Yoichiro Matsumoto

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In order to find out whether high intensity focused ultrasound (HIFU) might be useful against hepatocellular carcinoma, we analyzed the effect of a microbubble agent (Levovist) on the temperature rise and tissue necrosis induced by HIFU. Rabbits were given 7 ml Levovist (300 mg/ml) or saline intravenously. Up to six areas per rabbit liver were exposed to(More)
A polyacrylamide (PAA) gel containing egg white as a new model for irradiation experiments in high-intensity focused ultrasound HIFU is introduced. The gel is transparent except in thermally necrosed regions which are white. The model is similar to, and has the same benefits as, gels containing bovine serum albumin (BSA) protein, but egg is less expensive(More)
Cloud cavitation is potentially the most destructive form of cavitation. When the cloud cavitation is acoustically forced into a collapse, it has the potential to concentrate a very high pressure, more than 100 times the acoustic pressure, at its center. We experimentally investigate a method to control the collapse of high intensity focused ultrasound(More)
A new method for fluoroscopic tracking of a proximal bone fragment in femoral fracture reduction is presented. The proposed method combines 2-D and 3-D image registration from single-view fluoroscopy with tracking of the head center position of the proximal femoral fragment to improve the accuracy of fluoroscopic registration without the need for repeated(More)
Ultrasound (US)-mediated gene transfection in the presence of microbubbles is a recently developed and promising non-viral gene delivery method. Optimising the parameters used in ultrasonic transfection is urgently required in order to realise higher transfection efficiencies in clinical settings. This study examined the effect of ultrasound exposure(More)
It is well known that a bubble in contaminated water rises much slower than one in purified water, and the rising velocity in a contaminated system can be less than half that in a purified system. This phenomenon is explained by the so-called Marangoni effect caused by surfactant adsorption on the bubble surface. In other words, while a bubble is rising,(More)
Thermal decomposition of ultrathin oxide layers on silicon surface was investigated with temperature programed desorption. Oxide layers were formed on Si(100) at 400 degrees C by exposure to O(2) molecular beam. Desorption spectrum for oxygen coverages between 1.7 and 2.6 ML exhibits a single dominant peak with an additional broad peak at lower(More)
Erythrocytes, as well as microbubble contrast agents, are important factors in improving thermal effect of high-intensity focused ultrasound (US), or HIFU, and increasing the coagulation volume produced by HIFU irradiation. In vitro experiments used human plasma with various concentrations of human erythrocytes in combination with or without Levovist. In(More)
In the medical ultrasound field, microbubbles have recently been the subject of much interest. Controlling actively the effect of the microbubbles, a novel therapeutic method has been investigated. In this paper, our works on high intensity focused ultrasound (HIFU) lithotripsy with cavitating microbubbles are reviewed and the cavitation detection method to(More)