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Saager, Rolf B.
Publications (10 of 44) Show all publications
Saager, R. B., Rowland, R. A., Baldado, M. L., Kennedy, G. T., Bernal, N. P., Ponticorvo, A., . . . Durkin, A. J. (2019). Impact of hemoglobin breakdown products in the spectral analysis of burn wounds using spatial frequency domain spectroscopy. Journal of Biomedical Optics, 24(2), Article ID 020501.
Open this publication in new window or tab >>Impact of hemoglobin breakdown products in the spectral analysis of burn wounds using spatial frequency domain spectroscopy
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2019 (English)In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 24, no 2, article id 020501Article in journal (Refereed) Published
Abstract [en]

Burn wounds and wound healing invoke several biological processes that may complicate the interpretation of spectral imaging data. Through analysis of spatial frequency domain spectroscopy data (450 to 1000 nm) obtained from longitudinal investigations using a graded porcine burn wound healing model, we have identified features in the absorption spectrum that appear to suggest the presence of hemoglobin breakdown products, e.g., methemoglobin. Our results show that the calculated concentrations of methemoglobin directly correlate with burn severity, 24 h after the injury. In addition, tissue parameters such as oxygenation (StO2) and water fraction may be underestimated by 20% and 78%, respectively, if methemoglobin is not included in the spectral analysis.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2019
Keywords
burns; hemoglobin; methemoglobin; spectroscopy; multispectral imaging; spatial frequency domain spectroscopy
National Category
Dermatology and Venereal Diseases
Identifiers
urn:nbn:se:liu:diva-156326 (URN)10.1117/1.JBO.24.2.020501 (DOI)000463885200001 ()30724041 (PubMedID)2-s2.0-85061141061 (Scopus ID)
Available from: 2019-04-15 Created: 2019-04-15 Last updated: 2019-04-23Bibliographically approved
Ponticorvo, A., Rowland, R., Baldado, M., Kennedy, G. T., Saager, R. B., Burmeister, D. M., . . . Durkin, A. J. (2018). 529 Evaluating Clinical Observation, Spatial Frequency Domain Imaging (SFDI) and Laser Speckle Imaging (LSI) for the Assessment of Burns. Journal of Burn Care & Research, 39(Suppl_1), S238-S239
Open this publication in new window or tab >>529 Evaluating Clinical Observation, Spatial Frequency Domain Imaging (SFDI) and Laser Speckle Imaging (LSI) for the Assessment of Burns
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2018 (English)In: Journal of Burn Care & Research, ISSN 1559-047X, E-ISSN 1559-0488, Vol. 39, no Suppl_1, p. S238-S239Article in journal (Refereed) Published
Abstract [en]

Introduction

The current standard for diagnosis of burn severity and subsequent wound healing is through clinical examination, which is highly subjective. Several new technologies focus on burn care in an attempt to help clinicians quantify burn severity earlier and more accurately. Laser Speckle Imaging (LSI) is a technique that quantifies perfusion to assess burn wounds while Spatial Frequency Domain Imaging (SFDI) can quantify the structural damage caused by burns. Here we test each system’s ability to categorize burn wounds and compare their performance.

Methods

Clinical assessment of a Yorkshire pig (n=3) graded burn model was performed at 24 hours after burn injury. A commercial LSI (Periscan PIM 3, Perimed Inc.) and SFDI (OxImager RS, MI Inc.) device were used to measure hemodynamic (blood flow) and structural (reduced scattering coefficient) properties of the burn wounds. Burn severity was confirmed by histology. Additionally, both devices were used to collect preliminary data on clinical patients.

Results

Clinical assessments in the swine model were 83% percent accurate, while the LSI and SFDI systems were 81% and 85% percent accurate respectively. In addition to being more accurate than LSI in this study, SFDI data suggests that it can spatially resolve the heterogeneity of burn severity within a burn wound. This was not observed using the commercial LSI device. Preliminary results on clinical patients also showed both devices were capable of non-invasively predicting burn regions that would eventually require grafting.

