51 y.o.- i am trying to consider R mastectomy. Just had L mastectomy. I had augmentation in 1990 and regular mammograms and even some diagnostics over the past 19 years- all negative. I detected a small "frozen pea" thing on my right breast at the sternum, felt almost in the bone . U/S discovered another flatter tumor just above it. I had left mastectomy done 9/3/09 after the open biopsy  showed tumor #1) IDC grade II 1.1 cm (with in situ part 1.3 cm intermediate grade w necrosis); tumor #2) IDC grade I  .95 cm (with in situ 1.9 intermediate grade w necrosis), sentinel nodes neg; Ki-67 >30% Er + PR+ Her2 1+ (but I guess that is neg)  BUT the  Bilateral MRI with contrast day before R mastectomy said no other lesions on R and L was clear. BUT R breast came back with 2 more sites: tumor #3) .8 cm IDC with lobular features; other site DCIS - these NOT SEEN ON MRI prior to surgery. I can feel lump now in L breast way upper outer quad 1:00 pos. U/S rad said he could feel it too, couldn't really see it on U/S but-said trust MRI.  no info on #3 tumor  from mastectomy since it was not ordered. OncDX pending  on largest tumor. Should I trust MRI for L breast?