| 1. |
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| 2. |
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| 3. |
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| 4. |
- Ericson, Marica B, 1974, et al.
(författare)
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Two-photon laser-scanning fluorescence microscopy applied for studies of human skin
- 2008
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-0648 .- 1864-063X. ; 1:4, s. 320-330
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Tidskriftsartikel (refereegranskat)abstract
- Two-photon laser scanning fluorescence microscopy (TPM) has been shown to be advantageous for imaging optically turbid media such as human skin. The ability of performing three-dimensional imaging without presectioning of the samples makes the technique not only suitable for noninvasive diagnostics but also for studies of topical delivery of xenobiotics. Here, TPM is used as a method to visualize both autofluorescent and exogenous fluorophores in skin. Samples exposed to sulforhodamine B have been scanned from two directions to investigate attenuation effects. It is shown that optical effects play a major role. Thus, TPM is excellent for visualizing the localization and distribution of fluorophores in human skin, although quantification might be difficult. Furthermore, an image-analysis algorithm has been implemented to facilitate interpretation of TPM images of autofluorescent features of nonmelanoma skin cancer obtained ex vivo. The algorithm was designed to detect cell nuclei and currently has a sensitivity and specificity of 82% and 78% to single cell nuclei. However, in order to detect multinucleated cells, the algorithm needs further development. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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| 5. |
- Fredriksson, Ingemar, et al.
(författare)
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Forced detection Monte Carlo algorithms for accelerated blood vessel image simulations
- 2009
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Ingår i: JOURNAL OF BIOPHOTONICS. - : Wiley. - 1864-063X .- 1864-0648. ; 2:3, s. 178-184
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Tidskriftsartikel (refereegranskat)abstract
- Two forced detection (FD) variance reduction Monte Carlo algorithms for image simulations of tissue-embedded objects with matched refractive index are presented. The principle of the algorithms is to force a fraction of the photon weight to the detector at each and every scattering event. The fractional weight is given by the probability for the photon to reach the detector without further interactions. Two imaging setups are applied to a tissue model including blood vessels, where the ID algorithms produce identical results as traditional brute force simulations, while being accelerated with two orders of magnitude. Extending the methods to include refraction mismatches is discussed. The principle of forced detection; a part of the photon weight. based on the probability of reaching the detector without further interactions, is forced to the detector at each and every scattering event.
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| 6. |
- Gebru, Alem, et al.
(författare)
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Multiband modulation spectroscopy for the determination of sex and species of mosquitoes in flight
- 2018
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X .- 1864-0648. ; 11:8
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Tidskriftsartikel (refereegranskat)abstract
- We present a dual-wavelength polarimetric measurement method to distinguish species and sexes of disease transmitting mosquitoes in flight. By measuring co- and de-polarized backscattered light at 808 and 1550nm, the degree of linear polarization, wingbeat frequency, reflectance, spectral ratio and glossiness of mosquitoes can be retrieved. Body and wing contributions to these signals can be separated. Whereas the optical cross section is sensitive to the aspect of observation, thus the heading direction of the insect in flight, we demonstrate that polarimetric- and spectral-band ratios are largely invariant to the aspect of observation. We show that wing glossiness, as well as wing- and body-spectral ratios are particularly efficient in distinguishing Anopheles coluzzii and Anopheles arabiensis, 2 closely related species of malaria vectors. Spectral and polarimetric ratios relate to microstructural and melanization features of the wing and body of these species. We conclude that multiband modulation spectroscopy is a useful expansion of the parameter space that can be used to improve the specificity of entomological lidars.
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| 7. |
- Glasin, Joakim, et al.
(författare)
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Wireless vitals : Proof of concept for wireless patient monitoring in an emergency department setting
- 2019
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Ingår i: Journal of Biophotonics. - : Wiley-VCH Verlagsgesellschaft. - 1864-063X .- 1864-0648. ; 12:4
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Tidskriftsartikel (refereegranskat)abstract
- Vital sign assessment is a common task in emergency medicine, but resources for continuous monitoring are restricted, data is often recorded manually, and entangled wires cause frustration. Therefore, we designed a small, wireless photoplethysmographic device capable of continuously assessing pulse, respiratory frequency and oxygen saturation on the sternum and tested the performance and feasibility in an emergency department setting. Fifty (56.3 20.2 years), consenting emergency patients (29 male) were recruited. Heart rate, respiratory rate and oxygen saturation were recorded simultaneously using the device and standard monitoring equipment. Data was compared using Bland-Altman plotting (heart rate, respiratory rate) and mean difference (oxygen saturation). The bias for heart- and respiratory rate was 0.4 (limits of agreements -11.3, 12.2 and -6.1, 7.0). Mean difference for oxygen saturation was -0.21 +/- 2.35%. This may be the first wireless device to use photoplethysmography on the sternum for vital sign assessment. We noted good agreement with standard monitors, but lack of standardization in data processing between monitoring systems may limit the generalizability of these findings. Although further improvements are needed, the feasibility of this approach provides proof of concept for a new paradigm of large scale, wireless patient monitoring.
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| 8. |
- Henricson, Joakim, 1977-, et al.
(författare)
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Respiratory rate monitoring in healthy volunteers by central photoplethysmography compared to capnography
- 2022
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Ingår i: Journal of Biophotonics. - : Wiley-V C H Verlag GMBH. - 1864-063X .- 1864-0648. ; 15:4
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Tidskriftsartikel (refereegranskat)abstract
- Monitoring of respiration is a central task in clinical medicine, crucial to patient safety. Despite the uncontroversial role of altered respiratory frequency as an important sign of impending or manifest deterioration, reliable measurement methods are mostly lacking outside of intensive care units and operating theaters. Photoplethysmography targeting the central blood circulation in the sternum could offer accurate and inexpensive monitoring of respiration. Changes in blood flow related to the different parts of the respiratory cycle are used to identify the respiratory pattern. The aim of this observational study was to compare photoplethysmography at the sternum to standard capnography in healthy volunteers. Bland Altman analysis showed good agreement (bias -0.21, SD 1.6, 95% limits of agreement -3.4 to 2.9) in respiratory rate values. Photoplethysmography provided high-quality measurements of respiratory rate comparable to capnographic measurements. This suggests that photoplethysmography may become a precise, cost-effective alternative for respiratory monitoring.