Conclusions

The testing of these different imaging modalities in a controlled environment allows a direct comparison. Here we show that SFDI is capable of categorizing burn wounds in a swine model of histologically confirmed graded burn severity more accurately than clinical assessment or LSI. SFDI is also able to resolve spatial heterogeneity of burn severity within a wound. SFDI has the potential to improve clinical care with additional information related to tissue structure and function, thus aiding clinicians to make decisions on how to treat burn wounds accurately at earlier time points. Additionally, these noninvasive imaging technologies have the potential to enhance tracking of wound progression and treatment efficacy.

Applicability of Research to Practice

By improving diagnostic accuracy of which burn areas will require grafting, these devices may aid clinicians make appropriate treatment decisions sooner.

Place, publisher, year, edition, pages
Oxford University Press, 2018
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-152300 (URN)10.1093/jbcr/iry006.452 (DOI)
Available from: 2018-11-26 Created: 2018-11-26 Last updated: 2018-11-26Bibliographically approved
Torabzadeh, M., Stockton, P. A., Tromberg, B. J., Durkin, A. J., Saager, R. B., Kennedy, G. T. & Bartels, R. A. (2018). hyperspectral characterization of tissue simulating phantoms using a supercontinuum laser in a spatial frequency domain imaging instrument. In: Ramesh Raghavachari and Rongguang Liang (Ed.), Proceedings Volume 10486, Design and Quality for Biomedical Technologies XI; 104860G (2018): . Paper presented at SPIE BIOS, 27 January - 1 February 2018, San Francisco, California, United States. SPIE - International Society for Optical Engineering, 10486, Article ID 104860G.
Open this publication in new window or tab >>hyperspectral characterization of tissue simulating phantoms using a supercontinuum laser in a spatial frequency domain imaging instrument
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2018 (English)In: Proceedings Volume 10486, Design and Quality for Biomedical Technologies XI; 104860G (2018) / [ed] Ramesh Raghavachari and Rongguang Liang, SPIE - International Society for Optical Engineering, 2018, Vol. 10486, article id 104860GConference paper, Published paper (Refereed)
Abstract [en]

Hyperspectral Imaging (HSI) is a growing field in tissue optics due to its ability to collect continuous spectral features of a sample without a contact probe. Spatial Frequency Domain Imaging (SFDI) is a non-contact wide-field spectral imaging technique that is used to quantitatively characterize tissue structure and chromophore concentration. In this study, we designed a Hyperspectral SFDI (H-SFDI) instrument which integrated a supercontinuum laser source to a wavelength tuning optical configuration and a sCMOS camera to extract spatial (Field of View: 2cm×2cm) and broadband spectral features (580nm-950nm). A preliminary experiment was also performed to integrate the hyperspectral projection unit to a compressed single pixel camera and Light Labeling (LiLa) technique.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2018
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-152302 (URN)10.1117/12.2291369 (DOI)
Conference
SPIE BIOS, 27 January - 1 February 2018, San Francisco, California, United States
Available from: 2018-11-26 Created: 2018-11-26 Last updated: 2018-11-26Bibliographically approved
Saager, R. B., Baldado, M. L., Rowland, R. A., Kelly, K. M. & Durkin, A. J. (2018). Method using in vivo quantitative spectroscopy to guide design and optimization of low-cost, compact clinical imaging devices: emulation and evaluation of multispectral imaging systems. Journal of Biomedical Optics, 23(4), Article ID 046002.
Open this publication in new window or tab >>Method using in vivo quantitative spectroscopy to guide design and optimization of low-cost, compact clinical imaging devices: emulation and evaluation of multispectral imaging systems
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2018 (English)In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 23, no 4, article id 046002Article in journal (Refereed) Published
Abstract [en]

