Jump to Content

Increase text size Decrease text size

SPIE DL Tab

Proceedings Tab

Journals Tab

JBO Tab

EBooks Tab

My Subscription | My Email Alerts | My Article Collections

GENERAL INFORMATION

BROWSE VOLUMES

Year Range:

2012

Volume 17

2011

Volume 16

Issue 12 | December 2011 | 12xxxx

Issue 11 | November 2011 | 11xxxx

Issue 10 | October 2011 | 10xxxx

Issue 9 | September 2011 | 09xxxx

Issue 8 | August 2011 | 08xxxx

Issue 7 | July 2011 | 07xxxx

Issue 6 | June 2011 | 06xxxx

Issue 5 | May 2011 | 05xxxx

Issue 4 | April 2011 | 04xxxx

Issue 3 | March 2011 | 03xxxx

Issue 2 | February 2011 | 02xxxx

Issue 1 | January 2011 | 01xxxx

2010

Volume 15

2009

Volume 14

2008

Volume 13

2007

Volume 12

2006

Volume 11

2005

Volume 10

2004

Volume 9

2003

Volume 8

2002

Volume 7

2001

Volume 6

2000

Volume 5

1999

Volume 4

1998

Volume 3

1997

Volume 2

1996

Volume 1

Search Issue | RSS Feeds

RSS
Previous Issue

December 2011

Volume 16, Issue 12, Articles (12xxxx)

Lihong V. Wang, PhD, Editor-in-Chief
Department of Biomedical Engineering
Washington University in St. Louis

SECTION LISTING

Add

Add Items to Cart

View

View Items in Cart

SELECTED: Export Citations | Show Only | Show All | Show/HideHide Summaries | Add to MyArticles | Email

back to top

JBO Letters

Select this Article OPEN ACCESS		Quantitative biomarkers of colonic dysplasia based on intrinsic second-harmonic generation signal Shuangmu Zhuo, Xiaoqin Zhu, Guizhu Wu, Jianxin Chen, and Shusen Xie J. Biomed. Opt. 16, 120501 (Nov 22, 2011); http://dx.doi.org/10.1117/1.3659715 Online Publication Date: Nov 22, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract Most colorectal cancers arise from dysplastic lesions, such as adenomatous polyps, and these lesions are difficult to be detected by the current endoscopic screening approaches. Here, we present the use of an intrinsic second-harmonic generation (SHG) signal as a novel means to differentiate between normal and dysplastic human colonic tissues. We find that the SHG signal can quantitatively identify collagen change associated with colonic dysplasia that is indiscernible by conventional pathologic techniques. By comparing normal with dysplastic mucosa, there were significant differences in collagen density and collagen fiber direction, providing substantial potential to become quantitative intrinsic biomarkers for in vivo clinical diagnosis of colonic dysplasia.

Select this Article OPEN ACCESS		Measurement of anisotropic reflection of flowing blood using optical coherence tomography Kweon-Ho Nam, Bosu Jeong, In Oh Jung, Hojin Ha, Ki Hean Kim, and Sang Joon Lee J. Biomed. Opt. 16, 120502 (Nov 22, 2011); http://dx.doi.org/10.1117/1.3660299 Online Publication Date: Nov 22, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract Light reflectance of blood is a complex phenomenon affected by hematocrit and red blood cell (RBC) aggregation (rouleaux formation). According to the hypothesis that RBC rouleaux are aligned with the direction of blood flow, the spatial alignment of RBC rouleaux, as well as their size and quantity in the blood, may also affect light reflectance. The present study aims to investigate the effect of the spatial alignment and distribution of RBC rouleaux on light reflection using optical coherence tomography (OCT). Blood flow velocity and reflectance profiles in a rat jugular-femoral bypass loop were simultaneously measured using a Doppler swept-source OCT system at various incident angles from −30 to +30 deg. The reflectance profiles of flowing blood show nonmonotonous decay with a local negative peak at the center of the tube. The profiles vary depending on the incident angle. This angular dependence is stronger at a higher angle of incidence. The anisotropic reflectance of flowing blood is consistent with the hypothesis on the spatial alignment of RBC rouleaux.

Select this Article OPEN ACCESS		Multifocus confocal Raman microspectroscopy for rapid single-particle analysis Lingbo Kong, Pengfei Zhang, Peter Setlow, and Yong-qing Li J. Biomed. Opt. 16, 120503 (Nov 23, 2011); http://dx.doi.org/10.1117/1.3662456 \| Cited 1 time Online Publication Date: Nov 23, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract We have developed a multifocus confocal Raman microspectroscopy system that allows simultaneous analyses of ∼80 individual biological or airborne microparticles based on a precise image-guided technique. Multiple individual particles adhered in random positions on a coverslip were illuminated by a multifocus excitation pattern formed by rapidly steering a single laser beam with a pair of galvo-mirrors, and their Raman scatterings were synchronously projected with another galvo-mirror to different rows of a CCD chip for parallel spectroscopic analyses. We show that this technique can be used to rapidly identify single airborne particles or bacteria collected on a slide and to monitor germination dynamics of multiple bacterial spores in real-time.

