Department of Radiology, School of Medicine, University of Crete, Heraklion, Crete, Greece.
Institute of Computer Science, Foundation of Research and Technology, Heraklion, Greece.
J Magn Reson Imaging. 2019 Nov;50(5):1393-1404. doi: 10.1002/jmri.26707. Epub 2019 Mar 12.
According to the retrogenesis hypothesis, the rate of age-related changes in white matter (WM) myelin content varies between early myelinating (parietal, occipital) and late myelinating (prefrontal, lateral-posterior temporal) areas. The multiecho spin echo (MESE), PD-to-T -weighted sequence provides an index of myelin content (myelin water fraction [MWF]) derived from measurements of myelin water (via the short T component [10-50 msec]) and intra- and extracellular water (via the long T component [>50-200 msec]).
To assess the shape and regional variations in the rate of age-related myelin and water content changes in deep WM regions using the MESE sequence.
Prospective, cross-sectional.
In all, 90 healthy adults aged 22-81 years.
FIELD STRENGTH/SEQUENCE: 1.5T/ T w, T w, fluid attenuated inversion recovery (FLAIR), MESE sequences.
Short T , long T , and MWF values were measured in prefrontal, parietal, lateral-posterior temporal, and occipital normal-appearing WM (NAWM) areas.
Linear and quadratic effects of age on long T and MWF were assessed through regression analyses. Regional variations in the effect of age on long T and MWF values at both the individual and group level were examined, using regression and analysis of covariance (ANCOVA) analyses, respectively, controlling for total WM volume.
The rate of age-related changes in long T and MWF was higher for older persons and a significant increase or decline, respectively, was first noted at 60-69 years (P < 0.0033). MWF values peaked earlier (at 30 years of age) and displayed a steeper age-related reduction in prefrontal and lateral-posterior temporal NAWM as compared with the occipital lobes (P < 0.05). The opposite pattern of age-related effect was found for long T values.
Significant age-related reductions in myelin content were closely followed by corresponding increases in intra- and extracellular water content. These changes were more pronounced among elderly people and followed an anterior-posterior pattern.
2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:1393-1404.
根据逆行发生假说，白质（WM）髓鞘含量随年龄变化的速率在早期髓鞘形成（顶叶、枕叶）和晚期髓鞘形成（前额叶、外侧-后颞叶）区域之间有所不同。多回波自旋回波（MESE）、质子密度到 T 2 -加权序列提供了髓鞘含量的指标（髓鞘水分数[MWF]），该指标来自于对髓鞘水（通过短 T 成分[10-50msec]）和细胞内和细胞外水（通过长 T 成分[>50-200msec]）的测量。
使用 MESE 序列评估深部 WM 区域髓鞘和水含量随年龄变化的形态和区域变化。
前瞻性、横断面研究。
共有 90 名年龄在 22-81 岁的健康成年人。
磁场强度/序列：1.5T/T w 、T w 、液体衰减反转恢复（FLAIR）、MESE 序列。
在额、顶、外侧-后颞和枕叶正常表现的 WM（NAWM）区域测量短 T 、长 T 和 MWF 值。
通过回归分析评估年龄对长 T 和 MWF 的线性和二次效应。使用回归和协方差分析（ANCOVA）分析分别在个体和组水平上检查年龄对长 T 和 MWF 值的影响的区域变化，分别控制总 WM 体积。
长 T 和 MWF 随年龄的变化率随年龄的增长而增加，在 60-69 岁时（P <0.0033）首次出现显著的增加或下降。MWF 值更早达到峰值（30 岁），与枕叶相比，前额叶和外侧-后颞叶 NAWM 的髓鞘含量随年龄相关性降低更为陡峭（P <0.05）。长 T 值的年龄相关性效应则呈现相反的模式。
髓鞘含量的显著年龄相关性降低紧随其后的是细胞内和细胞外水含量的相应增加。这些变化在老年人中更为明显，呈前后分布。
2 技术功效：2 级。磁共振成像杂志 2019；50：1393-1404。
