Toshiyuki Matsunaka

Optical imaging in scattering medium by detection of ultrasonic phase shift due to light illumination

A method using ultrasonic velocity change due to light absorption was investigated in order to realize practical optical computed tomography. The phase shift of ultrasonic wave was observed even in the medium with a scattering coefficient equivalent to that of the human brain when ultrasonic wave passed through absorption object under light illumination. The optical image of the absorption region in a scattering medium was reconstructed from the projection data of ultrasonic phase shift due to light illumination. The shape of the absorbing object hidden in the chicken tissue was recognized by detecting the ultrasonic phase shift due to light illumination.

Optically assisted ultrasonic velocity-change images of visceral fat in a living animal

Noninvasive imaging method by detection of ultrasonic velocity change was proposed for diagnosis of visceral fat. The ultrasonic velocity-change images of the fat distribution in the excised rabbit lever and living rabbit lever. Experimental results suggest that this imaging method can be applied to a practical monitor of the visceral fat in a living human body.

P3D-5 Real Time Optical Tomography of Biological Tissue by Detection of Ultrasonic Velocity Change Due to Light Illumination

The ultrasonic velocity change induced by light was measured quickly by the remodeled commercial-type ultrasonic equipment with the multi-array transducer in order to investigate a practical optical tomography for medical diagnosis. The 3D view of the optical absorption region in the tissue mimic phantom was obtained by ultrasonic velocity change imaging

Spectroscopic Three-Dimensional Imaging of Light Scattering Medium by Detection of Ultrasonic Velocity Change owing to Light Illumination

An experimental apparatus that automatically detects the ultrasonic velocity change of a phantom due to light absorption was fabricated. Optical three-dimensional images of the phantom were constructed by illumination at a light intensity under the skin exposure limit of a continuous-wave diode laser. It was confirmed that the image of optical absorption distribution at the specified depth of the phantom could be obtained.

Imaging of Ultrasonic Velocity Change Corresponding to Optical Absorption Distribution

An imaging method using the velocity change of ultrasonics pulse induced by light illumination was investigated for application to medical diagnosis. The waveforms of echo pulses from the optical absorption region displayed the shift when the light illuminated the sample consisting of a scattering medium and an absorber. The ultrasonic velocity image constructed based on the time shift of echo pulses showed the absorption distribution in a dense scattering medium.

P5B-11 Monitoring Device of Au Nano-Particle Distribution in Living Body Using Ultrasonic Velocity Change Image

We could obtain ultrasonic velocity change images of Au nano-particles in the two phantoms which ware made of highly optical scattering ager and the chicken breast meet by using the remodeled diagnostic ultrasound equipment. All experimental results suggested that our imaging method could be applied to a practical monitor for the thermal therapy and the drug delivery system (DDS), and could be applied to biomaterial identification.

Tissue characterization using optically assisted ultrasonic velocity-change imaging method

Two kind of methods using the spectroscopic information of the materials and the dependence of ultrasonic velocity-change on temperature were investigated to indentify the distribution of objective material in the biological tissue. Experimental results showed the possibility that the biological tissue could be characterized using the optically assisted ultrasonic velocity-change imaging method.

Spectroscopic imaging of nano-particle distribution in biological tissue using optically assisted ultrasonic velocity-change detection

The optically assisted ultrasonic velocity-change imaging method was applied to obtain the spectroscopic image of nano-particles, which were expected as markers for drug delivery system and photo-thermal therapy, in tissue mimic phantoms. Phantoms including gold nano-rods or semiconductor nano-particles were prepared. The ultrasonic velocity-change images of phantoms were obtained using illumination of laser diodes with various emission wavelengths corresponded to the absorption spectrum of nano-particle. Experimental results showed that our method has the potential to find the optical absorption agent in biological tissue.

Development of non-invasive method for assessment of hepatic steatosis.

Steatosis is a critical feature of liver disease and is considered to play a pivotal role in the progression of nonalcoholic fatty liver disease, as well as being a surrogate marker of metabolic syndrome. The purpose of this study was to develop a non-invasive diagnostic method for assessment of liver steatosis. It is well known that ultrasonic velocity depends on materials and temperature. For example, the ultrasonic velocity in water is 1530m/s at 37°C and 1534m/s at 39°C, while that in fat is 1412m/s at 37°C and 1402m/s at 39°C. On this basis, we thought that the percentage of fat in hepatic steatosis could be assessed by detecting changes of ultrasonic in the liver, caused by warming. In order to confirm the effectiveness of this method, we obtained the ultrasonic velocity changes of tissue phantom including lard oil and the liver of living rabbit by ultrasonic warming, and then succeeded in 2-D imaging of ultrasonic velocity changes of the phantom and the liver of living rabbit. We named this the ultrasonic velocity-change method. The experimental results show the possibility that hepatic steatosis could be characterized using our novel, non-invasive method.

Optical computed tomography imaging of absorbers hidden in scattering medium by detection of ultrasonic phase-shift caused by laser illumination-ultrasonic velocity imaging

To obtain an optical CT (Computed Tomography) image of a living body, we proposed a method for detecting local temperature variation caused by optical absorption as the variation of ultrasonic velocity in a tissue mimicking material. Through a basic experiment, we confirmed that it was possible to detect the variation of ultrasonic velocity as the phase difference of an ultrasonic wave propagating in a medium with the scattering coefficient equivalent to that of a living body.