With recent proliferation in compact and/or low-cost clinical multispectral imaging approaches and commercially available components, questions remain whether they adequately capture the requisite spectral content of their applications. We present a method to emulate the spectral range and resolution of a variety of multispectral imagers, based on in-vivo data acquired from spatial frequency domain spectroscopy (SFDS). This approach simulates spectral responses over 400 to 1100 nm. Comparing emulated data with full SFDS spectra of in-vivo tissue affords the opportunity to evaluate whether the sparse spectral content of these imagers can (1) account for all sources of optical contrast present (completeness) and (2) robustly separate and quantify sources of optical contrast (crosstalk). We validate the approach over a range of tissue-simulating phantoms, comparing the SFDS-based emulated spectra against measurements from an independently characterized multispectral imager. Emulated results match the imager across all phantoms (<3  %   absorption, <1  %   reduced scattering). In-vivo test cases (burn wounds and photoaging) illustrate how SFDS can be used to evaluate different multispectral imagers. This approach provides an in-vivo measurement method to evaluate the performance of multispectral imagers specific to their targeted clinical applications and can assist in the design and optimization of new spectral imaging devices.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2018
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-152299 (URN)10.1117/1.jbo.23.4.046002 (DOI)
Available from: 2018-11-26 Created: 2018-11-26 Last updated: 2019-03-22Bibliographically approved
Horan, S. T., Gardner, A. R., Saager, R. B., Durkin, A. J. & Venugopalan, V. (2018). Recovery of layered tissue optical properties from spatial frequency-domain spectroscopy and a deterministic radiative transport solver. Journal of Biomedical Optics, 24(7), Article ID 071607.
Open this publication in new window or tab >>Recovery of layered tissue optical properties from spatial frequency-domain spectroscopy and a deterministic radiative transport solver
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2018 (English)In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 24, no 7, article id 071607Article in journal (Refereed) Published
Abstract [en]

We present a method to recover absorption and reduced scattering spectra for each layer of a two-layer turbid media from spatial frequency-domain spectroscopy data. We focus on systems in which the thickness of the top layer is less than the transport mean free path   (  0.1  −  0.8l  *    )  . We utilize an analytic forward solver, based upon the N’th-order spherical harmonic expansion with Fourier decomposition   (  SHEFN  )   method in conjunction with a multistage inverse solver. We test our method with data obtained using spatial frequency-domain spectroscopy with 32 evenly spaced wavelengths within λ  =  450 to 1000 nm on six-layered tissue phantoms with distinct optical properties. We demonstrate that this approach can recover absorption and reduced scattering coefficient spectra for both layers with accuracy comparable with current Monte Carlo methods but with lower computational cost and potential flexibility to easily handle variations in parameters such as the scattering phase function or material refractive index. To our knowledge, this approach utilizes the most accurate deterministic forward solver used in such problems and can successfully recover properties from a two-layer media with superficial layer thicknesses.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2018
Keywords
inverse problem; spatial frequency domain; staged inversion; analytic solver
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:liu:diva-156324 (URN)10.1117/1.JBO.24.7.071607 (DOI)30456934 (PubMedID)2-s2.0-85056712970 (Scopus ID)
Available from: 2019-04-15 Created: 2019-04-15 Last updated: 2019-04-23Bibliographically approved
Strömberg, T., Saager, R. B., Kennedy, G. T., Fredriksson, I., Salerud, G., Durkin, A. J. & Larsson, M. (2018). Spatial frequency domain imaging using a snap-shot filter mosaic camera with multi-wavelength sensitive pixels. In: Bernard Choi, and Haishan Zeng (Ed.), Proceedings Volume 10467, Photonics in Dermatology and Plastic Surgery 2018; 104670D (2018): . Paper presented at SPIE BIOS, 27 January - 1 February 2018, San Francisco, California, United States. SPIE - International Society for Optical Engineering, 10467, Article ID 104670D.
Open this publication in new window or tab >>Spatial frequency domain imaging using a snap-shot filter mosaic camera with multi-wavelength sensitive pixels
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2018 (English)In: Proceedings Volume 10467, Photonics in Dermatology and Plastic Surgery 2018; 104670D (2018) / [ed] Bernard Choi, and Haishan Zeng, SPIE - International Society for Optical Engineering, 2018, Vol. 10467, article id 104670DConference paper, Published paper (Refereed)
Abstract [en]

