Wilke N, Simm C, Zhang J, Ellermann J, Ya X, Merkle H, Path G, Lüdemann H, Bache R J, Uğurbil K
University of Erlangen, II, Medical Clinic, Germany.
Magn Reson Med. 1993 Apr;29(4):485-97. doi: 10.1002/mrm.1910290410.
The sensitivity of contrast-enhanced MR first pass perfusion imaging in detection and quantification of hypoperfused myocardium was evaluated using an instrumented, closed-chest dog model where graded regional hypoperfusion was induced by applying predetermined levels of stenosis to the left anterior descending artery (LAD). All measurements were performed at rest and under stress induced by dipyridamole (DIP). Myocardial perfusion was assessed both with MR and radiolabeled microspheres injected immediately before the administration of the MR contrast agent. Ultrafast MR imaging was performed using a Turbo FLASH sequence with a 180 degrees inversion prepulse. A Gd-DTPA bolus was injected into the left atrium and T1-weighted images were acquired with every heart beat. Signal intensity measured from the images in regions of the LAD and left circumflex (LCx) perfusion beds was plotted against time to generate signal intensity versus time curves (SI time curve). Various flow indices were derived according to the indicator dilution theory, and compared with and without volume correction due to vasodilation to the myocardial blood flow (MBF) calculated from radiolabeled microspheres. Correlation of the MR and MBF data demonstrated that different transmural and regional myocardial perfusion levels can be easily visualized in the perfusion images and accurately monitored by the SI time curves. Detection of the impairment of myocardial perfusion improved significantly after administration of DIP. The inverse mean transit time calculated from the SI time curve was found to yield a linear correlation to absolute MBF derived from the microsphere data. These results suggest that with intracardiac injections of exogenous contrast agent, myocardial perfusion can be assessed parametrically with first pass contrast enhanced ultrafast MRI.
使用一种仪器化的开胸犬模型评估对比增强磁共振首次通过灌注成像在检测和定量灌注不足心肌方面的敏感性，在该模型中，通过对左前降支动脉（LAD）施加预定水平的狭窄来诱导分级区域性灌注不足。所有测量均在静息状态下以及双嘧达莫（DIP）诱导的应激状态下进行。在注射磁共振造影剂之前立即通过磁共振和放射性微球评估心肌灌注。使用具有180度反转预脉冲的Turbo FLASH序列进行超快磁共振成像。将钆喷酸葡胺团注注入左心房，并在每次心跳时采集T1加权图像。绘制从LAD和左旋支（LCx）灌注床区域的图像中测量的信号强度与时间的关系图，以生成信号强度与时间曲线（SI时间曲线）。根据指示剂稀释理论得出各种血流指数，并与根据放射性微球计算的心肌血流量（MBF）进行有无血管扩张导致的体积校正的比较。磁共振和MBF数据的相关性表明，在灌注图像中可以轻松可视化不同的透壁和区域性心肌灌注水平，并通过SI时间曲线进行准确监测。注射DIP后，心肌灌注损伤的检测有显著改善。发现从SI时间曲线计算出的反向平均通过时间与从微球数据得出的绝对MBF呈线性相关。这些结果表明，通过心内注射外源性造影剂，可以通过首次通过对比增强超快磁共振成像对心肌灌注进行参数评估。
