title: Static and dynamic CT imaging of the cervical spine in patients with rheumatoid arthritis.
abstract: OBJECTIVE
  To compare CR with CT (static and dynamic) to evaluate upper spine instability and to determine if CT in flexion adds value compared to MR imaging in neutral position to assess compression of the subarachnoid space and of the spinal cord.
  
  
  METHODS
  Twenty-one consecutive patients with atlantoaxial subluxation due to rheumatoid arthritis planned for atlantoaxial fusion were included. CT and MRI were performed with the neck in the neutral position and CT also in flexion. CR in neutral position and flexion were obtained in all patients except for one subject who underwent examination in flexion and extension.
  
  
  RESULTS
  CR and CT measurements of atlantoaxial subluxation correlated but were larger by CR than CT in flexion, however, the degree of vertical dislocation was similar with both techniques irrespective of the position of the neck. Cervical motion was larger at CR than at CT. The spinal cord compression was significantly worse at CT obtained in the flexed position as compared to MR imaging in the neutral position.
  
  
  CONCLUSIONS
  Functional CR remains the primary imaging method but CT in the flexed position might be useful in the preoperative imaging work-up, as subarachnoid space involvement may be an indicator for the development of neurologic dysfunction.
authors.affiliation: Department of Radiology, Uppsala University Hospital, 751 85, Uppsala, Sweden, tomas.soderman@radiol.uu.se.
authors.forename: Tomas
authors.initials: T
authors.lastname: Söderman
authors.forename: Claes
authors.initials: C
authors.lastname: Olerud
authors.forename: Adel
authors.initials: A
authors.lastname: Shalabi
authors.forename: Kamran
authors.initials: K
authors.lastname: Alavi
authors.forename: Anders
authors.initials: A
authors.lastname: Sundin
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000175:diagnosis*; D002574:Cervical Vertebrae / Q000473:pathology / Q000601:surgery; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013117:Spinal Cord Compression / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed / Q000379:methods*