Definition:

Signal intensity at MRI that is identical or nearly identical to that of liver parenchyma.

If any portion of the observation differs unequivocally in intensity from liver:

• Do not characterize as isointensity. 

If there is equivocal hyperintensity or equivocal hypointensity:

• Characterize as isointensity.

Comments:

• May apply to any sequence or phase of MR imaging.
• Specifying the sequence or phase is necessary.