1st mammogram ever and abnormal, family history breast cancer. single group amorphous microcalcs in left breast. us birad 3 and now going for mri. biopsy?

Yes: due for abnormal mammogram ( and family history ) most likely your doctor will advise you to have image guided core needle biopsy and follow the advise .

A grouping: of amorphous calcifications is probably not appropriate for BIRAD category 3(probably benign). Although they are still likely going to be benign, stereotactic needle biopsy may be more appropriate management, and BIRAD 4 a more appropriate category. Breast MRI is generally not that useful in the imaging work up of microcalcifications.