Symmetricity analysis of time to peak parameter of indocyanine green dynamics
Author(s):
Yuri An;
Jungsul Lee;
Chulhee Choi
Show Abstract
We have previously discovered that near-infrared optical imaging of indocyanine green (ICG) signal and analyzing its dynamics can be applied for measurement of blood perfusion rate and detection of Raynaud’s phenomenon (RP). Especially, RP is closely associated with abnormal vasomotor responses and can progress to tissue necrosis due to excessively sustained vasoconstriction. Therefore, early detecting of RP is one of important implication to prevent tissue damage from peripheral vascular disorders. In the present study, we propose new analysis and scoring method of symmetricity of Tmax value of left and right extremities. Moreover, this symmetricity analysis can give further information about microvascular insufficiency. For validation of the proposed method, we tested whether the segmental and paired analysis of Tmax value (time-to-peak) of ICG dynamics can be used for sensitive diagnosis of microvascular abnormalities which cannot be detected by conventional methods. From the near-infrared images of diabetes mellitus patients with vascular complications, the trend of asymmetry in Tmax value was observed. We assumed that decreasing local blood perfusion by autonomic nerve dysfunction causes the asymmetric Tmax value of right and left feet. These results collectively indicate that the proposed method can be used as a useful diagnostic tool for RP or other microvascular disorders.
Photometric sensor system for a non-invasive real-time hemoglobin monitoring
Author(s):
Ulrich Timm;
Jens Kraitl;
Kirstin Schnurstein;
Hartmut Ewald
Show Abstract
Hemoglobin (Hb) is an important component of red blood cells. The primary function of Hb is the transport of oxygen
from the lungs to the tissue and carbon dioxide back to the lungs. The Hb concentration in human blood is an important
parameter in evaluating the physiological status of an individual and an essential parameter in every blood count.
Invasive methods are used to measure the Hb concentration, whereby blood is taken from the patient and subsequently
analyzed. Apart from the discomfort of drawing blood samples, an added disadvantage of this method is the delay
between the blood collection and its analysis, which does not allow real time patient monitoring in critical situations. A
non-invasive method allows pain free continuous on-line patient monitoring with minimum risk of infection and
facilitates real time data monitoring allowing immediate clinical reaction to the measured data.
Laser reflectance oximetry and Doppler flowmetry in assessment of complex physiological parameters of cutaneous blood microcirculation
Author(s):
Andrey V. Dunaev;
Victor V. Sidorov;
Neil A. Stewart;
Sergei G. Sokolovski;
Edik U. Rafailov
Show Abstract
The integration of multiple optical techniques within a single diagnostic device is used to address the difficulties in standardising measurement of cutaneous blood micro-dynamics caused by high variability. We demonstrate the benefits of simultaneous assessment of blood relative volume (Vb), microcirculation index (Im) and tissue oxygen saturation (StO2), during long-term examination of healthy volunteers. Consequently, five rhythmic components: endothelial, neurogenic, myogenic, breath and heart pulses were established showing high variability up to 30 – 50% as well as in initial parameters around 16%. All rhythmic components were synchronous with some latency between Im and StO2 in the myogenic component supports the hypothesis of strong correlation between peripheral hemodynamics and oxygen utilisation in tissues.
Non-contact tissue perfusion and oxygenation imaging using a LED based multispectral and a thermal imaging system, first results of clinical intervention studies
Author(s):
John H. G. M. Klaessens;
Martin Nelisse;
Rudolf M. Verdaasdonk;
Herke Jan Noordmans
Show Abstract
During clinical interventions objective and quantitative information of the tissue perfusion, oxygenation or temperature can be useful for the surgical strategy. Local (point) measurements give limited information and affected areas can easily be missed, therefore imaging large areas is required. In this study a LED based multispectral imaging system (MSI, 17 different wavelengths 370nm-880nm) and a thermo camera were applied during clinical interventions: tissue flap transplantations (ENT), local anesthetic block and during open brain surgery (epileptic seizure). The images covered an area of 20x20 cm, when doing measurements in an (operating) room, they turned out to be more complicated than laboratory experiments due to light fluctuations, movement of the patient and limited angle of view. By constantly measuring the background light and the use of a white reference, light fluctuations and movement were corrected. Oxygenation concentration images could be calculated and combined with the thermal images. The effectively of local anesthesia of a hand could be predicted in an early stage using the thermal camera and the reperfusion of transplanted skin flap could be imaged. During brain surgery, a temporary hyper-perfused area was witnessed which was probably related to an epileptic attack. A LED based multispectral imaging system combined with thermal imaging provide complementary information on perfusion and oxygenation changes and are promising techniques for real-time diagnostics during clinical interventions.
Super-resolution method for arbitrary retrospective sampling in fluorescence tomography with raster scanning photodetectors
Author(s):
Xiaofeng Zhang
Show Abstract
Dense spatial sampling is required in high-resolution optical imaging and many other biomedical optical imaging
methods, such as diffuse optical imaging. Arrayed photodetectors, in particular charge coupled device cameras are
commonly used mainly because of their high pixel count. Nonetheless, discrete-element photodetectors, such as
photomultiplier tubes, are often desirable in many performance-demanding imaging applications. However, utilization of
the discrete-element photodetectors typically requires raster scan to achieve arbitrary retrospective sampling with high
density. Care must be taken in using the relatively large sensitive areas of discrete-element photodetectors to densely
sample the image plane. In addition, off-line data analysis and image reconstruction often require full-field sampling.
