Normal Values of Diffusion Tensor Magnetic Resonance Imaging Parameters in the Cervical Spinal Cord

Study Design: Prospective study. Purpose: We evaluated the usefulness of diffusion tensor imaging (DTI) in diagnosing patients with cervical myelopathy by determining the accuracy of normal DTI parameter values. Overview of Literature: DTI can visualize white matter tracts in vivo and quantify anisotropy. DTI is known to be more sensitive than conventional magnetic resonance imaging (MRI) in detecting subtle pathological changes of the spinal cord. Methods: A total of 31 normal subjects (13 men and 18 women; age, 23-87 years; mean age, 46.0 years) were included in this study. The patients had no symptoms of myelopathy or radiculopathy. A Philips Achieva 3-Tesla MRI with SE-type Single Shot EPI was used to obtain diffusion tensor images. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were measured as DTI parameters on axial sections of several cervical levels. Subjects were divided into two groups: >40 years (n=16) and >= 40 years (n=15). A paired t-test was used to compare significant differences between the groups. ADC and FA values were most stable on axial sections. Results: For all subjects, mean ADC and FA values were 1.06 +/- 0.09x10(-3) mm(2)/sec and 0.68 +/- 0.05, respectively. ADC was significantly higher in subjects >40 years of age than in those <= 40 years. There was no significant difference in FA values between the two groups. The mean ADC value was significantly higher in normal subjects >40 years of age than in those <= 40 years. Conclusions: It is important to consider age when evaluating cervical myelopathy by DTI.