山口 匡

本論文では, 現在の超音波診断に用いられている断層画像(Bモード画像)に含まれるエコー情報と肝硬変の進行に伴う組織散乱体構造変化との関係を, シミュレーション画像と臨床画像を用いて検討している.病変進行度の異なる複数のBモード画像を用い, 画像中の様々な領域から得られるエコーの振幅分布特性を算出し, 基本となるレイリー分布との比較を行った.その結果, ランダムな散乱体からの情報からなる正常肝の画像は, 病変の進行とともに病変組織特有の散乱体分布情報が混在した画像に変化していくことがわかり, 病変進行と散乱体構造変化及びエコー情報変化の間には定量的な関係があることが確認された.

The cirrhotic liver has many fibrotic tissue structures known as nodule structures. Understanding this characteristic in diseased tissue is important for quantitative diagnosis. In this paper, we present a technique to extract quantitative three-dimensional information from a cirrhotic liver. Consecutive two-dimensional images acquired by fan like scanning were processed using constant false alarm rate (CFAR). The 2D processed images are accumulated to obtain 3D information. The nodular structure is clear in the constructed images.

The human liver is composed of small hexagonal structures known as the liver lobules. In this paper, we propose a modeling technique for the change of the scatterer distribution on liver tissue considering the liver lobule structure to obtain cirrhotic liver images of the continuous stage. We calculate the squared difference between the Rayleigh distribution and the probability density of the echo amplitude of each cirrhosis image. The difference increases with the progression of cirrhosis. These results agree well with the results obtained from clinical liver cirrhosis images. It is found that the proposed modeling technique is valid for analyzing the relationship between the change of characteristics of biological tissue and change of B-mode image on the progression of liver cirrhosis.