びまん性肝疾患の線維化評価におけるreal-time tissue elastography

The long-term prognosis for patients with diffuse liver disease depends on an accurate diagnosis of hepatic fibrosis and assessment and prediction of improvements in this fibrosis with treatment. These assessments are vital for determining the hepatic cancer risk. A histological diagnosis of liver biopsy specimens is regarded as the gold standard for the assessment of hepatic fibrosis; however, noninvasive and accurate assessment methods for hepatic fibrosis are desired because of difficultly with repeated assessments due to the invasiveness and sampling errors encountered with biopsy. Based on platelet count and hepatic fibrosis marker measurements as well as relevant blood tests, formulas for calculating hepatic fibrosis have been tested. A method of assessing hepatic fibrosis using ultrasound was also developed, and its usefulness has been reported. Real-time tissue elastography (RTE) is a technology developed in Japan that can be loaded into commercially available diagnostic equipment. It provides a color display of information on tissue hardness in real time using a fast computation method, Combined Autocorrelation Method (CAM), for relative hardness based on tissue deformation in vivo. RTE enables measurements to be performed simply and noninvasively for the assessment of hepatic fibrosis. Relationships between the degrees or severity of features on RTE images and various stage assessment methods for hepatic fibrosis have been reported, but RTE most favorably reflects fibrosis without the effects of inflammation, cholestasis, or fatty deposition. It also enables serial assessments of improvements in hepatic fibrosis in response to treatment to be performed.