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| 9. |
- Hernandez, Frank Jeyson, et al.
(författare)
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Label free optical sensor for Avidin based on single gold nanoparticles functionalized with aptamers
- 2009
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Ingår i: Journal of Biophotonics. - : Wiley-VCH Verlagsgesellschaft. - 1864-063X .- 1864-0648. ; 2:4, s. 227-231
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Tidskriftsartikel (refereegranskat)abstract
- Optical spectroscopy of a single gold nanoparticle, functionalized with an aptamer, is used to sense the specific binding of avidin. Herewith, the field of single noble metal nanoparticle biosensors is extended to the important field of aptamer based assays. The sensitivity of this initial, but not yet optimized apta-nano-sensor is in the range of 20 nM. Due to its nanoscopic size, this single nanoparticle based apta-sensor may be used in nanoscopic volumes such as in array type assays or even inside cells.
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| 10. |
- Hu, Lingna, et al.
(författare)
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Towards an optical diagnostic system for otitis media using a combination of otoscopy and spectroscopy
- 2019
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X .- 1864-0648. ; 12:6
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Tidskriftsartikel (refereegranskat)abstract
- An improved method, where conventional otoscope investigation of human suspicious otitis media is combined with diffuse reflectance spectroscopy and gas in scattering media absorption spectroscopy (GASMAS) is being developed. Otitis media is one of the most common infectious diseases in children, whose Eustachian tube connecting the middle ear with the nasal cavity is more horizontal than for adults, which leads to impaired fluid drainage. At present, the use of an otoscope to visually observe possible changes in the tympanic membrane appearance is the main diagnostics method for otitis media. Inaccurate diagnosis related to similar symptoms, and the difficulty for small children to describe the condition experienced, frequently leads to over-prescription of antibiotics and alarming increase in bacterial resistance development. More accurate diagnostic methods are highly desirable. Diffuse reflectance spectroscopy is a non-invasive quantitative spectroscopic technique that enables to objectively quantify changes in the hemoglobin content of the tympanic membrane related to inflammation. If an infection is present, the ventilatory function of the Eustachian tube is frequently impaired and the middle-ear cavity will be filled with fluid. GASMAS, a non-invasive detection method, can non-invasively determine if gas is replaced by fluid in the middle-ear cavity.
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| 11. |
- Hult, Jenny, et al.
(författare)
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Unique spectral signature of human cutaneous squamous cell carcinoma by photoacoustic imaging
- 2020
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X .- 1864-0648. ; 13:5
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Tidskriftsartikel (refereegranskat)abstract
- Cutaneous squamous cell carcinoma (cSCC) is a common skin cancer with metastatic potential. To reduce reoperations due to nonradical excision, there is a need to develop a technique for identification of tumor margins preoperatively. Photoacoustic (PA) imaging is a novel imaging technology that combines the strengths of laser optics and ultrasound. Our aim was to determine the spectral signature of cSCC using PA imaging and to use this signature to visualize tumor architecture and borders. Two-dimensional PA images of 33 cSCCs and surrounding healthy skin were acquired ex vivo, using 59 excitation wavelengths from 680 to 970 nm. The spectral response of the cSCCs was compared to healthy tissue, and the difference was found to be greatest at wavelengths in the range 765 to 960 nm (P <.05). Three-dimensional PA images were constructed from spectra obtained in the y-z plane using a linear stepper motor moving along the x-plane. Spectral unmixing was then performed which provided a clear three-dimensional view of the distribution of tumor masses and their borders.
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| 12. |
- Hultman, Martin, et al.
(författare)
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A 15.6 frames per second 1 megapixel Multiple Exposure Laser Speckle Contrast Imaging setup
- 2018
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Ingår i: Journal of Biophotonics. - : Wiley-VCH Verlagsgesellschaft. - 1864-063X .- 1864-0648. ; 11:2
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Tidskriftsartikel (refereegranskat)abstract
- A multiple exposure laser speckle contrast imaging (MELSCI) setup for visualizing blood perfusion was developed using a field programmable gate array (FPGA), connected to a 1000 frames per second (fps) 1-megapixel camera sensor. Multiple exposure time images at 1, 2, 4, 8, 16, 32 and 64 milliseconds were calculated by cumulative summation of 64 consecutive snapshot images. The local contrast was calculated for all exposure times using regions of 4 × 4 pixels. Averaging of multiple contrast images from the 64-millisecond acquisition was done to improve the signal-to-noise ratio. The results show that with an effective implementation of the algorithm on an FPGA, contrast images at all exposure times can be calculated in only 28 milliseconds. The algorithm was applied to data recorded during a 5 minutes finger occlusion. Expected contrast changes were found during occlusion and the following hyperemia in the occluded finger, while unprovoked fingers showed constant contrast during the experiment. The developed setup is capable of massive data processing on an FPGA that enables processing of MELSCI data in 15.6 fps (1000/64 milliseconds). It also leads to improved frame rates, enhanced image quality and enables the calculation of improved microcirculatory perfusion estimates compared to single exposure time systems.
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| 13. |
- Johansson, Johannes, 1977-, et al.
