Measurement of temperature dependence of sound velocity in biological tissues

Abstract

Transcatheter arterial chemo-embolization using Lipiodol ® is one of the treatments for hepatocellular carcinoma. During this procedure, it is important to monitor the Lipiodol ® deposited inside tumors. This study proposes a method for measurement of the temperature dependence of the velocity of sound in biological tissues. An ultrasonic pulse-echo method was used to measure the velocity of sound. The temperature coefficients of the velocity of sound for Lipiodol ® was −2.82 m s −1 °C−1 . Values of 1.07 and 1.59 m s −1 °C−1 were obtained for normal rat liver and cancerous liver tissue, respectively. Thus, this procedure may potentially allow for the evaluation of the infiltration of Lipiodol ® inside tumors.

Ultrasonic Heating Detects Lipiodol Deposition within Liver Tumors after Transarterial Embolization: An In Vivo Approach

“…In the previous study, the temperature coefficient of the sound velocity of Lipiodol showed negative values and that of rat liver tumor showed positive values [ 23 ]. Therefore, that of rat liver tumor injected with Lipiodol can show various values from negative to positive values depending on the degree of Lipiodol, which can reflect the amount of Lipiodol filled in the liver tumor.…”

“…This method has the potential to facilitate the in vivo evaluation of the volumetric distribution of Lipiodol inside tumors, since Lipiodol primarily consists of poppy-seed oil. A previous in vitro study demonstrated that tumors implanted in a rat liver and Lipiodol had different temperature coefficients of the sound velocity [ 23 ].…”

“…Tsujimoto et al measured the sound velocity of rat liver, and showed that there was a positive temperature coefficient near body temperature. They reported that Lipiodol’s temperature coefficient of the sound velocity showed a negative temperature coefficient [ 23 ]. On the other hand, the amount of heat generated by locally heating biological tissue by exposure to ultrasonic waves is proportional to the product of the ultrasonic attenuation coefficient and the ultrasonic intensity, and the temperature change caused by ultrasonic exposure is the heat production rate.…”

Basic and recent applied technologies of ultrasound in the field of clinical diagnosis

“…Therefore, the fat content of tissue can be characterized by measuring the change in sound velocity that occurs when biological tissue is heated non-invasively with ultrasonic waves [13]. Measurements of the rate of change in sound velocity between normal livers and those affected by hepatocellular carcinoma (HCC) in rats were 1:07 AE 0:02 m/s/ C and 1:59 AE 0:04 m/s/ C, respectively [15]. These results suggest the possibility of NASH diagnosis using thermophysical properties.…”

Extension of remote distance of electromagnetically spinning viscometer

“…Ultrasonic absorption is determined by the viscosity of a propagation medium. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] The viscosity can be classified into two types based on the deformation mode of the medium: the shear and volume viscosities. Many types of ultrasonic relaxation in aqueous solutions of ionic salts occur through the modification of temperature, which is the direct contribution of adiabatic volume compression.…”