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Nirmala Ramanujam - One of the best experts on this subject based on the ideXlab platform.

  • measuring tumor cycling hypoxia and angiogenesis using a side firing Fiber Optic Probe
    Journal of Biophotonics, 2014
    Co-Authors: Amy T Shah, Gregory M. Palmer, Nirmala Ramanujam, Bingqing Wang, Narasimhan Rajaram, Quanli Wang, Mark W Dewhirst
    Abstract:

    Hypoxia and angiogenesis can significantly influence the efficacy of cancer therapy and the behavior of surviving tumor cells. There is a growing demand for technologies to measure tumor hypoxia and angiogenesis temporally in vivo to enable advances in drug development and optimization. This paper reports the use of frequency-domain photon migration with a side-firing Probe to quantify tumor oxygenation and hemoglobin concentrations in nude rats bearing human head/neck tumors administered with carbogen gas, cycling hypoxic gas or just room air. Significant increase (with carbogen gas breathing) or decrease (with hypoxic gas breathing) in tumor oxygenation was observed. The trend in tumor oxygenation during forced cycling hypoxia (CH) followed that of the blood oxygenation measured with a pulse oximeter. Natural CH was also observed in rats under room air. The studies demonstrated the potential of the technology for longitudinal monitoring of tumor CH during tumor growth or in response to therapy.

  • Use of a multiseparation Fiber Optic Probe for the Optical diagnosis of breast cancer
    Journal of Biomedical Optics, 2005
    Co-Authors: Changfang Zhu, Tara M. Breslin, Fushen Xu, Gregory M. Palmer, Nirmala Ramanujam
    Abstract:

    We explore the effects of the illumination and collection geometry on Optical spectroscopic diagnosis of breast cancer. Fluorescence and diffuse reflectance spectroscopy in the UV-visible spectral range are made with a multiseparation Probe at three illumination-collection separations of 735, 980, and 1225 microm, respectively, from 13 malignant and 34 nonmalignant breast tissues. Statistical analysis is carried out on two types of data inputs: (1) the fluorescence and diffuse reflectance spectra recorded at each of the three illumination-collection separations and (2) the integrated fluorescence (at each excitation wavelength) or diffuse reflectance over the entire spectrum at all three illumination-collection separations. The results show that using the integrated fluorescence intensities recorded at a single excitation wavelength at all three illumination-collection separations can discriminate malignant from nonmalignant breast tissues with similar classification accuracy to that using spectral data measured at several excitation wavelengths with a single illumination-collection separation. These findings have significant implications with respect to the design of an Optical system for breast cancer diagnosis. Examining the intensity attenuation at a single wavelength rather than spectral intensities at multiple wavelengths can significantly reduce the measurement and data processing time in a clinical setting as well as the cost and complexity of the Optical system.

  • experimental proof of the feasibility of using an angled Fiber Optic Probe for depth sensitive fluorescence spectroscopy of turbid media
    Optics Letters, 2004
    Co-Authors: Quan Liu, Nirmala Ramanujam
    Abstract:

    An angled Fiber-Optic Probe that facilitates depth-sensitive fluorescence measurements was developed for enhancing detection of epithelial precancers. The Probe was tested on solid, two-layered phantoms and proved to be effective in selectively detecting fluorescence from different layers. Specifically, a larger illumination angle provides greater sensitivity to fluorescence from the top layer as well as yielding an overall higher fluorescence signal. Monte Carlo simulations of a theoretical model of the phantoms demonstrate that increasing the illumination angle results in an increased excitation photon density and, thus, in increased fluorescence generated in the top layer.

  • investigation of Fiber Optic Probe designs for Optical spectroscopic diagnosis of epithelial pre cancers
    Lasers in Surgery and Medicine, 2004
    Co-Authors: Melissa C Skala, Changfang Zhu, Gregory M. Palmer, Quan Liu, Kristin M Vrotsos, Crystal L Marshekstone, Annette Gendronfitzpatrick, Nirmala Ramanujam
    Abstract:

