Cui J, Tymofiyeva O, Desikan R, Flynn T, Kim H, Gano D, Hess C P, Ferriero D M, Barkovich A J, Xu D
From the Departments of Radiology and Biomedical Imaging (J.C., O.T., R.D., T.F., H.K., C.P.H., A.J.B., D.X.).
Pediatrics and Neurology (D.G., D.M.F.), University of California, San Francisco, San Francisco, California.
AJNR Am J Neuroradiol. 2017 Feb;38(2):343-348. doi: 10.3174/ajnr.A4997. Epub 2016 Nov 10.
Diffusion and fMRI has been providing insights to brain development in addition to anatomic imaging. This study aimed to evaluate the microstructure of white matter tracts underlying the default mode network in premature infants by using resting-state functional MR imaging in conjunction with diffusion tensor imaging-based tractography.
A cohort of 44 preterm infants underwent structural T1-weighted imaging, resting-state fMRI, and DTI at 3T, including 21 infants with brain injuries and 23 infants with normal-appearing structural imaging as controls. Neurodevelopment was evaluated with the Bayley Scales of Infant Development at 12 months' adjusted age. Probabilistic independent component analysis was applied to resting-state fMRI data to explore resting-state networks. The localized clusters of the default mode network were used as seeding for probabilistic tractography. The DTI metrics (fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity) of the reconstructed primary tracts within the default mode network-cingula were measured.
Results revealed decreased fractional anisotropy (0.20 ± 0.03) and elevated radial diffusivity values (1.24 ± 0.16) of the cingula in the preterm infants with brain injuries compared with controls (fractional anisotropy, 0.25 ± 0.03; < .001; radial diffusivity, 1.06 ± 0.16; = .001). The Bayley Scales of Infant Development cognitive scores were significantly associated with cingulate fractional anisotropy ( = .004) and radial diffusivity ( = .021); this association suggests that the microstructural properties of interconnecting axonal pathways within the default mode network are of critical importance in the early neurocognitive development of infants.
This study of combined resting-state fMRI and DTI at rest suggests that such studies may allow the investigation of key functional brain circuits in premature infants, which could function not only as diagnostic tools but also as biomarkers for long-term neurodevelopmental outcomes.
除解剖成像外，扩散加权成像和功能磁共振成像一直为脑发育研究提供重要信息。本研究旨在通过静息态功能磁共振成像结合基于扩散张量成像的纤维束成像，评估早产儿默认模式网络下白质纤维束的微观结构。
44例早产儿在3T条件下接受了结构T1加权成像、静息态功能磁共振成像和扩散张量成像，其中包括21例脑损伤婴儿和23例结构成像正常的婴儿作为对照。在矫正年龄12个月时，采用贝利婴儿发育量表评估神经发育情况。对静息态功能磁共振成像数据应用概率独立成分分析来探索静息态网络。默认模式网络的局部簇被用作概率纤维束成像的种子点。测量默认模式网络-扣带内重建主要纤维束的扩散张量成像指标（各向异性分数、平均扩散率、轴向扩散率和径向扩散率）。
结果显示，与对照组相比，脑损伤早产儿扣带的各向异性分数降低（0.20±0.03），径向扩散率值升高（1.24±0.16）（各向异性分数，0.25±0.03；P<0.001；径向扩散率，1.06±0.16；P = 0.001）。贝利婴儿发育量表认知评分与扣带各向异性分数（P = 0.004）和径向扩散率（P = 0.021）显著相关；这种关联表明，默认模式网络内相互连接的轴突通路的微观结构特性在婴儿早期神经认知发育中至关重要。
这项关于静息态功能磁共振成像和静息态扩散张量成像联合应用的研究表明，此类研究可能有助于对早产儿关键功能脑回路进行研究，其不仅可作为诊断工具，还可作为长期神经发育结局的生物标志物。
