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심으뜸 Graduate School, Korea University 2020 국내박사
Purpose To explore the feasibility of postoperative high-tesla diffusion tensor imaging (DTI) in cervical spondylotic myelopathy (CSM) and optimize its acquisition parameters using both single-shot (SS) echo-planar imaging (EPI) and multi-shot (MS) EPI. Method We enrolled twenty-seven patients with CSM scheduled for magnetic resonance imaging (MRI) at one month after cervical operations from December 2017 to March 2018, who were divided into three groups in the order in which they underwent the MRI scan; 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. However, cord visualization was superior with SS-EPI sequences than MS-EPI in the distal to metallic segment. 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 in the metallic segment and increases the success rate of fiber tractography in CSM patients with metal implants. However, in the ROI where is distal to the metallic segment, SS-EPI may be better than MS-EPI.