MR Spectroscopy in Health and Disease

Abstract

Magnetic resonance spectroscopy (MRS) enables the noninvasive quantification of up to 20 neurochemicals in selected brain regions and has found many applications in the study of the cerebellum in health and disease. The neurochemicals accessible by MRS include neuronal and glial markers, neurotransmitters, markers of cellular energetics, and antioxidants and, therefore, provide means to assess neuronal dysfunction/loss, glial activation, energy metabolism, and oxidative stress. As a result, the methodology has been applied to the study of many diseases that affect the cerebellum, including neurodegenerative diseases, cancer, metabolic disorders, alcoholism, and neuropsychiatric disorders. While MRS of the cerebellum poses challenges due to the caudal location of the structure in the brain, these have been overcome both on research and clinical scanners that operate at high and ultra-high magnetic fields, providing the potential for further applications of the technology with greater sensitivity and resolution than ever before to benefit basic and translational investigations in cerebellar disorders.

Two-site reproducibility of cerebellar and brainstem neurochemical profiles with short-echo, single-voxel MRS at 3T

“…This study demonstrates that nearly identical neurochemical profiles consisting of 13–17 metabolites are obtained in two different brain regions in relatively large healthy cohorts by different operators at two MR sites. The acquisition of high‐quality MRS data from the cerebellum and brainstem is particularly challenging due to their caudal location in the head and broader intrinsic linewidths relative to other cerebral VOI . We were able to obtain high‐quality MRS data in a dual‐site setting due the consistency of obtaining artifact‐free short T E spectra using an in‐house developed and highly optimized pulse sequence and identical B 0 and B 1 adjustment protocols.…”

“…A previously described semi‐LASER sequence was used to achieve lower apparent T 2 relaxation, minimal J ‐coupling evolution, and smaller chemical shift displacement errors relative to the standard PRESS sequence. Two relatively challenging brain regions were chosen for this two‐site comparison: the cerebellar vermis and pons .…”

Non‐invasive detection of neurochemical changes prior to overt pathology in a mouse model of spinocerebellar ataxia type 1

“…). Of note, the cerebellum presents challenges for MRS, such as broader intrinsic line widths than other brain regions (Öz ), however, its anatomical landmarks present an advantage for consistent placement of the VOI within and between animals. Thus, the mean test‐retest coefficient of variation using the same methodology in the mouse cerebellum is ≤ 5% for six of the reported metabolites, including tCr, tCho and Tau, and ≤ 10% for five reported metabolites, including Gln (Öz et al .…”

“…Interestingly, glucose and glycogen (the main storage form of glucose in the brain) levels in the cerebellum are higher than other brain regions (Swanson et al . ) and, together with high creatine kinase activity and tCr levels, the cerebellum appears to be distinct from other brain regions in its energy buffering capacity (Öz ).…”

Test‐retest reproducibility of neurochemical profiles with short‐echo, single‐voxel MR spectroscopy at 3T and 7T

“…We used coils that were capable of achieving sufficient B 1 for spectroscopy (with minimal chemical shift displacement) in deep brain regions at both fields. We focused on two brain regions that are of interest for neurological diseases and that present different levels of technical challenges for MRS: the posterior cingulate, a key node in the default mode network , which is affected in a number of neurological and psychiatric disorders , and the cerebellum, which is affected in multiple movement disorders and is technically more challenging for study by MRS (due to its caudal location in the brain and broader intrinsic linewidths than most other cortical areas).…”