CT and MRI features of hepatic steatosis
What are the CT and MR imaging features of hepatic steatosis?
Hepatic steatosis is most commonly diffuse but may alternatively be focal, multifocal, subcapsular, or perivascular in distribution. When focal or multifocal, geographic shapes with linear, angulated, or interdigitated margins are typically encountered, characteristically without mass effect upon hepatic vessels.
On CT, areas of hepatic steatosis have decreased attenuation in the liver relative to the spleen by at least 10 HU on unenhanced CT images or by at least 25 HU on contrast-enhanced CT images. Hepatic attenuation of <40 HU is also suggestive. However, CT is less sensitive than MRI for detection of hepatic steatosis.
On MRI, hepatic steatosis is confirmed when there is loss of signal intensity on out-of-phase T1-weighted images relative to in-phase T1-weighted images.