giant hemangioma of liver

The hemangioma was discovered in Sept of 1990 on a sonogram.  A scan was done and a biopsy.  The size was stated to be 10cc  A year or two ago I had a follow up sonogram (2009) the size was 12cc.  Recently another follow up was performed (sonogram and CT scan) with the size being 19+cc X 17+cc.  Now my DR wants me to have  bi-lateral imagery done.  I have no symptoms but am concerned about the size of the mass.  What will further testing prove that hasn't already been diagnosed and what can be done, if anything about the mass.  Is it safe to just leave it there?

Thank you.