Comparison of nuclear magnetic resonance imaging and computed tomography in the diagnosis of upper cervical spinal cord compression

Because of its ability to visualize soft-tissue structures in greater detail than any previous radiographic modality, nuclear magnetic resonance (NMR) has been heralded as one of the greatest advances in recent years. It is particularly well suited in diagnosis of spinal disorders since it can visualize the spinal cord and cerebrospinal fluid without intrathecal contrast agents. This is a preliminary report of our experience of NMR examination in 106 patients studied since November 1982 at Case Western Reserve University Hospital. One of the best applications of NMR is for compressive lesions of the upper cervical spine because "functional" images can be obtained. The information from NMR was compared with computed tomography (CT) in 14 patients with various etiologies of neural compression--atlanto-occipital subluxation in Down's syndrome, fixed post-traumatic atlantoaxial subluxation, rheumatoid atlantoaxial subluxation and basilar impression of the odontoid, ossification of the posterior longitudinal ligament, Klippel-Feil syndrome, congenital spinal stenosis, cervical spondylosis, Arnold-Chiari malformation, etc. Unlike CT, NMR can directly image in the sagittal plane without computer reformatting of axial cuts. This readily provides direct images of the spinal cord in neutral, flexion, and extension to show the mechanism of neural compression. Disadvantages of NMR compared with CT include poorer image resolution, slightly increased imaging time, and no patients with intracranial aneurysm clips or cardiac pacemakers can be studied. Advantages include no radiation exposure, no intrathecal contrast agent is required to differentiate CSF from neural tissue, and direct sagittal, coronal, and oblique images can be obtained. As a result of this preliminary experience, computed tomography and nuclear magnetic resonance imaging appear to be complimentary studies--CT provides better osseous detail, whereas NMR offers superior soft tissue resolution.