Application of Diffusion Tensor Imaging Cutoff Value to Evaluate the Severity and Postoperative Neurologic Recovery of Cervical Spondylotic Myelopathy

BACKGROUND: Magnetic resonance imaging (MRI) plays an important role in the assessment of spinal cord status for cervical spondylotic myelopathy (CSM). Diffusion tensor imaging (DTI) also is a novel investigation tool with good sensitivity to detect changes in CSM, but it is not routinely used in spinal cord evaluation. METHODS: Sixty-six patients with CSM who required surgical decompression were included. All the patients were divided into 4 subgroups according to Japanese Orthopaedic Association (JOA) recovery rate. A 3.0T MR system was applied to obtain DTI of the spinal cord. Clinical assessment was performed with the JOA scores system. RESULTS: DTI data of 61 patients were available for further analysis in this study. No significant differences in age, sex, cervical curvature, surgical approach, and preoperative JOA score between the 4 subgroups were found (P > 0.05). Significant differences in apparent diffusion coefficient (ADC) (P < 0.0001), mean diffusivity (MD), (P < 0.0001), axial diffusivity (AD) (P = 0.0459), and radial diffusivity (RD) (P < 0.0001) values were found between the 4 groups. The ADC (P < 0.0001), MD (P < 0.0001), AD (P = 0.0434), and RD (P < 0.0001) values were significantly correlated with JOA recovery rate. Cutoff values of ADC, MD, AD, and RD in this study were 1.378*10(-3), 1.378*10(-3), 2.386*10(-3), and 0.894*10(-3) mm(2)/s, respectively. CONCLUSION: DTI was closely related to the severity of CSM, and cutoff values of DTI enabled the surgeons to predict the surgical outcomes in patients with CSM. These evaluation metrics may reflect the pathologic conditions of the spinal cord quantitatively, and potentially evaluate the functional status of spinal cords.