Molecular and functional imaging of breast cancer.

BACKGROUND Significant efforts have been directed toward developing and enhancing imaging methods for the early detection, diagnosis, and characterization of small breast tumors. Molecular and functional imaging sets the stage for enhancement of current methodology. METHODS Current imaging modalities are described based on the molecular characteristics of normal and malignant tissue. New molecular imaging methods that have the potential for clinical use are also discussed. RESULTS Dynamic contrast-enhanced magnetic resonance imaging is more sensitive than mammography in BRCA1 carriers. It is used in screening and in the early evaluation of neoadjuvant therapy. Positron emission mammography is 91% sensitive and 93% specific in detecting primary breast cancers. Sentinel node scintigraphy is a key component of axillary lymph node evaluation. Other imaging modalities being studied include Tc99m sestamibi, radiolabeled thymidine or uridine, estrogen receptor imaging, magnetic resonance spectroscopy, and diffusion magnetic resonance imaging. CONCLUSIONS Molecular and functional imaging of the breast will likely alter clinical practice in diagnosing and staging primary breast cancer and assessing response to therapy since it will provide earlier information regarding the underlying biology of individual breast cancers, tumor stage, potential treatment strategies, and biomarkers for early evaluation of treatment effects.