What is the best imaging modality for diagnosing tenosynovitis (inflammation of the tendon sheath)?

From the Guidelines

Ultrasound is the best imaging modality for diagnosing tenosynovitis, as it provides excellent visualization of tendons and their surrounding synovial sheaths, allowing for real-time assessment of inflammation, fluid collection, and thickening of the tendon sheath. According to the American College of Radiology (ACR) Appropriateness Criteria, both MRI and ultrasound are considered equivalent and usually appropriate for evaluating suspected bursitis or long head of biceps tenosynovitis 1. The advantages of ultrasound include its cost-effectiveness, wide availability, lack of radiation, and ability to perform dynamic assessments during movement, as well as comparison with the contralateral side.

Key Points

• Ultrasound offers excellent visualization of tendons and their surrounding synovial sheaths, allowing for real-time assessment of inflammation, fluid collection, and thickening of the tendon sheath.
• MRI is an excellent alternative when ultrasound results are inconclusive or when deeper structures need evaluation, as it is useful for diagnosing infectious and noninfectious tenosynovitis in both the flexor and extensor wrist compartments 1.
• Typical ultrasound findings in tenosynovitis include hypoechoic or anechoic fluid surrounding the tendon, thickening of the tendon sheath, and increased vascularity on Doppler imaging.
• Ultrasound is also useful for confirming fluid content of a suspected ganglion cyst, identifying fluid surrounding a tendon affected by acute tenosynovitis, and demonstrating the relationship between a mass and adjacent neurovascular structures 1.

Recommendations

• The examination should be performed by an experienced musculoskeletal radiologist or rheumatologist for optimal results.
• While X-rays are often ordered initially, they primarily help rule out other conditions like fractures or arthritis rather than directly visualizing tenosynovitis.
• Ultrasound is the preferred initial imaging modality for suspected tenosynovitis due to its advantages and equivalent diagnostic accuracy compared to MRI, as supported by the ACR Appropriateness Criteria 1.

From the Research

Imaging Options for Tenosynovitis

• MRI is considered the gold standard modality for imaging synovitis and tenosynovitis in patients with inflammatory arthritis, as it can detect inflammation and vascularity of synovium 2.
• Ultrasound is also a useful tool for diagnosing and monitoring tenosynovitis, with high sensitivity and specificity for detecting ongoing inflammation 3, 4.
• Ultrasound-guided injection of corticosteroids has been shown to be more effective than conventional blind injection in treating tenosynovitis, with better short-term outcomes measured by functional, clinical, and ultrasound scores 5.

Characteristics of Imaging Modalities

• MRI can detect synovitis and tenosynovitis with high sensitivity, and can predict the development of erosions 2.
• Ultrasound can detect tenosynovitis and monitor its response to treatment, with excellent intra- and inter-reader agreement between trained investigators 3.
• Ultrasound-guided injection of corticosteroids can reduce pain and improve functional outcomes in patients with tenosynovitis 5.

Comparison of Imaging Modalities

• MRI and ultrasound have been compared in several studies, with MRI considered the gold standard for imaging synovitis and tenosynovitis 2.
• Ultrasound has been shown to be a useful tool for diagnosing and monitoring tenosynovitis, with high sensitivity and specificity for detecting ongoing inflammation 3, 4.
• Ultrasound-guided injection of corticosteroids has been shown to be more effective than conventional blind injection in treating tenosynovitis 5.