Potdevin T C, Fowlkes J B, Moskalik A P, Carson P L
Department of Radiology, University of Michigan, Ann Arbor, Michigan 48109-0553, USA.
Med Phys. 2004 Mar;31(3):623-32. doi: 10.1118/1.1649534.
Contrast destruction and replenishment by Flash Echo Imaging (FEI) (also referred to as interval or intermittent imaging) has been qualitatively and quantitatively used for tissue blood refill measurements. Many features and capabilities of contrast refill in tissue blood flow and perfusion remain to be elucidated. To aid the development and full reliable utilization of the technique in medical practice, in this paper we undertake physical and mathematical modeling to evaluate different measures derivable from FEI and to provide a basis for the further study of sensitivity and stability of such measures for the detection and measurement of various flow properties and abnormalities. A phantom was developed and used to conduct a dynamic contrast study. Refill curves were investigated as a means of calculating the mean transit time (MTT) and investigating other information that can be determined from their shape. Exponential and error function fits and the area above these curves were used to estimate MTT. The bubble disruption zone was visually measured and theoretically modeled. Computer simulated refill curves based on the flow phantom for different velocity ranges were then computed and compared to the experimental refill curves. The simulated refill curves closely matched the experimental curves in both shape and MTT. The simulated refill curves matched the shape of the experimental results for different velocity ranges. Another simulation examined how a real circulatory system might influence refill. Different refill curve shapes were obtained for different vascular models. Models including the large arteries and veins showed a much faster initial slope than models where the large vessels were not included. Likewise, simulated "shunting" displayed a different slope than models without "shunting" and specific portions of the refill curve that could maximally distinguish shunting. This computer simulation could lead to some experimental hypotheses about differences between normal and cancerous blood flow.
通过闪光回波成像（FEI）（也称为间隔或间歇成像）进行的对比剂破坏和补充已被定性和定量地用于组织血液再充盈测量。组织血流和灌注中对比剂再充盈的许多特征和能力仍有待阐明。为了帮助该技术在医学实践中的发展和全面可靠应用，在本文中，我们进行了物理和数学建模，以评估可从FEI得出的不同测量方法，并为进一步研究此类测量方法在检测和测量各种血流特性及异常方面的敏感性和稳定性提供依据。开发了一个体模并用于进行动态对比研究。研究再充盈曲线作为计算平均通过时间（MTT）的一种方法，并研究可从其形状确定的其他信息。使用指数和误差函数拟合以及这些曲线上方的面积来估计MTT。对气泡破裂区域进行了视觉测量和理论建模。然后计算基于不同速度范围的流动体模的计算机模拟再充盈曲线，并与实验再充盈曲线进行比较。模拟的再充盈曲线在形状和MTT上都与实验曲线紧密匹配。模拟的再充盈曲线与不同速度范围的实验结果形状相匹配。另一项模拟研究了真实循环系统可能如何影响再充盈。对于不同的血管模型获得了不同的再充盈曲线形状。包括大动脉和静脉的模型显示出比不包括大血管的模型更快的初始斜率。同样，模拟的“分流”显示出与无“分流”模型不同的斜率以及再充盈曲线中可最大程度区分分流的特定部分。这种计算机模拟可能会引发一些关于正常和癌性血流差异的实验假设。
