This PDF file contains the front matter associated with SPIE Proceedings Volume 10494 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

Sentinel lymph node status is a critical prognostic factor in breast cancer treatment and is essential to guide future adjuvant treatment. The estimation that 20-60% of micrometastases are missed by conventional pathology has created a demand for the development of more accurate approaches. Here, a paired-agent imaging approach is presented that employs a control imaging agent to allow rapid, quantitative mapping of microscopic populations of tumor cells in lymph nodes to guide pathology sectioning. To test the feasibility of this approach to identify micrometastases, healthy pig lymph nodes were stained with targeted and control imaging agent solution to evaluate the potential for the agents to diffuse into and out of intact nodes. Aby-029, an anti-EGFR affibody was labeled with IRDye 800CW (LICOR) as targeted agent and IRDye 700DX was hydrolyzed as a control agent. Lymph nodes were stained and rinsed by directly injecting the agents into the lymph nodes after immobilization in agarose gel. Subsequently, lymph nodes were frozen-sectioned and imaged under an 80-um resolution fluorescence imaging system (Pearl, LICOR) to confirm equivalence of spatial distribution of both agents in the entire node. The binding potentials were acquired by a pixel-by-pixel calculation and was found to be 0.02 ± 0.06 along the lymph node in the absence of binding. The results demonstrate this approach’s potential to enhance the sensitivity of lymph node pathology by detecting fewer than 1000 cell in a whole human lymph node.

Detection of surface-enhanced Raman scattering (SERS) tagged nanoparticles in-vivo is critical for its potential application in cancer diagnostics, inflammation monitoring, and glucose quantification. However, traditional optical methods are typically limited to surface level detection due to attenuation from layers of highly scattering and absorbing tissue. To break through this depth limitation, we utilize surface-enhanced spatially offset Raman spectroscopy (SESORS), a recent development for probing deep tissue that combines the high SERS signals generated by nanoparticles with a depth resolved detection technique called spatially offset Raman spectroscopy (SORS). We create a series of tissue phantoms that optically mimic tissue and embedded SERS tagged gold nanostars within them to demonstrate the ability of SESORS to distinguish signals from different layers by simply offsetting the excitation spot from the collection spot. We also show the ability to recover the subsurface SERS signal by a scaled subtraction between the spectra obtained at the 0 mm offset position and the spectra obtained at 10 mm offset position, demonstrating the ability of SESORS to isolate the subsurface SERS spectra of tagged nanoparticles.

Increased utilization of transplantation as treatment for patients with end-stage hepatic disease has resulted in a shortfall of available livers. Efforts to expand the available donor pool have resulted in the inclusion of donors who might not have been considered in the past. This has resulted in more requests for frozen section biopsy evaluation of the liver from "marginal" donors with significant co-morbidities. The information gained from the biopsy analysis determines whether the organ is suitable for transplantation. Critical to determining the adequacy of donor livers is analyzing the lipid content for macrosteatosis; high lipid livers are not suitable for transplant. Frozen section analysis (FSA) creates artifacts that limit tissue evaluation, exhausts tissue for downstream histological analysis, and requires a specialized team to evaluate these procedures in the hospital 24/7. We have developed a fluorescence microscopy system that utilizes structured illumination (SIM) to produce images of liver biopsies within seconds of removal from a deceased organ donor. Liver biopsies that require evaluation for donation suitability are stained with fast-acting fluorescent histology dyes and lipid specific stains in order to differentiate the lipids on SIM. The SIM images are compared to the standard-of-care FSA and the final pathology report. Here, we present the results of this blinded review performed by a liver pathology specialist. Imaging liver biopsies with SIM provides a more direct and accurate tool for determining macrosteatosis compared to standard FSA. SIM offers minimal tissue processing complexity and remote viewing capabilities, creating the potential to revolutionize tissue donation evaluation.

Spatial frequency domain imaging (SFDI) exploits properties of light diffused through a scattering medium to estimate the optical properties of the tissue under consideration. This non-invasive imaging modality provides full-field, quantitative and potentially real-time measurement of absorption and reduced scattering coefficient of tissues at low cost. Given the optical properties of the tissue at various wavelengths the concentration of the tissue constituents can be quantitatively estimated which can aide in medical diagnosis and health monitoring. In SFDI method, sinusoidally pattered light is projected onto the tissue/phantom and the diffuse reflectances are recorded at multiple spatial frequencies. This allows estimation of the modulation transfer function of the diffuse light propagation through the tissues. A least-square fit of the modulation transfer function with an analytical transport model or a Monte-carlo (MC) based forward model is used to estimate the optical properties of the tissues. For faster acquisition and processing, the state of the art uses a frequency-pair method where the diffuse reflectance at only two spatial frequencies [0 /mm, f /mm] are recorded and a pre-computed look-up table (computed from MC based forward model) is used for the inverse mapping to optical properties. However, the accuracy of estimation may vary with the choice of the frequency pair. In this study, the bias and variance in estimation of optical properties obtained from the frequency-pair method will be compared to values obtained from multi-frequency fits. This study aims at identifying the optimal spatial frequency that may be used to increase the accuracy of estimation of optical parameters.

