Noninvasive assessment of nonalcoholic fatty liver disease

Abstract

Nonalcoholic fatty liver disease (NAFLD) is ongoing pandemic of the 21st century. The noninvasive assessment includes serum biomarkers, predictive models, and imaging modalities. The “Steato test,” “NAFLD liver fat score,” and “Fatty liver index” are models developed for noninvasive assessment of hepatic steatosis. Out of the imaging modalities, magnetic resonance imaging proton density fat fraction is the most sensitive test to detect hepatic steatosis. Out of the various serum biomarkers to detect nonalcoholic steatohepatitis (NASH), cytokeratin-18 has been the most widely investigated. Recent approach for the diagnosis of NASH has targeted research toward genetic biomarkers such as PNPLA3 and microRNAs. However, none of the presently available biomarkers or imaging modalities are able to differentiate simple hepatic steatosis from NASH with a high sensitivity and specificity. Different models have been developed to predict fibrosis which are aspartate transaminase (AST)/platelet ratio index (APRI), fibrosis-4 (Fib-4) index, nonalcoholic fatty liver disease fibrosis (NFS) score and body mass index, AST: Alanine transaminase Ratio, diabetes (BARD) score. The accuracy of BARD, APRI, FIB-4, and NFS to detect advanced liver fibrosis was found to be of 0.76, 0.77, 0.84, and 0.84, respectively, in a large meta-analysis. Transient elastography, acoustic radiation force impulse, and magnetic resonance elastography (MRE) are imaging techniques available to detect liver fibrosis. MRE has shown to have a pooled accuracy 0.96 to detect advanced fibrosis in NAFLD patients. Noninvasive tests may not completely replace liver biopsy, but it may help to avoid it where probability of fibrosis is low.

Keywords

• nafld
• hepatic steatosis
• liver fibrosis
• noninvasive assessment