    Background and Objectives The first objective of this study was to evaluate the performance of fluorescence spectroscopy for diagnosing pre-cancers in stratified squamous epithelial tissues in vivo using two different Probe geometries with (1) overlapping versus (2) non-overlapping illumination and collection areas on the tissue surface. Probe (1) and Probe (2) are preferentially sensitive to the fluorescence originating from the tissue surface and sub-surface tissue depths, respectively. The second objective was to design a novel, angled illumination Fiber-Optic Probe to maximally exploit the depth-dependent fluorescence properties of epithelial tissues. Study Design/Materials and Methods In the first study, spectra were measured from epithelial pre-cancers and normal tissues in the hamster cheek pouch and analyzed with a non-parametric classification algorithm. In the second study, Monte Carlo modeling was used to simulate fluorescence measurements from an epithelial tissue model with the angled illumination Probe. Results An unbiased classification algorithm based on spectra measured with Probes (1) and (2), classified pre-cancerous and normal tissues with 78 and 94% accuracy, respectively. The angled illumination Probe design provides the capability to detect fluorescence from a wide range of tissue depths in an epithelial tissue model. Conclusions The first study demonstrates that fluorescence originating from sub-surface tissue depths (Probe (2)) is more diagnostic than fluorescence originating from the tissue surface (Probe (1)) in the hamster cheek pouch model. However in general, it is difficult to know a priori the optimal Probe geometry for pre-cancer detection in a particular epithelial tissue model. The angled illumination Probe provides the capability to measure tissue fluorescence selectively from different depths within epithelial tissues, thus obviating the need to select a single optimal Probe design for the fluorescence-based diagnosis of epithelial pre-cancers. Lasers Surg. Med. 34:25–38, 2004. © 2004 Wiley-Liss, Inc.

  • effect of Fiber Optic Probe geometry on depth resolved fluorescence measurements from epithelial tissues a monte carlo simulation
    Journal of Biomedical Optics, 2003
    Co-Authors: Nirmala Ramanujam
    Abstract:

    Developing Fiber Optic Probe geometries to selectively mea- sure fluorescence spectra from different sublayers within human epi- thelial tissues will potentially improve the endogenous fluorescence contrast between neoplastic and nonneoplastic tissues. In this study, two basic Fiber Optic Probe geometries, which are called the variable aperture (VA) and multidistance (MD) approaches, are compared for depth-resolved fluorescence measurements from human cervical epi- thelial tissues. The VA Probe has completely overlapping illumination and collection areas with variable diameters, while the MD Probe employs separate illumination and collection Fibers with a fixed sepa- ration between them. Monte Carlo simulation results show that the total fluorescence detected is significantly higher for the VA Probe geometry, while the probing depth is significantly greater for the MD Probe geometry. An important observation is that the VA Probe is more sensitive to the epithelial layer, while the MD Probe is more sensitive to the stromal layer. The effect of other factors, including numerical aperture (NA) and tissue Optical properties on the fluores- cence measurements with VA and MD Probe geometries, are also evaluated. The total fluorescence detected with both Probe geom- etries significantly increases when the Fiber NA is changed from 0.22 to 0.37. The sensitivity to different sublayers is found to be strongly dependent on the tissue Optical properties. The simulation results are used to design a simple Fiber Optic Probe that combines both the VA and MD geometries to enable fluorescence measurements from the different sublayers within human epithelial tissues. © 2003 Society of Photo-

Soumyo Mukherji - One of the best experts on this subject based on the ideXlab platform.

  • a silicon nitride coated lspr based Fiber Optic Probe for possible continuous monitoring of sucrose content in fruit juices
    Sensors and Actuators B-chemical, 2016
    Co-Authors: Shraddha K Chauhan, Nirmal Punjabi, D K Sharma, Soumyo Mukherji
    Abstract:

    Abstract This paper describes a sensor configuration for stable, long term, continuous monitoring of sugar content in the product of fruit juice packaging industry. An improvement in refractive index (RI) sensitivity of a gold nanoparticle (AuNP) coated, U-shaped Fiber-Optic Probe was achieved by a deposition of silicon nitride (SiNx) film on the Probe surface. AuNP of two distinct sizes, 18 nm and 39 nm, were bound to Fiber core surfaces to generate LSPR, when excited by light passing through the Fiber. Following this, a thin film of SiNx was deposited over the AuNP coated sensing region of the Fiber-Optic Probe, using hot filament chemical vapor deposition. We investigated the effect of SiNx film coating on RI sensitivity for five different thicknesses: 11 nm, 16 nm, 20 nm, 23 nm and 40 nm. Several concentrations of sucrose solution were used to vary the bulk RI from 1.333 to 1.387 in the sensing region. We have observed 1.24-times RI sensitivity enhancement in case of 39 nm AuNP covered with 20 nm SiNx film compared to only AuNP coated Fiber-Optic Probe. We also successfully determined the sugar content in three different packaged juices (at various dilution levels). The sensor proved its potential for measurement of sugar in solutions having complex composition with error

