Update on myelin imaging in neurological syndromes

Abstract

Purpose of reviewMyelin water imaging (MWI) is generally regarded as the most rigorous approach for noninvasive, in-vivo measurement of myelin content, which has been histopathologically validated. As such, it has been increasingly applied to neurological diseases with white matter involvement, especially those affecting myelin. This review provides an overview of the most recent research applying MWI in neurological syndromes.Recent findingsMyelin water imaging has been applied in neurological syndromes including multiple sclerosis, Alzheimer's disease, Huntington's disease, traumatic brain injury, Parkinson's disease, cerebral small vessel disease, leukodystrophies and HIV. These syndromes generally showed alterations observable with MWI, with decreased myelin content tending to correlate with lower cognitive scores and worse clinical presentation. MWI has also been correlated with genetic variation in the APOE and PLP1 genes, demonstrating genetic factors related to myelin health.SummaryMWI can detect and quantify changes not observable with conventional imaging, thereby providing insight into the pathophysiology and disease mechanisms of a diverse range of neurological syndromes.

Lower myelin content is associated with more rapid cognitive decline among cognitively unimpaired individuals

“…Partly due to the increasingly recognized limitations of the amyloid hypothesis, it has been proposed that alterations in myelination could be an additional central feature of the pathophysiological etiology of AD and, potentially, other dementias 48–50 . Indeed, patterns of myelination represent an important biomarker for several CNS disorders, as well as for neurodevelopment 51,52 .…”

“…Loss of oligodendrocytes, the main cells forming and maintaining myelin, and subsequent demyelination may serve as a trigger underlying the pathological events that may impede regional CNS connectivity. Emerging evidence demonstrates that common genetic, as well as reversible or nonreversible, risk factors directly contribute to the cognitive deficits and demyelination seen in mild cognitive impairment, AD and dementias, and normative aging 50 . From this perspective, the breakdown of myelin may promote the deposition of amyloid‐beta fibrils, which in turn causes further myelin breakdown and neurodegeneration 6 .…”

“…Partly due to the increasingly recognized limitations of the amyloid hypothesis, it has been proposed that alterations in myelination could be an additional central feature of the pathophysiological etiology of AD and, potentially, other dementias. [48][49][50] Indeed, patterns of myelination represent an important biomarker for several CNS disorders, as well as for neurodevelopment. 51,52 Loss of oligodendrocytes, the main cells forming and maintaining myelin, and subsequent demyelination may serve as a trigger underlying the pathological events that may impede regional CNS connectivity.…”

“…Emerging evidence demonstrates that common genetic, as well as reversible or nonreversible, risk factors directly contribute to the cognitive deficits and demyelination seen in mild cognitive impairment, AD and dementias, and normative aging. 50 From this perspective, the breakdown of myelin may promote the deposition of amyloid-beta fibrils, which in turn causes further myelin breakdown and neurodegeneration. 6 Indeed, a central role for myelination disorders in AD and dementia, as a complement to the amyloid hypothesis, has been put forward to account for the limited outcomes of clinical trials targeting amyloid, and shifts the focus of AD pathology from the burden of discrete lesions to include an emphasis on brain circuitry disruption, including in WM due to axonal degeneration or myelin breakdown.…”

Survey on the Most Current Image Processing Methods in Huntington's Disease Diagnostics and Progression Assessment

“…The number of publications on HD in the PubMed database between 1949 and 2022 reached 14, 504 and is growing rapidly since the early 1980s, but only 1, 538 of these (10.6%) were about medical imaging in HD, and only 664 of these (4.58%) were about the use of Artificial Intelligence (AI) for the diagnosis and treatment. Thus, an urgent need is evident to intensify the efforts of scientists, engineers and clinicians to improve this situation [6,49]. This is fostered by current trends in the development of eHealth, but also in preventive medicine, personalised medicine and precision medicine, aimed at the development of Clinic 4.0 -medical equivalent of Industry 4.0.…”