BREAST DENSITY QUANTIFICATION USING STRUCTURED-LIGHT DIFFUSE OPTICAL TOMOGRAPHY
Anatomical breast density is an independent risk factor for breast cancer, where women with larger amounts of dense fibroglandular tissue (FGT) are more likely to develop breast cancer. Clinical models that consider personal information about a woman (age, family history, and genetics) to predict her risk for breast cancer can help her customize their own screening options or consider preventative measures. Although magnetic resonance imaging (MRI) can be used to quantitatively measure the FGT volume, its high-cost makes it impractical to implement. Optical methods provide an appealing alternative, where the systems are low-cost and easily compactable, which makes clinical implementation easier. Optical tomography can spatially resolve and measure the concentration of relevant chromophores within the breast: water, lipid, oxy and deoxyhemoglobin. We have investigated the use of structured-light diffuse optical tomography (SL-DOT) in imaging the breast volume. In SL-DOT, spatially modulated light is illuminated and collected from the breast through the use of two digital micro-mirror devices (DMDs). Through both simulations and phantom studies, we found that SL-DOT is suitable for predicting the percentage of FGT when taking into consideration both the volume segmented from the chromophore maps and the recovered chromophore concentrations. A second independent risk factor in which we are interested is the functional breast density. After intravenous injection of a MRI contrast agent, the intensity of the FGT is enhanced to varying degrees among patients, referred to as background parenchymal enhancement (BPE). It has been shown that BPE is also correlated with breast cancer incidence, most likely due to the higher perfusion of nutrients in blood to the FGT. Because BPE is an indication of blood flow, we believe the hemoglobin content measured from SL-DOT will be correlated to the BPE seen in MRI; therefore, our technique can potentially measure two independent risk factors for breast cancer. Once clinically translated, SL-DOT can be used to measure both the anatomical and functional breast density inexpensively and quickly, allowing women to make informed decisions about their breast cancer screening.