Authors
K Ramachandran, MD, DMRD1
1Professor & HOD, Division of Imageology, Regional Cancer Centre, Trivandrum.
Abstract
Introduction: Hepatic fatty metamorphosis, or steatosis, is a metabolic complication stemming from diverse toxic, ischemic, and infectious insults to the liver. It is frequently observed in liver biopsies of alcoholics and in 50% of diabetic patients. With rising obesity rates, hepatic steatosis has become a major cause of hepatic dysfunction, encompassing conditions like macrovesicular fatty liver, non-alcoholic steatohepatitis (NASH), steatohepatitis with fibrosis, and cirrhosis.
Imaging Modalities and Findings:
Ultrasound: Fatty liver appears diffusely echogenic, with the degree of echogenicity correlating with steatosis. Sonographic changes parallel biochemical and clinical dysfunction, showing increased parenchymal brightness, numerous echogenic foci, and increased attenuation of the ultrasound beam leading to poor visualization of deep hepatic structures and veins. Focal fatty areas may present as hypoechoic masses.
Computed Tomography: Normal liver attenuation is typically 50-70 Hounsfield Units (HU). In fatty infiltration, liver attenuation is reduced, often appearing less dense than the portal and hepatic veins, which can mimic contrast enhancement.
Magnetic Resonance Imaging: Proton chemical shift imaging, or opposed phase gradient echo imaging, exploits the frequency difference between fat and water protons. This technique shows a loss of signal intensity on opposed phase images in lesions containing both fat and water, facilitating fat identification.
Conclusion: Imaging plays a crucial role in evaluating hepatic dysfunction, primarily to exclude obstructive pathology and hepatocellular carcinoma.