Ultrasonic tissue characterization with integrated backscatter during inotropic stimulation

Ultrasonic tissue characterization with integrated backscatter is an object ive method to quantitatively define the physical state of the myocardium. T o determine if backscatter imaging during inotropic stimulation could be us ed objectively to determine the myocardial viability and ischemia in patien ts with isc hemic heart disease, the backscatter changes were examined in 2 3 patients with myocardial infarction during dobutamine stress two-dimensio nal (2-D) echocardiography. Coronary angiography was performed within 1 to 2 days after the stress test. The results of this study demonstrated that c hanges in backscatter variability correlated significantly with the wall mo tion changes in stress echocardiography during dobutamine infusion (p < 0.0 001). In addition, it was shown that the backscatter changes were significa ntly different in various types of myocardial tissue. In 23 healthy control segments, the ultrasonic backscatter variability was preserved and unchang ed during inotropic stimulation (p = NS). In 15 viable infarct zones, resto ration or an increase in backscatter variability during low-dose dobutamine infusion was noted, this being lost when ischemia developing during high-d ose dobutamine infusion (p < 0.01). In 9 nonviable infarct zones, the phase -weighted variation was usually less than or equal to 0 and did not change significantly during inotropic stimulation, regardless of the patency of th e infarct-related arteries. In 15 remote ischemic myocardial zones, the bac kscatter variability was preserved at the baseline level, did not change du ring low-dose dobutamine infusion, but decreased significantly during high- dose dobutamine stress (p < 0.01). In conclusion, dobutamine stress tissue characterization could offer an objective approach for the detection of myo cardial viability and ischemia, and might be a useful adjunct to the conven tional stress echocardiography. (C) 2001 World Federation for Ultrasound in Medicine & Biology.