Focal fat (liver)

  • Regional or focal
  • Causes confusion if there is any underlying mass
  • Common sites: either side of falciform ligament, around gall bladder fossa, posterior aspect of segment IV
  • Variations in local blood supply and venous drainage responsible for difference in fat distribution
  • Unenhanced US and CT: angular margins, geographic appearance. Lack of mass effect, preservation of vascular architecture
  • When occurring in unusual locations, MRI is diagnostic. Chemical shift or in- and out-of-phase imaging is most accurate. Signal reduction in out-of-phase imaging confirms fat. 
  • No abnormal contrast enhancement will be seen in areas of fat alteration unlike when underlying mass lesions are present
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Prasad, Srinivasa R., et al. “Fat-containing lesions of the liver: radiologic-pathologic correlation.” Radiographics 25.2 (2005): 321-331.

Hamer, Okka W., et al. “Fatty liver: imaging patterns and pitfalls.” Radiographics 26.6 (2006): 1637-1653.