title: Image guided near-infrared spectroscopy of breast tissue in vivo using boundary element method.
abstract: We demonstrate quantitative functional imaging using image-guided near-infrared spectroscopy (IG-NIRS) implemented with the boundary element method (BEM) for reconstructing 3-D optical property estimates in breast tissue in vivo. A multimodality MRI-NIR system was used to collect measurements of light reflectance from breast tissue. The BEM was used to model light propagation in 3-D based only on surface discretization in order to reconstruct quantitative values of total hemoglobin (HbT), oxygen saturation, water, and scatter. The technique was validated in experimental measurements from heterogeneous breast-shaped phantoms with known values and applied to a total of seven subjects comprising six healthy individuals and one participant with cancer imaged at two time points during neoadjuvant chemotherapy. Using experimental measurements from a heterogeneous breast phantom, BEM for IG-NIRS produced accurate values for HbT in the inclusion with a <3% error. Healthy breast tissues showed higher HbT and water in fibroglandular tissue than in adipose tissue. In a subject with cancer, the tumor showed higher HbT compared to the background. HbT in the tumor was reduced by 9 μM during treatment. We conclude that 3-D MRI-NIRS with BEM provides quantitative and functional characterization of breast tissue in vivo through measurement of hemoglobin content. The method provides potentially complementary information to DCE-MRI for tumor characterization.
authors.affiliation: Dartmouth College, Thayer School of Engineering, Hanover, NH 03755, USA. subhadra.srinivasan@dartmouth.edu
authors.forename: Subhadra
authors.initials: S
authors.lastname: Srinivasan
authors.forename: Colin M
authors.initials: CM
authors.lastname: Carpenter
authors.forename: Hamid R
authors.initials: HR
authors.lastname: Ghadyani
authors.forename: Senate J
authors.initials: SJ
authors.lastname: Taka
authors.forename: Peter A
authors.initials: PA
authors.lastname: Kaufman
authors.forename: Roberta M
authors.initials: RM
authors.lastname: Diflorio-Alexander
authors.forename: Wendy A
authors.initials: WA
authors.lastname: Wells
authors.forename: Brian W
authors.initials: BW
authors.lastname: Pogue
authors.forename: Keith D
authors.initials: KD
authors.lastname: Paulsen
mesh_terms: D000328:Adult; D000465:Algorithms; D001943:Breast Neoplasms / Q000175:diagnosis*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation* / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019265:Spectroscopy, Near-Infrared / Q000295:instrumentation*; D013382:Subtraction Technique / Q000295:instrumentation*