Endoscopic Ultrasound Shear Wave Elastography: A Novel Tool for Fibrosis Screening in Patient With Elevated Body Mass Index and Suspected Non-Alcoholic Fatty Liver Disease or Steatohepatitis

Introduction:

Non-alcoholic fatty liver disease (NAFLD) is the most widespread chronic liver condition across the world. NAFLD over time can progress to its more severe form, non-alcoholic steatohepatitis (NASH), which is associated with increased speed of progression to advanced fibrosis and cirrhosis. Identification of patients with suspected NAFLD/NASH and early stage fibrosis is crucial for prompt clinical management in weight loss and optimization of metabolic disorders for reversal of fibrosis, but the gold standard of liver biopsy can be impractical due to high costs and risk of sampling error and procedural complications.

Elastography is a non-invasive imaging modality that provides information about tissue elasticity and is often used to measure liver stiffness as a correlation to fibrosis severity (F0-4). Elastography has been heralded as a promising alternative to liver biopsies given its non-invasive nature and improved cost effectiveness in the general population. Many elastography modalities exist, including Fibroscan, magnetic resonance elastography (MRE), and shear wave elastography (SWE).

Unfortunately, despite being highly sensitive and specific, routine MRE for NAFLD/NASH fibrosis screening can also be cost prohibitive. Fibroscan and SWE are more cost effective and are routinely performed via a transabdominal probe for liver fibrosis screening in patients with NAFLD/NASH, but their accuracy may be impeded in patients with obesity.

Endoscopic ultrasound (EUS) approaches to elastography may hold several technical advantages over transabdominal in patients with obesity due to EUS-SWE's ability to visualize the liver parenchyma under a thin sub-centimeter gastric or duodenal wall, unlike transabdominal approaches in which the quality may be impacted by a thick abdominal wall. The main disadvantage to EUS-SWE, however, is that it is a fairly novel technology with no established stiffness cutoffs for the various fibrosis grades, unlike VCTE of which fibrosis grade cutoffs are well studied and standardized for patients with NAFLD/ NASH.