I hesitate to even provide comment on this because it is such a complicated imaging question. They use "heterogenity" as one thing to look at when differentiating "possible masses" in the liver. The normal population has a percentage of benign findings on their liver, like aquamak said that it's just an area that is different. It can also be used to determine degree of fattiness or even some form of cirrhosis in some testing. The most important thing is that they said no discrete mass could be seen at this time. If you are interested in a very technical discussion on this, here is a good paper from a Radiologist at Washington U, but it's pretty technical and basically says different things can appear with the characteristics of heterogenity.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2727979/
The conclusion of this paper states exactly what Aquamak said, get an MRI if need: "If a lesion demonstrates imaging findings diagnostic of hemangioma or focal nodular hyperplasia (these are both benign masses), no further diagnostic evaluation of that lesion is needed. If the findings are suggestive but not diagnostic of a benign lesion, then further evaluation may include interval follow-up imaging, preferably MRI, or performance of a confirmatory imaging study (e.g., nuclear medicine or MRI with a hepatobiliary contrast agent).
Good luck, figuring this stuff out can be daunting. I do all of the research for my husband who has melanoma. He has scans next week.
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