Rheumatoid arthritis of the craniocervical region: assessment and characterization of inflammatory soft tissue proliferations with unenhanced and contrast-enhanced CT.

The aim of this study was to depict and characterize inflammatory soft tissue proliferations caused by rheumatoid arthritis (RA) in the craniocervical region by unenhanced and contrast-enhanced CT. Computed tomography of the craniocervical region was performed in 35 patients in the axial plane before and after the i.v. administration of contrast material. According to the densities and contrast enhancement of the inflammatory soft tissue proliferations, four groups were classified. Ancillary findings, such as a compression of the dural sac or spinal cord, erosions of the bony structures, and atlantoaxial subluxation, were also evaluated. Inflammatory soft tissue proliferations were depicted in 28 of 35 patients and could be differentiated by unenhanced and contrast-enhanced CT according to the above defined criteria: effusion in 6 patients (17%); hypervascular pannus in 8 (23%); hypovascular pannus in 5 (14%); and fibrous tissue in 9 patients (26%). A compression of the dural sac was seen in 11 (31%) patients; 3 of these had neurological symptoms. Erosions of the odontoid process were found in 20 (57%) patients; 16 (80%) of these also showed erosions of the atlas. Atlantoaxial subluxation was seen in 11 (31%) patients. Inflammatory soft tissue proliferations in the craniocervical region caused by RA can be reliably demonstrated and classified by unenhanced and contrast-enhanced CT, which can differentiate between joint effusion and various forms of pannus and depict ancillary findings. Computed tomography is an alternative method for patients unable to undergo an MRI examination.