Jerosch-Herold M, Wilke N, Stillman A E
Department of Radiology, University of Minnesota Medical School, Minneapolis 55455, USA.
Med Phys. 1998 Jan;25(1):73-84. doi: 10.1118/1.598163.
The myocardial perfusion reserve, defined as the ratio of hyperemic and basal myocardial blood flow, is a useful indicator of the functional significance of a coronary artery lesion. Rapid magnetic resonance (MR) imaging for the noninvasive detection of a bolus-injected contrast agent as a MR tracer is applied to the measurement of regional tissue perfusion during rest and hyperemia, in patients with microvascular dysfunction. A Fermi function model for the distribution of tracer residence times in the myocardium is used to fit the MR signal curves. The myocardial perfusion reserve is calculated from the impulse response amplitudes for rest and hyperemia. The assumptions of the model are tested with Monte Carlo simulations, using a multiple path, axially distributed mathematical model of blood tissue exchange, which allows for systematic variation of blood flow, vascular volume, and capillary permeability. For a contrast-to-noise ratio of 6:1, and over a range of flows from 0.5 to 4.0 ml/min per g of tissue, the ratio of the impulse response amplitudes for hyperemic and basal flows is linearly proportional to the ratio of model blood flows, if the mean transit time of the input function is shorter than approximately 9 s. The uncertainty in the blood flow reserve estimates grows both at low (< 1.0 ml/min/g) and high (> 3-4 ml/min/g) flows. The predictions of the Monte Carlo simulations agree with the results of MR first pass studies in patients without significant coronary artery lesions and microvascular dysfunction, where the perfusion reserve in the territory of the left anterior descending coronary artery (LAD) correlates linearly with the intracoronary Doppler ultrasound flow reserve in the LAD (r = 0.84), in agreement with previous PET studies.
心肌灌注储备定义为充血状态与基础状态下心肌血流量之比，是冠状动脉病变功能意义的一个有用指标。快速磁共振（MR）成像用于无创检测经静脉团注的造影剂作为MR示踪剂，以测量微血管功能障碍患者静息和充血状态下的局部组织灌注。利用费米函数模型拟合心肌中示踪剂停留时间的分布，以拟合MR信号曲线。根据静息和充血状态下的脉冲响应幅度计算心肌灌注储备。使用血液-组织交换的多路径轴向分布数学模型，通过蒙特卡罗模拟对模型假设进行检验，该模型允许系统改变血流量、血管容积和毛细血管通透性。对于6:1的对比噪声比，在每克组织0.5至4.0 ml/min的血流范围内，如果输入函数的平均通过时间短于约9秒，则充血状态与基础状态下血流的脉冲响应幅度之比与模型血流之比呈线性比例关系。在低血流（<1.0 ml/min/g）和高血流（>3 - 4 ml/min/g）时，血流储备估计值的不确定性都会增加。蒙特卡罗模拟的预测结果与无明显冠状动脉病变和微血管功能障碍患者的MR首过研究结果一致，在这些患者中，左前降支冠状动脉（LAD）供血区域的灌注储备与LAD内冠状动脉内多普勒超声血流储备呈线性相关（r = 0.84），这与之前的PET研究结果一致。
