Rheumatoid arthritis of the craniocervical region by MR imaging: detection and characterization

The purpose of our study was to evaluate the potential of contrast-enhanced MR imaging to detect and to characterize craniocervical rheumatoid arthritis in a large population group, to compare MR imaging with clinical and conventional radiographic findings, and to examine the relationship between the histopathologic and MR imaging findings in seven patients.

We performed contrast-enhanced MR imaging using T2-weighted gradient-echo sequences and T1-weighted spin-echo sequences in 136 patients with rheumatoid arthritis. Sequential T1-weighted images were obtained before, 3 min after, and 15 min after injection of contrast material. Plain films were acquired in all patients. Serologic status and neurologic status were determined in each patient within 2 days of MR imaging. Patients were categorized into one of four groups, depending upon whether they had joint effusion, hypervascular pannus, hypovascular pannus, or fibrous pannus according to signal patterns on contrast-enhanced MR images. Signal intensity was measured to assess the enhancement of synovial hypertrophy, joint capsule, joint effusion, and the various stages of pannus tissue. Histologic specimens were obtained from seven patients and were correlated with MR imaging findings.

Acute and chronic synovitis were differentiated with contrast-enhanced MR imaging as follows: joint effusion (n = 29), hypervascular pannus (n = 54), hypovascular pannus tissue (n = 8), and fibrous pannus (n = 22). Signal intensity differed significantly among the four groups on contrast-enhanced T1-weighted images. In 59 patients with effusion or hypervascular pannus tissue, atlantoaxial subluxation was diagnosed with plain films. Patients with negative findings on radiographic studies (n = 20) had joint effusion, hypervascular pannus tissue, hypovascular pannus formation, or fibrous pannus tissue on MR imaging studies. Cord compression was found in 10% of all cases and isolated sac compression in 16%. Neurologic findings showed no correlation with MR imaging features.

Contrast-enhanced T1-weighted spin-echo MR imaging can discriminate between joint effusion and various forms of pannus in patients with rheumatoid arthritis of the craniocervical region. MR imaging also can detect joint effusion and pannus tissue in patients with negative radiographic findings. No relationship between MR imaging findings and clinical symptoms were found. Tissue enhancement and histopathologic findings correlated in a limited number of autopsies.