Quantitative proton magnetic resonance spectroscopy of the cervical spinal cord

Abstract

Proton MR spectroscopy (1 H-MRS) provides indices of neuronal damage in the central nervous system (CNS); however, it has not been extensively applied in the spinal cord. This work describes an optimized proton spectroscopy protocol for examination of the human cervical spinal cord. B 0 field mapping of the cord revealed periodic inhomogeneities due to susceptibility differences with surrounding tissue. By combining field maps and experimental data, we found that the optimum voxel size was 9 ؋ 7 ؋ 35 mm 3 placed with the inferior end of the voxel above vertebral body C2. Metabolite concentrations were determined in the cervical cord in six healthy controls by shortecho point-resolved spectroscopy (PRESS) volume localization. The results were compared with metabolite concentrations in the brainstem, cerebellum, and cortex in the same individuals. The concentrations in the cervical cord were as follows: Nacetyl-aspartate (NAA) 17.3 ؎ 0.5, creatine (Cr) 9.5 ؎ 0.9, and choline 2.7 ؎ 0.5 mmol/l. The NAA concentration was significantly lower in the cord than in the brainstem (Mann-Whitney, P < 0.025), and higher than in the cortex (P < 0.005) and cerebellum (P < 0.005). Cr was significantly lower in the cord than in the cerebellum (P < 0.05). There were no significant differences between Cr concentrations in the spinal cord compared to the cortex and brainstem.Magn Proton magnetic resonance spectroscopy ( 1 H-MRS) is a valuable noninvasive technique for assessing the biochemistry of the human brain. This is reflected by the increasing clinical applications of spectroscopy to investigate neurological disorders (1,2). Proton MRS of the brain has applications in multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), space-occupying lesions, and various metabolic disorders (3). However, in 10 -15% of MS patients (4) and in other diseases, such as ALS, the clinical picture is dominated by spinal cord pathology. Furthermore, diseases such as Friedreich's ataxia, compressive syndromes, subacute combined degeneration, and anterior spinal artery syndrome all principally affect the spinal cord.Spinal cord atrophy (an indirect marker of irreversible axonal loss within the spinal cord) has been shown to correlate with disability in MS (5). We have shown in both stroke (6) and MS (7) that with the use of small spectroscopy voxels to target the main pathways of the motor system (i.e., the posterior limb of the internal capsule), it is possible to demonstrate a correlation between N-acetylaspartate (NAA) levels and clinical measures of function within that pathway. This suggests that 1 H-MRS of the cord itself would reveal abnormalities in those diseases in which pathology is specific to the cord. This may provide information regarding neuronal viability, and thus provide physiological, diagnostic, and prognostic insights.It is technically challenging to perform spectroscopy on the spinal cord. The spinal cord is small compared to the size of the voxel in a typical spectroscopy examination, which limits the available signal-t...

Quantitative Cervical Spinal Cord 3T Proton MR Spectroscopy in Multiple Sclerosis

“…Among the few cervical spine spectroscopy studies, [21][22][23][24][25][26][27]30,[32][33][34] only 4 provided data acquired in patients with MS and only 1 26 quantified the main metabolites on T2-weighted hyperintense plaques.…”

“…Six very selective suppression 29 saturation bands with a thickness 30 mm were placed contiguous to the volume of interest (VOI) to minimize fat contamination. Following the suggestions of Cooke et al 30 to prevent fat contamination, a rectangular 1 H-MR spectroscopy VOI with dimensions of approximately 7 ϫ 9 ϫ 35 mm (mean volume, 1.7 Ϯ 0.4 mL; ranging from 1.0 to 3.5 mL) was prescribed along the main axis of the cord, approximately between levels C2 and C3, over a plaque identified as hyperintense on previously acquired sagittal and coronal T2-weighted FSE and axial T2* weighted images, avoiding healthy tissue as much as possible (Fig 1).…”

Spinal Cord–Midbrain Functional Connectivity Is Related to Perceived Pain Intensity: A Combined Spino-Cortical fMRI Study

“…To minimize signal intensity variations along the z-direction (Cooke et al, 2004;Maieron et al, 2007) a compensatory slice-specific gradient momentum was used for the spinal slices (Finsterbusch et al, 2012). This "z-shim" was determined based on prescan acquisitions of the spinal subvolume with 21 equidistant gradient steps applied to all spinal slices and, subsequently, selecting the gradient setting yielding the maximum signal intensity within the spinal cord in each slice.…”

Diffusion Tensor MR Imaging of the Neurologically Intact Human Spinal Cord

“…Sections in the same transverse plane as intervertebral disks were excluded from analysis to decrease the effects of susceptibility-related distortions. 21 The remaining sections were pooled to create a single distribution per spinal segment for each subject (approximately 3-5 sections per segment per subject, or a total of approximately 200 -600 voxels per segment per subject). Finally, distributions for all subjects were pooled across respective spinal levels.…”

“…In particular, the regions of the spinal cord most sensitive to changes in B0 from susceptibility inhomogeneity are located proximal to the vertebral disk (because of the spinous process from the rostral vertebral level). 21 Furthermore, we used a Fourier-transform-based image registration algorithm to correct geometric distortions between the T2-weighted and DWIs. Regardless, the lack of B0 correction for susceptibility artifacts for both T2-weighted and DWIs may have distorted the images of our study.…”