动态SPECT右室心肌血流定量新技术对肺高压右心微循环障碍的实验研究

Right heart ischemia is an important factor that contributes to the progression of right heart failure in pulmonary arterial hypertension (PAH). Without evidence of obstructive epicardial coronary artery stenosis, right heart ischemia is mainly caused by impaired myocardial microcirculation. However, there is a lack of non-invasive in vivo imaging technique to absolute quantitatively analyse microcirculation function for the unique right heart. Based on a full physical correction method to avoid physical interference, a geometric mixed model of.pyramidal and ellipse to accurately orientate right myocardium segments and a novel mathematically kinetic model which takes spillover effect into account for the right heart to attenuate partial volume effect, the proposed project intends to adopt dynamic single photon emission tomography myocardial perfusion imaging to quantify right heart stress/rest myocardial blood flow and myocardial flow reserve as assessment of microcirculation dysfunction in animal models with PAH. Fluorescent microsphere and histologic examination of microvascular density and inner diameter are to be used as the “golden standard” to validate the accuracy of the quantification of right myocardial microcirculation. With establishment of this new technique, the project will offer an effective tool to quantitatively diagnosis of right heart ischemia in PAH, which is of great importance for early and optimal assessing right heart dysfunction and real-time monitoring therapeutic effects of novel anti-ischemia treatment.

右室心肌缺血是肺高压右心功能不全的重要机制，对临床预后影响显著。右室心肌缺血的主要病理改变并非冠脉大血管病变，而是心肌微循环障碍。然而，目前还缺乏有效的评价右心微循环缺血的无创性影像学技术。本项目拟利用肺高压动物模型，建立动态SPECT右室心肌血流定量新技术，将采用完整物理校正以有效消除物理因素的干扰，以混合形态几何模型对右室心肌精确定位，同时应用适合于右室的腔室动力学模型，该模型充分考虑放射性扩散效应，以克服部分容积效应对右室心肌的影响，从而准确计算得到右室心肌血流量和心肌血流储备，并观察抗缺血治疗后的右心血流的定量变化。以荧光微球和微血管组织学检测作为“金标准”，验证该技术评价右心微循环缺血的准确性。本项目的开展，将提供右心微循环缺血定量诊断的关键性新技术，对于肺高压右心衰竭的早期评估和抗缺血干预新策略的监测都具有重要的临床意义。

右心功能影像学评价是目前存在的临床难题，针对于此，本项目开展了肺动脉高压右室心肌血流定量新技术的研究。基于SPECT心肌灌注显像，采用动态采集、完整物理校正及适合右室形态特点的图像分析模型等关键技术，建立了评价右室心肌绝对血流量和血流储备的定量分析技术。同时，利用这一技术，对小型猪肺动脉高压模型进行了右室心肌血流定量分析研究，结果表明：右室静息心肌血流量随肺动脉压力增高而代偿性增加，而负荷心肌血流量在右室功能失代偿时明显降低，提示心肌缺血可能是右心衰竭的重要病理机制之一。在肺动脉高压患者的初步临床应用进一步证实了动物实验的结果。本项目的研究结果初步证实了SPECT右室心肌血流定量新技术的可行性，并具有较好的临床应用前景。