正常青年人群脑磁共振扩散张量成像的定量研究

Quantitative Study of Normal Young Adult Brain by Using Magnetic Resonance Diffusion Tensor Imaging

目的:运用扩散张量成像(DTI)方法研究正常青年人群不同脑组织及解剖部位的各向异性特点。方法:对40名正常青年人群行DTI成像,分析其表面扩散系数(ADC)图及各向异性分数(FA)图的特点,并对不同脑组织进行ADC及FA值的定量分析,通过统计学分析得出其扩散和各向异性特点。结果:扩散系数ADC不能区分脑灰质与脑白质(ADC分别为807.78±90.29,775.79±115.31×10-6mm2/s,P=0.098)。而脑脊液、脑灰质与脑白质间的FA值间差异均具有显著性意义(P<0.05)。不同解剖部位的脑白质间具有显著不同的各向异性(P<0.05)。胼胝体压部的各向异性程度最高(0.73±0.09),其次为胼胝体膝部与内囊后肢(0.68±0.05,0.67±0.06),半卵圆中心与枕钳最低(0.53±0.09,0.53±0.09)。脑灰质中以背侧丘脑具有最高的各向异性(0.31±0.04)。结论:FA可准确定量正常青年人群不同脑组织的扩散特点,DTI可清晰显示脑内白质的方向及走行。

Objective：To study the diffusion anisotropic features of different tissues and structures of normal young a dults brain by using magnetic resonance diffusion tensor imaging. Methods： Forty normal young adults were examined by magnetic resonance diffusion tensor imaging （DTI）. The signal features of different brain structures on both apparent diffusion coefficient （ADC） and fractional anisotropy （FA） maps were analyzed. The ADC and FA values were measured,and the results were analyzed statistically. Results：There was no significant difference between gray matter and white matter in ADC values （807.78±90.29 6 mm2/s and 775. 79± 115. 31× 10^-6 mmE/s,P=0. 098）. FA values were significantly different from region to region in the brain. FA values of the white matter were much larger than those of gray matter and cerebrospinal fluid （P〈0.05）. FA values were significantly different among different parts of white matter （P〈0.05）. Splenium of corpus callosum had the highest FA values （0.73!0.09）,followed by knee of corpus callosum and posterior limb of internal capsule （0.68±0.05 and 0. 67±0. 06 ,respectively）. Semi-oval center and occipital forceps white matter had the lowest values （0.53±0.09 and 0. 53±0. 09,respectively）. Dorsal thalamus had the highest FA values in gray matters （0.31±0.04）. Conclusion..FA value can precisely quantitatively determine the diffusion anisotropic properties of different intracerebral tissues of normal young adults,and DTI could well display intraeerebral neurofibers.