For the first time, all women diagnosed with breast cancer may need magnetic resonance imaging, or an M-R-I.
Right now most women begin treatment, including surgery, after a biopsy has confirmed breast cancer discovered in a self exam or a mammogram.
But the latest guideline calls for an MRI before the surgery to pinpoint the extent of the cancer, according to a study published by the National Comprehensive Cancer Network.
The guideline also urges doctors to consider doing an MRI on the opposite breast because in some cases, the cancer is in both breasts, even if the mammogram only discovers it in one breast.
At this time, the American Cancer Society, calls for MRIs only to be used for screening in women at a high risk of breast cancer, meaning those who've already had a cancer, or those with a family history of breast cancer.
The new guideline for additional MRIs will be more expensive, but its supporters say it may catch the one in six breast cancers that currently are missed by mammography alone.