Select this Article OPEN ACCESS		Development of a noncontact diffuse optical spectroscopy probe for measuring tissue optical properties Sheldon F. Bish, Narasimhan Rajaram, Brandon Nichols, and James W. Tunnell J. Biomed. Opt. 16, 120505 (Nov 29, 2011); http://dx.doi.org/10.1117/1.3662459 Online Publication Date: Nov 29, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract Optical reflectance probes are often used as tools to obtain optical spectra from superficial tissues and subsequently determine optical and physiological properties associated with early stage cancer. These probes, when placed directly on the tissue, are known to cause significant pressure-dependent changes in local optical properties. To address this, we fit the probe with an optical device that images the illumination and collection fibers onto the tissue surface, eliminating the influence of contact probe pressure on the sampling area. The noncontact probe addition addresses new optical conditions that may affect its performance such as tissue surface contour, and specular reflections by implementing an autofocusing mechanism and cross polarization. Extracted optical properties of tissue simulating phantoms yield errors of 3.46% in reduced scattering and 8.62% in absorbance. Autofocusing has extended the depth of field from 4 mm to throughout the 12 mm range of autofocus travel, while cross polarization has removed the incidence angle dependent specular reflection component from the collected signal.

Select this Article OPEN ACCESS		Unsupervised analysis of small animal dynamic Cerenkov luminescence imaging Antonello E. Spinelli and Federico Boschi J. Biomed. Opt. 16, 120507 (Dec 01, 2011); http://dx.doi.org/10.1117/1.3663442 Online Publication Date: Dec 01, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract Clustering analysis (CA) and principal component analysis (PCA) were applied to dynamic Cerenkov luminescence images (dCLI). In order to investigate the performances of the proposed approaches, two distinct dynamic data sets obtained by injecting mice with ³²P-ATP and ¹⁸F-FDG were acquired using the IVIS 200 optical imager. The k-means clustering algorithm has been applied to dCLI and was implemented using interactive data language 8.1. We show that cluster analysis allows us to obtain good agreement between the clustered and the corresponding emission regions like the bladder, the liver, and the tumor. We also show a good correspondence between the time activity curves of the different regions obtained by using CA and manual region of interest analysis on dCLIT and PCA images. We conclude that CA provides an automatic unsupervised method for the analysis of preclinical dynamic Cerenkov luminescence image data.

Select this Article OPEN ACCESS		Imaging the cellular response to transient shear stress using stroboscopic digital holography Maciej Antkowiak, Yoshihiko Arita, Kishan Dholakia, and Frank Gunn-Moore J. Biomed. Opt. 16, 120508 (Dec 16, 2011); http://dx.doi.org/10.1117/1.3665441 \| Cited 1 time Online Publication Date: Dec 16, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract We use stroboscopic quantitative phase microscopy to study cell deformation and the response to cavitation bubbles and transient shear stress resulting from laser-induced breakdown of an optically trapped nanoparticle. A bi-directional transient displacement of cytoplasm is observed during expansion and collapse of the cavitation bubble. In some cases, cell deformation is only observable at the microsecond time scale without any permanent change in cell shape or optical thickness. On a time scale of seconds, the cellular response to shear stress and cytoplasm deformation typically leads to retraction of the cellular edge most exposed to the flow, rounding of the cell body and, in some cases, loss of cellular dry mass. These results give a new insight into the cellular response to cavitation induced shear stress and related plasma membrane permeabilization. This study also demonstrates that laser-induced breakdown of a nanoparticle offers localized cavitation, which interacts with a single cell but without causing cell lysis.

Select this Article OPEN ACCESS		Time-resolved imaging refractometry of microbicidal films using quantitative phase microscopy Matthew T. Rinehart, Tyler K. Drake, Francisco E. Robles, Lisa C. Rohan, David Katz, and Adam Wax J. Biomed. Opt. 16, 120510 (Dec 19, 2011); http://dx.doi.org/10.1117/1.3665439 Online Publication Date: Dec 19, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract Quantitative phase microscopy is applied to image temporal changes in the refractive index (RI) distributions of solutions created by microbicidal films undergoing hydration. We present a novel method of using an engineered polydimethylsiloxane structure as a static phase reference to facilitate calibration of the absolute RI across the entire field. We present a study of dynamic structural changes in microbicidal films during hydration and subsequent dissolution. With assumptions about the smoothness of the phase changes induced by these films, we calculate absolute changes in the percentage of film in regions across the field of view.

Select this Article OPEN ACCESS		Simultaneous fluorescence and positron emission tomography for in vivo imaging of small animals Bin Zhang, Shuangquan Liu, Fei Liu, Xiaochun Zhang, Yanyan Xu, Jianwen Luo, Baoci Shan, and Jing Bai J. Biomed. Opt. 16, 120511 (Dec 05, 2011); http://dx.doi.org/10.1117/1.3665438 Online Publication Date: Dec 05, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract Simultaneous positron emission tomography (PET) and fluorescence tomography (FT) for in vivo imaging of small animals is proposed by a dual-modality system. This system combines a charge-coupled device-based near-infrared fluorescence imaging with a planar detector pair-based PET. With [¹⁸F]-2-fluoro-2-deoxy-d-glucose radioactive tracer and the protease activated fluorescence probe, on the one hand, the simultaneous metabolic activity and protease activity in tumor region are revealed by the PET and FT, respectively. On the other hand, the protease activity both on the surface layer and the deep tissue of the tumor is provided by the fluorescence reflection imaging and FT, respectively.

back to top

Research Papers: General

Select this Article		Ray-tracing optical modeling of negative dysphotopsia Xin Hong, Yueai Liu, Mutlu Karakelle, Samuel Masket, and Nicole R. Fram J. Biomed. Opt. 16, 125001 (Nov 22, 2011); http://dx.doi.org/10.1117/1.3656745 Online Publication Date: Nov 22, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract Negative dysphotopsia is a relatively common photic phenomenon that may occur after implantation of an intraocular lens. The etiology of negative dysphotopsia is not fully understood. In this investigation, optical modeling was developed using nonsequential-component Zemax ray-tracing technology to simulate photic phenomena experienced by the human eye. The simulation investigated the effects of pupil size, capsulorrhexis size, and bag diffusiveness. Results demonstrated the optical basis of negative dysphotopsia. We found that photic structures were mainly influenced by critical factors such as the capsulorrhexis size and the optical diffusiveness of the capsular bag. The simulations suggested the hypothesis that the anterior capsulorrhexis interacting with intraocular lens could induce negative dysphotopsia.

