Flexor Tenosynovitis in Early Untreated Rheumatoid Arthritis: What do Ultrasound and MRI Show TC01-TC04
Dr. Pradeep Bansal,
Associate Professor, Department of Radiodiagnosis, Subharti Medical College, Meerut-250005, Uttar Pradesh, India.
Introduction: Rheumatoid Arthritis (RA) is the most common inflammatory arthritis which primarily affects the synovial lining of joints. Tendon sheath is also composed of synovial lining and tendon involvement in RA is generally in the form of tenosynovitis. Modern imaging techniques like Ultrasonography (USG) and Magnetic Resonance Imaging (MRI) target mainly soft tissue pathological changes in RA, and have lead to the early diagnosis and prognostication of disease, which in turn has guided rheumatologist to start biologic therapy in the early stage of disease and thereby prevent complications.
Aim: To evaluate flexor tenosynovitis in untreated early RA using USG and to compare its findings with that of MRI along with studying distribution of flexor tenosynovitis using both USG and MRI across hand.
Materials and Methods: The present hospital based descriptive study was conducted in the Department of Radiodiagnosis of Subharti Medical College and hospital from January to December 2016. A total of 40 patients of RA underwent high frequency USG and MRI of 2nd to 5th Flexor Tendon Sheaths (FTS) of both hands whereas 25 healthy controls underwent only high frequency USG. Normal anatomy and inflammatory changes in the FTS were recorded on both the modalities by two radiologists specialised in doing musculoskeletal imaging. No patient had received prior steroid or Disease-Modifying Agents (DMARD). Diagnostic accuracy of USG was calculated using MRI as gold standard using agreement statistics. Statistical analysis was done using SPSS version 12.0.
Results: Flexor tenosynovitis was found in 102 (31.8%) of 320 FTS in 22 (55%) of 40 patients on ultrasound compared with 210 (65.6%) of 320 FTS in 32 (80%) of 40 patients on MRI. FTS were completely normal in control subjects on ultrasound. Considering MRI as the gold standard, the sensitivity, specificity, negative and positive predictive values for ultrasound were 0.52, 0.83, 0.69, and 0.70, respectively, for detecting flexor tenosynovitis. The most frequently involved FTS on both the modalities were the second and third.
Conclusion: Both ultrasound and MRI can be used for detection of flexor tenosynovitis in patients with early untreated RA. MRI is more sensitive for detecting flexor tenosynovitis for obvious reasons. A negative ultrasound scan does not exclude inflammation and an MRI should be considered. In developing countries like India, where MRI is limited in availability, ultrasound can become the imaging modality of choice specially to evaluate soft tissue changes in early RA.