Maurer G, Ong K, Haendchen R, Torres M, Tei C, Wood F, Meerbaum S, Shah P, Corday E
Circulation. 1984 Feb;69(2):418-29. doi: 10.1161/01.cir.69.2.418.
A computer algorithm was developed and applied to measure brightness decay rates of myocardial contrast opacification observed with two-dimensional echocardiography (2DE). An agitated mixture of diatrizoate meglumine and saline (Renografin-saline) was injected into the left main coronary artery of 17 closed-chest dogs during the control state as well as after placement of an intracoronary plug to induce 85% stenosis in the left anterior descending coronary artery (LAD) in five dogs. In 12 dogs, injections were also performed distally to complete intracoronary balloon occlusion of the LAD. For each injection, up to 35 electrocardiographic-gated, end-diastolic 2DE frames were digitized into an image-processing computer that determined mean pixel brightness of each of 12 myocardial segments per 2DE short-axis cross-section. Time-activity curves for each segment were generated, and contrast decay half-life (t 1/2) was calculated. Mean t 1/2 for control-state injections was found to be 24.1 +/- 7.7 sec, as opposed to 293.8 +/- 164.5 sec after complete coronary occlusion (p less than .001). In the five dogs in which 85% LAD stenosis was induced, prolongation of contrast t 1/2 from 18.3 +/- 8.9 sec during control to 44.3 +/- 21.0 sec (p less than .001) after plug insertion occurred in myocardial segments subserved by the stenosed vessel. No significant change occurred in segments that were not supplied by the stenosed vessel (21.9 +/- 9.1 sec during control vs 24.9 +/- 11.6 after plug insertion into the LAD). A reproducibility study of injection-to-injection t 1/2 in the control state indicated a correlation coefficient of r = .84 and a standard error of the estimate (SEE) equal to 5.86 sec, while interobserver t 1/2 reproducibility was r = .91 and SEE = 5.21 sec. The t 1/2 measurement derived by computer analysis of myocardial contrast 2DE may serve as an index for characterization of regional myocardial blood flow and may be applicable to evaluate interventions that alter perfusion.
开发了一种计算机算法，并将其应用于测量二维超声心动图（2DE）观察到的心肌对比剂消退率。在对照状态下以及在五只犬的左冠状动脉前降支（LAD）放置冠状动脉内栓子以诱导85%狭窄后，将泛影葡胺和生理盐水的搅拌混合物（Renografin-盐水）注入17只开胸犬的左冠状动脉主干。在12只犬中，还在LAD的冠状动脉内球囊完全闭塞的远端进行注射。对于每次注射，将多达35个心电图门控的舒张末期2DE帧数字化到图像处理计算机中，该计算机确定每个2DE短轴横截面的12个心肌节段中每个节段的平均像素亮度。生成每个节段的时间-活性曲线，并计算对比剂消退半衰期（t1/2）。发现对照状态下注射的平均t1/2为24.1±7.7秒，而完全冠状动脉闭塞后为293.8±164.5秒（p<0.001）。在诱导85%LAD狭窄的五只犬中，狭窄血管供血的心肌节段的对比剂t1/2从对照期间的18.3±8.9秒延长至栓子插入后的44.3±21.0秒（p<0.001）。未由狭窄血管供血的节段无显著变化（对照期间为21.9±9.1秒，LAD插入栓子后为24.9±11.6秒）。对照状态下注射间t1/2的重复性研究表明相关系数r=0.84，估计标准误差（SEE）等于5.86秒，而观察者间t1/2的重复性为r=0.91，SEE=5.21秒。通过计算机分析心肌对比2DE得出的t1/2测量值可作为表征局部心肌血流的指标，并可能适用于评估改变灌注的干预措施。