Spatial frequency domain imaging (SFDI) utilizes a digital light processing (DLP) projector for illuminating turbid media with sinusoidal patterns. The tissue absorption (μa) and reduced scattering coefficient (μ,s) are calculated by analyzing the modulation transfer function for at least two spatial frequencies. We evaluated different illumination strategies with a red, green and blue light emitting diodes (LED) in the DLP, while imaging with a filter mosaic camera, XiSpec, with 16 different multi-wavelength sensitive pixels in the 470-630 nm wavelength range. Data were compared to SFDI by a multispectral camera setup (MSI) consisting of four cameras with bandpass filters centered at 475, 560, 580 and 650 nm. A pointwise system for comprehensive microcirculation analysis was used (EPOS) for comparison. A 5-min arterial occlusion and release protocol on the forearm of a Caucasian male with fair skin was analyzed by fitting the absorption spectra of the chromophores HbO2, Hb and melanin to the estimatedμa. The tissue fractions of red blood cells (fRBC), melanin (/mel) and the Hb oxygenation (S02 ) were calculated at baseline, end of occlusion, early after release and late after release. EPOS results showed a decrease in S02 during the occlusion and hyperemia during release (S02 = 40%, 5%, 80% and 51%). The fRBC showed an increase during occlusion and release phases. The best MSI resemblance to the EPOS was for green LED illumination (S02 = 53%, 9%, 82%, 65%). Several illumination and analysis strategies using the XiSpec gave un-physiological results (e.g. negative S02 ). XiSpec with green LED illumination gave the expected change in /RBC , while the dynamics in S02 were less than those for EPOS. These results may be explained by the calculation of modulation using an illumination and detector setup with a broad spectral transmission bandwidth, with considerable variation in μa of included chromophores. Approaches for either reducing the effective bandwidth of the XiSpec filters or by including their characteristic in a light transport model for SFDI modulation, are proposed.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2018
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-152301 (URN)10.1117/12.2289357 (DOI)000451701900002 ()
Conference
SPIE BIOS, 27 January - 1 February 2018, San Francisco, California, United States
Available from: 2018-11-26 Created: 2018-11-26 Last updated: 2018-12-20Bibliographically approved
Saager, R. B., Dang, A. N., Huang, S. S., Kelly, K. M. & Durkin, A. J. (2017). Handheld spatial frequency domain spectrographic imager for depth-sensitive, quantitative spectroscopy of skin tissue. In: Bernard Choi, Haishan Zeng, and Nikiforos Kollias (Ed.), Proceedings Volume 10037, Photonics in Dermatology and Plastic Surgery; 1003703 (2017): . Paper presented at SPIE BIOS, 28 January - 2 February 2017, San Francisco, California, United States. SPIE - International Society for Optical Engineering, Article ID 1003703.
Open this publication in new window or tab >>Handheld spatial frequency domain spectrographic imager for depth-sensitive, quantitative spectroscopy of skin tissue
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2017 (English)In: Proceedings Volume 10037, Photonics in Dermatology and Plastic Surgery; 1003703 (2017) / [ed] Bernard Choi, Haishan Zeng, and Nikiforos Kollias, SPIE - International Society for Optical Engineering, 2017, article id 1003703Conference paper, Published paper (Refereed)
Abstract [en]

