Initial Imaging for Suspected Rheumatoid Arthritis
Plain X-rays of the hands, wrists, and feet should be performed first as the initial imaging modality in patients with suspected rheumatoid arthritis. 1
Primary Recommendation: Start with Plain Radiography
Conventional radiography (X-rays) of the hands and feet should be used as the initial imaging technique to detect structural damage and establish baseline documentation. 1 This recommendation carries the highest strength of recommendation (9.0 on a 0-10 scale) from EULAR guidelines. 1
Why X-rays First:
- X-rays detect erosions, which are predictive for the development of RA and disease persistence, making them essential for baseline assessment. 1
- Radiographic erosions increase the probability of developing RA from undifferentiated inflammatory arthritis and predict worse prognosis when present at baseline. 1
- X-rays should be repeated within 1 year if disease persists to monitor progression. 1
- Plain radiography is readily available, inexpensive, easily interpreted, and provides reproducible data for serial evaluation. 2
Role of Ultrasound: Adjunctive, Not First-Line
While ultrasound has superior sensitivity for detecting inflammation, there is insufficient evidence to recommend routine use of ultrasound for initial diagnosis or prognosis in undifferentiated inflammatory arthritis. 1
When to Consider Ultrasound:
- When diagnostic doubt exists after clinical examination and X-rays, ultrasound can improve diagnostic certainty (strength of recommendation 9.1). 1
- Ultrasound is superior to clinical examination for detecting joint inflammation, detecting synovitis 2.18-fold more frequently than clinical examination in hands and wrists. 3
- Ultrasound can predict progression to RA from undifferentiated inflammatory arthritis when power Doppler signal is present (strength of recommendation 7.9). 1
- If conventional radiographs show no damage but clinical suspicion remains high, ultrasound should be considered to detect damage at an earlier time point, especially in early RA. 1
Clinical Algorithm
Step 1: Obtain Plain X-rays
- Image hands, wrists, and feet bilaterally at baseline in all patients with suspected RA. 1
- Look specifically for erosions, joint space narrowing, and periarticular osteoporosis. 1
Step 2: Add Ultrasound When:
- X-rays are negative but clinical suspicion remains high for early inflammatory arthritis. 1
- Diagnostic uncertainty exists despite clinical criteria. 1
- More accurate quantification of inflammation is needed for treatment decisions. 3
- Predicting progression risk in undifferentiated inflammatory arthritis. 1
Step 3: Reserve MRI For:
- Highest diagnostic uncertainty when both X-rays and ultrasound are inconclusive. 1
- Detection of bone marrow edema, which is a strong independent predictor of radiographic progression. 1
Important Caveats
Do not skip X-rays in favor of ultrasound initially, even though ultrasound is more sensitive for inflammation. 1 The presence of erosions on plain radiography provides critical prognostic information and establishes a baseline for monitoring structural damage progression. 1
Ultrasound detects inflammation, not structural damage as reliably as X-rays in established disease. 1 While ultrasound can detect erosions earlier than X-rays, conventional radiography remains the standard for documenting and monitoring structural damage over time. 1, 2
The 2011 guidelines explicitly state that data were "too scarce to recommend routine use" of ultrasound for diagnosis or prognosis in undifferentiated inflammatory arthritis, though this may be considered when RA is specifically suspected. 1