Application of Quantitative Microstructural MR Imaging with Atlas-based Analysis for the Spinal Cord in Cervical Spondylotic Myelopathy

Abstract

Mapping of MR fiber g-ratio, which is the ratio of the diameter of the axon to the diameter of the neuronal fiber, is introduced in this article. We investigated the MR fiber g-ratio, the axon volume fraction (AVF) and the myelin volume fraction (MVF) to evaluate microstructural changes in the spinal cord in patients with cervical spondylotic myelopathy (CSM) in vivo, using atlas-based analysis. We used diffusion MRI data acquired with a new simultaneous multi-slice accelerated readout-segmented echo planar imaging sequence for diffusion analysis for AVF calculation and magnetization transfer saturation imaging for MVF calculation. The AVFs of fasciculus gracilis in the affected side spinal cord, fasciculus cuneatus and lateral corticospinal tracts (LSCT) in the affected and unaffected side spinal cord were significantly lower (P = 0.019, 0.001, 0019, 0.000, and 0.002, respectively) than those of normal controls. No difference was found in the MVFs. The fiber g-ratio of LSCT was significantly lower (P = 0.040) in the affected side spinal cords than in the normal controls. The pathological microstructural changes in the spinal cord in patients with CSM, presumably partial axonal degenerations with preserved myelin. This technique has the potential to be a clinical biomarker in patients with CSM in vivo.

Variability and Standardization of Quantitative Imaging

“… 158 Multiparametric quantitative MRI can also be used for extracting new measures that reflect subvoxel microstructural information such as myelin and axon density, axon diameter, and membrane permeability. 152 , 159 Geometric distortion of images, image misregistration, and different interpolation techniques will introduce errors in created maps; hence, these issues should be cautiously handled.…”

Towards in vivo g-ratio mapping using MRI: Unifying myelin and diffusion imaging

“…Despite the challenges associated with accurate measurement and calibration of the MVF and AVF, many studies have exploited the potential of in vivo g-ratio weighted imaging for a variety of different applications (see Table 1 for full details). These have ranged from g-ratio mapping in infants ( Melbourne et al, 2016 ) and children ( Dean et al, 2016 ) to healthy adults ( Mohammadi et al, 2015 ; Mancini et al, 2018 ; Berman et al, 2019 ; Drakesmith et al, 2019a ), during healthy aging ( Cercignani et al, 2017 ; Berman et al, 2018 ) and as a result of pathological change ( Hagiwara et al, 2017 ; Hori et al, 2018 ; Kamagata et al, 2019 ; Yu et al, 2019 ).…”

“…LA.1, LM.1, LM.4, LM.9 Duval et al, 2018 As in ( Stikov et al, 2011 ) SPGR (MTV) 8C Scan-rescan of g-ratio in spinal cord. LA.1, LM.1, LM.4, LM.9 Hori et al, 2018 DWI1 (NODDI) MPM with multi-echo SPGR (MTsat) 24P Clinical study: G-ratio maps of the spinal cord in Cervical Spondylotic Myelopathy. LA.3, LA.4, LM.2, LM.9 Jung et al, 2018 DWI2 (NODDI) Multi-echo SPGR (MET2*) 5C; 15M* Two calibration methods for estimating MVF from myelin-water fraction.…”

MR g-ratio-weighted connectome analysis in patients with multiple sclerosis

“…We determined the calibration factor based on all healthy controls involved in this study as a linearly proportional relationship between MVF and , an absolute quantitative marker of myelin 54 . The calibration factor of 0.1 was subsequently used to obtain a g-ratio of 0.7 in the corpus callosum as previously suggested 62,63 . Therefore, to estimate MVF maps, we multiplied all voxels in the map by 0.1.…”