  • novel u bent Fiber Optic Probe for localized surface plasmon resonance based biosensor
    Biosensors and Bioelectronics, 2009
    Co-Authors: V V R Sai, Tapanendu Kundu, Soumyo Mukherji
    Abstract:

    Abstract The aim of this study is to develop an Optical absorbance based biosensor suitable for wide scale use in resource-poor locales. A sensor for sensitive measurement of refractive index (RI) with the help of Optical absorbance properties of gold nanoparticles (GNP) coupled to an efficient Optical transducer in the form of a U-bent Fiber Optic Probe is described. A U-bent Probe was fabricated by a simple procedure. The absorbance due to the localized surface plasmon resonance (LSPR) of Fiber-bound GNP was found to be linear to refractive index changes between 1.33 and 1.35. A U-bent Probe of 200 μm diameter with a bend radius of 0.75 mm gave rise to a sensitivity of 35 ΔA/RIU at 540 nm. The resolution of the sensor Probe was 3.8 × 10−5 RIU. Label-free biosensing was demonstrated using these Probes with the help of IgG–anti IgG as bioreceptor–analyte pair.

  • novel u bent Fiber Optic Probe for localized surface plasmon resonance based biosensor
    Biosensors and Bioelectronics, 2009
    Co-Authors: V V R Sai, Tapanendu Kundu, Soumyo Mukherji
    Abstract:

    The aim of this study is to develop an Optical absorbance based biosensor suitable for wide scale use in resource-poor locales. A sensor for sensitive measurement of refractive index (RI) with the help of Optical absorbance properties of gold nanoparticles (GNP) coupled to an efficient Optical transducer in the form of a U-bent Fiber Optic Probe is described. A U-bent Probe was fabricated by a simple procedure. The absorbance due to the localized surface plasmon resonance (LSPR) of Fiber-bound GNP was found to be linear to refractive index changes between 1.33 and 1.35. A U-bent Probe of 200 microm diameter with a bend radius of 0.75 mm gave rise to a sensitivity of 35 DeltaA/RIU at 540 nm. The resolution of the sensor Probe was 3.8x10(-5) RIU. Label-free biosensing was demonstrated using these Probes with the help of IgG-anti IgG as bioreceptor-analyte pair.

V V R Sai - One of the best experts on this subject based on the ideXlab platform.

  • novel u bent Fiber Optic Probe for localized surface plasmon resonance based biosensor
    Biosensors and Bioelectronics, 2009
    Co-Authors: V V R Sai, Tapanendu Kundu, Soumyo Mukherji
    Abstract:

    Abstract The aim of this study is to develop an Optical absorbance based biosensor suitable for wide scale use in resource-poor locales. A sensor for sensitive measurement of refractive index (RI) with the help of Optical absorbance properties of gold nanoparticles (GNP) coupled to an efficient Optical transducer in the form of a U-bent Fiber Optic Probe is described. A U-bent Probe was fabricated by a simple procedure. The absorbance due to the localized surface plasmon resonance (LSPR) of Fiber-bound GNP was found to be linear to refractive index changes between 1.33 and 1.35. A U-bent Probe of 200 μm diameter with a bend radius of 0.75 mm gave rise to a sensitivity of 35 ΔA/RIU at 540 nm. The resolution of the sensor Probe was 3.8 × 10−5 RIU. Label-free biosensing was demonstrated using these Probes with the help of IgG–anti IgG as bioreceptor–analyte pair.

