| Diffuse optical tomography (DOT) is an imaging modality with potential use in breast cancer detection, diagnosis and monitoring, brain imaging, and small animal imaging. In this work we focus on breast cancer imaging. It has been observed that malignant and normal tissues differ in blood flow ( F) and oxygen consumption (OC). We are interested in using DOT to image those parameters since they are functionally related to the main absorbers of near infrared light in tissue, oxygenated and deoxygenated hemoglobin. In particular we look at dynamic changes in F and OC when the breast is put under mammo-graphic compression, as is done using an experimental combined X-ray/DOT system under development by our collaborators at Mass General Hospital. It is believed that these changes provide a potential source of contrast between tumor and other tissue. In this work we analyze, in a simulation scenario, the ability of the imposition of a hemodynamically constrained model of temporal changes in oxygen saturation (SO2) to improve our algorithm for extracting OC and F from reconstruction of hemoglobin concentrations. Using a three dimensional transmission measurement geometry we investigate how the recovery of metabolic parameters is influenced by the observation time interval, the SNR of the measurements, the regularization parameter choices, and a assumptions about the dynamic behavior of total hemoglobin concentration. We conclude that we can reconstruct a 1.5x OC and 2.5x F contrast for a spherical inclusion with less than 20% error as long as we use at least 90 seconds of 60dB SNR data even in the presence of variations in total hemoglobin concentration. Further more we have noticed that by introducing a dynamic model we are able to somewhat compensate for the errors in the reconstructed tumor OC. |
