儿童组织值特性的年龄相关性变化：利用合成磁共振成像同时定量弛豫时间和质子密度。
Age-Related Changes in Tissue Value Properties in Children: Simultaneous Quantification of Relaxation Times and Proton Density Using Synthetic Magnetic Resonance Imaging.
出版信息
Invest Radiol. 2018 Apr;53(4):236-245. doi: 10.1097/RLI.0000000000000435.
OBJECTIVES
The properties of brain tissue undergo dynamic changes during maturation. T1 relaxation time (T1), T2 relaxation time (T2), and proton density (PD) are now simultaneously quantifiable within a clinically acceptable time, using a synthetic magnetic resonance imaging (MRI) sequence. This study aimed to provide age-specific reference values for T1, T2, and PD in children, using synthetic MRI.
MATERIALS AND METHODS
We included 89 children (median age, 18 months; range, 34 weeks of gestational age to 17 years) who underwent quantitative MRI, using a multidynamic, multiecho sequence on 3 T MRI, between December 2015 and November 2016, and had no abnormal MRI/neurologic assessment findings. T1, T2, and PD were simultaneously measured in each of the 22 defined white matter and gray matter regions of interest. The measured values were plotted against age, and a curve fitting model that best explained the age dependence of tissue values was identified. Age-specific regional tissue values were calculated using a fit equation.
RESULTS
The tissue values of all brain regions, except cortical PD, decreased with increasing age, and the robust negative association was best explained by modified biexponential model of the form Tissue values = T1 × exp (-C1 × age) + T2 × exp (-C2 × age). The quality of fit to the modified biexponential model was high in white matter and deep gray matter (white matter, R = 97%-99% [T1], 88%-95% [T2], 88%-97% [PD]; deep gray matter, R = 96%-97% [T1], 96% [T2], 49%-88% [PD]; cortex, 70%-83% [T1], 87%-90% [T2], 5%-27% [PD]). The white matter and deep gray matter changed the most dynamically within the first year of life.
CONCLUSIONS
Our study provides age-specific regional reference values, from the neonate to adolescent, of T1, T2, and PD, which could be objective tools for assessment of normal/abnormal brain development using synthetic MRI.
目的
脑组织结构的特性在成熟过程中会发生动态变化。现在，通过一种合成磁共振成像（MRI）序列，可以在临床可接受的时间内同时定量测量 T1 弛豫时间（T1）、T2 弛豫时间（T2）和质子密度（PD）。本研究旨在使用合成 MRI 为儿童提供 T1、T2 和 PD 的特定年龄参考值。
材料与方法
我们纳入了 89 名儿童（中位年龄 18 个月；范围为 34 周胎龄至 17 岁），他们于 2015 年 12 月至 2016 年 11 月期间在 3T MRI 上接受了多动态、多回波序列的定量 MRI 检查，且 MRI/神经评估结果均无异常。在 22 个定义明确的白质和灰质感兴趣区中，每个区域都同时测量了 T1、T2 和 PD。将测量值与年龄进行绘制，并确定了最佳解释组织值与年龄相关性的曲线拟合模型。使用拟合方程计算特定年龄的区域组织值。
结果
除皮质 PD 外，所有脑区的组织值均随年龄的增长而降低，呈负相关关系，最佳拟合模型为 T1×exp（-C1×年龄）+T2×exp（-C2×年龄）的修正双指数模型。白质和深部灰质的拟合模型质量较高（白质：T1 的 R 值为 97%-99%[T1]、88%-95%[T2]、88%-97%[PD]；深部灰质：R 值为 96%-97%[T1]、96%[T2]、49%-88%[PD]；皮质：T1 的 R 值为 70%-83%[T1]、87%-90%[T2]、5%-27%[PD]）。白质和深部灰质在生命的头 1 年变化最为活跃。
结论
本研究提供了从新生儿到青少年的特定年龄的 T1、T2 和 PD 区域参考值，这可能成为使用合成 MRI 评估正常/异常脑发育的客观工具。
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