Krivokapich J, Smith G T, Huang S C, Hoffman E J, Ratib O, Phelps M E, Schelbert H R
Department of Medicine, UCLA School of Medicine 90024-1679.
Circulation. 1989 Nov;80(5):1328-37. doi: 10.1161/01.cir.80.5.1328.
Positron emission tomography (PET) was applied to the measurement of myocardial perfusion using the perfusion tracer 13N-labeled ammonia. 13N ammonia was delivered intravenously to 13 healthy volunteers both at rest and during supine bicycle exercise. Dynamic PET imaging was obtained in three cross-sectional planes for 10 minutes commencing with each injection. The left ventricle was divided into eight sectors, and a small region of interest was assigned to the left ventricular blood pool to obtain the arterial input function. The net extraction of 13N ammonia was obtained for each sector by dividing the tissue 13N concentration at 10 minutes by the integral of the input function from the time of injection to 10 minutes. With this approach for calculating net extractions, rest and exercise net extractions were not significantly different from each other. To obviate possible overestimation of the true 13N ammonia input function by contamination by 13N-labeled compounds other than 13N ammonia or by spillover from myocardium into blood pool, the net extractions were calculated using only the first 90 seconds of the blood and tissue time-activity curves. This approach for calculating net extractions yielded significant differences between rest and exercise, with an average ratio of exercise to rest of 1.38 +/- 0.34. Nonetheless, the increase was less than predicted from the average 2.7-2.8-fold increase in double product at peak exercise or the 1.7-fold increase in double product at 1 minute after exercise. However, when the first 90 seconds of dynamic data were fit with a two compartment tracer kinetic model, average perfusion rates of 0.75 +/- 0.43 ml/min/g at rest and 1.50 +/- 0.74 ml/min/g with exercise were obtained. This average increase in perfusion of 2.2-fold corresponded to similar average increases in double product. Thus, the noninvasive technique of PET imaging with 13N ammonia shows promise for future applications in determining absolute flows in patients with coronary artery disease.
正电子发射断层扫描（PET）被用于使用灌注示踪剂13N标记的氨来测量心肌灌注。13N氨通过静脉注射给予13名健康志愿者，分别在静息状态和仰卧位自行车运动期间。每次注射后，在三个横断面平面上进行10分钟的动态PET成像。左心室被分为八个节段，并在左心室血池指定一个小的感兴趣区域以获得动脉输入函数。通过将10分钟时的组织13N浓度除以从注射时刻到10分钟的输入函数积分，获得每个节段的13N氨净摄取量。采用这种计算净摄取量的方法，静息和运动时的净摄取量彼此无显著差异。为了避免由于13N氨以外的13N标记化合物的污染或心肌向血池的溢出而可能高估真正的13N氨输入函数，仅使用血液和组织时间-活性曲线的前90秒来计算净摄取量。这种计算净摄取量的方法在静息和运动之间产生了显著差异，运动与静息的平均比值为1.38±0.34。尽管如此，但增加幅度小于运动高峰时双乘积平均增加2.7 - 2.8倍或运动后1分钟双乘积增加1.7倍所预测的幅度。然而，当用双室示踪剂动力学模型拟合动态数据的前90秒时，静息时的平均灌注率为0.75±0.43 ml/min/g，运动时为1.50±0.74 ml/min/g。这种平均灌注增加2.2倍对应于双乘积的类似平均增加。因此，使用13N氨的PET成像无创技术在确定冠状动脉疾病患者的绝对血流量方面显示出未来应用的前景。
