Fatty liver disease, also known as nonalcoholic fatty liver disease (NAFLD), affects over one billion individuals worldwide, with a prevalence of up to 30% in the general population and even higher in people with type 2 diabetes. It is the third most common cause of hepatocellular carcinoma in the United States.
Assessing liver fat content is essential for identifying patients with or at risk for NAFLD and for following their disease over time. Liver biopsy is considered the gold standard for hepatcyte fat quantification, however the procedure is invasive and carries a risk of complications. The Kleiner score is commonly used to grade biopsy proven steatosis on the basis of a four-point classification : Grade 0, steatosis in less than 5% of hepatocytes; Grade 1, 5%–33% steatosis; Grade 2, 34%–66% steatosis; and Grade 3, greater than 66% steatosis.
Conventional B-mode Ultrasound is widely used to assess liver steatosis, and is reported to be around 90% sensitive to detect steatosis in at least 20% of hepatocytes, however it is less sensitive for detection of lower degrees of liver fat content and does not accurately quantify the degree of steatosis in more severe cases.
Attenuation Imaging is an innovative quantitative ultrasound technique that measures the energy loss of acoustic signals traveling through liver tissue, to give an overall grade of fatty content. Attenuation Imaging illustrates the degree of ultrasound beam attenuation as a color coded area on B mode scans. The technique has demonstrated good clinical results compared with liver biopsy and MRI proton density fat fraction scans, and shows promise as a safe, non-invasive quantification of moderate to severe liver steatosis. A 2020 study by Jesper et Al comparing liver biopsy scores with AI attenuation correction (AC) scores found patients with moderate to severe fatty infiltration of the liver demonstrated significantly higher attenuation coefficient (AC) values compared to those with a liver fat fraction of less than 33%, with no significant difference in AC values between patients with mild fatty infiltration of less than 5% and those with 5-32%. Overall, attenuation imaging demonstrated a sensitivity of 71% and a specificity of 92% for detecting hepatic steatosis of any grade. (1)
Ultrasound attenuation imaging is a promising innovative non-invasive tool for the detection and quantification of moderate to severe hepatic steatosis in patients with NAFLD or at risk of developing it. Overall, AI demonstrates a sensitivity of 71% and a specificity of 92% for detecting hepatic steatosis of any grade.
With further research, attenuation imaging may become a frontline non-invasive diagnostic tool for diagnosing, grading and managing NAFLD in order to reduce complications such as hepatocellular carcinoma.
1. Ultrasound-Based Attenuation Imaging for the Non-Invasive Quantification of Liver Fat – A Pilot Study on Feasibility and Inter-Observer Variability; Daniel Jesper; J Trans Eng Health and Med; June 2020
2. Ultrasound elastography in patients with fatty liver disease; Luiza de Campos ; Moreira da Silva ; Radiol Bras.; Jan-Feb 2020
3. Liver Stiffness Measurements by 2D Shear-Wave Elastography: Effect of Steatosis on Fibrosis Evaluation;
Takashi Kumada et al. ; Am J Roentgenol.; Oct 2022
4. The Role of Elastography in Non-Alcoholic Fatty Liver Disease; Constantinescu C et al ; Curr Health Sci J; Jul-Sep 2020
Panorama Radiology Specialists offers Attenuation Imaging Ultrasound scans for non-invasive assessment and grading of fatty liver in patients with known or at risk of Non Alcoholic Fatty Liver Disease.
Please contact our team with clinician enquiries about this service and our fees.