Pixel-by-pixel scanning is not only slow but also unnecessary in diffusion-limited imaging. We propose a superresolution
method that can recover the finer features of an image sampled with a coarse-scale sensor. This generalpurpose
method was established on the spatial transfer function of the photodetector-lens system, and achieved superresolution
by inversion of this linear transfer function. Regularized optimization algorithms were used to achieve
optimized deconvolution. Compared to the uncorrected blurred image, the proposed super-resolution method
significantly improved image quality in terms of resolution and quantitation. Using this reconstruction method, the
acquisition speed with a scanning photodetector can be dramatically improved without significantly sacrificing sampling
density or flexibility.
Portable wide-field hand-held NIR scanner
Author(s):
Young-Jin Jung;
Manuela Roman;
Jennifer Carrasquilla;
Sarah J. Erickson;
Anuradha Godavarty
Show Abstract
Near-infrared (NIR) optical imaging modality is one of the widely used medical imaging techniques for breast cancer
imaging, functional brain mapping, and many other applications. However, conventional NIR imaging systems are
bulky and expensive, thereby limiting their accelerated clinical translation. Herein a new compact (6 × 7 × 12 cm3),
cost-effective, and wide-field NIR scanner has been developed towards contact as well as no-contact based real-time
imaging in both reflectance and transmission mode. The scanner mainly consists of an NIR source light (between 700-
900 nm), an NIR sensitive CCD camera, and a custom-developed image acquisition and processing software to image an
area of 12 cm2. Phantom experiments have been conducted to estimate the feasibility of diffuse optical imaging by using
Indian-Ink as absorption-based contrast agents. As a result, the developed NIR system measured the light intensity
change in absorption-contrasted target up to 4 cm depth under transillumination mode. Preliminary in-vivo studies
demonstrated the feasibility of real-time monitoring of blood flow changes. Currently, extensive in-vivo studies are
carried out using the ultra-portable NIR scanner in order to assess the potential of the imager towards breast imaging..
High-resolution spectrometer: solution to the axial resolution and ranging depth trade-off of SD-OCT
Author(s):
Tahereh Marvdashti;
Hee Yoon Lee;
Audrey K. Ellerbee
Show Abstract
We demonstrate a cross-dispersed spectrometer for Spectral Domain Optical Coherence Tomography (SD-OCT). The resolution of a conventional SD-OCT spectrometer is limited by the available sizes of the linear array detectors. The adverse consequences of this finite resolution is a trade-off between achieving practical field of view (i.e. ranging depth) and maintaining high axial resolution. Inspired by spectrometer designs for astronomy, we take advantage of very high pixel-density 2D CCD arrays to map a single-shot 2D spectrum to an OCT A-scan. The basic system can be implemented using a high-resolution Echelle grating crossed with a prism in a direction orthogonal to the dispersion axis. In this geometry, the interferometric light returning from the OCT system is dispersed in two dimensions; the resulting spectrum can achieve more pixels than a traditional OCT spectrometer (which increases the ranging depth) and maintains impressive axial resolution because of the broad bandwidth of the detected OCT light. To the best of our knowledge, we present the first demonstration of OCT data using an Echelle-based cross-dispersed spectrometer. Potential applications for such a system include high-resolution imaging of the retina or the anterior segment of the eye over extended imaging depths and small animal imaging.
Sentinel lymph nodes detection with an imaging system using Patent Blue V dye as fluorescent tracer
Author(s):
F. Tellier;
J. Steibel;
R. Chabrier;
J. F. Rodier;
G. Pourroy;
P. Poulet
Show Abstract
Sentinel lymph node biopsy is the gold standard to detect metastatic invasion from primary breast cancer. This method
can help patients avoid full axillary chain dissection, thereby decreasing the risk of morbidity. We propose an alternative
to the traditional isotopic method, to detect and map the sentinel lymph nodes. Indeed, Patent Blue V is the most widely
used dye in clinical routine for the visual detection of sentinel lymph nodes. A Recent study has shown the possibility of
increasing the fluorescence quantum yield of Patent Blue V, when it is bound to human serum albumin. In this study we
present a preclinical fluorescence imaging system to detect sentinel lymph nodes labeled with this fluorescent tracer. The
setup is composed of a black and white CCD camera and two laser sources. One excitation source with a laser emitting at
635 nm and a second laser at 785 nm to illuminate the region of interest. The prototype is operated via a laptop.
Preliminary experiments permitted to determine the device sensitivity in the μmol.L-1 range as regards the detection of
PBV fluorescence signals. We also present a preclinical evaluation performed on Lewis rats, during which the
fluorescence imaging setup detected the accumulation and fixation of the fluorescent dye on different nodes through the
skin.
