Relationship between micro- and macro-acoustic properties of myocardium

The objective of the present study is to assess the relationship between micro- and macro-acoustic properties of myocardium. The values of ultrasonic attenuation and sound speed of the myocardium at 3.5 MHz were obtained by frequency domain analysis of the pulse response in order to determine the macro-acoustic properties. The micro-acoustic properties were obtained by a specially developed scanning acoustic microscope system operating in the frequency range of 100-200 MHz. At 3.5 MHz, the sound speed was 1600 m/s and the attenuation was 2.5 dB/cm in the normal myocardium, 1582 m/s and 5.8 dB/cm in the necrosis, respectively. At 130 MHz, both values were 1614 m/s and 1.1 dB/mm/MHz in the normal myocardium, 1578 m/s and 0.6 dB/mm/MHz in the necrosis, respectively. The results suggest that the ultrasonic attenuation is affected by both the chemical components and the structure of the tissue