Decreased Value of Highly Accurate Fractional Anisotropy Using 3-Tesla ZOOM Diffusion Tensor Imaging After Decompressive Surgery in Patients with Cervical Spondylotic Myelopathy: Aligned Fibers Effect

Abstract

Background Diffusion tensor imaging (DTI) is widely used; however, most of the prior studies have resulted in presurgical decreased fractional anisotropy (FA) values in patients with cervical spondylotic myelopathy (CSM). We used ZOOM DTI and could acquire highly accurate FA values during perioperative periods, which indicated different insights than preceding studies. The objective of this study was to assess the perioperative FA change in patients with CSM and determine the prognostic factor. Methods Twenty-eight patients with CSM and healthy control subjects were enrolled in this study. Twenty patients (71%) had intracordal high intensity before surgery. All patients underwent decompressive surgery. ZOOM DTI and the Japanese Orthopaedic Association (JOA) assessment were performed before and after surgery. The region of interest was manually contoured to omit the surrounding cerebrospinal fluid. The axial plane of the most stenotic cervical level was assessed. Results FA values before surgery and at 1 week after surgery, and FA values at 1 week after surgery and at 6 months after surgery differed significantly as determined. The FA values of patients with intracordal high intensity significantly decreased after surgery and significantly increased from 1 week to 6 months, whereas those of patients without intracordal high intensity did not significantly change. JOA scores at 6 months after surgery (13.1) improved significantly compared with JOA scores before surgery (10.8). Only FA values at 1 week after surgery had a significant positive relationship with JOA scores presurgery and at 6 months after surgery. Conclusions The presurgical FA value in patients with CSM did not differ from that of normal control subjects, but significantly decreased after surgery, and significantly increased 6 months after surgery. We concluded that the postsurgical FA value approximates the proper state of the damaged cord and the presurgical FA value includes a masked effect as an aligned fiber effect because of compression by degenerative construction. Only the FA value at 1 week had a significant positive relationship with the JOA score presugery and at 6 months, which established that the postsurgical FA value may be a more accurate prognostic factor than the presurgical FA value.

Utility of Advanced DWI in the Detection of Spinal Cord Microstructural Alterations and Assessment of Neurologic Function in Cervical Spondylotic Myelopathy Patients

“…Previous studies have addressed the application of DWI in patients with CSM 3,12,13 . We found that DWI metrics, which reflect unrestricted water movement (e.g., DTI FA, DKI FA, and NODDI ISOVF) and the rate of diffusion (e.g., DKI MD), contributed to the differentiation of healthy controls and patients with CSM and/or prognosis predictions, which agrees with previous studies 12,13,15,23 . A potential explanation for this is that microstructures impede water molecules' diffusion in the spinal cord, such as cell membranes, myelin sheaths, and white matter fiber tracts 23 .…”

The Evaluation and Prediction of Laminoplasty Surgery Outcome in Patients with Degenerative Cervical Myelopathy Using Diffusion Tensor MRI

“…In other words, FA might be elevated to some extent if the fibers are aligned due to compression so that FA reduction resulting from spinal cord dysfunction will be compensated. 14 Although most previous results reported that preoperative FA for the MC level was significantly correlated with both the preoperative and postoperative mJOA, there were several studies that reported nonsignificant correlations. Jones et al 9 found that the preoperative FA for the MC and C2-C3 levels was correlated with the preoperative mJOA but was not correlated with the postoperative mJOA.…”

“…While this finding is not fully consistent with the results in this study, it provides evidence that the spinal cord function is also associated with the DTI measurements at sites distant from the MC level. Iwasaki et al 14 also presented a nonsignificant correlation between the preoperative FA for the MC level and the postoperative mJOA. These studies (including the present study) have some differences in the methods, such as surgery strategy, statistics, prediction indexes, and so forth (Table 1).…”

Clinical and Research MRI Techniques for Assessing Spinal Cord Integrity in Degenerative Cervical Myelopathy—A Scoping Review

“…Specifically Dong et al found that DCM patients presenting with a higher FA score at the level of compression were the most likely group to achieve a better functional recovery after surgical decompression [ 199 ]. The conducted literature search indicated consistent findings of the correlation of FA and spinal cord integrity in DCM as well its significant role in prognosis [ 60 , 104 , 107 , 108 , 118 , 124 , 127 , 128 , 131 , 132 , 134 , 135 , 137 , 138 , 139 , 141 , 142 , 143 , 144 , 145 , 146 , 149 , 152 , 153 , 154 , 155 , 157 , 158 , 161 , 162 , 165 , 166 , 167 , 168 , 175 , 176 , 177 , 178 , 179 , 181 , 182 , 183 , 184 , 185 ]. Interestingly, Wang et al conducted a prospective longitudinal study of 93 ...…”