熊田 卓¹, 多田 俊史¹, 金森 明¹, 乙部 克彦², 竹島 賢治²

Takashi KUMADA¹, Toshifumi TADA¹, Akira KANAMORI¹, Katsuhiko OTOBE², Kenji TAKESHIMA²

¹大垣市民病院消化器内科, ²大垣市民病院診療検査科

¹Department of Gastroenterology and Hepatology, Ogaki Municipal Hospital, ²Department of Imaging Diagnosis, Ogaki Municipal Hospital

キーワード : contrast-enhanced ultrasound, vascular phase, post-vascular phase, hepatic tumor, hepatocellular carcinoma

本稿は，我国の肝腫瘍の造影超音波診断のためのガイドラインについて記載した．肝腫瘍の日本超音波医学会の診断基準は，最初1988年に出版された．しかし，超音波機器や肝腫瘍の疾患概念の変化や最近の機器の進歩により，以前のガイドラインでは対応できなくなってきた．現在，本邦ではSonazoid^®（ペルフルブタン，第一三共，東京，日本）が超音波造影剤として認可されている．今回の改正で，6つの主要な疾患（肝細胞癌，肝内胆管癌［胆管細胞癌］，転移性肝腫瘍，肝細胞腺腫，肝血管腫，限局性結節性過形成［FNH］）の鑑別診断に必要な，標準的な所見を掲載した．超音波所見はBモード所見，ドプラ所見および造影所見に分けた．Bモード所見は，腫瘍形状，境界線や輪郭，腫瘍マージン，腫瘍内，後方エコー，および付加所見から質的診断を行った．ドプラ所見は，血流，血管，血流特性（拍動波と定在波）および付加所見から質的診断を行った．造影超音波の時相は血管相および後血管相に分類した．血管相は動脈（優位）相と門脈（優位）相分けた．肝腫瘍の鑑別診断は，3つの相所見によって行われる．血管相は腫瘍の質的診断に，後血管相は腫瘍の存在診断に使用される．後血管イメージは「クッパーイメージ」ともよばれ，腫瘍における「クッパー細胞」の有無に密接に関係している．しかし，この言葉は，異論もあり今後の検討に委ねることとなった．

This article mainly provides a guideline for contrast-enhanced ultrasound diagnosis of hepatic tumors in Japan. Liver tumor diagnostic criteria were first published in 1988 by Japan Society of Ultrasonics in Medicine. With recent advances in ultrasound equipment and changes in the concept of liver tumors, various issues have emerged that cannot be handled by the previous guideline. Currently, Sonazoid^® (Daiichi-Sankyo, Tokyo, Japan), a lipid stabilized suspension of perfluorobutane gas microbubbles, has been licensed in Japan. In the present revision, typical findings necessary for differentiation of 6 major diseases (hepatocellular carcinoma, intrahepatic cholangiocarcinoma [cholangiocellular carcinoma], metastatic liver tumor, hepatocellular adenoma, hepatic hemangioma, and focal nodular hyperplasia [FNH]) are described. Ultrasound findings were divided into B-mode findings, Doppler findings, and contrast-enhanced findings. B-mode findings are based on the tumor shape, border and contour, tumor margin, intra-tumor, posterior echo, and additional findings. Doppler findings are based on the degree of blood flow, vascularity, blood flow characteristics (pulsatile wave and steady wave), and additional findings. The phases of contrast-enhanced ultrasound are classified into the vascular phase and post-vascular phase. The vascular phase is further divided into the arterial [predominant] phase and the portal [predominant] phase. The characterization of liver tumors is made by the findings of three phases. The vascular phase is used for characterization, and the post-vascular phase is used for detection. The post-vascular image is also called the “Kupffer image” and is closely correlated with the presence or absence of Kupffer cells in the tumor. However, this term is controversial and requires further consideration.