Select this Article		Using a melanin granule lattice model to study the thermal effects of pulsed and scanning light irradiations through a measurement aperture Do-Hyun Kim J. Biomed. Opt. 16, 125002 (Nov 22, 2011); http://dx.doi.org/10.1117/1.3656746 Online Publication Date: Nov 22, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract Optical radiation hazards of scanning light sources are often evaluated using pulsed light source criteria, with the relevant pulse parameter equivalent to the scanning light source determined by the energy delivered through a measurement aperture. However, physical equivalence has not been completely understood: a pulsed light source is temporally dynamic but spatially stationary, while a scanning light source is temporally stationary but spatially dynamic. This study introduces a numerical analysis based upon the melanin granule lattice model to investigate the equivalence of scanning and pulsed light sources through a measurement aperture and their respective thermal effects in the pigmented retinal layer. The numerical analysis calculates the thermal contribution of individual melanin granules with varying temporal sequence, and finds that temperature changes and thermal damage thresholds for the two different types of light sources were not equal. However, dwell times of 40 to 200 μsec did not produce significant differences between pulsed and scanning light sources in temperature change and thermal damage thresholds to the sample tissue.

Select this Article		Monte Carlo simulation of photon migration in a cloud computing environment with MapReduce Guillem Pratx and Lei Xing J. Biomed. Opt. 16, 125003 (Nov 22, 2011); http://dx.doi.org/10.1117/1.3656964 Online Publication Date: Nov 22, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract Monte Carlo simulation is considered the most reliable method for modeling photon migration in heterogeneous media. However, its widespread use is hindered by the high computational cost. The purpose of this work is to report on our implementation of a simple MapReduce method for performing fault-tolerant Monte Carlo computations in a massively-parallel cloud computing environment. We ported the MC321 Monte Carlo package to Hadoop, an open-source MapReduce framework. In this implementation, Map tasks compute photon histories in parallel while a Reduce task scores photon absorption. The distributed implementation was evaluated on a commercial compute cloud. The simulation time was found to be linearly dependent on the number of photons and inversely proportional to the number of nodes. For a cluster size of 240 nodes, the simulation of 100 billion photon histories took 22 min, a 1258 × speed-up compared to the single-threaded Monte Carlo program. The overall computational throughput was 85,178 photon histories per node per second, with a latency of 100 s. The distributed simulation produced the same output as the original implementation and was resilient to hardware failure: the correctness of the simulation was unaffected by the shutdown of 50% of the nodes.

Select this Article OPEN ACCESS		Effect of cross-linking with riboflavin and ultraviolet A on the chemical bonds and ultrastructure of human sclera Gyeong-Bok Jung, Hui-Jae Lee, Ji-Hye Kim, Jin Ik Lim, Samjin Choi, Kyung-Hyun Jin, and Hun-Kuk Park J. Biomed. Opt. 16, 125004 (Dec 08, 2011); http://dx.doi.org/10.1117/1.3662458 Online Publication Date: Dec 08, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract This study examined the effect of the cross-linking with riboflavin-ultraviolet A (UVA) irradiation on the chemical bonds and ultrastructural changes of human sclera tissues using Raman spectroscopy and atomic force microscopy (AFM). Raman spectroscopy of the normal and cross-linked human sclera tissue revealed different types of the riboflavin-UVA and collagen interactions, which could be identified from their unique peaks, intensity, and shape. Raman spectroscopy can prove to be a powerful tool for examining the chemical bond of collagenous tissues at the molecular level. After riboflavin-UVA treatment, unlike a regular parallel arrangement of normal collagen fibrils, the AFM image revealed interlocking arrangements of collagen fibrils. The observed changes in the surface topography of the collagen fibrils, as well as in their chemical bonds in the sclera tissue, support the formation of interfibrilar cross-links in sclera tissues.

back to top

Research Papers: Imaging

Select this Article OPEN ACCESS		Imaging scattering orientation with spatial frequency domain imaging Soren D. Konecky, Tyler Rice, Anthony J. Durkin, and Bruce J. Tromberg J. Biomed. Opt. 16, 126001 (Nov 22, 2011); http://dx.doi.org/10.1117/1.3657823 Online Publication Date: Nov 22, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract Optical imaging techniques based on multiple light scattering generally have poor sensitivity to the orientation and direction of microscopic light scattering structures. In order to address this limitation, we introduce a spatial frequency domain method for imaging contrast from oriented scattering structures by measuring the angular-dependence of structured light reflectance. The measurement is made by projecting sinusoidal patterns of light intensity on a sample, and measuring the degree to which the patterns are blurred as a function of the projection angle. We derive a spatial Fourier domain solution to an anisotropic diffusion model. This solution predicts the effects of bulk scattering orientation on the amplitude and phase of the projected patterns. We introduce a new contrast function based on a scattering orientation index (SOI) which is sensitive to the degree to which light scattering is directionally dependent. We validate the technique using tissue simulating phantoms, and ex vivo samples of muscle and brain. Our results show that SOI is independent of the overall amount of bulk light scattering and absorption, and that isotropic versus oriented scattering structures can be clearly distinguished. We determine the orientation of subsurface microscopic scattering structures located up to 600 μm beneath highly scattering (μ^′_s = 1.5 mm⁻¹) material.

