Pressure Gradient Measurement in the Coronary Artery: Towards Noninvasive Quantification of Fractional Flow Reserve

项目总结/摘要 血流储备分数（FFR）是一种评估功能性血流储备的侵入性程序。 通过测量跨瓣压差来确定中度狭窄的意义 这种狭窄非侵入性技术，如CT-FFR，使用计算 使用计算机断层扫描（CT）图像的流体动力学方法计算FFR 指数，已经显示出减少了需要侵入性手术的患者数量。 然而，在CT中使用电离辐射妨碍了对患者的纵向监测 他们被推迟了侵入性测试和治疗。为了解决这个问题，我们 提出了一种无创的冠状动脉压力测量技术， 磁共振成像（MRI），没有电离辐射。该方法 基于相位对比MRI（PC-MRI）测量的速度， Navier-Stokes方程来推导压力差，这已经在 各种血管，如主动脉、颈动脉、肾动脉和颅内动脉。应用 冠状动脉技术，心脏和呼吸运动等挑战 并且需要解决PC-MRI采集的高空间和时间分辨率。 在本研究中，我们的目标是通过使用1）心电图和导航门控来应对挑战 以最大限度地减少运动误差，2）使用 黄金角采样方案，以实现高的空间和时间分辨率。的 假设提出的PC-MRI技术可以进一步改善导航- Stokes分析，并由此导出压差指数。测量的速度 将比较拟定PC-MRI和推导的压差指数的值 以有创流量和压力来评价所提出方法的可行性及其 与临床黄金标准的相关性。这种非侵入性技术可能会获得 在一个成像会话中的解剖和功能信息， 风险、患者不适和高手术成本， 来自CT-FFR的辐射。

Project Summary/Abstract Fractional Flow Reserve (FFR) is an invasive procedure evaluating the functional significance of an intermediate stenosis by measurement of pressure differences across that particular stenosis. Noninvasive techniques such as CT-FFR, using computational fluid dynamic methods with computed tomography (CT) images to calculate the FFR index, have shown to reduce the number of patients requiring invasive procedures. However, the use of ionizing radiation in CT prevents longitudinal monitoring of patients who were deferred from invasive tests and treatment. To address the problem, we propose a noninvasive pressure measurement technique in the coronary arteries using magnetic resonance imaging (MRI), which has no ionizing radiation. The method is based on velocity measured from phase-contrast MRI (PC-MRI) in conjunction with navier-stokes equations to derive pressure differences, which has been studied in various vessels such as the aorta, carotid, renal and intracranial arteries. To apply the technique in the coronary arteries, challenges such as cardiac and respiratory motion and high spatial and temporal resolution for PC-MRI acquisitions need to be addressed. In this study, we aim to address the challenges by using 1) ECG and Navigator-gating to minimize motion errors and 2) 2D interleaved multi-slice radial acquisition using a golden-angle sampling scheme to achieve high spatial and temporal resolution. The hypothesis is that the proposed PC-MRI technique could further improve the navier- stokes analysis and thus, the derived pressure difference index. The measured velocity values from proposed PC-MRI and derived pressure difference index will be compared to invasive flow and pressure to evaluate the feasibility of the proposed method and its correlation to clinical gold standard. This noninvasive technique could potentially obtain both the anatomical and functional information in one imaging session without added risks, patient discomfort and high surgical costs from invasive procedures or ionizing radiation from CT-FFR.