Laser line scanning illumination scheme for the enhancement of contrast and resolution for fluorescence reflectance imaging
Author(s):
F. Fantoni;
L. Hervé;
V. Poher;
S. Gioux;
J. Mars;
J. M. Dinten
Show Abstract
Intraoperative fluorescence imaging in reflectance geometry is an attractive imaging modality as it allows to
noninvasively monitor fluorescence targeted tumors located below the tissue surface. The drawbacks of this technique are the poor resolution in the axial and lateral directions due to multiple light scattering and background
fluorescence decreasing the contrast.
We propose a novel fluorescence imaging method based on laser line illumination in reflectance geometry. We
scan the medium with the laser line and acquire images at each position of the line. We then detect only single
stripes of each image located on the excitation line or farther from it. We can also subtract the surrounding
signal to the detected stripe, the optimal detection scheme depending on the depth of the object of interest. This
allows us to reduce the contribution of parasite signals such as background fluorescence or excitation leaks and
also enhances the resolution. These operations on the images can either be digitally done in post-processing or
can directly be hardware implemented, allowing our method to be integrated in a handheld device for real-time
use.
This technique has been validated with tissue-like liquid phantoms with different levels of background fluorescence. Fluorescent inclusions are observed in several configurations at depths ranging from 1 mm to 1 cm. Our
results are compared to those obtained with a more classical wide-field detection scheme. Finally, we propose
a setup to optically implement the masking detection that will dramatically fasten the detection scheme and
optimize the fluorescence light throughput of the system.
Combination of widefield fluorescence imaging and nonlinear optical microscopy of oral epithelial neoplasia
Author(s):
Rahul Pal;
Kert Edward;
Tyra Brown;
Liang Ma;
Jinping Yang;
Susan McCammon;
Massoud Motamedi;
Gracie Vargas
Show Abstract
Multiphoton Autofluorescence Microscopy (MPAM) and Second Harmonic Generation Microscopy (SHGM) have shown the potential for noninvasive assessment of oral precancers and cancers. We have explored a combination of these nonlinear optical microscopic imaging techniques with widefield fluorescence imaging to assess morphometry similar to that of pathologic evaluation as well as information from endogenous fluorophores, which are altered with neoplastic transformation. Widefield fluorescence revealed areas of interest corresponding to sites with precancers or early tumors, generally resulting in a decrease in green emission or increase in red emission. Subsequent microscopy revealed significant differences in morphology between normal, dysplastic/neoplastic mucosa for all layers. Combination of a widefield and a microscopic technique provides a novel approach for tissue morphometric analysis along with large area assessment of tissue autofluorescence properties.
Infrared dermal thermography on diabetic feet soles to predict ulcerations: a case study
Author(s):
Chanjuan Liu;
Ferdi van der Heijden;
Marvin E. Klein;
Jeff G. van Baal;
Sicco A. Bus;
Jaap J. van Netten
Show Abstract
Diabetic foot ulceration is a major complication for patients with diabetes mellitus. If not adequately treated, these ulcers may lead to foot infection, and ultimately to lower extremity amputation, which imposes a major burden to society and great loss in health-related quality of life for patients. Early identification and subsequent preventive treatment have proven useful to limit the incidence of foot ulcers and lower extremity amputation. Thus, the development of new diagnosis tools has become an attractive option. The ultimate objective of our project is to develop an intelligent telemedicine monitoring system for frequent examination on patients’ feet, to timely detect pre-signs of ulceration. Inflammation in diabetic feet can be an early and predictive warning sign for ulceration, and temperature has been proven to be a vicarious marker for inflammation. Studies have indicated that infrared dermal thermography of foot soles can be one of the important parameters for assessing the risk of diabetic foot ulceration. This paper covers the feasibility study of using an infrared camera, FLIR SC305, in our setup, to acquire the spatial thermal distribution on the feet soles. With the obtained thermal images, automated detection through image analysis was performed to identify the abnormal increased/decreased temperature and assess the risk for ulceration. The thermography for feet soles of patients with diagnosed diabetic foot complications were acquired before the ordinary foot examinations. Assessment from clinicians and thermography were compared and follow-up measurements were performed to investigate the prediction. A preliminary case study will be presented, indicating that dermal thermography in our proposed setup can be a screening modality to timely detect pre-signs of ulceration.
Laser scanning cytometry as a tool for biomarker validation
Author(s):
Anja Mittag;
Christiane Füldner;
Jörg Lehmann;
Attila Tarnok
Show Abstract
Biomarkers are essential for diagnosis, prognosis, and therapy. As diverse is the range of diseases the broad is the range of biomarkers and the material used for analysis. Whereas body fluids can be relatively easily obtained and analyzed, the investigation of tissue is in most cases more complicated. The same applies for the screening and the evaluation of new biomarkers and the estimation of the binding of biomarkers found in animal models which need to be transferred into applications in humans. The latter in particular is difficult if it recognizes proteins or cells in tissue. A better way to find suitable cellular biomarkers for immunoscintigraphy or PET analyses may be therefore the in situ analysis of the cells in the respective tissue. In this study we present a method for biomarker validation using Laser Scanning Cytometry which allows the emulation of future in vivo analysis. The biomarker validation is exemplarily shown for rheumatoid arthritis (RA) on synovial membrane. Cryosections were scanned and analyzed by phantom contouring. Adequate statistical methods allowed the identification of suitable markers and combinations. The fluorescence analysis of the phantoms allowed the discrimination between synovial membrane of RA patients and non-RA control sections by using median fluorescence intensity and the “affected area”. As intensity and area are relevant parameters of in vivo imaging (e.g. PET scan) too, the presented method allows emulation of a probable outcome of in vivo imaging, i.e. the binding of the target protein and hence, the validation of the potential of the respective biomarker.