  • novel u bent Fiber Optic Probe for localized surface plasmon resonance based biosensor
    Biosensors and Bioelectronics, 2009
    Co-Authors: V V R Sai, Tapanendu Kundu, Soumyo Mukherji
    Abstract:

    The aim of this study is to develop an Optical absorbance based biosensor suitable for wide scale use in resource-poor locales. A sensor for sensitive measurement of refractive index (RI) with the help of Optical absorbance properties of gold nanoparticles (GNP) coupled to an efficient Optical transducer in the form of a U-bent Fiber Optic Probe is described. A U-bent Probe was fabricated by a simple procedure. The absorbance due to the localized surface plasmon resonance (LSPR) of Fiber-bound GNP was found to be linear to refractive index changes between 1.33 and 1.35. A U-bent Probe of 200 microm diameter with a bend radius of 0.75 mm gave rise to a sensitivity of 35 DeltaA/RIU at 540 nm. The resolution of the sensor Probe was 3.8x10(-5) RIU. Label-free biosensing was demonstrated using these Probes with the help of IgG-anti IgG as bioreceptor-analyte pair.

Rebecca Richardskortum - One of the best experts on this subject based on the ideXlab platform.

  • autofluorescence and diffuse reflectance spectroscopy of oral epithelial tissue using a depth sensitive Fiber Optic Probe
    Applied Optics, 2008
    Co-Authors: Richard A Schwarz, Rebecca Richardskortum, Wen Gao, Dania Daye, Michelle D Williams, Ann M Gillenwater
    Abstract:

    Optical spectroscopy can provide useful diagnostic information about the morphological and biochemical changes related to the progression of precancer in epithelial tissue. As precancerous lesions develop, the Optical properties of both the superficial epithelium and underlying stroma are altered; measuring spectral data as a function of depth has the potential to improve diagnostic performance. We describe a clinical spectroscopy system with a depth-sensitive, ball lens coupled Fiber-Optic Probe for noninvasive in vivo measurement of oral autofluorescence and diffuse reflectance spectra. We report results of spectroscopic measurements from oral sites in normal volunteers and in patients with neoplastic lesions of the oral mucosa; results indicate that the addition of depth selectivity can enhance the detection of Optical changes associated with precancer.

  • fluorescence and reflectance device variability throughout the progression of a phase ii clinical trial to detect and screen for cervical neoplasia using a Fiber Optic Probe
    Journal of Biomedical Optics, 2007
    Co-Authors: Adrian J Freeberg, Rebecca Richardskortum, Dan M Serachitopol, Nick Mckinnon, Roderick Price, Neely E Atkinson, Dennis D Cox, Calum Macaulay, Michele Follen, Brian M Pikkula
    Abstract:

    Large phase II trials of fluorescence and reflec- tance spectroscopy using a Fiber Optic Probe in the screen- ing and diagnostic settings for detecting cervical neoplasia have been conducted. We present accrual and histopathol- ogy data, instrumentation, data processing, and the prelimi- nary results of interdevice consistencies throughout the pro- gression of a trial. Patients were recruited for either a screening trial no history of abnormal Papanicolaou smears or a diagnostic trial a history of abnormal Papani- colaou smears. Colposcopy identified normal and abnor- mal squamous, columnar, and transformation zone areas that were subsequently measured with the Fiber Probe and biopsied. In the course of the clinical trial, two generations of spectrometers FastEEM2 and FastEEM3 were designed and utilized as Optical instrumentation for in vivo spectro- scopic fluorescence and reflectance measurements. Data processing of fluorescence and reflectance data is explained in detail and a preliminary analysis of the variability across each device and Probe combination is explored. One thou- sand patients were recruited in the screening trial and 850 patients were recruited in the diagnostic trial. Three clinical sites attracted a diverse range of patients of different ages, ethnicities, and menopausal status. The fully processed re- sults clearly show that consistencies exist across all device and Probe combinations throughout the diagnostic trial. Based on the stratification of the data, the results also show identifiable differences in mean intensity between normal and high-grade tissue diagnosis, pre- and postmenopausal status, and squamous and columnar tissue type. The mean intensity values of stratified data show consistent separation across each ofthe device and Probe combinations. By ana- lyzing trial spectra, we provide more evidence that bio- graphical variables such as menopausal status as well as tissue type and diagnosis significantly affect the data. Under- standing these effects will lead to better modeling param- eters when analyzing the performance of fluorescence and reflectance spectroscopy. © 2007 Society of Photo-Optical Instrumen-

  • depth sensitive Optical spectroscopy for noninvasive detection of oral cavity neoplasia
    Biosilico, 2006
    Co-Authors: Richard A Schwarz, Rebecca Richardskortum, Ann M Gillenwater
    Abstract:

    A ball lens coupled Fiber Optic Probe provides the ability to conduct depth sensitive spectroscopic measurements of oral epithelial tissue. Fluorescence and reflectance measurements of normal and abnormal human oral sites in vivo are reported.

