Myelin-Weighted Imaging Presents Reduced Apparent Myelin Water in Patients with Alzheimer's Disease.

Seung-Hyun Lim,Sumin Jung,Chang-Woo Ryu,Hak Young Rhee,Se-Hong Oh,Jiyoon Lee,Geon-Ho Jahng,Ah Rang Cho,Bokyung Kim,Soonchan Park

doi:10.3390/diagnostics12020446

Abstract

The purpose of this study was to investigate myelin loss in both AD and mild cognitive impairment (MCI) patients with a new myelin water mapping technique within reasonable scan time and evaluate the clinical relevance of the apparent myelin water fraction (MWF) values by assessing the relationship between decreases in myelin water and the degree of memory decline or aging. Twenty-nine individuals were assigned to the cognitively normal (CN) elderly group, 32 participants were assigned to the MCI group, and 31 patients were assigned to the AD group. A 3D visualization of the short transverse relaxation time component (ViSTa)-gradient and spin-echo (GraSE) sequence was developed to map apparent MWF. Then, the MWF values were compared between the three participant groups and was evaluated the relationship with the degree of memory loss. The AD group showed a reduced apparent MWF compared to the CN and MCI groups. The largest AUC (area under the curve) value was in the corpus callosum and used to classify the CN and AD groups using the apparent MWF. The ViSTa-GraSE sequence can be a useful tool to map the MWF in a reasonable scan time. Combining the MWF in the corpus callosum with the detection of atrophy in the hippocampus can be valuable for group classification.

Highlights

In a nervous system, a neuron is a cell that sends signals to other cells through fragile and thin axons while a glial cell forms a membranous sheath called myelin, which surrounds and eventually insulates, axons [1]
A gross signal drop in the aapparent myelin water fraction (MWF) signal was oobserved in tthhee AADDggrroouupp ccoommppaarred to the cognitively normal (CN) group in the white matter
The results showed that the MWF was significantly reduced in the Alzheimer’s disease (AD) group compared to the CN and mild cognitive impairment (MCI) groups and decreased with disease severity (Table 2)

Summary

Introduction

A neuron is a cell that sends signals to other cells through fragile and thin axons while a glial cell forms a membranous sheath called myelin, which surrounds and eventually insulates, axons [1]. The oligodendrocytes and schwann cells are specialized glial cells that produce the myelin sheaths of the central nervous system and peripheral nervous system, respectively. The Oligodendrocytes myelinate multiple axons in the central nervous system, while Schwann cells myelinate a single axon in the peripheral nervous system. Demyelination is the condition in which preexisting myelin sheaths are damaged without axonal damage. It can result from various medical conditions such as viral infection, inflammatory process, metabolic dysfunctions. Myelin loss can cause nerve dysfunction by slowing or stopping nerve conduction through the axons. Myelin pathology contributes to the decline of cognitive characteristics in patients with AD [8]. Developing an imaging biomarker, which could indicate myelin loss, would have important clinical implications for the diagnosis and prognosis of diseases

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