Biocompatible gold nanostars (GNS) with tip-enhanced electromagnetic and optical properties have been developed and applied for multifunctional cancer diagnostics and therapy (theranostics). Their multiple sharp branches acting like “lightning rods” can convert safely and efficiently light into heat. As with other nanoparticles, GNS sizes can be controlled so that they passively accumulate in tumors due to the enhanced permeability and retention (EPR) effect of tumor vasculature. This feature improves tumor-targeting precision and permits the use of reduced laser energy required to destroy the targeted cancer cells. The ability to selectively heat tumor areas where GNS are located while keeping surrounding healthy tissues at significantly lower temperatures offers significant advantages over other thermal therapies. GNS-mediated photothermal therapy combined with checkpoint immunotherapy was shown to reverse tumor-mediated immunosuppression, leading to the treatment of not only primary tumors but also cancer metastasis as well as inducing effective long-lasting immunity, i.e. an anticancer ‘vaccine’ effect.

Recently, we discovered microscopic spherules of hydroxyapatite (HAP) in aged human sub-retinal pigment epithelial (sub-RPE) deposits in the retinas of aged humans (PMID: 25605911), and developed evidence that the spherules may act to nucleate the growth of sub-RPE deposits such as drusen. Drusen are clinical hallmarks of age-related macular degeneration (AMD). We found that tetracycline-family antibiotics, long known to stain HAP in teeth and bones, also stained the HAP spherules, but in general the HAP-bound fluorescence excitation and emission spectra overlapped with the well-known autofluorescence of the RPE overlying drusen, making them difficult to resolve. However, we also found that certain tetracyclines exhibited substantial increases in fluorescence lifetime upon binding to HAP, and moreover these lifetimes were substantially greater than those previously observed (Dysli, et al., 2014) for autofluorescence in the human retina in vivo. Thus we were able to image the HAP spherules by fluorescence lifetime imaging microscopy (FLIM) in cadaveric retinas of aged humans. These findings suggest that FLIM imaging of tetracycline binding to HAP could become a diagnostic tool for the development and progression of AMD.

Surgical 3D endoscopy based on structured illumination has been built and evaluated for application in minimally invasive anastomosis surgery which offers advantages of smaller incision, low risk of infection, quick recovery times and reduced blood loss. When combined with robotic manipulations, surgeons can perform surgical tasks with higher precision and repeatability. For reconstructive surgery such as anastomosis, a supervised laparoscopic anastomosis using a surgical robot has recently been reported with an open-surgery approach using a large 3D camera. To push the technology into minimally-invasive setting, we report an endoscopic 3D system based on structured illumination technique to assist the surgical robot, particularly in anastomosis surgery. The recorded structural profile achieves a high depth quantification of 250 um for static objects, with 25 mm depth of field. The proposed system can be integrated into a flexible holding arm to move in accordance with the surgical robotic arm. We characterize the system performance using multiple porcine intestinal tissue samples with variations in surface textures, tissue pigmentation and thickness.

Incorrect placement of the needle causes medical complications in the epidural block, such as dural puncture or spinal cord injury. This study proposes a system which combines an optical coherence tomography (OCT) imaging probe with an automatic identification (AI) system to objectively identify the position of the epidural needle tip. The automatic identification system uses three features as image parameters to distinguish the different tissue by three classifiers. Finally, we found that the support vector machine (SVM) classifier has highest accuracy, specificity, and sensitivity, which reached to 95%, 98%, and 92%, respectively.

Brain cancer diagnosis requires histological, molecular, and genomic tumor analyses. Since conventional imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) don’t provide molecular characterisation, tumor sampling is often achieved using a targeted needle biopsy approach. Targeting errors and cancer heterogeneity are important limitations of this technique, causing inaccurate sampling resulting in non-diagnostic or poor quality samples leading and the need for repeated biopsies, which poses an elevated patient risk because of infections and potential hemorrhages. Previously, we presented the design of an optically-guided brain biopsy needle using high wavenumber Raman spectroscopy (RS) to characterize tissue prior to sample collection with demonstrated efficacy in a live animal. Using an intraoperative probe we further demonstrated in vivo high wavenumber or fingerprint RS can distinguish cancer and normal brain tissue with >90% accuracy. Here we report on the design, development, and validation of a new intraoperative cancer detection optical needle system based on the combination of fingerprint and high wavenumber RS for highly accurate brain biopsy targeting based on molecular tissue features. This optical cancer detection device was engineered into the internal cannula of a widely used commercially available biopsy needle allowing tumor analysis prior to tissue harvesting with minimal workflow disruption. First in-human results are presented setting the stage for the clinical translation of this optical molecular imaging method for high yield and safe targeted brain biopsy.

