Evaluation of normal age-related changes in anisotropy during infancy and childhood as shown by diffusion tensor imaging
Evaluation of normal age-related changes in anisotropy during infancy and childhood as shown by diffusion tensor imaging
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DOI：
10.2214/ajr.179.6.1791515
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发表时间：
2002-12-01
影响因子：
5
通讯作者：
Provenzale, JM
中科院分区：
文献类型：
--
作者：
McGraw, P;Liang, LX;Provenzale, JM
OBJECTIVE.本研究的第一个目的是使用扩散张量成像比较三个儿童年龄组中致密白色物质和非致密白色物质的各向异性程度。我们假设在每个年龄组中，致密白色物质的各向异性均高于非致密白色物质。本研究的第二个目的是比较儿童早期致密与非致密白色物质各向异性随时间的增加。我们假设在非致密的白色物质中各向异性的增加会更高。我们回顾性分析了66例儿科患者（年龄范围，4天-71个月;平均年龄，18.6个月）进行的扩散张量成像研究得出的各向异性图，这些患者接受了临床MR成像，在常规MR图像上没有发现异常。在三个致密的白色物质结构（胼胝体，内囊，大脑脚）和两个非致密的白色物质区域（放射冠和外周白色物质）中测量各向异性。根据年龄将患者分配至以下三组之一：第1组，小于12个月（n = 40）;第2组，12-35个月（n = 11）;第3组，36-71个月（n = 15）。首先，我们比较了每个年龄组非致密白色物质与致密白色物质的各向异性值。其次，我们比较了非致密白色物质区域与致密白色物质结构中各向异性随时间的增加。在所有三个年龄组中，致密白色物质结构的各向异性测量值高于非致密白色物质（p < 0.01）。第1、2和3组非致密白色物质的平均各向异性值分别为0.349、0.480和0.531。第1、2和3组致密白色物质的平均各向异性值分别为0.494、0.646和0.697。当年龄组进行比较时，在致密白色物质和非致密白色物质中均观察到各向异性的统计学显著增加（p < 0.01）。然而，当I组与3组（p < 0.01）以及I组与2组（p <0.01）比较时，非致密白色区的各向异性增加显著大于致密白色结构。虽然在所有三个年龄组中，致密白色物质的各向异性测量值均高于非致密物质，但在三个年龄组中，非致密白色物质的各向异性增加更大。这些数据表明，虽然髓鞘形成最初是更大的紧凑的白色的问题，髓鞘的变化可能是更大的非紧凑的白色的问题在婴儿期后的头几年。
OBJECTIVE. The first purpose of this study was to compare the degree of anisotropy in compact white matter and noncompact white matter in each of three pediatric age groups using diffusion tensor imaging. We hypothesized that anisotropy would be higher in compact white matter than in noncompact white matter in each age group. The second purpose of our study was to compare the increase in anisotropy over time in compact versus noncompact white matter during early childhood. We hypothesized that increases in anisotropy would be higher in noncompact white matter.MATERIALS AND METHODS. We retrospectively analyzed anisotropy maps derived from diffusion tensor imaging studies performed in 66 pediatric patients (age range, 4 days-71 months; mean age, 18.6 months) who underwent clinical MR imaging and were found to have no abnormalities on conventional MR images. Anisotropy was measured in three compact white matter structures (corpus callosum, internal capsule, cerebral peduncle) and two regions of noncompact white matter (corona radiata and peripheral white matter). Patients were assigned to one of the three following groups on the basis of age: group 1, younger than 12 months (n = 40); group 2, 12-35 months (n = 11); and group 3, 36-71 months (n = 15). First, we compared anisotropy values of noncompact white matter with those of compact white matter for each age group. Second, we compared the increase over time in anisotropy of noncompact white matter regions with that seen in compact white matter structures.RESULTS. Among all three age groups, anisotropy measurements in compact white matter structures were higher than those in noncompact white matter (p < 0.01). The mean anisotropy values in noncompact white matter for groups 1, 2, and 3, respectively, were 0.349, 0.480, and 0.531. The mean anisotropy values in compact white matter for groups 1, 2, and 3, respectively, were 0.494, 0.646, and 0.697. When age groups were compared, a statistically significant increase in anisotropy was seen in both compact white matter and noncompact white matter (p < 0.01). However, the increase in anisotropy was significantly greater in noncompact white matter regions than in compact white matter structures when comparing group I with group 3 (p < 0.01) as well as group I with group 2 (p < 0.01).CONCLUSION. Although anisotropy measurements were higher in compact than noncompact white matter in all three age groups, the increase in anisotropy was greater in noncompact white matter across each of the three groups. These data suggest that although myelination is initially greater in compact white matter, the change in myelination may be greater in noncompact white matter during the first few years after infancy.