Detection of unstable plaque phantom by ultrasonic velocity-change imaging method under cold exposure

Abstract

We have investigated the ultrasonic velocity-change (UVC) imaging method to detect unstable vessel plaques using the difference in the temperature coefficient of ultrasonic velocity between water and fat. Thus far, to obtain effective ultrasonic velocity changes in the UVC imaging method, a warming procedure using a laser or an ultrasonic wave has been used. In this study, we utilize a cooling procedure instead of the warming procedure for this imaging method. As a result, lipid areas inside a carotid artery phantom were more clearly identified in the UVC image obtained under cold exposure.

Composition and acoustic properties in a cartilage phantom

“…So far, although several phantoms for MRI apparatus based on agarose have been fabricated and evaluated, 35,36) there is no phantom considering dual use with the ultrasound device. In general, any phantom is used not only for cartilage evaluation but also for other applications such as the detection of vulnerable plaque 37) and treatment evaluation, 38) and is also useful for the performance evaluation of conventional equipment and the verification of new methods.…”

The removal method of the influence of heartbeat in the ultrasonic velocity-change method

“…In the related experiment, we succeeded in finding the fat region in the carotid artery phantom. [19][20][21][22] At the present stage, however, the success rate of finding an appropriate UVC image is low because of the fluctuation of the echo path caused by motion, such as a heartbeat. Therefore, we have proposed a method to remove the influence of motion in the UVC method.…”

“…[8][9][10][11][12] We have investigated a non-invasive method to identify lipid areas in the human body using the ultrasonic velocitychange (UVC) method. [13][14][15][16][17][18][19][20][21][22] The UVC method is based on the fact that the temperature dependence of ultrasonic velocity depends on the medium where ultrasonic waves propagate. Around body temperature, the temperature change rate of ultrasonic velocity in water is +1.9 m • s −1 • °C−1 and that in fat is −4.9 m • s −1 • °C−1 .…”

“…After that the ultrasonic array transducer (7.5 MHz) was set instead of the ice pack. 22,29) then, as shown in Fig. 3, RF echo signals were acquired every 3 s repeatedly in the same manner of the above method in Fig.…”

“…To this end, the time-shifts in those RF echo signals caused by a temperature rise were estimated from adjacent two RF echo signal data acquired in 3 s intervals. therefore determined by subtracting the original RF echo waveform from the time-shift RF echo waveform, [13][14][15][16][17][18][19][20][21][22] when a disturbance caused by motion is well-suppressed. When the velocity of ultrasonic waves becomes faster (slower) by temperature rise, the corresponding portion of the white line in Fig.…”