Here we present a handheld, implementation of Spatial Frequency Domain Spectroscopy (SFDS) that employs line imaging. The new instrument can measure 1088 spatial locations that span a 3 cm line as opposed to our benchtop system that only collects a single 1 mm diameter spot. This imager, however, retains the spectral resolution (~ 1 nm) and range (450 to 1000 nm) of our benchtop system. The device also has tremendously improved mobility and portability, allowing for greater ease of use in clinical setting. A smaller size also enables access to different tissue locations, which increases the flexibility of the device. The design of this portable system not only enables SFDS to be used in clinical settings, but also enables visualization of properties of layered tissues such as skin.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-152308 (URN)10.1117/12.2252518 (DOI)
Conference
SPIE BIOS, 28 January - 2 February 2017, San Francisco, California, United States
Available from: 2018-11-26 Created: 2018-11-26 Last updated: 2018-11-26Bibliographically approved
Saager, R. B., Dang, A. N., Huang, S. S., Kelly, K. M. & Durkin, A. J. (2017). Portable (handheld) clinical device for quantitative spectroscopy of skin, utilizing spatial frequency domain reflectance techniques. Review of Scientific Instruments, 88(9)
Open this publication in new window or tab >>Portable (handheld) clinical device for quantitative spectroscopy of skin, utilizing spatial frequency domain reflectance techniques
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2017 (English)In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 88, no 9Article in journal (Refereed) Published
Abstract [en]

Spatial Frequency Domain Spectroscopy (SFDS) is a technique for quantifying in-vivo tissue optical properties. SFDS employs structured light patterns that are projected onto tissues using a spatial light modulator, such as a digital micromirror device. In combination with appropriate models of light propagation, this technique can be used to quantify tissue optical properties (absorption, μa, and scattering, μs′, coefficients) and chromophore concentrations. Here we present a handheld implementation of an SFDS device that employs line (one dimensional) imaging. This instrument can measure 1088 spatial locations that span a 3 cm line as opposed to our original benchtop SFDS system that only collects a single 1 mm diameter spot. This imager, however, retains the spectral resolution (∼1 nm) and range (450–1000 nm) of our original benchtop SFDS device. In the context of homogeneous turbid media, we demonstrate that this new system matches the spectral response of our original system to within 1% across a typical range of spatial frequencies (0-0.35 mm−1). With the new form factor, the device has tremendously improved mobility and portability, allowing for greater ease of use in a clinical setting. A smaller size also enables access to different tissue locations, which increases the flexibility of the device. The design of this portable system not only enables SFDS to be used in clinical settings but also enables visualization of properties of layered tissues such as skin.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2017
National Category
Biological Sciences
Identifiers
urn:nbn:se:liu:diva-152304 (URN)10.1063/1.5001075 (DOI)
Available from: 2018-11-26 Created: 2018-11-26 Last updated: 2018-11-26Bibliographically approved
Ponticorvo, A., Burmeister, D. M., Rowland, R., Baldado, M., Kennedy, G. T., Saager, R. B., . . . Durkin, A. J. (2017). Quantitative long-term measurements of burns in a rat model using Spatial Frequency Domain Imaging (SFDI) and Laser Speckle Imaging (LSI). Lasers in Surgery and Medicine, 49(3), 293-304
Open this publication in new window or tab >>Quantitative long-term measurements of burns in a rat model using Spatial Frequency Domain Imaging (SFDI) and Laser Speckle Imaging (LSI)
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2017 (English)In: Lasers in Surgery and Medicine, ISSN 0196-8092, E-ISSN 1096-9101, Vol. 49, no 3, p. 293-304Article in journal (Refereed) Published
Abstract [en]

Background and Ojectives

The current standard for diagnosis of burn severity and subsequent wound healing is through clinical examination, which is highly subjective. Several new technologies are shifting focus to burn care in an attempt to help quantify not only burn depth but also the progress of healing. While accurate early assessment of partial thickness burns is critical for dictating the course of treatment, the ability to quantitatively monitor wound status over time is critical for understanding treatment efficacy. SFDI and LSI are both non‐invasive imaging modalities that have been shown to have great diagnostic value for burn severity, but have yet to be tested over the course of wound healing.