Non-invasive monitoring of the transcutaneous partial pressure of oxygen (tcpO2) has great potential as the new standard of care in post-operative monitoring of autologous free flaps following cancer, trauma, or other reconstructive surgeries. Tissue perfusion and oxygenation are critical performance measures in the assessment of wound healing and graft monitoring; however, current clinical methods using near-infrared spectroscopy to probe the tissue’s oxygen saturation (StO2) from the local vasculature obscure the skin, require a wired hardware connection, and are ultimately an indirect measure. Herein we demonstrate how an optical liquid bandage, when painted on the flap skin paddle of four women undergoing a deep inferior epigastric artery perforator (DIEP) flap reconstruction after mastectomy, can be used to visualize tissue oxygenation using a simple commercial DSLR camera. Our transparent paint-on bandage formulation consists of New-Skin liquid bandage embedded with an oxygen-sensing metallo-porphyrin exhibiting bright red phosphorescence and a green-fluorescing reference dye, fluorescein. Red and green filtered photographs of the bandage were acquired for 48 hours post-operatively, and temporal changes in phosphorescence corresponding to tcpO2 were compared directly to StO2 readings obtained from a standard near-infrared tissue oximeter (ViOptix) placed on the same flap. Preliminary results show that the relative phosphorescence intensity reported by the liquid bandage inversely correlates with the stO2 values provided by the current gold standard of care, the ViOptix, as expected, while being substantially less obtrusive and enabling visualization of the flap beneath, even in patients with high melanin content, providing an additional advantage over current methods.

Clinical translation of engineered tissue constructs requires noninvasive methods to assess construct health and viability after implantation in patients. However, current practices to monitor post-implantation construct integration are either qualitative (visual assessment) or destructive (tissue histology). As label-free fluorescence lifetime sensing can noninvasively characterize pre-implantation construct viability, we employed a handheld fluorescence lifetime spectroscopy probe to quantitatively and noninvasively assess tissue constructs that were implanted in a murine model. We designed the system to be suitable for intravital measurements: portability, localization with precise maneuverability, and rapid data acquisition. Our model tissue constructs were manufactured from primary human cells to simulate patient variability and were stressed to create a range of health states. Secreted amounts of three cytokines that relate to cellular viability were measured in vitro to assess pre-implantation construct health. In vivo optical sensing assessed tissue integration of constructs at one-week and three-weeks post-implantation. At one-week post-implantation, optical parameters correlated with in vitro pre-implantation secretion levels of all three cytokines (p < 0.05). This relationship was no longer seen at three-weeks post-implantation, suggesting comparable tissue integration independent of preimplantation health. Histology confirmed re-epithelialization of these constructs independent of pre-implantation health state, supporting the lack of a correlation. These results suggest that clinical optical diagnostic tools based on label-free fluorescence lifetime sensing of endogenous tissue fluorophores could noninvasively monitor post-implantation integration of engineered tissues.

Fluorescence Lifetime Spectroscopy (FLS) enables label-free characterization of tissues using their spectral and temporal fluorescence signature. Time-domain FLS using pulse sampling is fast and not affected by external illumination and is, therefore, a great candidate for real-time surgical guidance and other inpatient applications. As currently implemented by our group, fluorescence lifetime data acquisition is performed by a single fast micro-channel plate (MCP) detector and digitizer, where the simultaneous recording of fluorescence decays in multiple spectral bands is achieved by temporal multiplexing of the different wavelength bands using increasing lengths of delay fibers. In this current form, instrumentation costs limit the use of the system for point of care applications and the ability to run multicenter studies. Furthermore, MCPs are prone to damage by excessive current or vibrations and require high voltage supplies. Here, we propose to interface fast, inexpensive Si photodetectors and amplifiers (60 dB) with each optical channel. Signal obtained from each spectral band is then sampled with a DRS4 switched capacitor array waveform digitizing chip (500 MHz bandwidth, 5 GS/s). In this compact, much lower cost instrument, the signal amplitude is matched to the A/D dynamic range for each individual channel using inexpensive RF digital step attenuators. Additionally, the signal intermodal dispersion in the delay fibers is eliminated. The influence of the decreased analog bandwidth and increased noise of this new instrument will be evaluated experimentally and compared with state-of-the-art pulse sampling FLS instrumentation.

We propose a simple fluorescent bio-chip based on two types of alternative current-dielectrophoretic (AC-DEP) force, attractive (positive DEP) and repulsive (negative DEP) force, for simultaneous nano-molecules analysis. Various radius of micro-holes on the bio-chip are designed to apply the different AC-DEP forces, and the nano-molecules are concentrated inside the micro-hole arrays according to the intensity of the DEP force. The bio-chip was fabricated by Micro Electro Mechanical system (MEMS) technique, and was composed of two layers; a SiO₂ layer and Ta/Pt layer were accomplished for an insulation layer and a top electrode with micro-hole arrays to apply electric fields for DEP force, respectively. Each SiO₂ and Ta/Pt layers were deposited by thermal oxidation and sputtering, and micro-hole arrays were fabricated with Inductively Coupled Plasma (ICP) etching process. For generation of each positive and negative DEP at micro-holes, we applied two types of sine-wave AC voltage with different frequency range alternately. The intensity of the DEP force was controlled by the radius of the micro-hole and size of nano-molecule, and calculated with COMSOL multi-physics. Three types of nano-molecules labelled with different fluorescent dye were used and the intensity of nano-molecules was examined by the fluorescent optical analysis after applying the DEP force. By analyzing the fluorescent intensities of the nano-molecules, we verify the various nano-molecules in analyte are located successfully inside corresponding micro-holes with different radius according to their size.

