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The Moscone Center
San Francisco, California, United States
28 January - 2 February 2017
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Translational Research Presentations

Neurophotonics, Neurosurgery, and Optogenetics
(ordered by conference and paper number)

Coaxial cavity injected OCT and fiber laser ablation system for real-time monitoring of ablative processes, part 2: all fiber design and dispersion control
Paper 10050-10

Author(s):  Jamil Jivraj, Ryerson Univ. (Canada), et al.
Conference 10050: Clinical and Translational Neurophotonics
Session 3: Operative and Post Op. Therapy II

A novel system for fiber laser tissue ablation (λ = 1064nm, Pavg=10W, Ppeak = 1kW) with OCT feedback. (λc = 1310nm) was previously presented that did not need an output-stage dichroic mirror. Further performance and form-factor improvements have been made, with the ultimate goal being to create a compact, low-cost, high-precision laser scalpel to be used for various surgical osteotomies. We present an improved design that, unlike before, removes the need for bulk optics in the entire system other than focusing optics. Strategies for dispersion mismatch and resolution optimization are discussed. Initial results for depth-controlled ablation of tissue is presented.

In-situ photopolymerized and monitored spinal and brain implant
Paper 10050-12

Author(s):  Andreas Schmocker, Ecole Polytechnique Fédérale de Lausanne (Switzerland), et al.
Conference 10050: Clinical and Translational Neurophotonics
Session 3: Operative and Post Op. Therapy II

Currently implants or tissue replacements are inserted either as a whole implant or by injecting a liquid which polymerizes to form a solid implant at the appropriate location. This is either highly invasive or not controllable. We developed a tool to perform such surgeries in a minimally invasive and controllable way. It combines photopolymerization and fluorescence spectroscopy in a surgical apparatus. The device was successfully tested in-vitro to replace the core of intervertebral discs where it fulfilled the functionality of the tissue over more than 0.5 million loading cycles. Here we report on results to replace brain tissue.

A comparison between antidepressant effects of transcranial near-infrared laser and citalopram in a rat model of depression
Paper 10050-14

Author(s):  Farzad Salehpour, Neurosciences Research Ctr., Tabriz Univ. of Medical Sciences (Iran, Islamic Republic of), et al.
Conference 10050: Clinical and Translational Neurophotonics
Session 3: Operative and Post Op. Therapy II

The present study was designed to compare efficacy of transcranial near-infrared laser therapy (NILT) and Citalopram treatment in a rat model of depression. Animals were exposed to chronic mild stress for 4 weeks. Laser treatment were done by 810 nm at energy density of 1.2 J/cm2 for a total of 12 sessions. Citalopram (10 mg/kg, Intraperitoneal) was administered for 21 consecutive days. At the end of experiment depressive-like behaviors and serum cortisol levels were decreased in both laser and drug groups. Our findings showed that transcranial NILT was as effective as Citalopram for improve of depressive-like behaviors in rat.

Optical guidance for stereotactic brain tumor biopsy procedures-preliminary clinical evaluation
Paper 10050-3

Author(s):  Neda Haj-Hosseini, Univ. Hospital Linköping (Sweden), et al.
Conference 10050: Clinical and Translational Neurophotonics
Session 1: Operative and Post Op. Therapy I

During stereotactic biopsy on suspected tumors in the brain, tissue samples are harvested to determine the malignancy. To provide guidance for finding the diagnostic tumor sites and to avoid vessel rupture, an application specific probe was developed. The setup incorporated spectroscopy for detection of 5-aminolevulinic acid induced protoporphyrin (PpIX) fluorescence and blood flow using laser Doppler flowmetry. The PpIX fluorescence and backscattered light were significantly different in the tumor compared to the gliotic marginal zone (p < 0.05). In conclusion, the systems made real-time tumor detection and vessel tracking possible. Moreover, the autofluorescence and blood perfusion could be studied in the tumor.

Graphics processor unit acceleration enables realtime endovascular Doppler optical coherence tomography imaging: development and validation
Paper 10050-30

Author(s):  Dexter Barrows, Ryerson Univ. (Canada), et al.
Conference 10050: Clinical and Translational Neurophotonics
Session 6: Optical Spectroscopy and Tomography III

Endovascular Optical Coherence Tomography (OCT) has previously been used in both bench-top and clinical environments to produce vascular images, and can be helpful in characterizing plaque build-up and impedances to normal blood flow. However, the image processing is computationally expensive which has limited its use in a real-time environment. We leveraged Graphics Processing Units (GPUs) to perform live processing of Doppler OCT, making immediate usage with catheter-based clinical OCT systems in surgical procedures possible. Further, we validated flow data obtained in real time using a carotid flow phantom and controlled flow from an external pump.

Multimodal optical coherence tomography for in vivo imaging of brain tissue structure and microvascular network at glioblastoma
Paper 10050-33

Author(s):  Konstantin Yashin, Privolzhsky Federal Research Ctr. (Russian Federation), et al.
Conference 10050: Clinical and Translational Neurophotonics
Session PSun: Posters-Sunday

In the case of infiltrative brain tumors the surgeon faces difficulties in determining their boundaries to achieve total resection. The aim of the investigation was to evaluate the performance of multimodal OCT (MM OCT) for differential diagnostics of normal brain tissue and glioma using an experimental model of glioblastoma. The spectral domain OCT device, that was used for the study, provides simultaneously two modes: cross-polarization and microangiographic OCT. The comparative analysis of the both OCT modalities images from tumorous and normal brain tissue areas concurrently with histologic correlation shows certain difference between when accordingly to morphological and microvascular tissue features.

