Amplified Flow Imaging (aFlow): A Novel MRI-Based Tool to Unravel the Coupled Dynamics Between the Human Brain and Cerebrovasculature
Amplified Flow Imaging (aFlow): A Novel MRI-Based Tool to Unravel the Coupled Dynamics Between the Human Brain and Cerebrovasculature
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DOI：
10.1109/tmi.2020.3012932
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发表时间：
2020-12-01
影响因子：
10.6
通讯作者：
Kurt, Mehmet
中科院分区：
文献类型：
--
作者：
Abderezaei, Javid;Martinez, John;Kurt, Mehmet
随着每一次心跳，动脉血压的周期性变化沿着血管系统传递，导致动脉壁及其周围组织的局部变形。这种运动的量化可能有助于了解各种脑血管疾病，但到目前为止，它在技术上被证明是具有挑战性的。我们介绍了一种新的图像处理算法，称为放大流(AFLOW)，它可以通过结合电影放大和4D Flow MRI来研究脑-血流耦合运动。通过将一种称为动态模式分解的模式分析技术融入到算法中，FLOW能够捕获大脑中存在的瞬时事件和动脉壁变形的特征。为了验证FLOW，我们在模拟动脉壁运动的体模模拟上对其进行了测试，并观察到FLOW显示的信噪比几乎是其前身放大磁共振成像(AMRI)的两倍。然后，我们将FLOW应用于5名健康受试者的4D FLOW和电影磁共振数据集，发现选定脑区的血流速度与组织变形之间具有高度的相关性，桥脑、额叶和枕叶的相关系数分别为0.61、0.59和0.52p<；0.001。最后，我们通过研究颅内动脉瘤动力学来探索AFLOW的潜在诊断适用性，这似乎是破裂风险的指标。在两名患者中，FLOW成功地显示了难以察觉的动脉瘤壁运动，另外还量化了一年随访期后高频壁位移量的增加(20%，76%)。这些初步数据表明，FLOW可能为评估动脉瘤的演变提供一种新的成像生物标志物，具有重要的潜在诊断意义。
With each heartbeat, periodic variations in arterial blood pressure are transmitted along the vasculature, resulting in localized deformations of the arterial wall and its surrounding tissue. Quantification of such motions may help understand various cerebrovascular conditions, yet it has proven technically challenging thus far. We introduce a new image processing algorithm called amplified Flow (aFlow) which allows to study the coupled brain-blood flow motion by combining the amplification of cine and 4D flow MRI. By incorporating a modal analysis technique known as dynamic mode decomposition into the algorithm, aFlow is able to capture the characteristics of transient events present in the brain and arterial wall deformation. Validating aFlow, we tested it on phantom simulations mimicking arterial walls motion and observed that aFlow displays almost twice higher SNR than its predecessor amplified MRI (aMRI). We then applied aFlow to 4D flow and cine MRI datasets of 5 healthy subjects, finding high correlations between blood flow velocity and tissue deformation in selected brain regions, with correlation values r = 0.61, 0.59, 0.52 for the pons, frontal and occipital lobe (p < 0.001). Finally, we explored the potential diagnostic applicability of aFlow by studying intracranial aneurysm dynamics, which seems to be indicative of rupture risk. In two patients, aFlow successfully visualized the imperceptible aneurysm wall motion, additionally quantifying the increase in the high frequency wall displacement after a one-year follow-up period (20%, 76%). These preliminary data suggest that aFlow may provide a novel imaging biomarker for the assessment of aneurysms evolution, with important potential diagnostic implications.