Diagnostic Radiology, City of Hope National Medical Center, Duarte, CA, 91010, USA.
Zinv LLC, Albuquerque, NM, 87108, USA.
Brain Struct Funct. 2023 Jul;228(6):1443-1458. doi: 10.1007/s00429-023-02661-8. Epub 2023 Jun 18.
We hypothesized that brain normal aging maintains a balanced whole-brain functional connectivity (FC) in lifetime: some connections decline while other connections increase or retain, in a summation balance as a result of the cancellation of positive and negative connections. We validated this hypothesis through the use of the brain intrinsic magnetic susceptibility source (denoted by χ) as reconstructed from fMRI phase data. In implementation, we first acquired brain fMRI magnitude (m) and phase (p) data from a cohort of 245 healthy subjects in an age span of 20-60 years, then sought MRI-free brain χ source data by computationally solving an inverse mapping problem, thereby obtained triple datasets {χ, m, p} as brain images in different measurements. We performed GIG-ICA for brain function decomposition and constructed the FC matrices (χFC, mFC, pFC} (in size of 50 × 50 for a selection of 50 ICA nodes), followed by a comparative analysis on brain FC agings using {χ, m, p} data. In the results, we found that: (i) χFC aging upholds a FC balance in life span, in an intermediator between mFC and pFC agings by: mean(pFC) = -0.011 < mean(χFC) = 0.015 < mean(mFC) = 0.036; and (ii) the χFC aging exhibits a slight decline with a slightly downward fitting line in intermediation between the two slightly upward fitting lines for the mFC and pFC agings. On the rationale of the χ-depicted MRI-free brain functional state, the brain χFC aging is closer to the brain FC aging truth than the MRI-borne mFC and pFC agings.
我们假设大脑的正常衰老在一生中保持着平衡的全脑功能连接（FC）：一些连接下降，而另一些连接增加或保持不变，这是由于正负连接相互抵消的总和平衡。我们通过使用从 fMRI 相位数据重建的大脑固有磁化率源（用 χ 表示）来验证这一假设。在实施过程中，我们首先从 245 名年龄在 20-60 岁的健康受试者的大脑 fMRI 幅度（m）和相位（p）数据中获取大脑数据，然后通过计算求解逆映射问题来寻找无 MRI 的大脑 χ 源数据，从而获得三组数据集 {χ、m、p}作为不同测量的大脑图像。我们进行了 GIG-ICA 以进行大脑功能分解，并构建了 FC 矩阵（χFC、mFC、pFC}（选择 50 个 ICA 节点大小为 50×50），然后使用 {χ、m、p} 数据对大脑 FC 老化进行了比较分析。在结果中，我们发现：（i）χFC 老化在寿命中维持 FC 平衡，在 mFC 和 pFC 老化之间的中介者为：mean(pFC)=-0.011<mean(χFC)=0.015<mean(mFC)=0.036；（ii）在 mFC 和 pFC 老化的两条略微向上拟合线之间，χFC 老化呈现出轻微下降和略微向下的拟合线。基于 χ 描绘的无 MRI 大脑功能状态的原理，与 MRI 承载的 mFC 和 pFC 老化相比，大脑 χFC 老化更接近大脑 FC 老化的真相。
