Dependence of ultrasonic attenuation and absorption in dog soft tissues on temperature and thermal dose

Abstract

The effect of temperature and thermal dose (equivalent minutes at 43 degrees C) on ultrasonic attenuation in fresh dog muscle, liver, and kidney in vitro, was studied over a temperature range from room temperature to 70 degrees C. The effect of temperature on ultrasonic absorption in muscle was also studied. The attenuation experiments were performed at 4.32 MHz, and the absorption experiments at 4 MHz. Attenuation and absorption increased at temperatures higher than 50 degrees C, and eventually reached a maximum at 65 degrees C. The rate of change of tissue attenuation as a function of temperature was between 0.239 and 0.291 Np m-1 MHz-1 degree C-1 over the temperature range 50-65 degrees C. A change in attenuation and absorption was observed at thermal doses of 100-1000 min, where a doubling of these loss coefficients was observed over that measured at 37 degrees C, presumably the result of changes in tissue composition. The maximum attenuation or absorption was reached at thermal dosages on the order of 10(7) min. It was found that the rate at which the thermal dose was applied (i.e., thermal dose per min) plays a very important role in the total attenuation absorption. Lower thermal dose rates resulted in larger attenuation coefficients. Estimation of temperature-dependent absorption using a bioheat equation based thermal model predicted the experimental temperature within 2 degrees C.

Non-invasive estimation of hyperthermia temperatures with ultrasound

“…In particular, papers by Sun and Ying [23], Seip, Simon, Ebbini and coworkers [54][55][56], Maass-Moreno, Damianou and coworkers [57][58][59] and this group [29,60,61] have reported the changes in received ultrasonic signals due to changes in ultrasonic tissue characteristics with temperature. These changes have been investigated both theoretically and in vitro with an eye towards using these signals for non-invasive monitoring of thermal therapy.…”

“…Several groups have investigated the temperature dependence of tissue characteristics at temperatures above 50 C [59,64,65]. In measurements of insertion loss at room temperature before and after heating, increases in attenuation of up to 2.4 dB cm À1 at 3.5 MHz were found in porcine liver after heating to 80 C in 300 s [65].…”

“…In measurements of insertion loss at room temperature before and after heating, increases in attenuation of up to 2.4 dB cm À1 at 3.5 MHz were found in porcine liver after heating to 80 C in 300 s [65]. Damianou et al [59] investigated the temperature and frequency dependence of ultrasonic attenuation and absorption in soft tissues. They found that attenuation was highly dependent on temperature, but only at temperatures >50 C. Techavipoo et al [66] measured attenuation of canine tissue from C with different tissue samples heated to different target temperatures to reduce cumulative tissue degradation.…”

Fast FFT-based bioheat transfer equation computation

“…• The tissue parameters vary with the temperature and the tissue damage stage [23,24]. Some of the parameters variations can be integrated in (8) by updating Q as for example the attenuation and absorption coefficients of ultrasound in tissues.…”

Remote Temperature Estimation in Intravascular Photoacoustic Imaging

“…Ultrasound has been used as a means to determine temperature changes in biological tissues. Several parameters have been investigated to utilize ultrasound for temperature estimation including measurement of change in speed of sound (Bowen et al 1979;Nasoni and Bowen 1989;Rajagopalan et al 1979), attenuation coefficient (Bush et al 1993;Damianou et al 1997;Ribault et al 1998;Varghese et al 2002), ultrasound echo-shift (Maass-Moreno andDamianou 1996;Seip et al 1996;Shi et al 2005b;Varghese et al 2002;Zohdy et al 2006) and backscatter energy (Straube and Arthur 1994). In this work, we utilize the ultrasound-based strain estimates of temperature change as a method to determine thermal effects during photoacoustic imaging.…”