Methods

In this study, a hairless rat model (n = 6, 300–450 g) was used with a four pronged comb to create four identical partial thickness burns (superficial n = 3 and deep n = 3) that were used to monitor wound healing over a 28 days period. Weekly biopsies were taken for histological analysis to verify wound progression. Both SFDI and LSI were performed weekly to track the evolution of hemodynamic (blood flow and oxygen saturation) and structural (reduced scattering coefficient) properties for the burns.

Results

LSI showed significant changes in blood flow from baseline to 220% in superficial and 165% in deep burns by day 7. In superficial burns, blood flow returned to baseline levels by day 28, but not for deep burns where blood flow remained elevated. Smaller increases in blood flow were also observed in the surrounding tissue over the same time period. Oxygen saturation values measured with SFDI showed a progressive increase from baseline values of 66–74% in superficial burns and 72% in deep burns by day 28. Additionally, SFDI showed significant decreases in the reduced scattering coefficient shortly after the burns were created. The scattering coefficient progressively decreased in the wound area, but returned towards baseline conditions at the end of the 28 days period. Scattering changes in the surrounding tissue remained constant despite the presence of hemodynamic changes.

Conclusions Here, we show that LSI and SFDI are capable of monitoring changes in hemodynamic and scattering properties in burn wounds over a 28 days period. These results highlight the potential insights that can be gained by using non‐invasive imaging technologies to study wound healing. Further development of these technologies could be revolutionary for wound monitoring and studying the efficacy of different treatments.

Place, publisher, year, edition, pages
John Wiley & Sons, 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-152309 (URN)10.1002/lsm.22647 (DOI)
Available from: 2018-11-26 Created: 2018-11-26 Last updated: 2018-11-26Bibliographically approved
Saager, R. B., Quach, A., Kennedy, G. T., Tromberg, B. J. & Durkin, A. J. (2016). From theory to practice: the broadening role of polydimethylsiloxane phantoms as an intermediary between model validation and instrument performance testing (Conference Presentation). In: Ramesh Raghavachari, Rongguang Liang (Ed.), Proceedings Volume 9700, Design and Quality for Biomedical Technologies IX; 97000G (2016): . Paper presented at SPIE BIOS, 13-18 February 2016 San Francisco, California, United States,. SPIE - International Society for Optical Engineering, 9700, Article ID 97000G.
Open this publication in new window or tab >>From theory to practice: the broadening role of polydimethylsiloxane phantoms as an intermediary between model validation and instrument performance testing (Conference Presentation)
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2016 (English)In: Proceedings Volume 9700, Design and Quality for Biomedical Technologies IX; 97000G (2016) / [ed] Ramesh Raghavachari, Rongguang Liang, SPIE - International Society for Optical Engineering, 2016, Vol. 9700, article id 97000GConference paper, Published paper (Refereed)
Abstract [en]

Polydimethylsiloxane (PDMS) has been a popular medium to fabricate tissue simulating optical phantoms. Recently, its use has significantly expanded in instrument calibration and performance testing, validation of advanced models of light transport of complex tissue geometries and evaluation of novel measurement modalities. To meet these demands, fabrication methods of these optical phantoms have become more refined and its structure and constituent components (i.e. dyes and scattering agents) have evolved to better mimic optical properties of tissue spanning both visible and near infrared regimes. We present efforts at the Beckman Laser Institute that address these challenges through PDMS phantoms.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2016
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-152314 (URN)10.1117/12.2218388 (DOI)
Conference
SPIE BIOS, 13-18 February 2016 San Francisco, California, United States,
Available from: 2018-11-23 Created: 2018-11-23 Last updated: 2018-11-23Bibliographically approved
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