Heard from my oncologist by email yesterday evening. They tell me that the suspected mass is too small to light up a PET scan, so we're likely going with continued monitoring by CT. This means we'll recheck, presumably in May three months from now. If it has grown, that's pretty close to conclusive that it's a metastatic tumor, but will also indicate that a PET scan is necessary. If it has not grown, that's pretty close to conclusive that it's either a scar or a steatosis.
I'll know all this for certain next week, after I see the doctor on Wednesday.
So, looks like I get a few more months to live my life before the shit maybe hits the fan. I think I'm going to name my liver Damocles.