Investigation of prefrontal cerebral hemodynamics during quantitative autonomic testing using NIRS
Paper 10050-6

Author(s):  Zephaniah Phillips, Korea Univ. (Korea, Republic of), et al.
Conference 10050: Clinical and Translational Neurophotonics
Session 2: Optical Spectroscopy and Tomography I

In this work, we analyzed the clinical applicability of NIRS for use during Quantitative Autonomic Testing (QAT). QAT is a protocol used to diagnose a patient with disorders of the autonomic nervous system (ANS). The results of QAT are typically analyzed with blood pressure and heart rate data, however these readings can vary widely depending on the patient. We tested our custom built NIRS probe on a group of elderly patients during the QAT protocol. We found that prefrontal cerebral oxygenation correlated well with blood pressure and heart rate changes, making it a clinically feasible tool for observing ANS functionality.

Improved accuracy of brain oxygen metabolism measurements using multi-distance diffuse correlation spectroscopy and near infrared spectroscopy together with a Monte Carlo light transport model
Paper 10051-38

Author(s):  Stefan A. Carp, Athinoula A. Martinos Ctr. for Biomedical Imaging, Massachusetts Institute of Technology (United States), et al.
Conference 10051: Neural Imaging and Sensing
Session 9: NIR Imaging

Diffuse correlation spectroscopy (DCS) is being employed alongside near-infrared spectroscopy (NIRS) measurements to track the cerebral oxygen metabolic rate (CMRO2). However, both techniques employ diffusely reflected light that has traveled mostly through extracerebral tissues. The mismatch between the depth sensitivity profiles of these two methods can lead to erroneous conclusions with respect to the amount and perhaps even the direction of change in CMRO2. In this paper we employ Monte Carlo simulations based on a realistic head geometry as a light transport model and quantify the improvements offered vs. processing the measurements with a semi-infinite diffusion model.

Functional near infrared spectroscopy for awake monkey to accelerate neurorehabilitation study
Paper 10051-42

Author(s):  Hiroshi Kawaguchi, National Institute of Advanced Industrial Science and Technology (Japan), et al.
Conference 10051: Neural Imaging and Sensing
Session PMon: Posters-Monday

Functional near infrared spectroscopy (fNIRS) was applied to the measurement of the awake monkey to accelerate neurorehabilitation studies. The computer simulation of the light propagation in monkey head was performed on sophisticated anatomical models based on magnetic resonance images. We found that 15 mm is the optimal interval for the fNIRS measurement of monkey motor cortex. In the preliminary fNIRS measurement, the custom-made probe holder was attached over bilateral primary motor cortices of a monkey. Increases and decreases in oxy- and deoxy-hemoglobin were observed in the localized area in the hemisphere contralateral to the moved hand.

Method for leveling the signal-to-noise ratio in the multichannel functional near-infrared spectroscopy
Paper 10051-43

Author(s):  Toru Yamada, National Institute of Advanced Industrial Science and Technology (Japan), et al.
Conference 10051: Neural Imaging and Sensing
Session PMon: Posters-Monday

Difference in the signal-to-noise ratio (SNR) of multichannel functional near-infrared spectroscopy (fNIRS) is severe problem to quantitatively identify functional activation area. To level SNR at channels in fNIRS, a novel system equipped with optical attenuator for each light source and detector was developed. By modulating the attenuators based on a systematic procedure that mathematically formulated, light intensities at the detectors can be equalized. The apparent detector noises, thus the SNR at all the channels, are leveled through this procedure. The method was examined by using the optical phantom with partly hair-covered surface.

Photovoltaic restoration of sight in rodents with retinal degeneration
Paper 10052-16

Author(s):  Daniel V. Palanker, Stanford Univ. (United States), et al.
Conference 10052: Optogenetics and Optical Manipulation
Session 5: Stimulation III

Photovoltaic retinal prosthesis is designed to restore sight in patients blinded by the loss of photoreceptors. Visual information is projected onto the retina by video goggles using pulsed NIR light. Subretinal photovoltaic pixels convert light into pulsed electric current, stimulating the nearby inner retinal neurons. This wireless design greatly reduces the surgical complexity, allows scaling the implants to thousands of electrodes, and multiple modules can be tiled under the retina to expand the visual field. Photovoltaic arrays with 70um pixels restored visual acuity up to a single pixel pitch, which is only two times lower than natural acuity in rats.

Contralesional homotopic activity negatively influences functional recovery after stroke
Paper 10052-23

Author(s):  Adam Q. Bauer, Washington Univ. School of Medicine in St. Louis (United States), et al.
Conference 10052: Optogenetics and Optical Manipulation
Session 7: Application

Stroke disrupts functional connectivity (FC) within and across brain networks. Interestingly, acute interhemispheric homotopic FC is predictive of recovery potential. While indirect evidence suggests that homotopic brain activity may also directly impact recovery, results in humans are varied. A better understanding of how activity within networks functionally-connected to lesioned tissue influences brain plasticity might improve therapeutic strategies. We combine optogenetic targeting with optical intrinsic signal imaging to assess how contralesional activity in excitatory pyramidal neurons relates to FC, cortical remapping, and behavior after stroke. Our results suggest that increased homotopic contralesional activity negatively influences spontaneous recovery in mice following stroke.

Important Dates

Author Notification
26 September 2016

Manuscripts Due
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Journal of Biomedical Optics

Journal of Biomedical OpticsPublishes peer-reviewed papers that utilize modern optical technology for improved health care and biomedical research.