MRI baseline of BIRAD2 now a year later BIRAD 4B

I have two sisters who are breast cancer survivors (one at age 37 & the other at age 48); both have tested negative for the BRCA gene. My mother passed as a result of metastatic gall bladder cancer and my father had early stages of prostate cancer. For the past two years I have had some type of ultrasound or mammogram every 6 months. Last year I told my MD that I needed some other type of testing done because I was concerned that I kept coming back every 6 months and now another sister (age 48) had just been recently diagnosed with CA. My case: I have a strong family history of breast cancer, I have extreme dense breast tissue and apparently the radiologist continues to have me come back for more follow up tests. She suggested an MRI. Last year (March 2011) I had my first MRI with a BI-RAD of 2 on both breasts. A year later (March 2012); my MRI report reads “Left breast: 3.3 cm lower outer quadrant area of progressive nonmasslike enhancement abutting an intact saline implant. Recommend targeted 2nd look ultrasound and biopsy”. If not identified on 2nd look ultrasound, MR guided biopsy is recommended. Right breast MRI bi-rads: 2, Left breast MRI bi-rads: 4B

An ultrasound was done last week but nothing was seen. I will know have a guided MRI biopsy. I am concerned. Can anyone share if you have had a similar situation and your outcome?