis dissecans, loose bodies, or history of cartilage/meniscal repair. 1
Alternative Considerations
MR arthrography (intra-articular gadolinium injection) is typically not indicated as a second examination but reserved for patients with known prior meniscal surgery, chondral and osteochondral lesions, and suspected loose bodies. 1
Ultrasound may be more appropriate than MRI for confirming effusion, guiding aspiration, evaluating medial plica, and assessing popliteal cysts. 3, 5