飯島 尋子^{1, 2}, 多田 俊史^{1, 4}, 蜂屋 弘之³, 西村 貴士^{1, 2}, 西村 純子², 吉田 昌弘², 會沢 信弘¹, 平田 慎之介⁵, 熊田 卓⁶

Hiroko IIJIMA^{1, 2}, Toshifumi TADA^{1, 4}, Hiroyuki HACHIYA³, Takashi NISHIMURA^{1, 2}, Junko NISHIMURA², Masahiro YOSHIDA², Nobuhiro AIZAWA¹, Shinnosuke HIRATA⁵, Takashi KUMADA⁶

¹兵庫医科大学消化器内科, ²兵庫医科大学超音波センター, ³東京工業大学工学院システム制御系, ⁴姫路赤十字病院内科, ⁵千葉大学フロンティア医工学センター, ⁶岐阜協立大学看護科

¹Division of Gastroenterology and Hepatology, Department of Internal Medicine, Hyogo College of Medicine, ²Ultrasound Imaging Center, Hyogo College of Medicine, ³Department of Systems and Control Engineering, Tokyo Institute of Technology, ⁴Department of Internal Medicine, Himeji Red Cross Hospital, ⁵Center for Frontier Medical Engineering, Chiba University, ⁶Faculty of Nursing, Gifu Kyoritsu University

キーワード : liver fibrosis, shear wave elastography, inflammation, liver stiffness

目的：超音波エラストグラフィによる肝硬度は，肝線維化だけでなく肝の炎症，黄疸やうっ血などの影響を受けるとされる．肝の線維化および壊死・炎症が肝硬度に与える影響に関して検討した．対象と方法：7,825例の慢性肝疾患のうち測定基準に合致した809名を対象に，TEおよびVTQから得られた値を用い組織学的に診断された線維化および壊死炎症のグレードと比較検討した．結果と考察：TEおよびVTQの線維化診断能AUROCは，F2≦，F3≦，F4はそれぞれ，TEが0.809，0.860，0.947，VTQが0.793，0.836，0.941であった．肝線維化の進行とともに肝硬度は有意に上昇した．また肝の壊死・炎症の進行でも肝硬度は有意に上昇した．線維化グレードごとの検討でも肝硬変例を除いて炎症が高値なほど肝硬度は高値であった．結論：肝硬度は肝線維化の非侵襲的な診断法として有用であるが，肝の炎症にも影響を受け，値の解釈には注意が必要である．

Purpose: Liver stiffness (LS) measured using ultrasound shear wave elastography is reported to be influenced not only by liver fibrosis but also by other clinical conditions such as hepatic inflammation, jaundice, and liver congestion. The aim of this study was to investigate the influence of liver fibrosis, hepatic necrosis, and inflammation on LS. Materials and Methods: Of 7,825 chronic liver disease cases, 809 patients who met our study criteria were included. LS measurements obtained using transient elastography (TE) and Virtual Touch Quantification (VTQ) were compared with histologically evaluated liver fibrosis stage and necro-inflammatory activity grade. Results and Discussion: The area under the receiver-operating characteristic curve of TE to predict F2≦, F3≦, and F4 was 0.809, 0.860, and 0.947, respectively, and that of VTQ was 0.793, 0.836, and 0.941, respectively. LS showed significant increase with the progression of fibrosis. In addition, LS showed significant increase with the progression of hepatic necrosis and inflammation. In the analysis based on each fibrosis grade, LS showed an increase along with the severity of inflammation, except in F4 (liver cirrhosis) cases. Conclusions: LS measurement is useful in predicting liver fibrosis stage noninvasively, but it can be influenced by hepatic inflammation. Therefore, LS measurements should be interpreted with caution.