藤井 康友¹, 谷口 信行¹, 高野 隆一², 王 怡¹, 重田 浩一朗¹, 尾本 きよか¹, 小野 倫子¹, 佐藤 泉¹, 伊東 紘一¹

Yasutomo FUJII¹, Nobuyuki TANIGUCHI¹, Ryuichi TAKANO², Yi WANG¹, Kouichiro SHIGETA¹, Kiyoka OMOTO¹, Tomoko ONO¹, Izumi SATOH¹, Kouichi ITOH¹

¹自治医科大学臨床検査医学, ²自治医科大学腎臓内科

¹Department of Clinical Laboratory Medicine, Jichi Medical School, ²Department of Nephrology, Jichi Medical School

キーワード : histogram, fibrous liver, rat, radio-frequency signal, tissue characterization, ultrasound

To estimate severity of fibrosis without biopsy, the valve of signal-noise-ratio (SNR), skewness, and kurtosis were measured using a 10MHz transducer with the texture analysis in conjunction with an alternative method of evaluating fibrous rat livers. This method segments the region of interest (ROI) into multiple layers (sub-ROIs). In each sub-ROI of a homogenous medium, the histogram of enveloped-amplitude of radio-frequency (RF) backscattered echoes resembles a Rayleigh distribution. In theory, SNR, skewness, and kurtosis for Rayleigh statistics are constant and independent of mean scattering intensity, which is enhanced by such undesirable effects as tissue attenuation, beam diffraction, and incident wave forms. Thus, these values, which are averages of the corresponding sub-ROI values, constitute an unbiased estimator. All fibrous liver specimens were induced using the dimethylnitrosamine method. Fiber content was estimated quantitatively as fibrosis index by computer processing of pathological images obtained by light microscopy. The valve of SNR, skewness and kurtosis, expressed as averages of corresponding values from each sub-ROI, correlated closely with fibrosis index. These results make it possible to predict severity of liver fibrosis from data obtained without resorting to biopsy. This data, obtained from our earlier study on rats, may be used to quantitatively evaluate human hepatitis by measuring these three values. This method may make it possible to estimate degree of severity in chronic liver disease non-invasively.