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Core Imaging Methods and Technologies

The imaging systems and methodologies developed in this group all are based on one fundamental optical technique for characterizing and quantifying optical parameters from highly scattering media like tissue: Spatial Frequency Domain Imaging/Spectroscopy (SFDI/S). This is a relatively new technique that has several appealing attributes as a general measurement platform: low cost, quantitative in optical contrast, depth selective and spatially scalable. This technique measures the differentiated response of remitted light from tissue, when patterns (sinusoidal intensity projections of varying spatial frequency) are projected on to it. This approach quantifies the effective Modulation TransferFunction (MTF) of a diffuse optical system (in this case: tissue) and relates this function in terms of contributions from absorption and scattering.

Our lab advances spectroscopic methods in a way that exploits the molecular sensitivity, quantitation and non-invasiveness of SFDI/S, but extends the spatial resolution and depth selectivity through the use of recent advances in imaging technology (e.g. snap-shot hyperspectral imagers) and compressive sensing (e.g. single pixel imagers), as well as novel computational methods and models of light transport in order to translate these technologies into clinical settings.

(Left): Clinical photo of biopsied skin, 2 weeks post; (middle): the determined absorption coefficient at 630nm which is related to hemoglobin concentrations, melanin, water, lipid, carotenoids; (right): the reduced scattering coefficient at 630nm, related to subcellular objects and collagen structures

Clinical Applications and Deployment

The primary thrust of our research is focused on applications and collaborations that seek to address unmet needs in either primarily dermatological or models of disease in pre-clinical (small animal) settings:

• In terms of diagnostics, this measurement platform presents the opportunity to isolate (in space and depth) physiological and functional properties that directly relates to the biological processes present in disease or cancer. We seek to develop non-invasive imaging tools with increased sensitivity and specificity to biological processes, thereby developing new, quantitative platform to study disease rather than just differentiating it.
• In terms of advancing light based therapies, this platform has the opportunity to characterize the optical properties present within affected tissue and therefore inform energy distribution of the light dose, as well as the therapeutic response. Light based treatment methods provide an exciting alternative to current cancer treatment methods as they could be (1) highly targeted, resulting in minimal collateral damage to healthy tissue, as well as (2) non- (or minimally) invasive, mitigating risks associated with surgical procedures. These methods, however, have yet to gain clinical acceptance due to a lack of quantitative imaging and evaluation tools. Two classes of therapies of particular interest are Photothermal Therapy (PTT) and Photodynamic Therapy (PDT).
• Lastly, this platform has the opportunity to monitor structural changes in tissue in response to intervention, therapy and wound healing. Preliminary data indicate that all phases of the wound healing response (i.e. Hemostasis, Inflammation, Proliferation/ Granulation, and Tissue Remodeling/Maturation) and can be non-invasively identified and monitored longitudinally by the quantitative optical methods and models available in our lab. This platform not only allows for predictive therapeutic response, but also invites collaborations to study interventions that may promote and/or accelerate wound healing; thereby help expedite drug development in regenerative medicine.