IEEE Trans Med Imaging. 2021 Jun;40(6):1711-1725. doi: 10.1109/TMI.2021.3065219. Epub 2021 Jun 1.
Our approach differs from the usual global measure of cardiac efficiency by using PET/MRI to measure efficiency of small pieces of cardiac tissue whose limiting size is equal to the spatial resolution of the PET scanner. We initiated a dynamic cardiac PET study immediately prior to the injection of 15.1 mCi of C-acetate acquiring data for 25 minutes while simultaneously acquiring MRI cine data. 1) A 3D finite element (FE) biomechanical model of the imaged heart was constructed by utilizing nonrigid deformable image registration to alter the Dassault Systèmes FE Living Heart Model (LHM) to fit the geometry in the cardiac MRI cine data. The patient specific FE cardiac model with estimates of stress, strain, and work was transformed into PET/MRI format. 2) A 1-tissue compartment model was used to calculate wash-in (K) and the linear portion of the decay in the PET C-acetate time activity curve (TAC) was used to calculate the wash-out k(mono) rate constant. K was used to calculate blood flow and k(mono) was used to calculate myocardial volume oxygen consumption ( MVO ). 3) Estimates of stress and strain were used to calculate Myocardial Equivalent Minute Work ( MEMW ) and Cardiac Efficiency = MEMW/MVO was then calculated for 17 tissue segments of the left ventricle. The global MBF was 0.96 ± 0.15 ml/min/gm and MVO ranged from 8 to 17 ml/100gm/min. Six central slices of the MRI cine data provided a range of MEMW of 0.1 to 0.4 joules/gm/min and a range of Cardiac Efficiency of 6 to 18%.
我们的方法不同于通常的心脏效率全球测量方法，它使用 PET/MRI 来测量心脏组织小块的效率，其限制尺寸等于 PET 扫描仪的空间分辨率。我们在注射 15.1 mCi 的 C-乙酸盐之前立即进行了动态心脏 PET 研究，在 25 分钟内采集数据，同时采集 MRI 电影数据。1）利用非刚性变形图像配准，构建了所成像心脏的 3D 有限元（FE）生物力学模型，以改变 Dassault Systèmes 的 FE 活体心脏模型（LHM），使其适应心脏 MRI 电影数据中的几何形状。将具有估计的应力、应变和功的患者特定 FE 心脏模型转换为 PET/MRI 格式。2）使用 1 组织室模型来计算灌注（K），并且 PET C-乙酸盐时间活动曲线（TAC）的线性部分用于计算洗脱 k（单）速率常数。K 用于计算血流量，k（单）用于计算心肌容积耗氧量（MVO）。3）估计的应力和应变用于计算心肌等效每分钟功（MEMW），然后计算左心室 17 个节段的心脏效率= MEMW/MVO。整体 MBF 为 0.96±0.15ml/min/gm，MVO 范围为 8 至 17ml/100gm/min。MRI 电影数据的六个中央切片提供了 0.1 至 0.4 焦耳/gm/min 的 MEMW 范围和 6 至 18%的心脏效率范围。