(författare)
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A multipixel diffuse correlation spectroscopy system based on a single photon avalanche diode array
- 2019
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Ingår i: Journal of Biophotonics. - : Wiley-Blackwell. - 1864-063X .- 1864-0648. ; 12:11
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Tidskriftsartikel (refereegranskat)abstract
- The autocorrelation of laser speckles from coherent near infrared light is used for noninvasive estimates of relative changes in blood perfusion in techniques such as laser Doppler flowmetry (LDF) and diffuse correlation spectroscopy (DCS). In this study, a 2D array of single photon avalanche diodes (SPADs) was used to combine the strengths of multiple detectors in LDF with high light sensitivity in DCS. The system was tested on milk phantoms with varying detector fiber diameter (200 and 600 μm), source‐detector fiber separation (4.6‐10.2 mm), fiber‐SPAD distance (2.5‐36.5 mm), contiguous measurement time per repetition for the autocorrelation (1‐33 ms) and temperature (15.6‐46.7°C). An in vivo blood occlusion test was also performed. The multipixel approach improved signal‐to‐noise ratio (SNR) and, in our setup, the use of a multimode detector fiber was beneficial for SNR. In conclusion, the multipixel system works, but improvements and further studies regarding, for example, the data acquisition and optimal settings are still
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| 14. |
- Johansson, Johannes, et al.
(författare)
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Intracerebral quantitative chromophore estimation from reflectance spectra captured during deep brain stimulation implantation
- 2013
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Ingår i: Journal of Biophotonics. - Weinheim : Wiley-VCH Verlagsgesellschaft. - 1864-063X .- 1864-0648. ; 6:5, s. 435-445
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Tidskriftsartikel (refereegranskat)abstract
- Quantification of blood fraction (fblood), blood oxygenation (S), melanin, lipofuscin and oxidised and reduced Cytochrome aa 3 and c was done from diffuse reflectance spectra captured in cortex, white matter, globus pallidus internus (GPi) and subthalamus during stereotactic implantations of 29 deep brain stimulation (DBS) electrodes with the aim of investigating whether the chromophores can give physiological information about the targets for DBS. Double-sided Mann-Whitney U -tests showed more lipofuscin in GPi compared to white matter and subthalamus (p < 0.05). Compared to the other structures, fbloodwas significantly higher in cortex (p < 0.05) and S lower in GPi (p < 0.05). Median values and range for fblood were 1.0 [0.2–6.0]% in the cortex, 0.3 [0.1–8.2]% in white matter, 0.2 [0.1–0.8]% in the GPi and 0.2 [0.1–11.7]% in the subthalamus. Corresponding values for S was 20 [0–81]% in the cortex, 29 [0–78]% in white matter, 0 [0–0]% in the GPi and 0 [0–92]% in the subthalamus. In conclusion, the measurements indicate very low oxygenation and blood volume for DBS patients, especially in the GPi. It would be of great interest to investigate whether this is due to the disease, the normal situation or an artefact of doing invasive measurements.
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| 15. |
- Kantere, Despoina, et al.
(författare)
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Anti-Stokes fluorescence from endogenously formed protoporphyrin IX - Implications for clinical multiphoton diagnostics.
- 2013
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Ingår i: Journal of biophotonics. - : Wiley. - 1864-0648 .- 1864-063X. ; 6:5, s. 409-415
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Tidskriftsartikel (refereegranskat)abstract
- Multiphoton imaging based on two-photon excitation is making its way into the clinics, particularly for skin cancer diagnostics. It has been suggested that endogenously formed protoporphyrin IX (PpIX) induced by aminolevulinic acid or methylaminolevulinate can be applied to improve tumor contrast, in connection to imaging of tissue autofluorescence. However, previous reports are limited to cell studies and data from tissue are scarce. No report shows conclusive evidence that endogenously formed PpIX increases tumor contrast when performing multiphoton imaging in the clinical situation. We here demonstrate by spectral analysis that two-photon excitation of endogenously formed PpIX does not provide additional contrast in superficial basal cell carcinomas. In fact, the PpIX signal is overshadowed by the autofluorescent background. The results show that PpIX should be excited at a wavelength giving rise to one-photon anti-Stokes fluorescence, to overcome the autofluorescent background. Thus, this study reports on a plausible method, which can be implemented for clinical investigations on endogenously formed PpIX using multiphoton microscopy (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).
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| 16. |
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| 17. |
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| 18. |
- Larsson, Jim, et al.
(författare)
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Comparison of dermal vs internal light administration in human lungs using the TDLAS-GASMAS technique—Phantom studies
- 2019
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X .- 1864-0648. ; 12:8
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Tidskriftsartikel (refereegranskat)abstract
- Oxygen and water vapor content, in the lungs of a 3D-printed phantom model based on CT-images of a preterm infant, is evaluated using Tunable Diode Laser Absorption Spectroscopy (TDLAS) in Gas in Scattering Media Absorption Spectroscopy (GASMAS), that is, the TDLAS-GASMAS technique. Oxygen gas is detected through an absorption line near 764 nm and water vapor through an absorption line near 820 nm. A model with a lung containing interior structure is compared to a model with a hollow lung. Compared to the model with the hollow lung, both the mean absorption path length and the transmitted intensity are found to be lower for the model with the structured lung. A new approach, where laser light is delivered internally into the model through an optical fiber, is compared to dermal light administration, that is, illumination onto the skin, for the model with structure inside the lung. The internal light administration generally resulted in larger gas absorption, and higher signal-to-noise ratios, compared to the dermal light administration. The results from the phantom measurements show great promise for the internal illumination approach and a natural next step would be to investigate it further in clinical studies.
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| 19. |
- Leppänen, Olli, et al.