Select this Article		Improvement of fluorescence-enhanced optical tomography with improved optical filtering and accurate model-based reconstruction algorithms Yujie Lu, Banghe Zhu, Chinmay Darne, I-Chih Tan, John C. Rasmussen, and Eva M. Sevick-Muraca J. Biomed. Opt. 16, 126002 (Dec 14, 2011); http://dx.doi.org/10.1117/1.3659291 \| Cited 1 time Online Publication Date: Dec 14, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract The goal of preclinical fluorescence-enhanced optical tomography (FEOT) is to provide three-dimensional fluorophore distribution for a myriad of drug and disease discovery studies in small animals. Effective measurements, as well as fast and robust image reconstruction, are necessary for extensive applications. Compared to bioluminescence tomography (BLT), FEOT may result in improved image quality through higher detected photon count rates. However, background signals that arise from excitation illumination affect the reconstruction quality, especially when tissue fluorophore concentration is low and/or fluorescent target is located deeply in tissues. We show that near-infrared fluorescence (NIRF) imaging with an optimized filter configuration significantly reduces the background noise. Model-based reconstruction with a high-order approximation to the radiative transfer equation further improves the reconstruction quality compared to the diffusion approximation. Improvements in FEOT are demonstrated experimentally using a mouse-shaped phantom with targets of pico- and subpico-mole NIR fluorescent dye.

Select this Article		Depth profiling of photothermal compound concentrations using phase sensitive optical coherence tomography Guangying Guan, Roberto Reif, Zhihong Huang, and Ruikang K. Wang J. Biomed. Opt. 16, 126003 (Nov 28, 2011); http://dx.doi.org/10.1117/1.3659211 Online Publication Date: Nov 28, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract A model that describes the concentration of photothermal (light-to-heat converters) compounds as a function of depth in a turbid medium is developed. The system consists of a pump laser (808 nm modulated at 400 Hz), which heats a photothermal compound, and a phase sensitive spectral domain optical coherence tomography system, which detects the changes in the optical path length of the sample induced by the temperature increase. The model is theoretically derived and the coefficients are empirically determined using solid homogeneous gel phantoms. The model is validated by reconstructing the concentration of a photothermal compound in thick single and double layer solid phantoms.

Select this Article		Lensless multispectral digital in-line holographic microscope James P. Ryle, Susan McDonnell, and John T. Sheridan J. Biomed. Opt. 16, 126004 (Dec 16, 2011); http://dx.doi.org/10.1117/1.3659681 Online Publication Date: Dec 16, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract An compact multispectral digital in-line holographic microscope (DIHM) is developed that emulates Gabor's original holographic principle. Using sources of varying spatial coherence (laser, LED), holographic images of objects, including optical fiber, latex microspheres, and cancer cells, are successfully captured and numerically processed. Quantitative measurement of cell locations and percentage confluence are estimated, and pseudocolor images are also presented. Phase profiles of weakly scattering cells are obtained from the DIHM and are compared to those produced by a commercially available off-axis digital holographic microscope.

Select this Article		Noncontact common-path Fourier domain optical coherence tomography method for in vitro intraocular lens power measurement Yong Huang, Kang Zhang, Jin U. Kang, Don Calogero, Robert H. James, and Ilko K. Ilev J. Biomed. Opt. 16, 126005 (Nov 23, 2011); http://dx.doi.org/10.1117/1.3660313 Online Publication Date: Nov 23, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract We propose a novel common-path Fourier domain optical coherence tomography (CP-FD-OCT) method for noncontact, accurate, and objective in vitro measurement of the dioptric power of intraocular lenses (IOLs) implants. The CP-FD-OCT method principle of operation is based on simple two-dimensional scanning common-path Fourier domain optical coherence tomography. By reconstructing the anterior and posterior IOL surfaces, the radii of the two surfaces, and thus the IOL dioptric power are determined. The CP-FD-OCT design provides high accuracy of IOL surface reconstruction. The axial position detection accuracy is calibrated at 1.22 μm in balanced saline solution used for simulation of in situ conditions. The lateral sampling rate is controlled by the step size of linear scanning systems. IOL samples with labeled dioptric power in the low-power (5D), mid-power (20D and 22D), and high-power (36D) ranges under in situ conditions are tested. We obtained a mean power of 4.95/20.11/22.09/36.25 D with high levels of repeatability estimated by a standard deviation of 0.10/0.18/0.2/0.58 D and a relative error of 2/0.9/0.9/1.6%, based on five measurements for each IOL respectively. The new CP-FD-OCT method provides an independent source of IOL power measurement data as well as information for evaluating other optical properties of IOLs such as refractive index, central thickness, and aberrations.

Select this Article		Broadband superluminescent diode–based ultrahigh resolution optical coherence tomography for ophthalmic imaging Dexi Zhu, Meixiao Shen, Hong Jiang, Ming Li, Michael R. Wang, Yuhong Wang, Lili Ge, Jia Qu, and Jianhua Wang J. Biomed. Opt. 16, 126006 (Nov 28, 2011); http://dx.doi.org/10.1117/1.3660314 Online Publication Date: Nov 28, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract Spectral domain optical coherence tomography (SD-OCT) with ultrahigh resolution can be used to measure precise structures in the context of ophthalmic imaging. We designed an ultrahigh resolution SD-OCT system based on broadband superluminescent diode (SLD) as the light source. An axial resolution of 2.2 μm in tissue, a scan depth of 1.48 mm, and a high sensitivity of 93 dB were achieved by the spectrometer designed. The ultrahigh-resolution SD-OCT system was employed to image the human cornea and retina with a cross-section image of 2048 × 2048 pixels. Our research demonstrated that ultrahigh -resolution SD-OCT can be achieved using broadband SLD in a simple way.