The goal of fluorescence-guided surgery (FGR) is to provide real-time enhancement of tumors to maximize safe resection. The optical property mapping ability of spatial frequency domain imaging (SFDI) has enabled quantitative fluorescence imaging (qFI) of protoporphyrin IX (PpIX) in gliomas in the pre-clinical setting. The goal of this study was to evaluate the feasibility of using SFDI to allow for qFI to enhance FGR. Specifically, we modified a benchtop SFDI system to mount directly to a commercial surgical microscope(Zeiss). A commercially available digital light processing module (DLI Austin, TX) was used to modulate light from a xenon arc lamp to illuminate the field. White light excitation and a liquid crystal tunable filter (LCTF Verispec) was used to measure diffuse reflectance at discreet wavelengths from 420 nm to 720 nm on a CMOS camera. An illumination side filter wheel allowed for excitation of PpIX fluorescence at 405 nm and 635 nm and the LCTF measured fluorescence emission at 670 nm and 710 nm. The ability of the clinical microscope to perform optical mapping and qFI was tested with tissue simulating phantoms and live mouse models. The results of these tests showed that SFDI can be implemented in a clinical microscope and the optical mapping and qFI abilities of SFDI may be used to enhance FGR.

Visualization and identification of critical structures such as blood vessels and tumor margins during surgery can often be difficult. The impact of misidentification of such structures can range from internal bleeding to inadequate excision of a malignant tumor and the subsequent need for additional surgery. We are developing an intraoperative device which will provide surgeons with the ability to visualize specified anatomic structures in real-time and without the use of labels (i.e. reagents). This imaging tool employs diffuse reflectance Molecular Chemical Imaging (MCI), a technology combining molecular spectroscopy and digital imaging for non-invasive, non-contact and reagentless evaluation of human tissues. In order to implement real-time sensing, we have developed a new approach to MCI, based on the principles of compressive sensing, and involving a novel, multivariate liquid crystal tunable filter technology. This technology can facilitate real-time detection of biological materials versus complex backgrounds with equal performance to that achieved by conventional MCI instruments. In this paper, we will present results demonstrating the capabilities and performance of a proof-of-concept intraoperative MCI surgical device.

Vibroacoustography (VA) is an imaging technology that utilizes the acoustic response of tissues to a localized, low frequency radiation force to generate a spatially resolved, high contrast image. Previous studies have demonstrated the utility of VA for tissue identification and margin delineation in cancer tissues. However, the relationship between specimen viscoelasticity and vibroacoustic emission remains to be fully quantified. This work utilizes the effects of variable acoustic wave profiles on unique tissue-mimicking phantoms (TMPs) to maximize VA signal power according to tissue mechanical properties, particularly elasticity. A micro-indentation method was utilized to provide measurements of the elastic modulus for each biological replica. An inverse relationship was found between elastic modulus (E) and VA signal amplitude among homogeneous TMPs. Additionally, the difference frequency (Δf ) required to reach maximum VA signal correlated with specimen elastic modulus. Peak signal diminished with increasing Δf among the polyvinyl alcohol specimen, suggesting an inefficient vibroacoustic response by the specimen beyond a threshold of resonant Δf. Comparison of these measurements may provide additional information to improve tissue modeling, system characterization, as well as insights into the unique tissue composition of tumors in head and neck cancer patients.

Tendinopathies and tendon tears heal slowly because tendons have a limited blood supply. Intense therapeutic ultrasound (ITU) is a treatment modality that creates very small, focal coagula in tissue, which can stimulate a healing response. This pilot study investigated the effects of ITU on rabbit and rat models of partial Achilles tendon rupture. The right Achilles tendons of 20 New Zealand White rabbits and 118 rats were partially transected. Twenty-four hours after surgery, ITU coagula were placed in the tendon and surrounding tissue, alternating right and left legs. At various time points, the following data were collected: ultrasound imaging, optical coherence tomography (OCT) imaging, mechanical testing, gene expression analysis, histology, and multiphoton microscopy (MPM) of sectioned tissue. Ultrasound visualized cuts and treatment lesions. OCT showed the effect of the interventions on birefringence banding caused by collagen organization. MPM showed inflammatory infiltrate, collagen synthesis and organization. By day 14- 28, all tendons had a smooth appearance and histology, MPM and OCT still could still visualize residual healing processes. Few significant results in gene expression were seen, but trends were that ITU treatment caused an initial decrease in growth and collagen gene expression followed by an increase. No difference in failure loads was found between control, cut, and ITU treatment groups, suggesting that sufficient healing had occurred by 14 days to restore all test tissue to control mechanical properties. These results suggest that ITU does not cause harm to tendon tissue. Upregulation of some genes suggests that ITU may increase healing response.

