Ct scan revealed small hyperdense lesion in right lobe of liver that is "more prominent than on recent study 7 months ago". what does this mean?

No easy answer: Hyperdense may mean it enhances with contrast, is calcified, or contains blood products. Do you have a history of cancer? Check with your doctor to see if the lesion is considered suspicious and if 'more prominent' means it is larger.

Depends: This depends on whether the ct was done w/ contrast/dye or not. If it enhances w/ contrast it could a hemangioma which is a benign. If you take birth control pill it could be an adenoma. If you have cirrhosis it could be a primary liver cancer. If you have breast or lung or other cancer, it could be a metastasis from those cancer. Your doctor can determine if the lesion need biopsy or not.