Low-field MRI in the evaluation of rheumatoid cervical spine. Comparison with neurological findings and routine plain radiography.

The usefulness of a low-field magnetic resonance imaging (MRI) instrument in the evaluation of cervical spine abnormalities was studied in 20 patients with rheumatoid arthritis and known anterior atlantoaxial subluxation (AAS) (16 patients) or other cervical spine abnormalities (4 patients). The MRI results were compared with routine plain radiographs and with neurological findings. Three patients had a clinical suspicion of cervical spinal cord compression. This was confirmed by MRI, which additionally detected one more patient with compressive myelopathy. Anterior AAS in MR images was seen in 4 patients, but proper flexion images were not obtained. Atlantoaxial impaction was detected by a recent method of Sakaguchi-Kauppi in 16 patients as compared to 9 patients by the McGregor method and 4 patients by MRI. Most of the clinically important consequences of rheumatoid cervical spine are seen with a low-field MR imager, but detailed bony changes and precise measurements are better evaluated with plain X-rays.