Characterization of acoustic shock wave will guarantee efficient tissue differentiation as feedback to reduce the probability of undesirable damaging (i.e. cutting) of tissues in laser surgery applications. We ablated hard (bone) and soft (muscle) tissues using a nanosecond pulsed Nd:YAG laser at 532 nm and a microsecond pulsed Er:YAG laser at 2.94 μm. When the intense short ns-pulsed laser is applied to material, the energy gain causes locally a plasma at the ablated spot that expands and propagates as an acoustic shock wave with a rarefaction wave behind the shock front. However, when using a μs-pulsed Er:YAG laser for material ablation, the acoustic shock wave is generated during the explosion of the ablated material. We measured and compared the emitted acoustic shock wave generated by a ns-pulsed Nd:YAG laser and a μs-pulsed Er:YAG laser measured by a calibrated microphone. As the acoustic shock wave attenuates as it propagates through air, the distance between ablation spots and a calibrated microphone was at 5 cm. We present the measurements on the propagation characteristics of the laser generated acoustic shock wave by measuring the arrival time-of-flight with a calibrated microphone and the energy-dependent evolution of acoustic parameters such as peak-topeak pressure, the ratio of the peak-to-peak pressures for the laser induced breakdown in air, the ablated muscle and the bone, and the spectral energy.

We present an optical coherence tomography (OCT) imaging system that effectively compensates unwanted axial motion with micron-scale accuracy. The OCT system is based on a swept-source (SS) engine (1060-nm center wavelength, 100-nm full-width sweeping bandwidth, and 100-kHz repetition rate), with axial and lateral resolutions of about 4.5 and 8.5 microns respectively. The SS-OCT system incorporates a distance sensing method utilizing an envelope-based surface detection algorithm. The algorithm locates the target surface from the B-scans, taking into account not just the first or highest peak but the entire signature of sequential A-scans. Subsequently, a Kalman filter is applied as predictor to make up for system latencies, before sending the calculated position information to control a linear motor, adjusting and maintaining a fixed system-target distance. To test system performance, the motioncorrection algorithm was compared to earlier, more basic peak-based surface detection methods and to performing no motion compensation. Results demonstrate increased robustness and reproducibility, particularly noticeable in multilayered tissues, while utilizing the novel technique. Implementing such motion compensation into clinical OCT systems may thus improve the reliability of objective and quantitative information that can be extracted from OCT measurements.

We present a method for an intraoperative microscope-mounted Fourier-domain optical coherence tomography (FD-OCT) system to maintain high image contrast while dynamic adjusting focal planes. Because two imaging system with different imaging depth are integrated into one system, active control of OCT imaging conditions is indispensible for functioning high quality imaging modality. For the purpose of active adjustment of the focal plane, an electrically focus tunable lens (FTL) was used in the sample arm of the OCT system. Because the OCT image contrast at a depth is given by roll-off characteristics of the FD-OCT that is a function of difference in OPL between the sample and reference arm, we should compensate the difference in the OPL to enhance image contrast. We proposed the use of a piezoelectric actuator (PZT) attached to a reflection optic to actively control the OPL in the reference arm. With active controlling the FTL and PZT simultaneously, we can optimize and keep the OCT image contrast while maintaining image depth positions. From a surface position in the OCT image, the focal length variations with the FTL are calculated and the focal length of the FTL is tuned to match on the sample surface. Contrast optimization with the PZT is performed with compensating the optical path length difference from the additional focal length of the FTL. We integrated the OCT to a conventional surgical microscope and demonstrate feasible observation of OCT image with high contrast at constant imaging depth under the change of focal plane of the microscope.

Deep vein thrombosis (DVT), happening in inpatients usually and especially with the postoperative population, is a serious disease characterized by an increased incidence. The venography is the golden standard to diagnose DVT. However, it involves invasive contrast agent injection and give patients physical and mental pressure. Functional nearinfrared spectroscopy (fNIRS) has been reported recently to diagnose DVT. Thrombolytic therapy activates the dissolution system with an exogenous activator that dissolves coronary thrombosis. The vena cava filter is a medical filter used for the treatment of thrombosis and the prevention of pulmonary embolism. Here we attempt to use portable NIRS for the DVT monitoring in the whole process of vena cava filter implantation and thrombolytic treatment, and contrast the patients of untreated, vena cava filter implantation and thrombolytic treatment. 19 DVT patients and 12 normal subjects were recruited. Thereinto, 7 patients have taken vena cava filter implantation, and 6 patients have taken the thrombolytic treatment. It was found that deoxyhemoglobins (Δ[Hb]) fluctuates and even increases in DVT. After vena cava filter implantation, Δ[Hb] increases first, then decreases. However, it emerges the rising trend and converge to the curves of normal subjects in thrombolytic treatment. The oxyhemoglobins (Δ[HbO₂]) emerges opposite trend in most paradigms. The findings reveal the potential of fNIRS for monitoring DVT and therapeutic effect evaluation of thrombolysis and vena cava filters.

