I have stage 2b prostate cancer and a small low dense lesiion was found in the dome of my liver during ct scan with contrast. could this mean metases?

Slight possibility: A metastasis to the liver in your situation is very unlikely. However, "Never say always or never". It should be followed up with other studies to make sure it is not a metastasis. There is also the possibility that it is caused by a condition other than the prostate cancer. Have you been treated for the primary prostate cancer?