• Characterize as isoenhancement

Comments:

• Applies to observations that, after contrast injection:
  • Unequivocally enhance less than liver and
  • Are lower in attenuation or intensity than liver
  • May apply to arterial phase, portal venous phase, or delayed phase.

• Specifying the phase is necessary
• Depending on the phase, may apply to the entire observation or to part of an observation:
  • Arterial phase hypoenhancement: the observation in whole hypoenhances.
  • Portal venous phase hypoenhancement or delayed phase hypoenhancement: the observation in whole or in part hypoenhances

• The enhancement of the observation should be compared to that of the adjacent liver parenchyma. If the liver parenchyma visually consists of both nodules and fibrosis, then enhancement of the observation should be compared to that of the composite liver tissue (i.e., a visual average of the nodules and fibrosis) (see schematics for “washout”, portal venous phase hypoenhancement, and delayed phase hypoenhancement).