ASSESSMENT OF MYOCARDIAL PERFUSION & VIABILITY

改进的定量平面和单光子发射断层扫描(SPECT) 成像技术允许更准确地评估区域 冠心病患者的心肌血流灌注和存活能力 都是需要的。这项研究计划的目标是：(1)获取 对铊-210(Tl-210)心肌转运动力学的进一步认识 和99m甲氧基异丁基异腈(MIBI) 在短暂性或持续性缺血期间，完全冠状动脉后的情况 在动物和人类的冠状动脉闭塞和再灌注后，以及 (2)开发和测试更理想的In的定量成像方法 活体危险区域及存活与不可逆性损伤的鉴别 心肌。在实验方案中，以下假设是为了 被测试：(1)静息状态下Tl-201摄取和再分配的定量 将更准确地识别有活力但未灌流的心肌 冠状动脉狭窄远端，而不是MIBI摄取；(2)MIBI摄取模式 在实验过程中会低估心肌挽救的程度 在出现严重的脑梗塞再灌流后给药 残余狭窄；(3)再通后过早给予MIBI将反映 再灌注量超过存活量导致对程度的高估 心肌挽救的风险范围；以及，(4)危险区域分布 完整动物的冠状动脉闭塞可通过以下方法准确定量 SPECT MIBI显像，MIBI危险区和TL-Tl双同时显像 201再分配应加强对生存能力的检测。在动物身上 实验中，局部血流是通过放射性微球测量的，在体内 MIBI放射自显影的危险区域和解剖危险区域的梗塞面积 组织化学技术。 设计了平行临床研究方案：(1)区分 分次注射运动核素扫描中因疤痕引起的缺血 相隔2小时的MIBI；(2)开发双同时成像技术 用TL-201和MIBI更好地定量体内危险区域并提供 更可靠地检测存活但受损的心肌； 开发用于MIBI成像的定量SPECT方法以进行临界比较 使用类似的平面技术来检测和确定 生理性重要的冠心病；(4)提高心肌梗死的检测水平 通过早期交换的定量系列评估TL-201的活性 动力学，并将该方法与24小时延迟重新分配进行比较 成像；以及，(5)确定同时定量的价值 心电门控MIBI血流灌注的节段性室壁运动和收缩期增厚 使用主成分分析进行研究。 预计这项研究将有助于改进热释光技术的应用。 201和MIBI显像对脑缺血的无创检测和评价 心肌的存活能力。

Improved quantitative planar and single photon emission tomographic (SPECT) imaging techniques permitting more accurate assessment of regional myocardial perfusion and viability in patients with coronary artery disease are needed. The objectives of this research proposal are, (1) to acquire further knowledge of myocardial transport kinetics of thallium-210 (Tl-210) and technetium-99m methoxy isobutyl isonitrile (MIBI) under normal conditions, during transient or sustained ischemia, after total coronary occlusion and after coronary reperfusion in both animals and humans, and (2) to develop and test more optimum imaging methods for quantitation of in vivo risk area and distinguishing viable from irreversibly injured myocardium. In the experimental protocols, the following hypotheses are to be tested: (1) quantitation of Tl-201 uptake and redistribution at rest will be more accurate for identifying viable but underperfused myocardium distal to a coronary stenosis, than MIBI uptake; (2) MIBI uptake patterns will underestimate degree of myocardial salvage during experimental infarction when administered after reperfusion in the presence of a severe residual stenosis; (3) MIBI given too early after reperfusion will reflect reperfusion flow more than viability resulting in overestimation of degree of myocardial salvage; and, (4) risk area in the distribution of an occluded coronary artery in intact animals can accurately be quantitated by SPECT MIBI imaging, and dual simultaneous imaging of MIBI risk area and Tl- 201 redistribution should enhance detection of viability. In animal experiments, regional flow is measured by radioactive microspheres, in vivo risk areas by MIBI autoradiography and anatomic risk area infarct size by histochemical techniques. Parallel clinical research protocols are designed: (1) to differentiate ischemia from scar during exercise scintigraphy using split dose injections of MIBI 2 hrs apart; (2) to develop dual simultaneous imaging techniques with Tl-201 and MIBI to better quantitate in vivo risk area and provide more reliable detection of viable but jeopardized myocardium; (3) to develop quantitative SPECT methods for MIBI imaging to critically compare with similar planar techniques for detecting and determining extent of physiologically important CAD; (4) to improve detection of myocardial viability with Tl-201 by quantitative serial assessment of early exchange kinetics and to compare this approach with 24-hr delayed redistribution imaging; and, (5) to determine the value of simultaneous quantitation of regional wall motion and systolic thickening on ECG-gated MIBI perfusion studies using Principal Components Analysis. It is expected that this research will lead to improved applications of Tl- 201 and MIBI imaging for noninvasive detection of ischemia and assessment of myocardial viability.