Select this Article		Correlation of within-individual fluctuation of depressed mood with prefrontal cortex activity during verbal working memory task: optical topography study Hiroki Sato, Ryuta Aoki, Takusige Katura, Ryoichi Matsuda, and Hideaki Koizumi J. Biomed. Opt. 16, 126007 (Nov 28, 2011); http://dx.doi.org/10.1117/1.3662448 Online Publication Date: Nov 28, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract Previous studies showed that interindividual variations in mood state are associated with prefrontal cortex (PFC) activity. In this study, we focused on the depressed-mood state under natural circumstances and examined the relationship between within-individual changes over time in this mood state and PFC activity. We used optical topography (OT), a functional imaging technique based on near-infrared spectroscopy, to measure PFC activity for each participant in three experimental sessions repeated at 2-week intervals. In each session, the participants completed a self-report questionnaire of mood state and underwent OT measurement while performing verbal and spatial working memory (WM) tasks. The results showed that changes in the depressed-mood score between successive sessions were negatively correlated with those in the left PFC activation for the verbal WM task (ρ = −0.56, p < 0.05). In contrast, the PFC activation for the spatial WM task did not co-vary with participants’ mood changes. We thus demonstrated that PFC activity during a verbal WM task varies depending on the participant's depressed mood state, independent of trait factors. This suggests that using optical topography to measure PFC activity during a verbal WM task can be used as a potential state marker for an individual's depressed mood state.

Select this Article		Full-range swept source optical coherence tomography based on carrier frequency by transmissive dispersive optical delay line Tong Wu, Zhihua Ding, Chuan Wang, and Minghui Chen J. Biomed. Opt. 16, 126008 (Dec 01, 2011); http://dx.doi.org/10.1117/1.3662450 Online Publication Date: Dec 01, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract A high speed swept source optical coherence tomography (SS-OCT) system capable of full-range imaging is presented. Wave-number carrier frequency is introduced into the spectral interference signal by a transmissive dispersive optical delay line (TDODL). High carrier frequency in the spectral interference signal corresponding to an equivalent distance-shift is exploited to obtain full-range OCT imaging. Theoretical development is conducted with the instantaneous coherence function introduced for a complete description of a spectral interference signal. Performance advantage of the TDODL-based method over the conventional approach where only one side (positive or negative path length difference) is used for imaging to avoid overlaying mirror artifacts is confirmed by the measured envelopes of spectral interference signal. Feasibility of the proposed method for full-range imaging is validated in a custom-built SS-OCT system by in vivo imaging of a biological sample.

Select this Article		Effects of motion on optical properties in the spatial frequency domain John Quan Nguyen, Rolf B. Saager, David J. Cuccia, Kristen M. Kelly, James Jakowatz, David Hsiang, and Anthony J. Durkin J. Biomed. Opt. 16, 126009 (Dec 14, 2011); http://dx.doi.org/10.1117/1.3662454 \| Cited 1 time Online Publication Date: Dec 14, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract Spatial frequency domain imaging (SFDI) is a noncontact and wide-field optical imaging technology currently being used to study the optical properties and chromophore concentrations of in vivo skin including skin lesions of various types. Part of the challenge of developing a clinically deployable SFDI system is related to the development of effective motion compensation strategies, which in turn, is critical for recording high fidelity optical properties. Here we present a two-part strategy for SFDI motion correction. After verifying the effectiveness of the motion correction algorithm on tissue-simulating phantoms, a set of skin-imaging data was collected in order to test the performance of the correction technique under real clinical conditions. Optical properties were obtained with and without the use of the motion correction technique. The results indicate that the algorithm presented here can be used to render optical properties in moving skin surfaces with fidelities within 1.5% of an ideal stationary case and with up to 92.63% less variance. Systematic characterization of the impact of motion variables on clinical SFDI measurements reveals that until SFDI instrumentation is developed to the point of instantaneous imaging, motion compensation is necessary for the accurate localization and quantification of heterogeneities in a clinical setting.

Select this Article		Low-cost three-dimensional imaging system combining fluorescence and ultrasound Baoqiang Li, Maxime Abran, Carl Matteau-Pelletier, Léonie Rouleau, Tina Lam, Rishi Sharma, Eric Rhéaume, Ashok Kakkar, Jean-Claude Tardif, and Frédéric Lesage J. Biomed. Opt. 16, 126010 (Dec 06, 2011); http://dx.doi.org/10.1117/1.3662455 Online Publication Date: Dec 06, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract In this paper, we present a dual-modality imaging system combining three-dimensional (3D) continuous-wave transillumination fluorescence tomography with 3D ultrasound (US) imaging. We validated the system with two phantoms, one containing fluorescent inclusions (Cy5.5) at different depths, and another varying-thickness semicylindrical phantom. Using raster scanning, the combined fluorescence/US system was used to collect the boundary fluorescent emission in the X-Y plane, as well as recovered the 3D surface and position of the inclusions from US signals. US images were segmented to provide soft priors for the fluorescence image reconstruction. Phantom results demonstrated that with priors derived from the US images, the fluorescent reconstruction quality was significantly improved. As further evaluation, we show pilot in vivo results using an Apo-E mouse to assess the feasibility and performance of this system in animal studies. Limitations and potential to be used in artherosclerosis studies are then discussed.

