THALLIUM KINETICS IN NORMAL AND ISCHEMIC MYOCARDIUM

心肌相对铊活度随时间变化的测定 在连续成像研究中， 用于检测或评估冠状动脉疾病。 时间 心肌铊浓度的行为与心肌细胞的 心肌摄取和内源性洗脱的平衡，但 这些到正常和缺血状态的动力学参数还有待确定。 本建议的总体目标是提供一个逻辑框架， 理解和解释各种铊吸收模式， 再分配，并测量重要的输运系数， 改变灌注状态和MVO 2的功能。 使用动能的可能性 以铊的交换率作为衡量 冠状动脉狭窄的严重程度也将被探索。 实验将 在犬模型中进行，1）确定浸提分数 作为心肌血流量函数的铊值，2）测量 不同生理状态下~（201）铊心肌内洗率 改变心肌血流量、MVO 2或两者的条件，3） 确定这些改变对心肌摄取的影响， 静脉注射放射性核素后的再分布，以及4） 测量直接给药后患者的固有心肌铊洗脱率 冠状动脉内注射，并将这些测量结果与 冠状动脉狭窄和局部室壁运动异常。 是 预期从这些犬和患者研究中获得的信息 将为理解和正确利用 心肌铊动力学对心肌梗塞患者的心肌铊动力学评价 疑似或确认的冠状动脉疾病。

The determination of relative myocardial thallium activity as a function of time in sequential imaging studies is being increasingly used in the clinical setting for the detection or evaluation of coronary artery disease. The temporal behavior of myocardial thallium concentration is necessarily related to the balance of myocardial uptake and intrinsic washout, yet the relationship of these kinetic parameters to normal and ischemic states has yet to be determined. The overall objective of this proposal is to provide a logical framework for understanding and interpreting various patterns of thallium uptake and redistribution, and to measure the important transport coefficients as a function of altered perfusion states and MVO2. The possibility of using kinetic exchange rates of thallium as a means of quantitating the functional degree of severity of coronary artery stenoses will also be explored. Experiments will be carried out in canine models in order, 1) to determine extraction fraction values for thallium as a function of myocardial blood flow, 2) To measure intrinsic myocardial washout rates of thallium-201 under various physiologic conditions which alter either myocardial blood flow, MVO2 or both, 3) To determine the effects of these alterations on myocardial uptake and redistribution following intravenous injection of the radionuclide, and 4) to measure intrinsic myocardial thallium washout rates in patients following direct intracoronary injection and to relate these measurements to the degree of coronary artery narrowing and regional wall motion abnormalities. It is expected that the information obtained from these canine and patient studies will provide a fundamental basis for the understanding and proper utilization of myocardial thallium kinetics for scintigraphic assessment of patients with suspected or recognized coronary artery disease.