  • reflectance spectroscopy for diagnosis of epithelial precancer model based analysis of Fiber Optic Probe designs to resolve spectral information from epithelium and stroma
    Applied Optics, 2005
    Co-Authors: Dizem Arifler, Sung K Chang, Richard A Schwarz, Rebecca Richardskortum
    Abstract:

    Reflectance spectroscopy is a promising technology for detection of epithelial precancer. Fiber-Optic Probes that selectively collect scattered light from both the epithelium and the underlying stroma are likely to improve diagnostic performance of in vivo reflectance spectroscopy by revealing diagnostic features unique to each layer. We present Monte Carlo models with which to evaluate Fiber-Optic Probe geometries with respect to sampling depth and depth resolution. We propose a Probe design that utilizes half-ball lens coupled source and detector Fibers to isolate epithelial scattering from stromal scattering and hence to resolve spectral information from the two layers. The Probe is extremely compact and can provide easy access to different organ sites.

  • ball lens coupled Fiber Optic Probe for depth resolved spectroscopy of epithelial tissue
    Optics Letters, 2005
    Co-Authors: Richard A Schwarz, Sung K Chang, Rebecca Richardskortum, Dizem Arifler, Ina Pavlova, Insiya Hussain, Vivian Mack, Bobby Knight, Ann M Gillenwater
    Abstract:

    A ball lens coupled Fiber-Optic Probe design is described for depth-resolved measurements of the fluorescence and reflectance properties of epithelial tissue. A reflectance target, fluorescence targets, and a two-layer tissue phantom consisting of fluorescent microspheres suspended in collagen are used to characterize the performance of the Probe. Localization of the signal to within 300 μm of the Probe tip is observed by use of reflectance and fluorescence targets in air. Differential enhancement of the fluorescence signal from the top layer of the two-layer tissue phantom is observed.

Deric P Jones - One of the best experts on this subject based on the ideXlab platform.

  • cerebral arterial oxygen saturation measurements using a Fiber Optic pulse oximeter
    Neurocritical Care, 2010
    Co-Authors: Justin P. Phillips, Serene H. Chang, Kishore Maney, Richard M. Langford, Panayiotis A. Kyriacou, Deric P Jones
    Abstract:

    Background A pilot investigation was undertaken to assess the performance of a novel Fiber-Optic cerebral pulse oximetry system. A Fiber-Optic Probe designed to pass through the lumen of a cranial bolt of the type used to make intracranial pressure measurements was used to obtain Optical reflectance signals directly from brain tissue.

  • Measurements of cerebral arterial oxygen saturation using a Fiber-Optic pulse oximeter
    2009 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2009
    Co-Authors: Justin P. Phillips, Serene H. Chang, Kishore Maney, Richard M. Langford, Panayiotis A. Kyriacou, Deric P Jones
    Abstract:

    This pilot investigation was undertaken to assess the performance of a novel Fiber-Optic cerebral pulse oximetry system. A Fiber-Optic Probe designed to pass through the lumen of a cranial bolt of the type used to make intracranial pressure measurements was used to obtain Optical reflectance signals directly from the brain tissue. Preliminary results from seven patients measured in the operating theatre and ITU are presented. Estimations of cerebral arterial oxygen saturation derived from a frequency domain-based algorithm are compared with pulse oximetry (SpO2) and hemoximeter (SaO2) blood samples. The mean (plusmnSD) difference between cerebral oxygen saturation (ScaO2) and finger SpO2 (in saturation units) was -7.47(plusmn3 .4)%. The mean (plusmnSD) difference between ScaO2 and blood SaO2 was -7.37(plusmn2.8)%.