Duchenne muscular dystrophy (DMD) is an X-linked debilitating muscular disease of mutations in the gene encoding dystrophin, a cytoskeletal protein that stabilizes the muscle membrane. The lack of dystrophin also disrupts the recruitment of neuronal nitric oxide synthase (nNOS) to the sarcolemma which may decrease NO production and lead to functional muscular ischemia. This study proposed using functional near-infrared spectroscopy (fNIRS) to evaluate the dynamic changes in muscle oxygen consumption during a 6-minute-walk test (6MWT) and a venous occlusion test (VOT) in DMD patients. A total of 60 subjects (30 DMD patients and 30 age-matched controls) were recruited. The DMD patients were classified into two groups, ambulatory (N=18) and non-ambulatory groups (N=12). Muscle oxygen consumption of forearm was evaluated noninvasively before, during and after VOT using fNIRS in all participants, while dynamic muscle oxygen consumption of gastrocnemius muscle during 6MWT was determined using fNIRS in all ambulatory participants and controls. The results revealed that impaired muscle oxygenation was observed during walking in DMD patients. Moreover, the variation of Δ[HbO2] and Δ[Hb] during VOT are significant difference among all three groups. The results implied that worsen muscle function was associated with a slower increase of muscle oxygenation during VOT. Our results suggested that the changes of muscle oxygenation during VOT are suitable for monitoring disease severity of DMD. Therefore, the method of fNIRS possesses great potential in future evaluations of DMD patients that implies a good feasibility for clinical application.

Spinal cord lesions can cause a series of severe complications, which can even lead to paralysis with high mortality. However, the traditional diagnosis of spinal cord lesion relies on complicated imaging modalities and other invasive and dangerous methods. Here, we have designed a small monitor based on NIRS technology for noninvasive monitoring for spinal cord lesions. The development of the instrument system includes the design of hardware circuits and the program of software. In terms of hardware, OPT101¹ is selected as the light detector, and the appropriate probe distribution structure is selected according to the simulation result of Monte Carlo Simulation. At the same time, the powerful controller is selected as our system’s central processing chip for the circuit design, and the data is transmitted by serial port to the host computer for post processing. Finally, we verify the stability and feasibility of the instrument system. It is found that the spinal signal could be obviously detected in the system, which indicates that our monitor based on NIRS technology has the potential to monitor the spinal lesion.

Detecting important anatomic structures including ureters and mesenteric vessels is of utmost importance to preventing unintended injury, facilitating intraoperative decision making, and potentially reducing operative time, in minimally invasive procedures performed in the abdomen. Diffuse reflectance spectroscopy (DRS) has been investigated previously for augmenting surgeon’s knowledge of tissue types intraoperatively. The potential of detecting a hollow structure by DRS is not only bounded by the parametric differences between that hollow structure and peripheral tissues including solid organs, but also determined by the relative scale between the hollow structure and the sampling depth of the probe. We have developed an applicator-probe with a 10mm source-detector distance that can be mounted on an 8mm laparoscopic instrument and passed through a 12mm trocar port for laparoscopic operability. The 10mm source-detector separation of this laparoscopically adaptable applicator probe renders sampling depth of a few millimeters for the potential of better discrimination between a hollow structure and a solid tissue parenchyma. DRS using this applicator-probe was performed on a number of hollow structures and solid organs intraoperatively in pigs. The hollow structures included urinary bladder, ureter, large intestine, small intestine, stomach, gallbladder, and mesenteric vessel. The solid organs or tissues included kidney, liver, and ovary. The ratio between the model-based normalized DRS signals at 700nm and 800nm was used as an index. An index value of 1 separates the hollow structures including ureter, bladder, and stomach (between 1 and 2) from other hollow structures including intestines and mesenteric vessel and solid organs (less than 0.7).

We previously reported a new algorithm “PV[O]H” for continuous, noninvasive, in vivo monitoring of hematocrit changes in blood and have since shown its utility for monitoring in humans during 1) hemodialysis, 2) orthostatic perturbations and 3) during blood loss and fluid replacement in a rat model. We now show that the algorithm is sensitive to changes in hemoglobin oxygen saturation. We document the phenomenology of the effect and explain the effect using new results obtained from humans and rat models. The oxygen sensitivity derives from the differential absorption of autofluorescence originating in the static tissues by oxy and deoxy hemoglobin. Using this approach we show how to perform simultaneous, noninvasive, in vivo, continuous monitoring of hematocrit, vascular volume, hemoglobin oxygen saturation, pulse rate and breathing rate in mammals using a single light source. We suspect that monitoring of changes in this suite of vital signs can be provided with improved time response, sensitivity and precision compared to existing methodologies. Initial results also offer a more detailed glimpse into the systemic oxygen transport in the circulatory system of humans.

