超音波検査技術

In this session, clinical laboratory data, conventional US and US elastography for diagnosing NAFLD/NASH were discussed after having lectures of basic concept and pathological diagnosis of NAFLD/NASH. Following descriptions of below are highlights of this session.

NAFLD has been categorized as one of metabolic syndrome of the liver, which diagnosed as fatty liver by imaging modalities and hepatic biopsy except alcoholic fatty liver diseases. NAFLD is classified into NAFL and NASH. NASH progresses to liver cirrhosis after 20 years, and developing HCC after 5 to 10 years. NAFLD/NASH will be increasing rapidly as underlying condition of LC and HCC in the near future, so that taking some measures are matters of great urgency. Pathologically, NASH is defined by more than 5% fat deposition, infiltrating inflammation cells into lobules hepatitis and ballooning degeneration. Especially ballooning degeneration, fibrosis and Mallory-Denk body are important findings relating to hepatocellular injury and progressive disease.

NAFLD should be enclosed by performing US once for metabolic syndrome patients, further diagnosis of NASH can be made by combination of more than two markers such as NAFLD fibrosis score, NAFIC score, FIB-4 index and platelet counts. The diagnostic criteria proposed by Japanese Society of Gastroenterology of NAFLD are bright liver, hepato-renal contrast, deep attenuation and vascular blurring. Good measurement precision and reproducibility of US elastography were presented. Attenuation parameter which can presume amount of fat deposition in the liver, measured by FibroScan® and general use US system are well correlated to Hounsfield Unit of CT and Alanine transaminase. High elasticity (12 kPa＜), low CAP level (260 dB/m＞) and complication of DM are possible high risk group of HCC. Fatty liver findings of B mode US are well correlated to pathological diagnosis. US elasticity measured in NBNC patients tended to estrange from pathological diagnosis (less than 10%). Fibrosis can be more accurately diagnosed by elastography than B mode US.

In closing this session, recognizing NAFLD/NASH are national disease is important, performing US to pick up fatty liver in metabolic syndrome patients, further estimation of laboratory data and US elastography can make enclosing liver fibrosis. Clinical laboratory team and clinicians should cooperated closely in enclosing high risk patients in daily practice of NAFLD/NASH.