Age-related total gray matter and white matter changes in normal adult brain. Part II: quantitative magnetization transfer ratio histogram analysis.
Age-related total gray matter and white matter changes in normal adult brain. Part II: quantitative magnetization transfer ratio histogram analysis.
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发表时间：
2002-09
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通讯作者：
Y. Ge;R. Grossman;J. Babb;Marcie L. Rabin;L. J. Mannon;D. Kolson
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作者：
Y. Ge;R. Grossman;J. Babb;Marcie L. Rabin;L. J. Mannon;D. Kolson
背景与目的磁化传递比（MTR）是大脑潜在结构变化的一个敏感和定量的标识。我们定量评估了健康成人全球灰质（GM）和全球白质（WM）中与年龄和性别相关的MTR变化。方法52名年龄20 ~ 86岁的健康志愿者（男21名，女31名）分别在有和无饱和脉冲的情况下进行双回波快速自旋回波和磁化转移成像。利用计算机辅助的半自动分割技术对GM和WM进行了区分。对每个受试者的各节段组织生成MTR直方图，并在年龄和性别组之间进行比较。结果无论是GM还是WM，老年组（50岁或=50岁）MTR直方图的平均值、中位数、第一四分位数和峰值高度均显著低于年轻组（<50岁）。这些值的年龄依赖性可以在整个成年期以二次曲线表示。两种组织的MTRs仅在大约40岁后才开始下降。性别间MTR直方图测量结果无统计学差异。结论两个年龄组中GM和WM的MTR值不同，提示GM和WM随年龄的增长发生显著的显微变化，但这些神经健康成人的MTR值没有明显的性别差异。这些基于mri固有对比的规范性数据在研究特定的衰老疾病中是必不可少的，它们可能对我们理解衰老大脑中GM和WM的总体结构变化具有重要意义。
BACKGROUND AND PURPOSE The magnetization transfer ratio (MTR) is a sensitive and quantitative identifier of underlying structural changes in the brain. We quantitatively evaluated age- and sex-related MTR changes in global gray matter (GM) and global white matter (WM) in healthy adults. METHODS Fifty-two healthy volunteers (21 men, 31 women) aged 20-86 years underwent dual-echo fast spin-echo and magnetization transfer imaging performed with and then without a saturation pulse. GM and WM were distinguished by using a computer-assisted semiautomated segmentation technique. MTR histograms were generated for each segmented tissue in each subject and compared among age and sex groups. RESULTS The mean, median, first quartile, and peak height of the MTR histogram were significantly lower in the older group (> or =50 years) than those in the younger group (<50 years) for both GM and WM. The age dependency of these values can be expressed in a quadratic fashion over the entire span of adulthood. The MTRs started to decline only after the age of approximately 40 years in both tissues. No statistically significant differences in MTR histogram measurements between the sexes were observed. CONCLUSION The different MTR values for both GM and WM in the two age groups suggest that notable microscopic changes occur in GM and WM with advancing age, yet no significant sex-related variations in MTR measurements were found in these neurologically healthy adults. Such normative data based on the inherent contrast in MTRs are essential in studies of specific disorders of aging, and they may have implications for our understanding of the gross structural changes in both GM and WM in the aging brain.