This is a study looking at advanced imaging such as PET/CT and MRI to see if they can provide a more accurate assessment of the patient with dense breasts or difficult to interpret mammograms. In addition, the ability to determine whether one or the other is more accurate or whether both together would be appropriate in this clinical situation, may be able to be measured.

The MRI studies are very sensitive for detection of breast histopathology but less specific in differentiating between small low grade malignancies are more benign pathologies. Multifocal pathology can be challenging in determining site(s) for biopsy.

PET scanning is specific in the measurement of metabolic glucose activity of various histopathologies and is accurate in differentiating aggressive from benign pathology in multifocal breast disease. A further drawback of PET is the lack of ability to observe lesions less than 3-4mm in diameter.

In select cases the combination of MR and PET/CT is able to come to a more conclusive diagnosis - specifically with bilateral or multifocal breast disease.

Inclusion Criteria:

• Woman who have breast volumes allowing utilization of MRI breast coil
• Patients who are considered, by radiologist reading the mammograms, to have non interpretable or difficult to interpret x-ray studies. These patients may or may not have palpable breast lumps and may and may not have suspicious areas on their x-ray mammograms.

Exclusion Criteria:

• Women of child bearing potential not practicing a medically accepted method of birth control
• Women who are pregnant or breast-feeding

Subjects will be recruited from Breast Care Clinic and local physicians.