Wide-field flexible endoscope for simultaneous color and NIR fluorescence image acquisition during surveillance colonoscopy
Author(s):
P. Beatriz García-Allende;
Wouter B. Nagengast;
Jürgen Glatz;
Vasilis Ntziachristos
Show Abstract
Colorectal cancer (CRC) is the third most common form of cancer and, despite recent declines in both incidence and
mortality, it still remains the second leading cause of cancer-related deaths in the western world. Colonoscopy is the
standard for detection and removal of premalignant lesions to prevent CRC. The major challenges that physicians face
during surveillance colonoscopy are the high adenoma miss-rates and the lack of functional information to facilitate
decision-making concerning which lesions to remove. Targeted imaging with NIR fluorescence would address these
limitations. Tissue penetration is increased in the NIR range while the combination with targeted NIR fluorescent agents
provides molecularly specific detection of cancer cells, i.e. a red-flag detection strategy that allows tumor imaging with
optimal sensitivity and specificity. The development of a flexible endoscopic fluorescence imaging method that can be
integrated with standard medical endoscopes and facilitates the clinical use of this potential is described in this work. A
semi-disposable coherent fiber optic imaging bundle that is traditionally employed in the exploration of biliary and
pancreatic ducts is proposed, since it is long and thin enough to be guided through the working channel of a traditional
video colonoscope allowing visualization of proximal lesions in the colon. A custom developed zoom system magnifies
the image of the proximal end of the imaging bundle to fill the dimensions of two cameras operating in parallel providing
the simultaneous color and fluorescence video acquisition.
Real-time endoscopic guidance using near-infrared fluorescent light for thoracic surgery
Author(s):
Vivek Venugopal;
Alan Stockdale;
Florin Neacsu;
Frank Kettenring;
John V. Frangioni;
Sidharta P. Gangadharan;
Sylvain Gioux
Show Abstract
Lung cancer is the leading cause of cancer death in the United States, accounting for 28% of all cancer deaths. Standard of care for potentially curable lung cancer involves preoperative radiographic or invasive staging, followed by surgical resection. With recent adjuvant chemotherapy and radiation studies showing a survival advantage in nodepositive patients, it is crucial to accurately stage these patients surgically in order to identify those who may benefit. However, lymphadenectomy in lung cancer is currently performed without guidance, mainly due to the lack of tools permitting real-time, intraoperative identification of lymph nodes. In this study we report the design and validation of a novel, clinically compatible near-infrared (NIR) fluorescence thoracoscope for real-time intraoperative guidance during lymphadenectomy. A novel, NIR-compatible, clinical rigid endoscope has been designed and fabricated, and coupled to a custom source and a dual channel camera to provide simultaneous color and NIR fluorescence information to the surgeon. The device has been successfully used in conjunction with a safe, FDA-approved fluorescent tracer to detect and resect mediastinal lymph nodes during thoracic surgery on Yorkshire pigs. Taken together, this study lays the foundation for the clinical translation of endoscopic NIR fluorescence intraoperative guidance and has the potential to profoundly impact the management of lung cancer patients.
Exploiting multimode waveguides for pure fibre based fluorescence imaging
Author(s):
Tomáš Čižmár;
Kishan Dholakia
Show Abstract
There has been an immense drive in modern microscopy towards miniaturisation and _bre based technology.
This has been necessitated by the need to access hostile or difficult environments particulalrly in-situ and in-vivo.
Strategies to date have included the use of specialist fibres and miniaturised scanning systems accompanied by
ingenious microfabricated lenses. In parallel recent studies of randomized light fields and their holographic control
opened up new ways for imaging. We present a novel approach for this field by utilising disordered light within
a standard multimode optical fibre for minimally invasive lenseless microscopy and optical mode conversion. We
demonstrate scanning uorescence microscopy at acquisition rates allowing observation of dynamic processes
such as Brownian motion of mesoscopic particles. As the sample plane can be defined at any distance from
the fibre facet, we eliminate the need for complex or elaborate focusing optics (e.g. miniaturized objectives,
GRIN lenses) and instead reconfigure the system dynamically to image different axial planes. Furthermore,
we show how such control can realise a new form of mode converter and generate various types of advanced
light fields such as propagation-invariant beams and optical vortices. These may be useful for future fibre based
implementations of super-resolution or light sheet microscopy. To the best of our knowledge, this technology
represents the narrowest possible image guiding system based on light propagation.
