The quantitative assessment of perfusion is important for early recognition of a variety of heart diseases, determination of disease severity and their cure. In conventional approach of measuring cardiac perfusion by arterial spin labeling, the relative difference in the apparent T1 relaxation times in response to selective and non-selective inversion of blood entering the region of interest is related to perfusion via a two-compartment tissue model. But accurate determination of T1 in small animal hearts is difficult and prone to errors due to long scan times. The purpose of this study is to develop a fast, robust and simple method to quantitatively assess myocardial perfusion using arterial spin labeling. The proposed method is based on signal intensities (SI) of inversion recovery slice-select, non-select and steady-state images. Especially in this method data are acquired at a single inversion time and at short repetition times.;This study began by investigating the accuracy of assessment of perfusion using a two compartment system. First, determination of perfusion by T1 and SI were implemented to a simple, two-compartment phantom model. Mathematical model developed for full spin exchange models (in-vivo experiments) by solving a modified Bloch equation was modified to develop mathematical models (T1 and SI) for a phantom (zero spin exchange). The phantom result at different flow rates shows remarkable evidence of accuracy of the two-compartment model and SI, T1 methods: the SI method has less propagation error and less scan time. Next, twelve healthy C57BL/6 mice were scanned for quantitative perfusion assessment and three of them were repeatedly scanned at three different time points for a reproducibility test. The myocardial perfusion of healthy mice obtained by the SI-method, 5.7+/-1.6 ml/g/min, was similar (p=0.38) to that obtained by the conventional T1 method, 5.6+/- 2.3 ml/g/min. The reproducibility of the SI method shows acceptable results: the maximum percentage deviation is about 5%.;Then the SI-method was used in comparison to a delayed enhanced method to qualitatively and quantitatively assess perfusion deficits in an ischemia-reperfusion (IR) mouse model. The infarcted region of the perfusion map is comparable to the hyper intense region of the delayed enhanced image of the IR mouse. The SI method also used to record a chronological comparison of perfusion on delta sarcoglycan null (DSG) mice. Perfusion of DSG and wild-type (WT) mice at ages of 12 weeks and 32 weeks were compared and percentage change of perfusion was estimated. The result shows that in DSG mice perfusion changes considerably.;Finally, the SI method was implemented on a 3 Tesla Philip scanner by modifying to data acquisition method. The perfusion obtained in this is consistent with literature values but further adjustment of pulse sequence and modification of numerical solution is needed. The most important benefit of the SI method is that it reduces scan time 30%--40% and lessens motion artifacts of images compared to the T1 method. This study demonstrates that the signal intensity-based ASL method is a robust alternative to the conventional T1-method.
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机译：灌注的定量评估对于早期识别各种心脏病，确定疾病的严重程度及其治愈方法非常重要。在通过动脉自旋标记测量心脏灌注的常规方法中，响应于进入关注区域的血液的选择性和非选择性倒置，表观T1弛豫时间的相对差异与通过两室组织模型的灌注有关。但是在小动物心脏中准确测定T1是困难的，而且由于扫描时间长，容易产生错误。这项研究的目的是开发一种快速，可靠和简单的方法，以使用动脉自旋标记法定量评估心肌灌注。所提出的方法基于反转恢复切片选择，非选择和稳态图像的信号强度（SI）。尤其是在这种方法中，数据是在单个反演时间和较短的重复时间下获取的。这项研究始于研究使用两室系统进行灌注评估的准确性。首先，将T1和SI的灌注确定值应用于一个简单的两室幻影模型。通过解决修改的Bloch方程为全自旋交换模型（体内实验）开发的数学模型被修改，以开发用于幻像（零自旋交换）的数学模型（T1和SI）。在不同流速下的幻象结果显示了两室模型和SI，T1方法的准确性的显着证据：SI方法具有较小的传播误差和较少的扫描时间。接下来，扫描十二只健康的C57BL / 6小鼠以进行定量灌注评估，并在三个不同的时间点重复扫描其中三只以进行再现性测试。通过SI方法获得的健康小鼠的心肌灌注为5.7 +/- 1.6 ml / g / min，与常规T1方法获得的心肌灌注为5.6 +/- 2.3 ml / g / min相似（p = 0.38）。 。 SI方法的重现性显示出可接受的结果：最大百分比偏差约为5％。然后将SI方法与延迟增强方法进行比较，以定性和定量评估缺血再灌注（IR）小鼠的灌注不足模型。灌注图的梗塞区域与IR小鼠的延迟增强图像的高强度区域相当。 SI方法还用于记录对δsarcoglycan null（DSG）小鼠灌注的时间顺序比较。比较了12周龄和32周龄的DSG和野生型（WT）小鼠的灌注，并评估了灌注百分比变化。结果表明，在DSG小鼠中，灌注发生了很大变化。最后，通过修改为数据采集方法，在3 Tesla Philip扫描仪上实施了SI方法。由此获得的灌注与文献值一致，但是需要进一步调整脉冲序列和修改数值解。 SI方法最重要的好处是，与T1方法相比，它可以将扫描时间减少30％-40％，并减少图像的运动伪像。这项研究表明，基于信号强度的ASL方法是常规T1方法的可靠替代方案。
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