Select this Article		Optical imaging of alpha emitters: simulations, phantom, and in vivo results Federico Boschi, Sergio Lo Meo, Pier Luca Rossi, Riccardo Calandrino, Andrea Sbarbati, and Antonello E. Spinelli J. Biomed. Opt. 16, 126011 (Dec 01, 2011); http://dx.doi.org/10.1117/1.3663441 Online Publication Date: Dec 01, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract There has been growing interest in investigating both the in vitro and in vivo detection of optical photons from a plethora of beta emitters using optical techniques. In this paper we have investigated an alpha particle induced fluorescence signal by using a commercial CCD-based small animal optical imaging system. The light emission of a ²⁴¹Am source was simulated using GEANT4 and tested in different experimental conditions including the imaging of in vivo tissue. We believe that the results presented in this work can be useful to describe a possible mechanism for the in vivo detection of alpha emitters used for therapeutic purposes.

Select this Article		Myofibrillogenesis in live neonatal cardiomyocytes observed with hybrid two-photon excitation fluorescence-second harmonic generation microscopy Honghai Liu, Wan Qin, Yonghong Shao, Zhen Ma, Tong Ye, Tom Borg, and Bruce Z. Gao J. Biomed. Opt. 16, 126012 (Dec 05, 2011); http://dx.doi.org/10.1117/1.3662457 Online Publication Date: Dec 05, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract We developed a hybrid two-photon excitation fluorescence-second harmonic generation (TPEF-SHG) imaging system with an on-stage incubator for long-term live-cell imaging. Using the imaging system, we observed the addition of new sarcomeres during myofibrillogenesis while a cardiomyocyte was spreading on the substrate. The results suggest that the TPEF-SHG imaging system with an on-stage incubator is an effective tool for investigation of dynamic myofibrillogenesis.

Select this Article		Quantitative fluorescence imaging of protoporphyrin IX through determination of tissue optical properties in the spatial frequency domain Rolf B. Saager, David J. Cuccia, Steve Saggese, Kristen M. Kelly, and Anthony J. Durkin J. Biomed. Opt. 16, 126013 (Dec 15, 2011); http://dx.doi.org/10.1117/1.3665440 \| Cited 1 time Online Publication Date: Dec 15, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract The ability to quantitatively determine tissue fluorescence is of interest for the purpose of better understanding the details of photodynamic therapy of skin cancer. In particular, we are interested in quantifying protoporphyrin IX (PpIX) in vivo. We present a method of correcting fluorescence for effects of native tissue absorption and scattering properties in a spatially resolved manner that preserves the resolution of the fluorescence imaging system, based off a homogeneous representation of tissue. Validation was performed using a series of liquid turbid phantoms having varying concentrations of absorber, scatterer, and fluorophore (PpIX). Through the quantification of tissue optical properties via spatial frequency domain imaging, an empirical model based on Monte Carlo simulations was deployed to successfully decouple the effects of absorption and scattering from fluorescence. From this we were able to deduce the concentration of the PpIX to within 0.2 μg/ml of the known concentration. This method was subsequently applied to the determination of PpIX concentration from in vivo normal skin where the model-based correction determined a concentration of 1.6 μg/ml, which is in agreement with literature.

back to top

Research Papers: Sensing

Select this Article		Discriminating adenocarcinoma from normal colonic mucosa through deconvolution of Raman spectra Patricia Cambraia Lopes, Joaquim Agostinho Moreira, Abilio Almeida, Artur Esteves, Ivan Gregora, Martin Ledinsky, Jose Machado Lopes, Rui Henrique, and Albino Oliveira J. Biomed. Opt. 16, 127001 (Nov 23, 2011); http://dx.doi.org/10.1117/1.3658756 Online Publication Date: Nov 23, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract In this work, we considered the feasibility of Raman spectroscopy for discriminating between adenocarcinomatous and normal mucosal formalin-fixed colonic tissues. Unlike earlier studies in colorectal cancer, a spectral deconvolution model was implemented to derive spectral information. Eleven samples of human colon were used, and 55 spectra were analyzed. Each spectrum was resolved into 25 bands from 975 to 1720 cm⁻¹, where modes of proteins, lipids, and nucleic acids are observed. From a comparative study of band intensities, those presenting higher differences between tissue types were correlated to biochemical assignments. Results from fitting procedure were further used as inputs for linear discriminant analysis, where combinations of band intensities and intensity ratios were tested, yielding accuracies up to 81%. This analysis yields objective discriminating parameters after fitting optimization. The bands with higher diagnosis relevance detected by spectra deconvolution enable to confine the study to some spectral regions instead of broader ranges. A critical view upon limitations of this approach is presented, along with a comparison of our results to earlier ones obtained in fresh colonic tissues. This enabled to assess the effect of formalin fixation in colonic tissues, and determine its relevance in the present analysis.

Select this Article		Nonintrusive gas monitoring in neonatal lungs using diode laser spectroscopy: feasibility study Märta Lewander, Anders Bruzelius, Sune Svanberg, Katarina Svanberg, and Vineta Fellman J. Biomed. Opt. 16, 127002 (Dec 05, 2011); http://dx.doi.org/10.1117/1.3663211 \| Cited 1 time Online Publication Date: Dec 05, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract A feasibility study on noninvasive, real-time monitoring of gases in lungs of preterm infants is reported, where a laser-spectroscopic technique using diode lasers tuned to oxygen and water vapor absorption lines was employed on realistic tissue phantoms. Our work suggests that the technique could provide a new possibility for surveillance of the lung function of preterm infants, in particular the oxygenation, which is of prime importance in this patient group.