(författare)
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Bioluminescence imaging of energy depletion in vascular pathology: Patent ductus arteriosus and atherosclerosis
- 2012
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X .- 1864-0648. ; 5, s. 336-344
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Forskningsöversikt (refereegranskat)abstract
- The artery wall may develop energy depletion due to insufficient nutritional supply. However, until recently it has not been possible to validate this hypothesis because no available technology has allowed assessment of energy metabolism with sufficient spatial resolution. We use high resolution bioluminescence metabolic imaging to study energy metabolism in two mechanistically different vascular pathologies: patent ductus arteriosus and atherosclerosis. Physiological energy depletion in postnatally constricting ductus arteriosus promotes permanent closure. Insufficient ductus energy depletion, common in preterm infants, is associated with persistent patent ductus arteriosus, a condition with significantly increased morbidity and mortality. In contrast, in atherosclerosis, energy depletion in the macrophage-rich lesion core promotes cell death contributing to lesion instability and disease progression. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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| 20. |
- Li, Meng, et al.
(författare)
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Bark beetles as lidar targets and prospects of photonic surveillance
- 2021
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X .- 1864-0648. ; 14:4
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Tidskriftsartikel (refereegranskat)abstract
- Forestry is raising concern about the outbreaks of European spruce bark beetle, Ips typographus, causing extensive damage to the spruce forest and timber values. Precise monitoring of these beetles is a necessary step towards preventing outbreaks. Current commercial monitoring methods are catch‐based and lack in both temporal and spatial resolution. In this work, light scattering from beetles is characterized, and the feasibility of entomological lidar as a tool for long‐term monitoring of bark beetles is explored. Laboratory optical properties, wing thickness, and wingbeat frequency of bark beetles are reported, and these parameters can infer target identity in lidar data. Lidar results from a Swedish forest with controlled bark beetle release event are presented. The capability of lidar to simultaneously monitor both insects and a pheromone plume mixed with chemical smoke governing the dispersal of many insects is demonstrated. In conclusion, entomological lidar is a promising tool for monitoring bark beetles.
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| 21. |
- Lin, Xiaobo, et al.
(författare)
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Ripening of avocado fruits studied by spectroscopic techniques
- 2020
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X .- 1864-0648. ; 13:8
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Tidskriftsartikel (refereegranskat)abstract
- Avocados are considered very healthy due to the high content mono-unsaturated lipid, essential vitamins and minerals, minimal sugar and no cholesterol and are therefore sometimes referred to as “the perfect fruits”. Avocados, mainly grown in Latin-America, are harvested unripe and sent overseas. However, the ripening process is very difficult to assess visually and tactilely. A tool for precise noninvasive judgment of the status would be valuable as the fruit is too expensive to be cut open unripe or overdue. A white-light source and a light-emitting diode unit with four excitation wavelengths (365, 385, 395, and 405 nm) were used for reflectance and fluorescence spectroscopy in a fiber-coupled set-up for noninvasive monitoring. Twelve non-ripe avocados, with approximately the same size and appearance, were studied and divided into three groups and kept at three different storage conditions; at room temperature, in a refrigerator and a combination of the two. We showed that fluorescence was useful for following the ripening process. A method, which compensates for the spatial variations in spectral properties around a fruit, is described. Remote fluorescence monitoring, intended for orchard use, was also demonstrated. A low-cost device based on fluorescence for avocado ripeness assessment is proposed.
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| 22. |
- Lindbergh, Tobias, et al.
(författare)
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Improved model for myocardial diffuse reflectance spectra by including mitochondrial cytochrome aa3, methemoglobin, and inhomogenously distributed RBC
- 2011
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Ingår i: Journal of Biophotonics. - : John Wiley & Sons. - 1864-063X .- 1864-0648. ; 4:4, s. 268-276
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Tidskriftsartikel (refereegranskat)abstract
- Hemo- and myoglobin oxygen saturation and cytochrome aa3 oxidation was locally assessed using calibrated diffuse reflectance spectroscopy in fourteen patients undergoing coronary artery bypass grafting. Diffuse spectral reflectance data, recorded with a handheld fiberoptic probe with a single source-detector separation, was analyzed using an empirical light transport model relating the absorption and reduced scattering coefficients to the measured spectrum. The absorption coefficient has previously been modeled as a sum of hemoglobin and myoglobin, fat, and water. In this study, inclusion of cytochrome aa3 and the sum of methemoglobin and metmyoglobin improved the spectral fit, especially in the wavelength regions where their absorption is prominent. On average, the extended model increased the mean R2 from 0.96 to 0.99 and displayed 4% units higher saturation levels. After aorta cross-clamping, the sum of hemo- and myoglobin oxygen saturation increased while cytochrome aa3 oxidation decreased slightly. Opposite trends were observed during cardiac arrest. At reperfusion, the saturation increased compared to the levels found at cardiac arrest, and the cytochrome aa3 oxidation was restored. The estimated tissue chromophore fractions, saturation and oxidation, were in agreement with other studies.
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| 23. |
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| 24. |
- Malyshev, Dmitry, et al.
(författare)
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Reactive oxygen species generated by infrared laser light in optical tweezers inhibits the germination of bacterial spores
- 2022
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Ingår i: Journal of Biophotonics. - : John Wiley & Sons. - 1864-063X .- 1864-0648. ; 15:8
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial spores are highly resistant to heat, radiation and various disinfection chemicals. The impact of these on the biophysical and physicochemical properties of spores can be studied on the single-cell level using optical tweezers. However, the effect of the trapping laser on spores' germination rate is not fully understood. In this work, we assess the impact of 1064 nm laser light on the germination of Bacillus thuringiensis spores. The results show that the germination rate of spores after laser exposure follows a sigmoid dose-response relationship, with only 15% of spores germinating after 20 J of laser light. Under anaerobic growth conditions, the percentage of germinating spores at 20 J increased to 65%. The results thereby indicate that molecular oxygen is a major contributor to the germination-inhibiting effect observed. Thus, our study highlights the risk for optical trapping of spores and ways to mitigate it.
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| 25. |
- Markwardt, Niklas, et al.