Mobile large area confocal scanner for imaging tumor margins: initial testing in the pathology department
Author(s):
Sanjee Abeytunge;
Yongbiao Li;
Bjorg Larson;
Gary Peterson;
Ricardo Toledo-Crow;
Milind Rajadhyaksha
Show Abstract
Surgical oncology is guided by examining pathology that is prepared during or after surgery. The preparation time for Mohs surgery in skin is 20-45 minutes, for head-and-neck and breast cancer surgery is hours to days. Often this results in incomplete tumor removal such that positive margins remain. However, high resolution images of excised tissue taken within few minutes can provide a way to assess the margins for residual tumor. Current high resolution imaging methods such as confocal microscopy are limited to small fields of view and require assembling a mosaic of images in two dimensions (2D) to cover a large area, which requires long acquisition times and produces artifacts. To overcome this limitation we developed a confocal microscope that scans strips of images with high aspect ratios and stitches the acquired strip-images in one dimension (1D). Our “Strip Scanner” can image a 10 x 10 mm2 area of excised tissue with sub-cellular detail in about one minute. The strip scanner was tested on 17 Mohs excisions and the mosaics were read by a Mohs surgeon blinded to the pathology. After this initial trial, we built a mobile strip scanner that can be moved into different surgical settings. A tissue fixture capable of scanning up to 6 x 6 cm2 of tissue was also built. Freshly excised breast and head-and-neck tissues were imaged in the pathology lab. The strip-images were registered and displayed simultaneously with image acquisition resulting in large, high-resolution confocal mosaics of fresh surgical tissue in a clinical setting.
In-depth performance analysis of the HyperFlux spectrometer
Author(s):
Jeffrey T. Meade;
Bradford B. Behr;
Yusuf Bismilla;
Andrew T. Cenko;
Arsen R. Hajian
Show Abstract
Tornado Spectral Systems introduced the HyperFluxTM spectrometer to the market in early 2012. The Hyper-
Flux is the world’s first HTVS (high-throughput virtual slit) enabled spectrometer and is able to achieve much
greater system flux compared to slit-based spectrometers. Since the HyperFlux’s debut extensive studies into
the manufacturability, stability, and detector electronic performance have been performed and are presented in
this paper. A generalized quantitative approach to spectrometer comparison by using a clearly-defined Quality
Factor is presented at the end of the paper.
Raman microspectrometer combined with scattering microscopy and lensless imaging for bacteria identification
Author(s):
S. A. Strola;
E. Schultz;
C. P. Allier;
B. DesRoches;
J. Lemmonier;
J.-M. Dinten
Show Abstract
In this paper, we report on a compact prototype capable both of lensfree imaging, Raman spectrometry and scattering
microscopy from bacteria samples. This instrument allows high-throughput real-time characterization without the need
of markers, making it potentially suitable to field label-free biomedical and environmental applications.
Samples are illuminated from above with a focused-collimated 532nm laser beam and can be x-y-z scanned. The bacteria
detection is based on emerging lensfree imaging technology able to localize cells of interest over a large field-of-view of
24mm2.
Raman signal and scattered light are then collected by separate measurement arms simultaneously. In the first arm the
emission light is fed by a fiber into a prototype spectrometer, developed by Tornado Spectral System based on Tornado’s
High Throughput Virtual Slit (HTVS) novel technology. The enhanced light throughput in the spectral region of interest
(500-1800 cm-1) reduces Raman acquisition time down to few seconds, thus facilitating experimental protocols and
avoiding the bacteria deterioration induced by laser thermal heating. Scattered light impinging in the second arm is
collected onto a charge-coupled-device. The reconstructed image allows studying the single bacteria diffraction pattern
and their specific structural features.
The characterization and identification of different bacteria have been performed to validate and optimize the acquisition
system and the component setup.
The results obtained demonstrate the benefits of these three techniques combination by providing the precise bacteria
localization, their chemical composition and a morphology description. The procedure for a rapid identification of
particular pathogen bacteria in a sample is illustrated.
Classification of Raman spectra of bacteria using rank order kernels
Author(s):
Alexandros Kyriakides;
Evdokia Kastanos;
Katerina Hadjigeorgiou;
Costas Pitris
Show Abstract
The range of applications of Raman-based classification has expanded significantly, including applications in
bacterial identification. In this paper, we propose the use of Rank Order Kernels to classify bacterial samples.
Rank Order Kernels are two-dimensional image functions which operate on two-dimensional images. The first
step in the classification therefore, is to transform the Raman spectra to two-dimensional images. This is achieved
by splitting the spectra into segments and calculating the ratio between the mean value of each and every other
segment. This creates a two-dimensional matrix of ratios for each Raman spectrum. A similarity metric based
on rank order kernels operating on the two-dimensional matrices is then used with a nearest neighbor algorithm
for classification. Our results show that this method is comparable in accuracy to other methods which were
used previously for the same data set.
