Campaign free MRIs for dense breasts

I was sent for an MRI after diagnosis by ultrasound and then mammogram. I am interested in what you are saying about dense breasts though because I have breast cancer but I also have two girls in their twenties. Their father comes from a family where all but one of the women have the BCR1 mutation - his mother, grandmother, great aunties, and all his sisters.  They have all had breast cancer and it's only in the last decade that we've realised why.  I don't know if my girls have inherited this mutation but they are at very high risk and they have dense breasts. My doctor has recommended they get ultrasounds done biannually as mammograms are not likely to be very informative.  MRIs have not been recommended, perahps due to cost.