(författare)
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405 nm versus 633 nm for protoporphyrin IX excitation in fluorescence-guided stereotactic biopsy of brain tumors
- 2016
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Ingår i: Journal of Biophotonics. - : Wiley-VCH Verlagsgesellschaft. - 1864-063X .- 1864-0648. ; 9:9, s. 901-912
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Tidskriftsartikel (refereegranskat)abstract
- Fluorescence diagnosis may be used to improve the safety and reliability of stereotactic brain tumor biopsies using biopsy needles with integrated fiber optics. Based on 5-aminolevulinic-acid-induced protoporphyrin IX (PpIX) fluorescence, vital tumor tissue can be localized in vivo during the excision procedure to reduce the number of necessary samples for a reliable diagnosis. In this study, the practical suitability of two different PpIX excitation wavelengths (405 nm, 633 nm) was investigated on optical phantoms. Violet excitation at 405 nm provides a 50-fold higher sensitivity for the bulk tumor; this factor increases up to 100 with decreasing fluorescent volume as shown by ray tracing simulations. Red excitation at 633 nm, however, is noticeably superior with regard to blood layers obscuring the fluorescence. Experimental results on the signal attenuation through blood layers of well-defined thicknesses could be confirmed by ray tracing simulations. Typical interstitial fiber probe measurements were mimicked on agarose-gel phantoms. Even in direct contact, blood layers of 20-40 µm between probe and tissue must be expected, obscuring 405-nm-excited PpIX fluorescence almost completely, but reducing the 633-nm-excited signal only by 25.5%. Thus, 633 nm seems to be the wavelength of choice for PpIX-assisted detection of high-grade gliomas in stereotactic biopsy. PpIX signal attenuation through clinically relevant blood layers for 405 nm (violet) and 633 nm (red) excitation.
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| 26. |
- McNamara, Paul N, et al.
(författare)
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Tissue viability (TiVi) imaging: temporal effects of local occlusion studies in the volar forearm
- 2010
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Ingår i: Journal of Biophotonics. - : John Wiley & Sons. - 1864-063X .- 1864-0648. ; 3:1-2, s. 66-74
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Tidskriftsartikel (refereegranskat)abstract
- Tissue Viability (TiVi) imaging is a promising new technology for the assessment of microcirculation in the upper human dermis. Although the technique is easily implemented and develops large amounts of observational data, its role in the clinical workplace awaits the development of standardised protocols required for routine clinical practice. The present study investigates the use of TiVi technology in a human, in vivo, localized, skin blood flow occlusion protocol. In this feasibility study, the response of the cutaneous microcirculation after provocation on the volar surface of the forearm was evaluated using a high temporal-low spatial resolution TiVi camera. 19 healthy subjects - 10 female and 9 male - were studied after a localized pressure was applied for 5 different time periods ranging from 5 to 25 seconds. Areas corresponding to 100 x 100 pixels (2.89 cm(2)) were monitored for 60 seconds prior to, during and after each occlusion period. Our results demonstrated the removal of blood from the local area and a hyperaemic response supporting the suitability of TiVi imaging for the generation of detailed provocation response data of relevance for the physiological function of the skin microcirculation in health and disease.
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| 27. |
- Mücksch, Jonas, et al.
(författare)
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Transient state imaging of live cells using single plane illumination and arbitrary duty cycle excitation pulse trains
- 2015
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Ingår i: Journal of Biophotonics. - : Wiley-VCH Verlagsgesellschaft. - 1864-063X .- 1864-0648. ; 8:5, s. 392-400
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the applicability of Single Plane Illumination Microscopy to Transient State Imaging (TRAST), offering sensitive microenvironmental information together with optical sectioning and reduced overall excitation light exposure of the specimen. The concept is verified by showing that transition rates can be determined accurately for free dye in solution and that fluorophore transition rates can be resolved pixel-wise in live cells. Furthermore, we derive a new theoretical framework for analyzing TRAST data acquired with arbitrary duty cycle pulse trains. By this analysis it is possible to reduce the overall measurement time and thereby enhance the frame rates in TRAST imaging.
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| 28. |
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| 29. |
- Pacheco, Andrea, et al.
(författare)
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Numerical investigation of the influence of the source and detector position for optical measurement of lung volume and oxygen content in preterm infants
- 2022
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X .- 1864-0648. ; 15:7
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Tidskriftsartikel (refereegranskat)abstract
- There is an urgent need for improved respiratory surveillance of preterm infants. Gas in scattering media absorption spectroscopy (GASMAS) is emerging as a potential clinical cutaneous monitoring tool of lung functions in neonates. A challenge in the clinical translation of GASMAS is to obtain sufficiently high signal-to-noise ratios in the measurements, since the light attenuation is high in human tissue. Previous GASMAS studies on piglets have shown higher signal quality with an internal source, as more light propagates through the lung and the loss due to scattering and absorption is less. In this article we simulated light propagation with an intratracheal and a dermal source, and investigated the signal quality and lung volume probed. The results suggest that GASMAS has the potential to measure respiratory volumes; and the sensitivity is higher for an intratracheal source which also enables to probe most of the lung.
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| 30. |
- Persson, Henrik, et al.
(författare)
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Spatial mapping of affinity changes for the integrin LFA-1 during cell migration using clusters identified based on local density
- 2019
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X .- 1864-0648. ; 12:3
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Tidskriftsartikel (refereegranskat)abstract
- Localization microscopy methods like Stochastic Optical Reconstruction Microscopy (STORM) are very well suited for exploring clustering of proteins, as the data inherently provide a list of molecular coordinates. Here we use state-of-art cluster analysis algorithms (DBSCAN) to explore the clustering behaviour of different affinity forms of the integrin LFA-1. It has been suggested that LFA-1 may form clusters, in order to increase the avidity to ICAM-1. However, this hypothesis still seems to be controversial. In this study, we found, variations in clustering behaviour among the different affinity forms of LFA-1 in migrating T-cells. We found that panLFA-1 is located in clusters throughout the polarised cell on ICAM-1, with an increased density of molecules and clusters in the mid area and rear of the cell, whereas the intermediate and high affinity form of LFA-1 showed an increased number in the mid area of a migrating cell and the high affinity form of LFA-1 in the front and rear. Together, these data suggest that, in addition to LFA-1 conformation, protein clustering might play a role in controlling cell-substrate adhesion on ICAM-1.By applying the cluster analysis algorithm DBSCAN to localization microscopy data, integrin clusters could be identified and different cluster parameters could be quantified.
