Magnetization Transfer Magnetic Resonance Imaging of the Brain, Spinal Cord, and Optic Nerve

Abstract

Summary:Magnetic resonance imaging is highly sensitive in revealing CNS abnormalities associated with several neurological conditions, but lacks specificity for their pathological substrates. In addition, MRI does not allow evaluation of the presence and extent of damage in regions that appear normal on conventional MRI sequences and that postmortem studies have shown to be affected by pathology. Quantitative MR-based techniques with increased pathological specificity to the heterogeneous substrates of CNS pathology have the potential to overcome such limitations. Among these techniques, one of the most extensively used for the assessment of CNS disorders is magnetization transfer MRI (MT-MRI). The application of this technique for the assessment of damage in macroscopic lesions, in normal-appearing white and gray matter, and in the spinal cord and optic nerve of patients with several neurological conditions is providing important in vivo information-dramatically improving our understanding of the factors associated with the appearance of clinical symptoms and the accumulation of irreversible disability. MT-MRI also has the potential to contribute to the diagnostic evaluation of several neurological conditions and to improve our ability to monitor treatment efficacy in experimental trials.

Overcoming the Clinical–MR Imaging Paradox of Multiple Sclerosis: MR Imaging Data Assessed with a Random Forest Approach

“…Our MR imaging acquisition scheme included the following: T2-weighted scans, which are sensitive to macroscopic MS-related abnormalities 26 ; T1-weighted scans, which allow measuring atrophy and, as a consequence, provide an estimate of irreversible tissue damage 26 ; DTI, which allows quantifying injury to critical WM pathways 8 ; and magnetization transfer MR imaging, which reliably quantifies the extent of MS damage to the cervical cord. 22 In line with the results of many previous MR imaging reports in MS, 1,2 we found significant between-group differences for most of the MR imaging variables studied. As expected, considering the number of variables included, the classic analysis showed poor-to-moderate correlations between clinical EDSS scores and some of the MR imaging measures of structural damage to the brain and spinal cord.…”

“…Cord crosssectional area and average magnetization transfer ratio values were measured. 21,22 The details of MR imaging data analysis are described in the On-line Appendix.…”

MRI in Multiple Sclerosis: What’s Inside the Toolbox?

“…The reader is referred to recent reviews, including one from this journal, which include a discussion of the technical aspects of MTI. 79,80 Injury to CNS structures can cause a decrease in exchange of tissue mobile protons. This abnormality can be captured on MTI as a decreased magnetization transfer ratio (MTR) (FIG.…”

Magnetization Transfer Imaging in Premanifest and Manifest Huntington Disease

“…9,10 MTI offers a way of examining tissue structure and structural components that are normally not resolvable with conventional MR imaging. 11 This allows for examination of structural integrity in a different and possibly more sensitive manner than volumetric changes alone.…”

“…MTI has been used to characterize many different disorders, including multiple sclerosis, Alzheimer disease, and Parkinson disease. 9 This study aims to examine MTR measures in a well-defined premanifest and manifest HD population, and to determine associations between MTR and clinical features of HD. By examining MTR in this sample, we aim to advance understanding of the timing of pathophysiological changes in HD and also evaluate the suitability of MTI/MTR as a potential biomarker for HD.…”