ASSESSMENT OF MYOCARDIAL PERFUSION & VIABILITY

改进的定量平面和单光子发射断层扫描（SPECT） 成像技术可以更准确地评估区域 冠心病患者心肌灌注和存活性的研究 是必要的。 本研究的目的是：（1）获得 对铊-210心肌转运动力学的进一步认识 和锝-99m甲氧基异丁基异腈（MIBI）在正常 条件，在短暂或持续缺血期间，全冠状动脉后 闭塞和冠状动脉再灌注后，以及 (2)开发和测试更优化的成像方法，用于定量 体内风险区域和区分存活与不可逆损伤 心肌 在实验方案中，以下假设是为了 测试：（1）静息时Tl-201摄取和再分布的定量 将更准确地识别存活但灌注不足的心肌 冠状动脉狭窄远端，比MIBI摄取;（2）MIBI摄取模式 会低估实验性心肌保护的程度 当在存在严重的缺血性脑梗死的情况下再灌注后给药时， （3）再灌注后过早给予MIBI， 再灌注流量大于生存能力，导致高估程度 心肌挽救;（4）危险区分布 完整动物中闭塞的冠状动脉可以通过 SPECT MIBI成像，以及MIBI风险区域和T1-T2的双重同时成像。 201重新分配应加强可行性的检测。 在动物 实验中，区域流量测量放射性微球，在体内 通过MIBI放射自显影确定危险区域，通过 组织化学技术。 平行临床研究方案设计：（1）区分 分次注射运动血管造影中瘢痕缺血 （2）发展双同步显像技术 与Tl-201和MIBI一起使用，以更好地定量体内风险区域，并提供 更可靠地检测存活但受损的心肌;（3） 开发MIBI成像的定量SPECT方法， 用类似的平面技术来检测和确定 生理学上重要的CAD;（4）提高心肌的检测 通过早期交换的定量系列评估使用Tl-201的存活率 动力学，并将该方法与24小时延迟再分布进行比较 成像;以及（5）确定同时定量的 ECG门控MIBI灌注的局部室壁运动和收缩期增厚 使用主成分分析进行研究。 预计这项研究将导致改进的应用T1- 201和MIBI成像用于缺血的非侵入性检测和评估 心肌存活率

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.