Integrated fingerprint and high wavenumber confocal Raman spectroscopy for in vivo diagnosis of cervical precancer
Author(s):
Shiyamala Duraipandian;
Wei Zheng;
Joseph Ng;
Jeffrey J. H. Low;
A. Ilancheran;
Zhiwei Huang
Show Abstract
Raman spectroscopy is a vibrational spectroscopic technique capable of optically probing the compositional,
conformational, and structural changes in the tissue associated with disease progression. The main goal of this work is to
develop an integrated fingerprint (FP) and high wavenumber (HW) in vivo confocal Raman spectroscopy for
simultaneous FP/HW tissue Raman spectral measurements. This work further explores the potential of integrated FP/HW
Raman spectroscopy developed as a diagnostic tool for in vivo detection of cervical precancer. A total of 473 in vivo
integrated FP/HW Raman spectra (340 normal and 133 precancer) were acquired from 35 patients within 1 s during
clinical colposcopy. The major tissue Raman peaks are noticed around 854, 937, 1001, 1095, 1253, 1313, 1445, 1654,
2946 and 3400 cm-1, related to the molecular changes (e.g., proteins, lipids, glycogen, nucleic acids, water, etc.) that
accompany the dysplastic transformation of tissue. The FP (800 - 1800 cm-1), HW (2800 - 3800 cm-1) and the integrated
FP/HW Raman spectra were analyzed using partial least squares-discriminant analysis (PLS-DA) together with the
leave-one patient-out, cross-validation. The developed PLS-DA classification models and receiver operating
characteristics (ROC) curves for the FP, HW and integrated FP/HW spectroscopy further discloses that the performance
of integrated FP/HW Raman spectroscopy is superior to that of all others in discriminating the dysplastic cervix. The
results of this work indicate that the co-contributions of underlying rich biochemical information revealed by the
complementary spectral modalities (FP and HW Raman) can improve the in vivo early diagnosis of cervical precancer at
clinical colposcopy
Tissue measurement using 1064 nm dispersive Raman spectroscopy
Author(s):
Chad A. Lieber;
Huawen Wu;
William Yang
Show Abstract
The use of Raman spectroscopy to provide characterization and diagnosis of biological tissues has shown increasing
success in recent years. Most of this work has been performed using near-infrared laser sources such as 785 or 830 nm,
in a balance of reduced intrinsic fluorescence in the tissues and quantum efficiency in the silicon detectors often used.
However, even at these wavelengths, many tissues still exhibit strong or prohibitive fluorescence, and these wavelengths
still cause autofluorescence in many common sampling materials, such as glass. In this study, we demonstrate the use of
1064 nm dispersive Raman spectroscopy for the study of biological tissues. A number of tissues are evaluated using the
1064 nm system and compared with the spectra obtained from a 785 nm system. Sampling materials are similarly
compared. These results show that 1064 nm dispersive Raman spectroscopy provides a viable solution for measurement
of highly fluorescent biological tissues such as liver and kidney, which are difficult or impossible to extract Raman at
785 nm.
Utilization of fringe projection technique for evaluation of wound dimensions and of healing progress
Author(s):
Marcia T. Saito;
Elisabeth M. Yoshimura;
Francisco F. Palácios;
Antonio C. L. Lino;
Guillermo F. Palácios;
Marcelo V. P. Sousa
Show Abstract
Background: The methods used for evaluating wound dimensions, especially the chronic ones, are invasive and inaccurate. The fringe projection technique with phase shift is a non-invasive, accurate and low-cost optical method. Objective: The aim is to validate the technique through the determination of dimensions of objects of known topography and with different geometries and colors to simulate the wounds and tones of skin color. Taking into account the influence of skin wound optical factors, the technique will be used to evaluate actual patients’ wound dimensions and to study its limitations in this application. Methods: Four sinusoidal fringe patterns, displaced ¼ of period each, were projected onto the objects surface. The object dimensions were obtained from the unwrapped phase map through the observation of the fringe deformations caused by the object topography and using phase shift analysis. An object with simple geometry was used for dimensional calibration and the topographic dimensions of the others were determined from it. After observing the compatibility with the data and validating the method, it was used for measuring the dimensions of real patients’ wounds. Results and Conclusions: The discrepancies between actual topography and dimensions determined with Fringe Projection Technique and for the known object were lower than 0.50 cm. The method was successful in obtaining the topography of real patient’s wounds. Objects and wounds with sharp topographies or causing shadow or reflection are difficult to be evaluated with this technique.
Bloodstain age analysis: toward solid state fluorescent lifetime measurements
Author(s):
Kevin Guo;
Natalia Zhegalova;
Samuel Achilefu;
Mikhail Y. Berezin
Show Abstract
One of the most pressing unsolved challenges in forensic science is the determination of time since deposition (TSD) of bloodstains at crime scenes. Despite a number of high profile cases over the past couple hundred years involving controversy over TSD methods, no reliable quantitative method has been established. We present here an approach that has yet to be explored by forensic scientist: measuring the fluorescence lifetime of solid-state blood. Such a method would allow for on-site measurements of bloodstains utilizing the appropriate device, and would allow for rapid results returned in real-time to investigators.
Using color intensity projections to visualize air flow in operating theaters with the goal of reducing infections
Author(s):
Keith S. Cover;
Niek van Asperen;
Joost de Jong;
Rudolf M. Verdaasdonk
Show Abstract
Infection following neurosurgery is all too common. One possible source of infection is the transportation of dust and other contaminates into the open wound by airflow within the operating theatre. While many modern operating theatres have a filtered, uniform and gentle flow of air cascading down over the operating table from a large area fan in the ceiling, many obstacles might introduce turbulence into the laminar flow including lights, equipment and personal. Schlieren imaging - which is sensitive to small disturbances in the laminar flow such as breathing and turbulence caused by air warmed by a hand at body temperature – was used to image the air flow due to activities in an operating theatre. Color intensity projections (CIPs) were employed to reduce the workload of analyzing the large amount of video data. CIPs – which has been applied to images in angiography, 4D CT, nuclear medicine and astronomy – summarizes the changes over many gray scale images in a single color image in a way which most interpreters find intuitive. CIPs uses the hue, saturation and brightness of the color image to encode the summary. Imaging in an operating theatre showed substantial disruptions to the airflow due to equipment such as the lighting. When these disruptions are combined with such minor factors as heat from the hand, reversal of the preferred airflow patterns can occur. These reversals of preferred airflow patterns have the potential to transport contaminates into the open wound. Further study is required to understand both the frequency of the reversed airflow patterns and the impact they may have on infection rates.