At the present time a definite assessment of cancer diagnosis can only be made after the microscopic analysis of histological cuts of tissue biopsies. Pathologists have to prepare and analyze a considerable amount of histological slides. The accuracy of diagnostics strongly relies on the experience of medical doctor performing histological analysis. Hence, the search for new efficient techniques helping pathologists to sort out the vast majority of histological slides and significantly reduce the time of diagnostic is of paramount importance. The potential of Mueller polarimetry to become a new optical tool for digitally assisted automated polarized light histology was exploited within the framework of differential Mueller matrix formalism. The measurements of thin scattering anisotropic phantoms and histological slides of fixed unstained healthy and cancerous human tissue (basal cell carcinoma of skin, adenocarcinoma of colon) were performed in transmission configuration with custom-build Mueller polarimetric microscope. In-house Monte Carlo software for the solution of vector radiative transfer equation in scattering anisotropic media was used for the interpretation of experimental Mueller matrices. The use of phenomenological theory of anisotropic scattering fluctuating medium based on differential Mueller matrix formalism (i. e. logarithmic decomposition of Mueller matrices) combined with an appropriate algorithm of polarimetric image segmentation and statistical analysis of experimental data provide new insight on set of optical markers (e.g. linear/circular retardance, linear/circular depolarization) which increase significantly the contrast between cancerous and healthy zones of tissue histological cuts and assure high sensitivity and specificity of polarimetric optical diagnostics of cancer.

Early detection and treatment of arthritis is essential for a successful outcome of the treatment, but it has proven to be very challenging with existing diagnostic methods. Novel methods based on the optical imaging of the affected joints are becoming an attractive alternative. A non-contact multispectral imaging (MSI) system for imaging of small joints of human hands and feet is being developed. In this work, a numerical simulation of the MSI system is presented. The purpose of the simulation is to determine the optimal design parameters. Inflamed and unaffected human joint models were constructed with a realistic geometry and tissue distributions, based on a MRI scan of a human finger with a spatial resolution of 0.2 mm. The light transport simulation is based on a weighted-photon 3D Monte Carlo method utilizing CUDA GPU acceleration. An uniform illumination of the finger within the 400-1100 nm spectral range was simulated and the photons exiting the joint were recorded using different acceptance angles. From the obtained reflectance and transmittance images the spectral and spatial features most indicative of inflammation were identified. Optimal acceptance angle and spectral bands were determined. This study demonstrates that proper selection of MSI system parameters critically affects ability of a MSI system to discriminate the unaffected and inflamed joints. The presented system design optimization approach could be applied to other pathologies.

Near infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS) has been used to measure brain activation, which are clinically important. Monte Carlo simulation has been applied to the near infrared light propagation model in biological tissue, and has the function of predicting diffusion and brain activation. However, previous studies have rarely considered hair and hair follicles as a contributing factor. Here, we attempt to use MCVM (Monte Carlo simulation based on 3D voxelized media) to examine light transmission, absorption, fluence, spatial sensitivity distribution (SSD) and brain activation judgement in the presence or absence of the hair follicles. The data in this study is a series of high-resolution cryosectional color photograph of a standing Chinse male adult. We found that the number of photons transmitted under the scalp decreases dramatically and the photons exported to detector is also decreasing, as the density of hair follicles increases. If there is no hair follicle, the above data increase and has the maximum value. Meanwhile, the light distribution and brain activation have a stable change along with the change of hair follicles density. The findings indicated hair follicles make influence of NIRS in light distribution and brain activation judgement.

The location of the source-detector relative to the anomaly whose optical properties is different from normal tissue has an important influence on the detection effect based on near - infrared spectroscopy for intracranial anomaly detection. In this study we propose a distribution structure of Single-Source Multi-Detectors (SS-MD) in order to realize the rapid localization of intracranial anomaly. A novel approach we use differential optical density difference to determine the location of anomaly, since the shape of the differential optical density curve of the two adjacent detectors is significantly related to the position of the anomaly.The finite element optical simulations were performed on anomaly with different sizes, horizontal positions and depths using SS-MD distribution structure. The distribution structure of SS-MD and the differential optical density difference curve can be used to quickly and accurately realize the localization of the anomaly, which plays an important role in optimizing the location of the source-detectors in the near infrared spectroscopy and improving the accuracy of the clinical detection of anomaly.

Wide-field tissue imaging is usually not capable of resolving tissue microstructure. We present High Spatial Frequency Domain Imaging (HSFDI) - a noncontact imaging modality that spatially maps the tissue microscopic scattering structures over a large field of view. Based on an analytical reflectance model of sub-diffusive light from forward-peaked highly scattering media, HSFDI quantifies the spatially-resolved parameters of the light scattering phase function from the reflectance of structured light modulated at high spatial frequencies. We have demonstrated with ex vivo cancerous tissue to validate the robustness of HSFDI in significant contrast and differentiation of the microstructutral parameters between different types and disease states of tissue.

Oral cancer is the 11th most common cancer worldwide, especially in a male adult. The median age of death in oral cancer was 55 years, 10-20 years earlier than other cancers. Presently, oral cancer is often found in late stage, because the lesion is often flat in early stage and is difficult to diagnose under traditional white light imaging. The only definitive method for determining cancer is an invasive biopsy and then using histology examination. How to detect precancerous lesions or early malignant lesions is an important issue for improving prognosis of oral cancer. Optical coherence tomography (OCT) is a new optical tool for diagnosing early malignant lesions in the skin or gastrointestinal tract recently. Here we report a new method for detecting precancerous or early malignant oral lesions by using swept source polarization-sensitive optical coherence tomography (PS-OCT) with center-wavelength 1310 nm, bandwidth 110 nm and 100 kHz swept rate. We used all single-mode fiber design to detect the change of birefringence information in the epithelium structure. This system has an advantage that enables measurement of backscattered intensity and birefringence simultaneously with only one A-scan per transverse location. In preliminary result, we computed the slope of the every A-scan signal in tissue part using a linear-curve fitting in backscattered intensity and birefringence on the enface. In this research, we used an oral cancer mice model for observing the change of structure and birefringence properties in different stages of oral cancer mice. We presented the parametric enface imaging that can detect the early oral malignant lesions.