Select this Article		Role of the prefrontal cortex in the cognitive control of reaching movements: near-infrared spectroscopy study Kotaro Goto, Yoko Hoshi, Masashi Sata, Masatoshi Kawahara, Makoto Takahashi, and Harumitsu Murohashi J. Biomed. Opt. 16, 127003 (Nov 28, 2011); http://dx.doi.org/10.1117/1.3658757 Online Publication Date: Nov 28, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract To elucidate the role of the prefrontal cortex in cognitive control of reaching movements, by multichannel near-infrared spectroscopy we examine changes in oxygenated hemoglobin (oxy-Hb) as an indicator of changes in regional cerebral blood flow in the bilateral dorsolateral (DLPFC), ventrolateral prefrontal cortex (VLPFC), and frontopolar cortex (FPC) during a reaching task with normal visual feedback (a consistent task) and a reaching task with flipped horizontal visual feedback (an inconsistent task). Subjects first perform 12 trials of the consistent task, and then perform six blocks of the inconsistent task, each of which consists of six trials. During the consistent task, oxy-Hb is increased only in the right VLPFC. During the first block of the inconsistent task, increases in oxy-Hb are observed in the bilateral DLPFC and the right VLPFC, whereas the increased oxy-Hb was gradually reduced as the block proceeded, which was accompanied by an improvement in the task performance. Eventually, there were no differences in the degree of change in oxy-Hb between the consistent and inconsistent tasks in the DLPFC and VLPFC. These findings suggest that the DLPFC is engaged in higher order cognitive control, while the right VLPFC is engaged in both higher and lower order cognitive controls.

Select this Article		Raman spectroscopy of normal oral buccal mucosa tissues: study on intact and incised biopsies Atul Deshmukh, S. P. Singh, Pankaj Chaturvedi, and C. Murali Krishna J. Biomed. Opt. 16, 127004 (Nov 29, 2011); http://dx.doi.org/10.1117/1.3659680 Online Publication Date: Nov 29, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract Oral squamous cell carcinoma is one of among the top 10 malignancies. Optical spectroscopy, including Raman, is being actively pursued as alternative/adjunct for cancer diagnosis. Earlier studies have demonstrated the feasibility of classifying normal, premalignant, and malignant oral ex vivo tissues. Spectral features showed predominance of lipids and proteins in normal and cancer conditions, respectively, which were attributed to membrane lipids and surface proteins. In view of recent developments in deep tissue Raman spectroscopy, we have recorded Raman spectra from superior and inferior surfaces of 10 normal oral tissues on intact, as well as incised, biopsies after separation of epithelium from connective tissue. Spectral variations and similarities among different groups were explored by unsupervised (principal component analysis) and supervised (linear discriminant analysis, factorial discriminant analysis) methodologies. Clusters of spectra from superior and inferior surfaces of intact tissues show a high overlap; whereas spectra from separated epithelium and connective tissue sections yielded clear clusters, though they also overlap on clusters of intact tissues. Spectra of all four groups of normal tissues gave exclusive clusters when tested against malignant spectra. Thus, this study demonstrates that spectra recorded from the superior surface of an intact tissue may have contributions from deeper layers but has no bearing from the classification of a malignant tissues point of view.

Select this Article		Spatial sensitivity of acousto-optic and optical near-infrared spectroscopy sensing measurements Sonny Gunadi and Terence S. Leung J. Biomed. Opt. 16, 127005 (Nov 23, 2011); http://dx.doi.org/10.1117/1.3660315 \| Cited 3 times Online Publication Date: Nov 23, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract Near-infrared spectroscopy (NIRS) is a popular sensing technique to measure tissue oxygenation noninvasively. However, the region of interest (ROI) is often beneath a superficial layer, which affects its accuracy. By applying focused ultrasound in the ROI, acousto-optic (AO) techniques can potentially minimize the effect of physiological changes in the superficial layer. Using absorption perturbation experiments in both transmission and reflection modes, we investigated the spatial sensitivity distributions and mean penetration depths of an AO system based on a digital correlator and two popular NIRS systems based on i. intensity measurements using a single source and detector configuration, and ii. spatially resolved spectroscopy. Our results show that for both transmission and reflection modes, the peak relative sensitivities of the two NIRS systems are near to the superficial regions, whereas those of the AO technique are near to the ROIs. In the reflection mode, when the ROI is deeper than 14 mm, the AO technique has a higher absolute mean sensitivity than the two NIRS techniques. As the focused ultrasound is moved deeper into the turbid medium, the mean penetration depth increases accordingly. The focused ultrasound can shift the peak relative sensitivity of the AO measurement toward its focused region.

Select this Article		Detection of anthrax lef with DNA-based photonic crystal sensors Bailin Zhang, Shatha Dallo, Ralph Peterson, Syed Hussain, Tao Weitao, and Jing Yong Ye J. Biomed. Opt. 16, 127006 (Dec 08, 2011); http://dx.doi.org/10.1117/1.3662460 Online Publication Date: Dec 08, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract Bacillus anthracis has posed a threat of becoming biological weapons of mass destruction due to its virulence factors encoded by the plasmid-borne genes, such as lef for lethal factor. We report the development of a fast and sensitive anthrax DNA biosensor based on a photonic crystal structure used in a total-internal-reflection configuration. For the detection of the lef gene, a single-stranded DNA lef probe was biotinylated and immobilized onto the sensor via biotin-streptavidin interactions. A positive control, lef-com, was the complementary strand of the probe, while a negative control was an unrelated single-stranded DNA fragment from the 16S rRNA gene of Acinetobacter baumannii. After addition of the biotinylated lef probe onto the sensor, significant changes in the resonance wavelength of the sensor were observed, resulting from binding of the probe to streptavidin on the sensor. The addition of lef-com led to another significant increase as a result of hybridization between the two DNA strands. The detection sensitivity for the target DNA reached as low as 0.1 nM. In contrast, adding the unrelated DNAs did not cause an obvious shift in the resonant wavelength. These results demonstrate that detection of the anthrax lef by the photonic crystal structure in a total-internal-reflection sensor is highly specific and sensitive.