Label-free biosensor based on long period grating
Author(s):
Francesco Baldini;
Francesco Chiavaioli;
Ambra Giannetti;
Massimo Brenci;
Cosimo Trono
Show Abstract
Long period gratings have been recently proposed as label-free optical devices for biochemical sensing. A biochemical interaction along the grating region changes the biolayer refractive index and a change in the fiber transmission spectrum occurs. The fiber biofunctionalization was performed with a novel chemistry using Eudragit L100 copolymer as opposed to the commonly-used silanization procedure. An IgG/anti-IgG bioassay was carried out for studying the antigen/antibody interaction. The biosensor was fully characterized, monitoring the kinetics during the antibody immobilization and achieving the calibration curve of the assay. To compare the biosensor performance, two LPG-based biosensors with distinct grating periods were characterized following the same bioassay protocol. Experimental results demonstrated an enhancement of the biosensor performance when the fundamental core mode of a single-mode fiber couples with a higher order cladding mode. Considering an LPG manufactured on a bare optical fiber, in which the coupling occurs with the 7-th cladding mode, a dynamic signal range of 0.33 nm, a working range of 1.7 – 1450 mg L-1 and a LOD of 500 μg L-1 were achieved
A portable microfluidic-based biophotonic sensor for extracellular H2O2 measurements
Author(s):
V. Koman;
G. Suárez;
Ch. Santschi;
V. J. Cadarso;
J. Brugger;
N. von Moos;
V. I. Slaveykova;
O. J. F. Martin
Show Abstract
In this work a portable analytical biosensor for real-time extracellular monitoring of released hydrogen peroxide (H2O2 )
is presented. The biosensor is based on the optical detection of the cytochrome c (cyt c) oxidation state. The setup
consists of an integrated microscope combined with a compact spectrometer. The light being absorbed by cyt c is
enhanced via multiscattering produced by random aggregates of polystyrene beads in a cross-linked cyt c matrix. Using
ink-jet printing technique, the sensing elements, namely cyt c loaded polystyrene aggregates, are fabricated with high
reliability in terms of repeatability of size and sensitivity. Additionally, the sensing elements are enclosed in a
microfluidic channel assuring a fast and efficient analytes delivery. As an example, the effect of trace concentrations of
functionalized cadmium selenide/zinc sulfide (CdSe/ZnS) core shell quantum dots on the green algae Chlamydomonas
reinhardtii is investigated, showing extracellular H2O2 release with different production rates over a period of 1 hour. In
conclusion, the presented portable biosensor enables the highly sensitive and non-invasive real-time monitoring of the
cell metabolism of C. reinhardtii.
Glucose measurement in interstitial fluid by microdialysis for the calibration of minimally invasive blood glucose monitoring
Author(s):
Dachao Li;
Ridong Wang;
Hao Chong;
Yu Liu;
Kexin Xu
Show Abstract
According to the requirement of the calibration in minimally invasive blood glucose monitoring, a method based on microdialysis was presented to monitor glucose level in interstitial fluid continuously. An experimental system simulating the continuous change of glucose concentration in vivo was built. The influences on recovery of microdialysis caused by flow rate, glucose concentration, and temperature etc. were studied. The results led to the conclusion that the recovery fell by 71.7% when perfusion rate increased from 0.3 μL/min to 3.0 μL/min, while the different concentrations of glucose solutions scarcely contribute to the recovery instead, and the temperatures from 25 to 58 °C caused the recovery to increase by 34.6%.
An optimized algorithm of image stitching in the case of a multi-modal probe for monitoring the evolution of scars
Author(s):
R. Kassab;
S. Treuillet;
F. Marzani;
C. Pieralli;
J. C. Lapayre
Show Abstract
We propose a new system that makes possible to monitor the evolution of scars after the excision of a tumorous
dermatosis. The hardware part of this system is composed of a new optical innovative probe with which two types of
images can be acquired simultaneously: an anatomic image acquired under a white light and a functional one based on
autofluorescence from the protoporphyrin within the cancer cells. For technical reasons related to the maximum size of
the area covered by the probe, acquired images are too small to cover the whole scar. That is why a sequence of
overlapping images is taken in order to cover the required area.
The main goal of this paper is to describe the creation of two panoramic images (anatomic and functional). Fluorescence
images do not have enough salient information for matching the images; stitching algorithms are applied over each
couple of successive white light images to produce an anatomic panorama of the entire scar. The same transformations
obtained from this step are used to register and stitch the functional images. Several experiments have been implemented
using different stitching algorithms (SIFT, ASIFT and SURF), with various transformation parameters (angles of
rotation, projection, scaling, etc…) and different types of skin images. We present the results of these experiments that
propose the best solution.
