12 - Frontiers in Optical Imaging
Florida 1 14:00 - 16:00
|Chair(s): Regine Choe, Chao Zhou|
14:00 Monitoring hemodynamic responses to treatments for bone graft and breast cancer with diffuse optical and correlation tomography R Choe*, University of Rochester
Abstract: Diffuse optical and correlation tomography quantifies 3D distribution of microvascular oxyhemoglobin, deoxyhemoglobin, water and lipid concentrations, scattering and blood flow in deep tissue using photons in the near-infrared spectral window. These physiological parameters have great potential to assess therapeutic efficacy of breast cancer treatments and tissue-engineering based treatments for bone grafts. In addition, the use of light which is non-ionizing and inexpensive instrumentation makes diffuse optical and correlation tomography attractive for translational research. Here, we introduce clinical and preclinical research tools and approaches to test the capabilities of diffuse optics in early prediction of therapeutic efficacy. For monitoring vascularization of bone graft, we developed a non-contact scanning scheme to acquire large spatial dataset necessary for reliable 3D image reconstruction. Different temporal and spatial blood flow responses between autograft and allograft were observed, demonstrating the potential to utilize blood flow for prediction of treatment efficacy. In a murine breast tumor model, we found a close correlation between the tumor volume and the blood flow changes. Clinical data showing feasibility to predict treatment efficacy at early time point will be presented.
14:20 An Integrated Optical Coherence Microscopy Imaging and Optical Stimulation System for Optogenetic Pacing in Drosophila melanogaster A Alex, Lehigh University
; A Li, Massachusetts General Hospital; J Men, Lehigh University; J Jerwick, Lehigh University; RE Tanzi, Massachusetts General Hospital; C Zhou*, Lehigh University
Abstract: Electrical stimulation is the clinical standard for cardiac pacing. Although highly effective in controlling cardiac rhythm, the invasive nature, non-specificity to cardiac tissues and possible tissue damage limits its applications. Optogenetic pacing of the heart is a promising alternative, which is non-invasive and more specific, has high spatial and temporal precision, and avoids the shortcomings in electrical stimulation. Drosophila melanogaster, which is a powerful model organism with orthologs of nearly 75% of human disease genes, has not been studied for optogenetic pacing in the heart. Here, we developed a non-invasive integrated optical pacing and optical coherence microscopy (OCM) imaging system to control the heart rhythm of Drosophila at different developmental stages using light. The OCM system is capable of providing high imaging speed (130 frames/s) and ultrahigh imaging resolutions (1.5 μm and 3.9 μm for axial and transverse resolutions, respectively). A light-sensitive pacemaker was developed in Drosophila by specifically expressing the light-gated cation channel, channelrhodopsin-2 (ChR2) in transgenic Drosophila heart. We achieved non-invasive and specific optical control of the Drosophila heart rhythm throughout the fly's life cycle (larva, pupa, and adult) by stimulating the heart with 475 nm pulsed laser light. Heart response to stimulation pulses was monitored non-invasively with OCM. This integrated non-invasive optogenetic control and in vivo imaging technique provides a novel platform for performing research studies in developmental cardiology.
14:40 Miniature MEMS-scanned dual-axis confocal microscopes for point-of-care pathology JTC Liu*, UW Seattle
Abstract: Recent advances in the design and miniaturization of optomechanical components have enabled the development of handheld and endoscopic confocal microscopes for point-of-care analyses of tissue microanatomy and molecular biomarkers of disease. We are currently developing a handheld line-scanned dual-axis confocal microscope, with MEMS-based scanning, for high-speed (>15 Hz) microscopic imaging of superficial (<250-microns deep) tissues. The line-scanned DAC architecture enables fast frame rates to mitigate motion artifacts during handheld clinical use. Validation studies, performed with reflectance targets and fluorescently stained fresh tissues, show that this device has the potential to enable early detection and surgical guidance. Future clinical applications include the examination of suspicious lesions in the oral cavity as well as for guiding the resection of brain tumors.
15:00 Personalizing Photodynamic therapy based treatment strategies with Photoacoustic imaging S Mallidi*, Harvard Medical School
; M Ichikawa, Harvard Medical School; A Alkhateeb, Harvard Medical School; AP Khan, Harvard Medical School; Z Mai, Harvard Medical School; T Hasan, Harvard Medical School
Abstract: To achieve effective outcome in photodynamic therapy (PDT), it is paramount to understand the dynamic changes in the tumor microenvironment (oxygenation), photosensitizer consumption and adjust light dose accordingly. Towards this goal, I will present the utility of non-invasive 3D ultrasound guided photoacoustic imaging (PAI) to understand the heterogeneous changes in blood oxygen saturation during treatment and post treatment. Photoacoustic imaging, as the nomenclature suggests, involves acoustic signal generation by irradiating tissue with nanosecond laser pulses that satisfy the thermal stress confinement conditions. PAI provides tissue optical absorption information at deeper penetration depths with sensitivity similar to optical imaging and resolution on par with ultrasound imaging. Given that PAI and ultrasound imaging share the same receiver electronics, the images are inherently co-registered to provide both anatomical and tissue optical information. Leveraging the 3D imaging and real-time imaging capabilities of ultrasound guided PAI, we identify regions not responding to PDT and have the potential to recur using various subcutaneous and orthotopic mouse models. We further compare the predictive capability of photoacoustic imaging with the more predominantly used fluorescence imaging and immunohistochemistry techniques for both Benzoporphyrin derivative and aminolevulinic acid based PDT. Finally the strategies to push the envelop for ultrasound-guided PAI as an important aid in tumor diagnosis, customizing patient-specific treatment, and monitoring the therapeutic progression and outcome in vivo not only for PDT but other therapies will be discussed.
15:20 Porphyrin-phospholipid Liposomes : Emerging Applications in Chemophototherapy JF Lovell*, SUNY Buffalo
Abstract: Near infrared (NIR) light penetrates human tissues with limited depth, thereby providing a method to deliver non-ionizing radiation within the bounds of well-defined target tissue volumes. Light-based therapies including photodynamic therapy (PDT) and laser-induced thermal therapy (LITT ) have been validated clinically for curative and palliative treatment of solid tumors. However, these monotherapies can suffer from incomplete tumor killing and have not displaced existing ablative modalities. The combination of phototherapy and chemotherapy (chemophototherapy, CPT), when carefully planned, can be an effective cancer treatment option that is relatively unexplored. Here, we will discuss our lab's efforts to develop light responsive nanovesicles based on porphyrin-phospholipid (PoP) liposomes to enable enhanced drug deposition at tumor sites. PoP liposomes also enable unique imaging approaches and facile ligand-targeting of the nanovesicles to target tissues.