黒田 英克, 阿部 珠美, 藤原 裕大, 長澤 倫明, 滝川 康裕

Hidekatsu KURODA, Tamami ABE, Yudai FUJIWARA, Tomoaki NAGASAWA, Yasuhiro TAKIKAWA

岩手医科大学附属病院内科学講座消化器内科分野

Division of Gastroenterology and Hepatology, Department of Internal Medicine, Iwate Medical University

キーワード : ultrasound-guided attenuation parameter, hepatic steatosis, non-alcoholic fatty liver disease, attenuation coefficient

本研究は，非アルコール性脂肪肝疾患（non-alcoholic fatty liver disease：NAFLD）の肝脂肪化診断におけるultrasound-guided attenuation parameter（UGAP）の診断精度を評価し，attenuation imaging（ATI）およびcontrolled attenuation parameter（CAP）と直接比較することを目的に実施された．対象は，2019年10月から2021年4月に当院でUGAP，ATI，CAPおよび肝生検検査を同日に施行されたNAFLD症例105名である．UGAPによって推定された超音波減衰係数（attenuation coefficient：AC）の肝脂肪化診断能は，肝病理組織学的所見をリファレンスにROC解析を用いて評価され，ATI，CAPによって測定されたACならびにCAP値と比較された．UGAPの測定成功率は100％であった．複数回測定によるIQR/medの中央値は4.0％で，ATIおよびCAPよりも有意に低値を示した（P ＜ 0.0001）．肝脂肪化grade別のUGAPで測定したACの中央値は，S0 （n＝20） / S1 （51） / S2 （28） / S3（26）：0.590 / 0.670 / 0.750 / 0.845 dB/cm/MHzと肝脂肪化に伴い高値を示した（P ＜ 0.0001）．肝脂肪化grade S1以上，S2以上およびS3を識別するためのUGAPのAUROCは 0.890，0.906，0.912であり，肝脂肪化grade S3診断におけるUGAPのAUROCはCAPより高値を示した（P ＜ 0.05）．UGAPとATI間の相関係数は0.803で強い相関関係が示された（P ＜ 0.0001）．UGAPは，高い測定成功率と再現性が特徴で，NAFLD患者に対する高精度な肝脂肪化診断能を有する可能性が示唆された．

The purpose of this study was to evaluate the diagnostic accuracy of the ultrasound-guided attenuation parameter (UGAP) using the LOGEQ E10 for hepatic steatosis in non-alcoholic fatty liver disease (NAFLD) patients and directly compare UGAP with attenuation imaging (ATI) and controlled attenuation parameter (CAP). We prospectively analyzed 105 consecutive patients with NAFLD who underwent UGAP, ATI, CAP, and liver biopsy on the same day between October 2019 and April 2021. The diagnostic ability of the UGAP-determined attenuation coefficient (AC) was evaluated using receiver operating characteristic (ROC) curve analysis, and its correlation with ATI-determined AC values or CAP values was investigated. The success rate of UGAP was 100%. The median IQR/med obtained by UGAP was 4.0%, which was lower than that of ATI and CAP (P < 0.0001). The median ACs obtained by UGAP for grades S0 (control), S1, S2, and S3 were 0.590, 0.670, 0.750, and 0.845 dB/cm/MHz, respectively, demonstrating a stepwise increase with increasing hepatic steatosis severity (P < 0.0001). The areas under the ROC curve of UGAP for identifying ≧ S1, ≧ S2, and S3 were 0.890, 0.906, and 0.912, respectively, which were significantly better than the results obtained with CAP for identifying S3. Furthermore, the correlation coefficient between UGAP-AC and ATI-AC values was 0.803 (P < 0.0001), indicating a strong relationship. Our results indicate that UGAP has high diagnostic accuracy for detecting and grading hepatic steatosis in patients with NAFLD.