back to top

Research Papers: Therapeutic

Select this Article		Assessment of thermal effects of interstitial laser phototherapy on mammary tumors using proton resonance frequency method Kelvin Le, Xiaosong Li, Daniel Figueroa, Rheal A. Towner, Philippe Garteiser, Debra Saunders, Nataliya Smith, Hong Liu, Tomas Hode, Robert E. Nordquist, and Wei R. Chen J. Biomed. Opt. 16, 128001 (Dec 05, 2011); http://dx.doi.org/10.1117/1.3659200 Online Publication Date: Dec 05, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract Laser immunotherapy (LIT) uses a synergistic approach to treat cancer systemically through local laser irradiation and immunological stimulation. Currently, LIT utilizes dye-assisted noninvasive laser irradiation to achieve selective photothermal interaction. However, LIT faces difficulties treating deeper tumors or tumors with heavily pigmented overlying skin. To circumvent these barriers, we use interstitial laser irradiation to induce the desired photothermal effects. The purpose of this study is to analyze the thermal effects of interstitial irradiation using proton resonance frequency (PRF). An 805-nm near-infrared laser with an interstitial cylindrical diffuser was used to treat rat mammary tumors. Different power settings (1.0, 1.25, and 1.5 W) were applied with an irradiation duration of 10 min. The temperature distributions of the treated tumors were measured by a 7 T magnetic resonance imager using PRF. We found that temperature distributions in tissue depended on both laser power and time settings, and that variance in tissue composition has a major influence in temperature elevation. The temperature elevations measured during interstitial laser irradiation by PRF and thermocouple were consistent, with some variations due to tissue composition and the positioning of the thermocouple's needle probes. Our results indicated that, for a tissue irradiation of 10 min, the elevation of rat tumor temperature ranged from 8 to 11°C for 1 W and 8 to 15°C for 1.5 W. This is the first time a 7 T magnetic resonance imager has been used to monitor interstitial laser irradiation via PRF. Our work provides a basic understanding of the photothermal interaction needed to control the thermal damage inside a tumor using interstitial laser treatment. Our work may lead to an optimal protocol for future cancer treatment using interstitial phototherapy in conjunction with immunotherapy.

Select this Article		Three-dimensional Monte Carlo model of pulsed-laser treatment of cutaneous vascular lesions Matija Milanič and Boris Majaron J. Biomed. Opt. 16, 128002 (Nov 23, 2011); http://dx.doi.org/10.1117/1.3659205 Online Publication Date: Nov 23, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract We present a three-dimensional Monte Carlo model of optical transport in skin with a novel approach to treatment of side boundaries of the volume of interest. This represents an effective way to overcome the inherent limitations of “escape” and “mirror” boundary conditions and enables high-resolution modeling of skin inclusions with complex geometries and arbitrary irradiation patterns. The optical model correctly reproduces measured values of diffuse reflectance for normal skin. When coupled with a sophisticated model of thermal transport and tissue coagulation kinetics, it also reproduces realistic values of radiant exposure thresholds for epidermal injury and for photocoagulation of port wine stain blood vessels in various skin phototypes, with or without application of cryogen spray cooling.

Select this Article		Targeted microinjection into cells and retina using optoporation Ling Gu and Samarendra K. Mohanty J. Biomed. Opt. 16, 128003 (Dec 06, 2011); http://dx.doi.org/10.1117/1.3662887 Online Publication Date: Dec 06, 2011 Full Text: Read Online (HTML) \| Download PDF
	+ -	Show Abstract The laser microbeam has enabled highly precise noncontact delivery of exogenous materials into targeted cells without compromising cell viability, which has been a highly challenging task for traditional methods. Here, we report targeted delivery of impermeable substances into mammalian cells and goldfish retinal explants subsequent to ultrafast laser microbeam assisted injection. Introduction of impermeable dye into the cell through localized pore formation was confirmed by distinct fluorescence at the site of pore formation on the membrane and its spatiotemporal diffusion pattern through the nucleus. Indirect optoporation by bubble formation, external to cell, led to a similar spatial diffusion pattern but with a larger time constant for injection. Using optimized laser intensity, exposure, and a spatial irradiation pattern, desired spatial transfection patterns in goldfish retina explants were achieved as confirmed by the expression of injected plasmids encoded for light-activable channelrhodopsin-2 ion-channel, tagged with fluorescent protein. Laser assisted delivery of exogenous material into a specific area of three-dimensional neuronal tissue, such as the retina, will help to understand the functioning of neuronal circuitry of normal and degenerated retina.

back to top

Book Reviews

Select this Article OPEN ACCESS		Handbook of Biomedical Optics, by David A Boas, Constantinos Pitris, and Nimmi Ramanujam Robert R. Alfano, Reviewer J. Biomed. Opt. 16, 129901 (Nov 22, 2011); http://dx.doi.org/10.1117/1.3659228 \| Cited 1 time Online Publication Date: Nov 22, 2011 Full Text: \| Download PDF
	+ -	Show Abstract A book review of a recently released title.

View presentations in solar, OLEDs, and more

Field Guide to Geometrical Optics

Join SPIE