Feasibility of postoperative 3-tesla diffusion tensor imaging in cervical spondylotic myelopathy: A comparison of single-shot EPI and multi-shot EPI

Purpose: To explore the feasibility of postoperative high-tesla DTI in CSM and optimize its acquisition parameters using both single-shot (SS) echo-planar imaging (EPI) and multi-shot (MS) EPI, and to evaluate correlation between image degradation and operative methods. Method: We enrolled twenty-seven patients with CSM scheduled for MRI at one month after cervical operations who were divided into three groups; 11 patients in group 1; 11 in group 2; and 5 in group 3. The patient in each group underwent two sets of DTI using both SS-EPI and MS-EPI with different diffusion gradient directions. Qualitative and quantitative analysis of fractional anisotropy (FA) and color-coding maps were performed to evaluate image distortion and spinal cord visualization and were compared between SS- and MS-EPI. DTI indices, including the number of reconstructed fibers, mean apparent diffusion coefficient (ADC) values, and mean FA values, were acquired. Results: In the metallic segment, MS-EPI with 6 diffusion gradients showed significantly less distortion and better cord visualization than SS-EPI. Fiber tracking was also superior with MS-EPI sequences. Scores in the subjective motor improvement scale showed a moderately positive correlation correlated only with the mean ADC at 1 month postoperatively. Regarding the operation methods, DTI in patients who underwent anterior cervical discectomy and fusion showed the least image distortion and 100 % success rate of fiber tractography. Conclusions: Compared with SS-EPI, MS-EPI with motion correction significantly improves image distortions and increases the success rate of fiber tractography in CSM patients with metal implants.