Mischi M, den Boer J A, Korsten H H M
Department of Electrical Engineering, Eindhoven University of Technology, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands.
Physiol Meas. 2008 Mar;29(3):281-94. doi: 10.1088/0967-3334/29/3/001. Epub 2008 Feb 11.
The analysis of intravascular indicator dynamics is important for cardiovascular diagnostics as well as for the assessment of tissue perfusion, aimed at the detection of ischemic regions or cancer hypervascularization. To this end, indicator dilution curves are measured after the intravenous injection of an indicator bolus and fitted by parametric models for the estimation of the hemodynamic parameters of interest. Based on heuristic reasoning, the dilution process is often modeled by a gamma variate. In this paper, we provide both a physical and stochastic interpretation of the gamma variate model. The accuracy of the model is compared with the local density random walk model, a known model based on physics principles. Dilution curves were measured by contrast ultrasonography both in vitro and in vivo (20 patients). Blood volume measurements were used to test the accuracy and clinical relevance of the estimated parameters. Both models provided accurate curve fits and volume estimates. In conclusion, the proposed interpretations of the gamma variate model describe physics aspects of the dilution process and lead to a better understanding of the observed parameters, increasing the value and credibility of the model, and possibly expanding its diagnostic applications.
血管内指示剂动力学分析对于心血管诊断以及组织灌注评估都很重要，目的是检测缺血区域或癌症血管过度增生。为此，在静脉注射指示剂团注后测量指示剂稀释曲线，并通过参数模型进行拟合，以估计感兴趣的血流动力学参数。基于启发式推理，稀释过程通常用伽马变量来建模。在本文中，我们对伽马变量模型提供了物理和随机两种解释。将该模型的准确性与局部密度随机游走模型进行了比较，后者是一个基于物理原理的已知模型。通过对比超声在体外和体内（20名患者）测量了稀释曲线。使用血容量测量来测试估计参数的准确性和临床相关性。两种模型都提供了准确的曲线拟合和容量估计。总之，对伽马变量模型提出的解释描述了稀释过程的物理方面，有助于更好地理解观察到的参数，提高了模型的价值和可信度，并可能扩大其诊断应用。
