Microwave spectroscopy of myocardial ischemia and infarction. 1. Experimental study

The purpose of this study was to assess whether physiologic changes in cani ne myocardium due to coronary blood flow reduction, ischemia, and infarctio n could be detected by changes in dielectrical properties. Measurements wer e made in the frequency range of 0.2-6.0 GHz. Percent coronary blood flow r eduction was linearly related to the decrease in epsilon" at frequencies of 0.2GHz(R=-0.997) and 1.1GHz(R = -0.9987). In 2 h occlusions, increased con duction time in the infarct area mirrored the temporal changes in dielectri cal properties. In 2-week-old infarctions differences, in epsilon' between normal and central infarct zones were statistically significant (P<0.05) fo r all frequencies. For epsilon" the differences between normal and central infarct zones were also significant for all frequencies (P<0.01). In conclu sion, coronary blood flow reduction, ischemia, and infarction can be detect ed by microwave spectroscopy and potentially can form the basis for a physi ologic microwave tomographic imaging system. (C) 2000 Biomedical Engineerin g Society. [S0090-6964(00)00101-6].