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| 31. |
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| 32. |
- Ramser, Kerstin, et al.
(författare)
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Optical manipulation for single cell studies
- 2010
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X .- 1864-0648. ; 3:4, s. 187-206
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Tidskriftsartikel (refereegranskat)abstract
- In the last decade optical manipulation has evolved from a field of interest for physicists to a versatile tool widely used within life sciences. This has been made possible in particular due to the development of a large variety of imaging techniques that allow detailed information to be gained from investigations of single cells. The use of multiple optical traps has high potential within single-cell analysis since parallel measurements provide good statistics. Multifunctional optical tweezers are, for instance, used to study cell heterogeneity in an ensemble, and force measurements are used to investigate the mechanical properties of individual cells. Investigations of molecular motors and forces on the single-molecule level have led to discoveries that would have been difficult to make with other techniques. Optical manipulation has prospects within the field of cell signalling and tissue engineering. When combined with microfluidic systems the chemical environment of cells can be precisely controlled. Hence the influence of pH, salt concentration, drugs and temperature can be investigated in real time. Fast advancing technical developments of automated and user-friendly optical manipulation tools and cross-disciplinary collaboration will contribute to the routinely use of optical manipulation techniques within the life sciences.
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| 33. |
- Reistad, Nina, et al.
(författare)
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Distinguishing tumor from healthy tissue in human liver ex vivo using machine learning and multivariate analysis of diffuse reflectance spectra
- 2022
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-0648 .- 1864-063X. ; 15:10
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to evaluate the capability of diffuse reflectance spectroscopy to distinguish malignant liver tissues from surrounding tissues, and to determine whether an extended wavelength range (450–1550 nm) offers any advantages over using the conventional wavelength range. Furthermore, multivariate analysis combined with a machine learning algorithm, either linear discriminant analysis or the more advanced support vector machine, was used to discriminate between and classify freshly excised human liver specimens from 18 patients. Tumors were distinguished from surrounding liver tissues with a sensitivity of 99%, specificity of 100%, classification rate of 100%, and a Matthews correlation coefficient of 100% using the extended wavelength range and a combination of principal component analysis and support vector techniques. The results indicate that this technology may be useful in clinical applications for real-time tissue diagnostics of tumor margins where rapid classification is important.
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| 34. |
- Rejmstad, Peter, et al.
(författare)
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A method for monitoring of oxygen saturation changes in brain tissue using diffuse reflectance spectroscopy
- 2017
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Ingår i: Journal of Biophotonics. - : Wiley-VCH Verlagsgesellschaft. - 1864-063X .- 1864-0648. ; 10:3, s. 446-455
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Tidskriftsartikel (refereegranskat)abstract
- Continuous measurement of local brain oxygen saturation (SO2) can be used to monitor the status of brain trauma patients in the neurocritical care unit. Currently, micro-oxygen-electrodes are considered as the “gold standard” in measuring cerebral oxygen pressure (pO2), which is closely related to SO2 through the oxygen dissociation curve (ODC) of hemoglobin, but with the drawback of slow in response time. The present study suggests estimation of SO2 in brain tissue using diffuse reflectance spectroscopy (DRS) for finding an analytical relation between measured spectra and the SO2 for different blood concentrations. The P3 diffusion approximation is used to generate a set of spectra simulating brain tissue for various levels of blood concentrations in order to estimate SO2. The algorithm is evaluated on optical phantoms mimicking white brain matter (blood volume of 0.5–2%) where pO2 and temperature is controlled and on clinical data collected during brain surgery. The suggested method is capable of estimating the blood fraction and oxygen saturation changes from the spectroscopic signal and the hemoglobin absorption profile.
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| 35. |
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| 36. |
- Svensson, Tomas, et al.
(författare)
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Towards accurate in vivo spectroscopy of the human prostate
- 2008
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X .- 1864-0648. ; 1:3, s. 200-203
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Tidskriftsartikel (refereegranskat)abstract
- The recent interest in photodynamic therapy of human prostate cancer is accompanied by a need for techniques for in vivo monitoring of optical and physiological characteristics. We propose time-of-flight (TOF) spectroscopy in combination with Monte Carlo evaluation as a reliable optical technique for quantitative assessment of absorption, scattering, hemoglobin content and tissue oxygenation in the human prostate. For the first time, we demonstrate Monte Carlo-based evaluation of in vivo TOF photon migration data. We show that this approach is crucial in order to avoid the large errors associated with the use of time-resolved diffusion theory of light propagation in prostate-like tissues. This progress also allows us to present the first in vivo scattering spectroscopy of human prostate tissue. Furthermore, TOF spectroscopy. in contrast to the more common steady-state approach, is insensitive to bleedings, and has been found highly reliable (100% success rate). (C) 2008 by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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| 37. |
- Tampu, Iulian Emil, et al.
