Electrical Engineering, Stanford University, Stanford, CA, USA.
Neuroimage. 2011 Jan 15;54(2):1112-21. doi: 10.1016/j.neuroimage.2010.08.068. Epub 2010 Sep 7.
Diffusion imaging and bound pool fraction (BPF) mapping are two quantitative magnetic resonance imaging techniques that measure microstructural features of the white matter of the brain. Diffusion imaging provides a quantitative measure of the diffusivity of water in tissue. BPF mapping is a quantitative magnetization transfer (qMT) technique that estimates the proportion of exchanging protons bound to macromolecules, such as those found in myelin, and is thus a more direct measure of myelin content than diffusion. In this work, we combined BPF estimates of macromolecular content with measurements of diffusivity within human white matter tracts. Within the white matter, the correlation between BPFs and diffusivity measures such as fractional anisotropy and radial diffusivity was modest, suggesting that diffusion tensor imaging and bound pool fractions are complementary techniques. We found that several major tracts have high BPF, suggesting a higher density of myelin in these tracts. We interpret these results in the context of a quantitative tissue model.
扩散成像和结合池分数 (BPF) 图是两种定量磁共振成像技术，可测量脑白质的微观结构特征。扩散成像是对组织中水扩散率的定量测量。BPF 图是一种定量磁化转移 (qMT) 技术，可估计与大分子结合的交换质子的比例，如髓鞘中的那些质子，因此比扩散更直接地测量髓鞘含量。在这项工作中，我们将大分子含量的 BPF 估计与人类白质束内的扩散测量相结合。在白质内，BPF 与扩散率测量（如各向异性分数和径向扩散率）之间的相关性适中，表明扩散张量成像和结合池分数是互补的技术。我们发现，一些主要的束具有较高的 BPF，这表明这些束中的髓鞘密度较高。我们在定量组织模型的背景下解释这些结果。
