title: Imaging in breast cancer: diffuse optics in breast cancer: detecting tumors in pre-menopausal women and monitoring neoadjuvant chemotherapy.
abstract: Diffuse optical spectroscopy (DOS) and diffuse optical imaging (DOI) are non-invasive diagnostic techniques that employ near-infrared (NIR) light to quantitatively characterize the optical properties of centimeter-thick, multiple-scattering tissues. Although NIR was first applied to breast diaphanography more than 70 years ago, quantitative optical methods employing time- or frequency-domain 'photon migration' technologies have only recently been used for breast imaging. Because their performance is not limited by mammographic density, optical methods can provide new insight regarding tissue functional changes associated with the appearance, progression, and treatment of breast cancer, particularly for younger women and high-risk subjects who may not benefit from conventional imaging methods. This paper reviews the principles of diffuse optics and describes the development of broadband DOS for quantitatively measuring the optical and physiological properties of thick tissues. Clinical results are shown highlighting the sensitivity of diffuse optics to malignant breast tumors in 12 pre-menopausal subjects ranging in age from 30 to 39 years and a patient undergoing neoadjuvant chemotherapy for locally advanced breast cancer. Significant contrast was observed between normal and tumor regions of tissue for deoxy-hemoglobin (p = 0.005), oxy-hemoglobin (p = 0.002), water (p = 0.014), and lipids (p = 0.0003). Tissue hemoglobin saturation was not found to be a reliable parameter for distinguishing between tumor and normal tissues. Optical data were converted into a tissue optical index that decreased 50% within 1 week in response to neoadjuvant chemotherapy. These results suggest a potential role for diffuse optics as a bedside monitoring tool that could aid the development of new strategies for individualized patient care.
authors.affiliation: Laser Microbeam and Medical Program, Beckman Laser Institute, University of California, Irvine, CA, USA. bjtrombe@uci.edu
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Tromberg
authors.forename: Albert
authors.initials: A
authors.lastname: Cerussi
authors.forename: Natasha
authors.initials: N
authors.lastname: Shah
authors.forename: Montana
authors.initials: M
authors.lastname: Compton
authors.forename: Amanda
authors.initials: A
authors.lastname: Durkin
authors.forename: David
authors.initials: D
authors.lastname: Hsiang
authors.forename: John
authors.initials: J
authors.lastname: Butler
authors.forename: Rita
authors.initials: R
authors.lastname: Mehta
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology*; D002986:Clinical Trials as Topic; D005260:Female; D006801:Humans; D020360:Neoadjuvant Therapy; D055095:Optics and Photonics; D010347:Patient Care Planning; D019095:Point-of-Care Systems; D017697:Premenopause; D012307:Risk Factors; D012680:Sensitivity and Specificity; D019265:Spectroscopy, Near-Infrared; D016896:Treatment Outcome