秌田 雅彦, 上田 光宏

Masahiko AKITA, Mitsuhiro UEDA

東京工業大学精密工学研究所

Research Laboratory of Precision Machinery and Electronics, Tokyo Institute of Technology

キーワード : In vivo measurement, Backscattering coefficient, Attenuation coefficient, Correlation function, Correlation length

　Echoes scattered in biological tissue can be measured quantitatively in term of a backscattering coefficient. The formula for measuring the backscattering coefficient which is independent on the transducer geometry has been reported by us before. But, in oder to apply it to in vivo measurement of the backscattering coefficient, it becomes necessary to estimate the total attenuation between the transducer and the tissues whose backscattering coefficient is to be measured. There have been reported several techniques for in vivo measurement of the attenuation coefficient, but they are only concerned with the relative attenuation between two layers in the uniform tissues. Consequentry a new estimation technique which gives the backscattering and attenuation coefficients simultaneously is proposed in this paper. The basic idea of the method lies in the comparison the spectrum of echo scattered by the tissues with the theoretically estimated one which is derived by assuming the linearly frequency dependent attenuation and the Gausian or exponential correlation function for a statistical model of the tissues. The availability of the method is shown in the experiments where suspensions are in place of the tissues. Finally, the backscattering coefficient of human liver is measured, and A-mode displays of correlation length, variance of amplitude reflection coefficient and attenuation coefficient of human liver are shown.