Evaluation of Pannus and Vascularization of the Metacarpophalangeal and Proximal Interphalangeal Joints in Rheumatoid Arthritis by High-resolution Ultrasound (multidimensional Linear Array)

Objective: To evaluate the extent of intraarticular vascularization and pannus formation in metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints of patients with rheumatoid arthritis (RA) by high-resolution ultrasound (US).

Methods: A newly developed, high-resolution multidimensional linear array US was utilized to obtain longitudinal and transverse scans of joints with active RA (n = 21), moderately active RA (n = 39), or inactive RA (n = 93), and of joints from healthy controls (n = 120).

Results: Healthy joints had no detectable pannus, whereas pannus could be detected in 52% of the joints with active RA, 82% of the joints with moderately active RA, and 67% of the joints with inactive RA. There was a significant difference in vascularization in the joints of all subgroups of RA patients and those of healthy subjects (P < 0.001). Moreover, vascularization differed significantly among the RA subgroups: inactive versus moderately active RA (P < 0.02) and inactive versus active RA (P < 0.05). Both pannus and vascularization appeared to be localized preferentially on the radial side of the joints.

Conclusion: Evaluation of pannus and the extent of vascularization within the joints of patients with RA by high-resolution US might be helpful in the assessment of disease activity, and thus influence therapeutic strategies.