Use of High Resolution 3D Diffusion Tensor Imaging to Study Brain White Matter Development in Live Neonatal Rats.
Use of High Resolution 3D Diffusion Tensor Imaging to Study Brain White Matter Development in Live Neonatal Rats.
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DOI：
10.3389/fpsyt.2011.00054
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发表时间：
2011
影响因子：
4.7
通讯作者：
An H
中科院分区：
文献类型：
--
作者：
Cai Y;McMurray MS;Oguz I;Yuan H;Styner MA;Lin W;Johns JM;An H
高分辨率弥散张量成像（DTI）可以提供大脑发育的重要信息，但它是具有挑战性的，由于新生大鼠的大脑体积小，运动敏感的DTI性质。活的新生大鼠的成像比固定的脑扫描有明显的优势，因为纵向和功能研究对于了解神经发育异常是可行的。在这项研究中，我们开发的成像策略，可用于获得高分辨率的三维DTI图像在活的新生大鼠出生后第5天（PND 5）和PND 14，仅使用3小时的成像采集时间。优化的3D DTI脉冲序列和适当的动物设置，以尽量减少生理运动伪影是成功的高分辨率3D DTI成像的关键。因此，实施了具有双导航回波的3D快速采集弛豫增强DTI序列，以加快成像采集时间并最小化运动伪影。研究表明，新生哺乳动物具有独特的能力，可以耐受轻度至中度的低温和缺氧，而不会产生长期影响。因此，我们还利用这种能力，通过使用轻度至中度低温将呼吸率仔细抑制到PND 5的15/min左右和PND 14的30/min左右，来最大限度地减少磁共振图像中的运动伪影。这些成像策略已经成功地实施，以研究可卡因暴露在母鼠中的效果如何影响其幼鼠的大脑发育。从该体内DTI研究得到的图像质量与离体扫描相当。分数各向异性值在实时和固定脑扫描之间也是相似的。获得高质量的在体DTI成像的能力提供了一个宝贵的机会，在真实的生活环境中研究大脑发育中的许多神经系统疾病。
High resolution diffusion tensor imaging (DTI) can provide important information on brain development, yet it is challenging in live neonatal rats due to the small size of neonatal brain and motion-sensitive nature of DTI. Imaging in live neonatal rats has clear advantages over fixed brain scans, as longitudinal and functional studies would be feasible to understand neuro-developmental abnormalities. In this study, we developed imaging strategies that can be used to obtain high resolution 3D DTI images in live neonatal rats at postnatal day 5 (PND5) and PND14, using only 3 h of imaging acquisition time. An optimized 3D DTI pulse sequence and appropriate animal setup to minimize physiological motion artifacts are the keys to successful high resolution 3D DTI imaging. Thus, a 3D rapid acquisition relaxation enhancement DTI sequence with twin navigator echoes was implemented to accelerate imaging acquisition time and minimize motion artifacts. It has been suggested that neonatal mammals possess a unique ability to tolerate mild-to-moderate hypothermia and hypoxia without long term impact. Thus, we additionally utilized this ability to minimize motion artifacts in magnetic resonance images by carefully suppressing the respiratory rate to around 15/min for PND5 and 30/min for PND14 using mild-to-moderate hypothermia. These imaging strategies have been successfully implemented to study how the effect of cocaine exposure in dams might affect brain development in their rat pups. Image quality resulting from this in vivo DTI study was comparable to ex vivo scans. fractional anisotropy values were also similar between the live and fixed brain scans. The capability of acquiring high quality in vivo DTI imaging offers a valuable opportunity to study many neurological disorders in brain development in an authentic living environment.