Audience: Radiologists, Residents and Fellows
Learning Objectives:Identify the different patterns of steatosis
Diffuse
Geographic
Focal
Multifocal
Transient Steatosis:
Can have sub-acute / acute accumulation of hepatic lipid
Prolonged fasting resulting in ketogenic state
One or multiple consecutive extremely fatty meals
Severe alcohol intoxication
Steatosis may resolve in days to weeks
The mechanisms for drug induced steatosis are variable. Tamoxifen is felt to cause steatosis without inflammation, while other drugs such are irinotecan may impact liver function and increase morbidity in those undergoing hepatic resection for liver metastasis
“Third inflow” - non-portal venous inflow to the liver diminishes local portal venous perfusion
Diminished portal venous perfusion alters local metabolism
Non-uniform exposure of hepatocytes to insulin
Altered exposure to ingested lipid, amino acids, and carbohydrates
Altered local metabolism results in focal fat deposition or focal fat sparing
Summary:
Diffuse hepatic steatosis can result from multiple systemic conditions and may be heterogeneous or homogeneous
Non-diffuse steatosis often presents in classic locations related to the “third inflow”
Nodular steatosis can mimic neoplasms but rarely has mass effect
Geographic fatty sparing and focal fat tend to have a non-circular appearance and occur in typical locations
