Non-invasive imaging biomarkers for liver steatosis in non-alcoholic fatty liver disease: present and future

Abstract

Non-alcoholic fatty liver disease is currently the most common chronic liver disease, affecting up to 25% of the world's population. Simple fatty liver, in which fat is deposited in the liver without fibrosis, has been regarded as a benign disease in the past, but it is now known to be prognostic. In the future, more emphasis should be placed on the quantification of liver fat.Traditionally, fatty liver has been assessed by histological evaluation, which requires an invasive examination, but technological innovations have made it possible to evaluate fatty liver by noninvasive imaging methods such as ultrasonography, computed tomography, and magnetic resonance imaging. In addition, quantitative as well as qualitative measurements for the detection of fatty liver have become available. In this review, we summarize currently used qualitative evaluations of fatty liver and discuss quantitative evaluations that are expected to further develop in the future.

Non-invasive imaging biomarkers for liver steatosis in non-alcoholic fatty liver disease: present and future

“…There are different serum biomarkers and composite scores used to evaluate hepatic fibrosis such as the Enhanced Liver Fibrosis (ELF) test and Fibrosis-4 (FIB-4), but the scope of this editorial revolves around the role of imaging in liver steatosis. As mentioned in the recently published review article by Nogami et al 6 , multiple tests exist to identify steatosis including abdominal ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI). US is a simple and popular type of imaging to diagnose fatty liver.…”

“…B mode findings such as bright liver, vascular blurring attenuation, and hepatorenal echo contrast indicate fatty liver however the sensitivity and specificity decrease when intra-hepatic steatosis is less than 30%. 6 CT scans can identify fatty liver, yet they are costly, time-consuming, a relatively poor indicator to quantify steatosis, and are associated with inevitable radiation exposure. 6 On CTs, fatty liver is usually diagnosed by comparing the liver fat content relative to that of the spleen.…”

“…6 CT scans can identify fatty liver, yet they are costly, time-consuming, a relatively poor indicator to quantify steatosis, and are associated with inevitable radiation exposure. 6 On CTs, fatty liver is usually diagnosed by comparing the liver fat content relative to that of the spleen. MRI is an excellent method to quantify fat content in the liver as the signals are obtained from protons belonging to water and fat molecules, and there is no risk of exposure compared to CT.…”

“…In 2010, the controlled attenuation parameter (CAP) was introduced to measure the degree of fat attenuation, allowing it to quantify liver steatosis. 6 Initially, obesity was considered a limitation until the XL probe was introduced, which allows for deeper penetration to generate signals in patients with a higher body mass index (BMI). As mentioned by Nogami et al 6 , CAP is essential in evaluating S ≥1, 2, and 3 however it has not been reported whether the measurement of liver steatosis is useful for long term follow up.…”

“…4 Moreover, every procedure is associated with risks, and the incidence of serious complications and mortality has been reported to be 0.3-0.57% and 0.01% respectively. 5 As mentioned by Nogami et al 6 , the importance of assessing the degree of fibrosis rather…”