(författare)
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Diseased thyroid tissue classification in OCT images using deep learning: towards surgical decision support
- 2023
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X .- 1864-0648. ; 16:2
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Tidskriftsartikel (refereegranskat)abstract
- Intraoperative guidance tools for thyroid surgery based on optical coherence tomography (OCT) could aid distinguish between normal and diseased tissue. However, OCT images are difficult to interpret, thus, real-time automatic analysis could support the clinical decision-making. In this study, several deep learning models were investigated for thyroid disease classification on 2D and 3D OCT data obtained from ex vivo specimens of 22 patients undergoing surgery and diagnosed with several thyroid pathologies. Additionally, two open-access datasets were used to evaluate the custom models. On the thyroid dataset, the best performance was achieved by the 3D vision transformer model with a Matthews correlation coefficient (MCC) of 0.79 (accuracy = 0.90) for the normal-versus-abnormal classification. On the open-access datasets, the custom models achieved the best performance (MCC > 0.88, accuracy > 0.96). Results obtained for the normal-versus-abnormal classification suggest OCT, complemented with deep learning-based analysis, as a tool for real-time automatic diseased tissue identification in thyroid surgery.
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| 38. |
- Thomsen, Hanna, 1989, et al.
(författare)
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Exploring photoinactivation of microbial biofilms using laser scanning microscopy and confined two-photon excitation.
- 2018
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Ingår i: Journal of biophotonics. - : Wiley. - 1864-0648 .- 1864-063X. ; 11:10
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Tidskriftsartikel (refereegranskat)abstract
- One pertinent complication in bacterial infection is the growth of biofilms, i.e., communities of surface-adhered bacteria resilient to antibiotics. Photodynamic inactivation has been proposed as an alternative to antibiotic treatment; however, novel techniques complementing standard efficacy measures are required. Herein, we present an approach employing multiphoton microscopy complemented with Airyscan super-resolution microscopy, to visualize the distribution of curcumin in Staphylococcus epidermidis biofilms. The effects of complexation of curcumin with hydroxypropyl-γ-cyclodextrin (HPγCD) were studied. It was shown that HPγCD-curcumin demonstrated higher bioavailability in the biofilms compared to curcumin, without affecting the subcellular uptake. Spectral quantification following photodynamic inactivation demonstrates a method for monitoring elimination of biofilms in real time using noninvasive 3D imaging. Additionally, spatially confined two-photon inactivation was demonstrated for the first time in biofilms. These results support the feasibility of advanced optical microscopy as a sensitive tool for evaluating treatment efficacy in biofilms towards improved mechanistic studies of photodynamic inactivation. This article is protected by copyright. All rights reserved.
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| 39. |
- Toll John, Rani, 1975-, et al.
(författare)
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A cool response : the influence of ambient temperature on capillary refill time
- 2018
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Ingår i: Journal of Biophotonics. - : Wiley-VCH Verlagsgesellschaft. - 1864-063X .- 1864-0648. ; 11:6
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Tidskriftsartikel (refereegranskat)abstract
- ObjectiveTo describe the effect of low ambient temperature on skin temperature and capillary refill (CR) time in forehead, sternum and finger pulp.MethodsAn observational, nonrandomized experimental study on 15 healthy subjects (6 females) in a cold room (8°C). Outcome measures were skin temperature and quantified CR test after application of a standardized blanching pressure (9 N/cm2) using digital photographic polarization spectroscopy to generate CR times.ResultsThe finger pulp showed marked temperature fall and prolonged CR times (>10 seconds). The CR registrations of the forehead and sternum were more comparable to curves observed in a control material at room temperature, and skin temperature falls were less marked. CR times were not prolonged in forehead measurements. At the sternum, some individuals showed CR times beyond guideline recommendations despite only a marginal reduction in skin temperature.ConclusionsLow ambient temperature is a strong independent factor for CR time at peripheral sites. Reservation about sternum as a site of measurement is warranted since cold provocation produced prolonged CR times in some individuals. We found that the forehead is the most thermostable of the 3 sites and thus the preferred site to avoid ambient temperature artifact in measuring CR time.
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| 40. |
- Toll John, Rani, et al.
(författare)
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Reflectance spectroscopy : to shed new light on the capillary refill test
- 2018
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Ingår i: Journal of Biophotonics. - : Wiley-VCH Verlagsgesellschaft. - 1864-063X .- 1864-0648. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- To use Bioengineering methodology is used to achieve, at five anatomical sites, a detailed, quantitative assessment of the return of blood content to the blanched area, during the Capillary Refill (CR) test. An observational, non-randomized, experimental study on 23 healthy subjects (14 females) was performed in our climate controlled skin physiology laboratory. Our main outcome measures were based on the chronological assessment and quantification of red blood cell concentration (RBC) after the release of blanching pressure in the CR test, using Tissue Viability Imaging (TiVi), a digital photographic technique based on polarisation spectroscopy. TiVi enabled collection of detailed data on skin RBC concentration during the CR test. The results were shown as curves with skin blood concentration (TiVi-value) on the y-axis and the time on the x-axis. Quantitative CR responses showed site and temperature variability. We also suggest possible objective endpoint values from the capillary refill curve. Detailed data on skin RBC concentration during the CR test is easily obtained and allows objective determination of end points not possible to achieve by naked eye assessment. These findings have the potential to place the utility of the CR test in a clinical setting in a new light. Picture: Regular photograph and TiVi Image showing CR test and corresponding graph for the CR response. [GRAPHICS] .
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| 41. |
- Wolfson, D., et al.
(författare)
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Rapid 3D fluorescence imaging of individual optically trapped living immune cells
- 2015
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-0648 .- 1864-063X. ; 8:3, s. 208-216
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate an approach to rapidly characterize living suspension cells in 4 dimensions while they are immobilized and manipulated within optical traps. A single, high numerical aperture objective lens is used to separate the imaging plane from the trapping plane. This facilitates full control over the position and orientation of multiple trapped cells using a spatial light modulator, including directed motion and object rotation, while also allowing rapid 4D imaging. This system is particularly useful in the handling and investigation of the behavior of non-adherent immune cells. We demonstrate these capabilities by imaging and manipulating living, fluorescently stained Jurkat T cells.
