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Cerebral white matter tract integrity is associated with sensory and motor functions in patients with cervical degenerative myelopathy: A diffusion spectrum imaging study
cervical myelopathy,diffusion spectrum imaging,tract-based automatic analysis,white matter microstructural characteristics,sensory and motor function,
|Publication Year :||2019|
Introduction: Cervical myelopathy is a common degenerative condition caused by compression on the spinal cord that is characterized by clumsiness in hands and gait imbalance. Patients demonstrated multiple symptoms and signs, including sensory, motor, control and cognition relate complaints. Severe cases require surgery, but in some cases the symptoms still persist after surgery. Previous studies reported that patients with cervical myelopathy showed higher mean diffusivity (MD) and lower fractional anisotropy (FA) than normal subjects between each spinal level. However, whether this local change would affect white matter tracts in the brain is not clear. In this study, we aimed to compare the differences of cerebral white matter microstructural property between patients with cervical myelopathy and health controls, and we aimed to identify the functional correlation of the change tracts in the brain.
Subjects: Two groups of participants were recruited in the study: 27 healthy older adults (age: 56.63 ± 13.05, 18 males and 9 females), 27 patients with cervical myelopathy (age: 55.30 ± 13.03, 18 males and 9 females).
Imaging: All participants received T1-weighted imaging and DSI on a 3T Siemens Prisma MRI System (Siemens Medical, Erlangen, Germany) with a 32-channel phased array head coil in National Taiwan University Hospital. The parameters were as follow. T1-weighted imaging used a three-dimensional magnetization-prepared rapid gradient-echo (MPRAGE) sequence, TR/TE = 2000/3 ms, FOV = 352 x 290 x 208 mm3, flip angle = 9o, resolution = 1 x 1 x 1 mm3. Diffusion spectrum imaging (DSI) used an echo planer imaging (EPI) diffusion sequence, TR/TE = 9600/130 ms, matrix size = 80 x 80, FOV = 200 x 200 mm2, resolution = 2.5 mm, 102 diffusion encoding gradients with bmax = 4000 s/mm2.
Image Quality Assurance (QA): Only images with signal-to-noise ratio (SNR) higher than 25 were included for subsequent analysis.
Analysis: We used whole brain tract-based automatic analysis (TBAA) to obtain a 2D connectogram for each DSI dataset. The connectogram provides generalized fractional anisotropy (GFA), fractional anisotropy (FA), axial diffusivity (AD), mean diffusivity (MD) and radial diffusivity (RD) profiles of 76 white matter tract bundles. Each profile contained 100 sampled values at 100 equidistant steps along the tract. We used threshold free cluster weighted (TFCW) scores for group analysis. We calculated the effect size of each step between groups, and estimated weighted scores to select the most different tract steps among the two groups. We did the linear multiple regression to identify the main contributor of the tracts for the specific functional item.
Result: A total of 23 segments were found to show top 5% difference in the weighted scores of GFA, AD or RD when comparing patients with cervical myelopathy with normal controls. The values of GFA of the affected segments were uniformly lower in patients.
Conclusion: As expected, we found significant reduction in GFA in the sensorimotor tracts, which were supposed to be the primary affected tracts in cervical myelopathy. Moreover, we also found altered tracts that were mostly related to cognitive functions, such as the left fornix, right frontal-striatum to the ventral lateral prefrontal cortex, and the splenium of the corpus callosum. Our results are consistent with previous studies reporting that cognitive dysfunctions may be related to disorders of the cervical spine or spinal cord. We speculate that patients with cervical myelopathy may be subjected to emotion problems due to reduced mobility, which may lead to cognitive decline as reflected by the impairment of cognitive-related tracts. The relationship between cognitive function and white matter changes in the brain needs to be further studied.
|Appears in Collections:||醫療器材與醫學影像研究所|
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