秋山 いわき¹, 大矢 晃久², 中村 みちる³, 谷口 信行³, 伊東 紘一³

Iwaki AKIYAMA¹, Akihisa OHYA², Michiru NAKAMURA³, Nobuyuki TANIGUCHI³, Kouichi ITOH³

¹湘南工科大学電気工学科, ²筑波大学電子情報工学系, ³自治医科大学臨床病理学教室

¹Department of Electrical Engineering, Shonan Institute of Technology, ²Institute of Information Sciences and Electronics, Usiversity of Tsukuba, ³Department of Clinical Pathology, Jichi Medical School

キーワード : Fractal analysis, Self similarity, Liver, Thyroid, B-mode image

This paper describes the fractal analysis of a B-mode image for tissue characterization. We consider that if a self similarity can be assumed in structures of the tissues, the ultrasonic images will be affected by the structures dependent on the pathological states. We calculated the Hurst coefficients of B-mode images in cases of normal and fatty liver, and cirrhosis of the liver. Using 10 MHz ultrasonic waves for rat's liver in vitro we observed that the relationship of the Hurst coefficient was fatty<normal<cirrhosis. Using 3.5 and 5 MHz ultrasonic waves for human liver we observed a similar relationship, although the difference between them was very small, since image degradation occurred due to the use of a lower frequency and subcutaneous fat. Thus, in thyroid cases with normal, Hashimoto, and hyperthyroiditism, we used 10 MHz ultrasonic waves to calculate the Hurst coefficients, the relationship between which was normal<Hashimoto<hyperthyroiditism. Consequently, we found that the Hurst coefficient indicating a degree of self similarity is one of the parameters for characterizing tissue structures. For the relationship between Hurst coefficients of the B-mode images and tissues structures, further study is required.