Thus, clinician has two panoramic images superimposed and usable for diagnostic support. A collaborative layer is
added to the system to allow sharing panoramas among several practitioners over different places.
The effect of borate polymer layers on glucose measurement by surface plasmon resonance
Author(s):
Dachao Li;
Jia Yang;
Peng Wu;
Di Yang;
Bo Wang;
Yuan Lin;
Kexin Xu
Show Abstract
A new borate polymer PAA-ran-PAAPBA that can adsorb glucose specifically is introduced into the glucose
measurement based on surface plasmon resonance. Six and twelve layers of borate polymer are bound onto the SPR
sensors respectively through the layer-by-layer self-assembly binding method, and then the effect of different layers on
the glucose concentration measurement is studied. The experiment is conducted in three concentration ranges,
1~10mg/dL, 10~100mg/dL and 100~1000mg/dL. The Results show that the performance of 12-layer-polymer sensor is
better than that of the 6-layer-polymer sensor in the first two ranges, and the measuring result has no big difference in the
range of 100~1000mg/d. It indicates that the enhancement of polymer layer on the surface of SPR sensor can
dramatically improve the glucose measurement in the low concentration range.
Raman spectroscopy using time-correlated photon-counting detection
Author(s):
Zhaokai Meng;
Shuna Cheng;
Georgi I. Petrov;
Javier A. Jo;
Vladislav V. Yakovlev
Show Abstract
A highly sensitive, shot-noise-limited Raman signal acquisition is achieved using frequency-time transformation in a single-mode fiber and time-correlated photon counting system. To spectrally disperse Raman signal excited by a picosecond laser pulse, the light is directed into a sufficiently long single-mode fiber. The output end of the fiber is coupled into a time-gated photon multiplier tube (PMT). Due to a frequency-time conversion provided by the fiber core, photons of different frequencies experience different transient times. In this way, by measuring the photons’ arrival time, Raman peaks can be recorded and separated. Moreover, in some cases the fluorescence background can be eliminated from Raman signals due to its much longer life-time. Consequently, a fluorescent background free Raman spectrum can be attained using the time-correlated photon-counting Raman spectroscopy. In this report, by using a 400m SM600 single-mode fiber and a Hamamatsu R3809U-50 PMT, we demonstrate the Raman spectrum of dimethyl sulfoxide excited by a short-pulsed laser.
Normalized fluorescence lifetime imaging for tumor identification and margin delineation
Author(s):
Adria J. Sherman;
Asael Papour;
Siddharth Bhargava;
Maie A. R. St. John;
William H. Yong;
Zach Taylor;
Warren S. Grundfest;
Oscar M. Stafsudd
Show Abstract
Fluorescence lifetime imaging microscopy (FLIM) is a technique that has been proven to produce quantitative and qualitative differentiation and identification of substances with good specificity and sensitivity based on lifetime extracted information. This technique has shown the ability to also differentiate between a wide range of tissue types to identify malignant from benign tissue in vivo and ex vivo. However, the complexity, long duration and effort required to generate this information has limited the adoption of these techniques in a clinical setting. Our group has developed a time-resolved imaging system (patent pending) that does not require the extraction of lifetimes or use of complex curve fitting algorithms to display the needed information. The technique, entitled Lifetime Fluorescence Imaging (LFI, or NoFYI), converts fluorescence lifetime decay information directly into visual contrast. Initial studies using Fluorescein and Rhodamine-B demonstrated the feasibility of this approach. Subsequent studies demonstrated the ability to separate collagen and elastin powders. The technique uses nanosecond pulsed UV LEDs at 375 nm for average illumination intensities of ~4.5 μW on the tissue surface with detection by a gated CCD camera. To date, we have imaged 11 surgical head and neck squamous cell carcinoma and brain cancer biopsy specimens including 5 normal and 6 malignant samples. Images at multiple wavelengths clearly demonstrate differentiation between benign and malignant tissue, which was later confirmed by histology. Contrast was obtained between fluorophores with 35 μm spatial resolution and an SNR of ~30 dB allowing us to clearly define tumor margins in these highly invasive cancers. This method is capable of providing both anatomical and chemical information for the pathologist and the surgeon. These results suggest that this technology has a possible role in identifying tumors in tissue specimens and detecting tumor margins during procedures.
A time-domain diffuse optical/fluorescent tomography using multi-dimensional TCSPC design
Author(s):
Yiming Lu;
Wei Zhang;
Linhui Wu;
Liming Zhang;
Feng Gao
Show Abstract
Techniques of time-correlated single-photon counting (TCSPC) have been widely used in diffuse optical tomography (DOT) and diffuse fluorescence tomography (DFT). While a multi-channel TCSPC-based DOT/DFT system can be conveniently constructed using independent modules, the state-of-the-art TCSPC technique has extended its multidimensional function by facilitating a compact and cost-effective design of the multi-channel as well as multi-wavelength data-acquisition. We herein present a revised multi-channel TCSPC system that is based the multidimensional function of the TCSPC device. We also design a series of DOT and DFT experiments to validate effectiveness of the system.