Brain death is defined as permanent loss of the brain functions. The evaluation of it has many meanings, such as the relief of organ transplantation stress and family burden. However, it is hard to be judged precisely. The standard clinical tests are expensive, time consuming and even dangerous, and some auxiliary methods have limitations. Functional near infrared spectroscopy (fNIRS), monitoring cerebral hemodynamic responses noninvasively, evaluate brain death in some papers published, but there is no discussion about which experimental mode can monitor brain death patient more sensitively. Here, we attempt to use our fNIRS to evaluate brain death and find which experimental mode is effective. In order to discuss the problem, we detected eleven brain death patients and twenty normal patients under natural state. They were provided different fraction of inspiration O₂ (FIO₂) in different phase. We found that the ratio of ∆[HbO₂] (the concentration changes in oxyhemoglobin) to ∆[Hb] (the concentration changes in deoxyhemoglobin) in brain death patients is significantly higher than normal patients in FIO₂ experiment. Combined with the data analysis result, restore oxygen change process and low-high-low paradigm is more sensitively.

Two-thirds of out-of-hospital cardiac arrest patients, who survive to hospital admission, die in the hospital from neurological injuries related to cerebral hypoperfusion. Hyperspectral near infrared spectroscopy (hNIRS) is a noninvasive technique that measures the major chromophores in the brain, such as oxygenated hemoglobin, deoxygenated hemoglobin and cytochrome C oxidase ([CCO]), an intracellular marker of oxygen consumption. We have demonstrated that hNIRS is feasible and can detect changes in cerebral oxygenation and metabolism in patients undergoing transcatheter aortic valve insertion (TAVI) – a procedure that temporarily induces sudden hypotension and hypoperfusion that mimics cardiac arrest. Using multi-distance hNIRS, we found that while measured regional oxygen saturation (rSO2) changes resulted mainly from the extra-cerebral tissues, [CCO] changes during cardiac arrests occurred mainly in the brains of patients. We also applied the hNIRS algorithm based on the “2-layer model” to the data to measure cerebral oxygen saturation and [CCO] in patients during the procedure.

Functional gastrointestinal disorders (FGID) are the most common gastrointestinal disorders. The term "functional" is generally applied to disorders where there are no structural abnormalities. One of the major factors for FGID is abnormal gastrointestinal motility. We have proposed a system for assessing the function of gastric motility using a 3D endoscope. In this previous study, we established a method for estimating characteristics of contraction wave extracted from a 3D shape include contraction wave obtained from stereo endoscope. Because it is difficult to fix the tip position of the endoscope during the examination, estimation of the 3D position between the endoscope and the gastric wall is necessary for the accurate assessment. Then, we have proposed a motion compensation method using 3D scene flow. However, since mucosa has few feature points, it is difficult to obtain 3D scene flow from RGB images. So, we focused on spectral imaging that can enhance visualization of mucosal structure. Spectral image can be obtained without switching optical filters by using technique to estimate spectral reflectance by image processing. In this paper, we propose registration method of measured 3D shape in time series using estimated spectral image. The spectral image is estimated from the RGB image for each frame. 3D scene flow of feature points, that is, enhanced mucosal structure calculated by spectral images in a time series. The position change between the endoscope and gastric wall is estimated by 3D scene flow. We experimented to confirm the validity of the proposed method using papers with a grid of colors close to the background color.

There currently is a limited ability to interactively study developmental cardiac mechanics and physiology. We therefore combined light-sheet fluorescence microscopy (LSFM) with virtual reality (VR) to provide a hybrid platform for 3- dimensional (3-D) architecture and time-dependent cardiac contractile function characterization. By taking advantage of the rapid acquisition, high axial resolution, low phototoxicity, and high fidelity in 3-D and 4-D (3-D spatial + 1-D time or spectra), this VR-LSFM hybrid methodology enables interactive visualization and quantification otherwise not available by conventional methods such as routine optical microscopes. We hereby demonstrate multi-scale applicability of VR-LSFM to 1) interrogate skin fibroblasts interacting with a hyaluronic acid-based hydrogel, 2) navigate through the endocardial trabecular network during zebrafish development, and 3) localize gene therapy-mediated potassium channel expression in adult murine hearts. We further combined our batch intensity normalized segmentation (BINS) algorithm with deformable image registration (DIR) to interface a VR environment for the analysis of cardiac contraction. Thus, the VR-LSFM hybrid platform demonstrates an efficient and robust framework for creating a user-directed microenvironment in which we uncovered developmental cardiac mechanics and physiology with high spatiotemporal resolution.