Artifactual Reductions of Segmental Indicator Tissue Concentrations on Tomographic Images of the Heart Caused by Regional Wall Motion Abnormalities

摘要

Possible effects of regional wall motion abnormalities on apparent regional myocardial tracer concentrations on emission tomographic images were evaluated in 6 open chest dogs. Each dog was studied twice: In Run 1, N-13 ammonia and microspheres were injected during a 6 min coronary occlusion, and serial images acquired with positron-emission tomography during occlusion and reperfusion. In Run 2, one hour later, N-13 ammonia and microspheres were reinjected at control and serial images recorded at control, during a repeat 6 min coronary occlusion, and after reperfusion. Segmental function was monitored with ultrasonic crystals, and N-13 tissue concentrations determined in vivo from the tomographic images and postmortem by well counting. In Run 1, fractional shortening in ischemic segments fell by 89 +- 16% SD from control. The ischemic versus control segment ratio for N-13 activity concentrations averaged 0.29 +- 0.08 and for microspheres 0.20 +- 0.15. In Run 2, the ischemic versus control segment ratio was at control 0.77 +- 0.12 for N-13 tissue activity and 0.85 +- 0.07 for microspheres. Fractional shortening fell during occlusion by 131 +- 29% from control, returned to control early and then fell again by 11 +- 16% late during reperfusion. These changes were paralleled by changes in apparent regional N-13 tissue concentrations of the pre-labeled myocardium. (ERA citation 09:012809)