Reneman R S, Jageneau A H, van Gerven W, Dony J, Beirnaert P
Pflugers Arch. 1975;353(4):337-47. doi: 10.1007/BF00587030.
In this study, we have tried to determine the magnitude of the inaccuracy of the radioactive microsphere method - due to variations in the diameter distribution of the spheres - for measuring regional myocardial blood flow after coronary artery occlusion. In 5 mongrel dogs, three types of 15 mum microspheres, labelled with 125I, 141Ce or 85Sr, were injected simultaneously after the descending branch of the left coronary artery had been ligated. Myocardial samples wert taken from the left ventricle and divided into four groups according to the number of spheres per sample. The radioactivity of the various isotopes per gram tissue was expressed as percentage of their activity per milliliter of the reference sample. The diameter distribution of microspheres, labelled with each of the isotopes, was determined light-microscopically in suspensions belonging to three different batches. The relative error, as determined from the difference in relative radioactivity of the various types of microspheres in the tissue samples, was higher than the theoretical error for each of the number of spheres per sample. It is very likely that this discrepancy is caused by the differences in diameter distribution of the various types of microspheres, resulting in non-random error. The smaller spheres tended to go to low flow areas and the larger ones to high flow areas. Because of the non-randomness, the error due to diameter variations in the spheres can be diminished by randomizing the order of injection of the various isotopes. The present study indicates that the relatively high degree of accuracy of the microsphere method for the determination of blood flow to large parts of the myocardium with an unimpeded coronary circulation, as was described in literature, cannot be extrapolated to the determination of regional myocardial blood flow after coronary artery occlusion, when the combination of small tissue samples, variations in the diameter distribution of the spheres and an unevenly distributed myocardial blood flow unfavourably affect the accuracy of the method.
在本研究中，我们试图确定放射性微球法在测量冠状动脉闭塞后局部心肌血流时，因微球直径分布变化而导致的测量误差大小。在5只杂种狗中，在结扎左冠状动脉降支后，同时注射了三种类型的15μm微球，分别用125I、141Ce或85Sr标记。从左心室采集心肌样本，并根据每个样本中的微球数量分为四组。每克组织中各种同位素的放射性以其每毫升参考样本活性的百分比表示。通过光学显微镜在属于三个不同批次的悬浮液中测定了用每种同位素标记的微球的直径分布。根据组织样本中不同类型微球相对放射性的差异确定的相对误差，高于每个样本微球数量的理论误差。这种差异很可能是由各种类型微球直径分布的差异引起的，从而导致非随机误差。较小的微球倾向于流向低血流区域，而较大的微球则流向高血流区域。由于这种非随机性，通过随机化各种同位素的注射顺序，可以减少微球直径变化引起的误差。本研究表明，文献中描述的微球法在测定冠状动脉循环未受阻碍时大部分心肌的血流方面具有较高的准确性，但当小组织样本、微球直径分布变化以及心肌血流分布不均等因素综合起来对该方法的准确性产生不利影响时，不能将其外推用于测定冠状动脉闭塞后的局部心肌血流。