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| 42. |
- Xia, Qingling, et al.
(författare)
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Inhibition of cortical neural networks using infrared laser
- 2019
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Ingår i: Journal of Biophotonics. - : WILEY-V C H VERLAG GMBH. - 1864-063X .- 1864-0648. ; 12:7
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study is to optimize parameters for inhibiting neuronal activity safely and investigating thermal inhibition of rat cortex neural networks in vitro by continuous infrared (IR) laser. Rat cortex neurons were cultured on multi-electrode arrays until neural networks were formed with spontaneous neural activity. Neurons were then irradiated to inhibit the activity of the networks using different powers of 1550 nm IR laser light. A finite element heating model, calibrated by the open glass pipette method, was used to calculate temperature increases at different laser irradiation intensities. A damage signal ratio (DSR) was evaluated to avoid excessive heating that may damage cells. The DSR predicted that cortex neurons should be safe at temperatures up to 49.6 degrees C for 30 seconds, but experiments suggested that cortex neurons should not be exposed to temperatures over 46 degrees C for 30 seconds. Neural response experiments showed that the inhibition of neural activity is temperature dependent. The normal neural activity could be inhibited safely with an inhibition degree up to 80% and induced epileptiform activity could be suppressed. These results show that continuous IR laser radiations provide a possible way to safely inhibit the neural network activity.
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| 43. |
- Brackmann, Christian, 1973, et al.
(författare)
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Non-linear microscopy of smooth muscle cells in artificial extracellular matrices made of cellulose
- 2012
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X. ; 5:5-6, s. 404-414
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Tidskriftsartikel (refereegranskat)abstract
- Non-linear microscopy has been used to characterize bovine smooth muscle cells and their proliferation, migration, and differentiation in hydrogel cellulose scaffolds, toward the development of fully functional blood vessel implants. The extracellular matrix (ECM) composed of cellulose and endogenous collagen fibers was imaged using Second Harmonic Generation (SHG) microscopy and the cell morphology by Coherent Anti-Stokes Raman Scattering (CARS) microscopy. Images prove that cells adhere on the cellulose scaffold without additional surface modification and that both contractile and proliferating phenotypes are developed. This work shows that non-linear microscopy contributes with unique insights in cell interactions with (artificial) ECM components and has the potential to become an established characterization method in tissue engineering.
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| 44. |
- Huang, Jing, et al.
(författare)
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Assessment of human sinus cavity air volume using tunable diode laser spectroscopy, with application to sinusitis diagnostics.
- 2015
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X. ; 8:11-12, s. 985-992
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Tidskriftsartikel (refereegranskat)abstract
- Sinusitis is a very common disease and improved diagnostic tools are desirable also in view of reducing over-prescription of antibiotics. A non-intrusive optical technique called GASMAS (GAs in Scattering Media Absorption Spectroscopy), which has a true potential of being developed into an important complement to other means of detection, was utilized in this work. Water vapor in the frontal sinuses, related to the free gas volume, was studied at around 937 nm in healthy volunteers. The results show a good stability of the GASMAS signals over extended times for the frontal sinuses for all volunteers, showing promising applicability to detect anomalies due to sinusitis. Measurements were also performed following the application of a decongestion spray. No noticeable signal change was observed, which is consistent with the fact that the water vapor concentration is given by the temperature only, and is not influenced by changes in cavity ventilation. Evaluated GASMAS data recorded on 6 consecutive days show signal stability for the left and right frontal sinus in one of the test volonteers.
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| 45. |
- Larsson, Jim, et al.
(författare)
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Development of a 3-dimensional tissue lung phantom of a preterm infant for optical measurements of oxygen—Laser-detector position considerations
- 2018
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X. ; 11:3
-
Tidskriftsartikel (refereegranskat)abstract
- There is a need to further improve the clinical care of our most vulnerable patients—preterm infants. Novel diagnostic and treatment tools facilitate such advances. Here, we evaluate a potential percutaneous optical monitoring tool to assess the oxygen and water vapor content in the lungs of preterm babies. The aim is to prepare for further clinical studies by gaining a detailed understanding of how the measured light intensity and gas absorption signal behave for different possible geometries of light delivery and receiver. Such an experimental evaluation is conducted for the first time utilizing a specially developed 3-dimensional-printed optical phantom based on a geometry model obtained from computer tomography images of the thorax (chest) of a 1700-g premature infant. The measurements yield reliable signals for source–detector distances up to about 50 mm, with stronger gas absorption signals at long separations and positions related to the lower part of the lung, consistent with a larger relative volume of this. The limitations of this study include the omission of scattering tissue within the lungs and that similar optical properties are used for the wavelengths employed for the 2 gases, yielding no indication on the optimal wavelength pair to use.
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| 46. |
- Li, Wansha, et al.
(författare)
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Detection of free oxygen and water vapor in fertilized and unfertilized eggs by diode laser spectroscopy-Exploration of diagnostics possibilities
- 2018
-
Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X. ; 11:3
-
Tidskriftsartikel (refereegranskat)abstract
- Nonintrusive methods for characterizing food products are of increasing interest related to the greater awareness of food safety issues. Hen eggs are an important part in food consumption in most parts of the world. We have investigated an optical method utilizing tunable diode lasers for monitoring free gas in eggs. We show that oxygen signals, recorded around 760nm, increase steadily as eggs become older. Further, we investigated fertilized eggs, which show a quite different temporal behavior during the hatching time. The oxygen signal decreases here with time, while water vapor, recorded around 937nm, shows a steady increase. Conclusions regarding the size of the air cell and the oxygen availability in fertilized eggs are drawn. The technique might be developed for automatic control of egg freshness, as well as for assessing if eggs are fertilized or not.
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| 47. |
- Liao, Peilang, et al.
(författare)
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Computer simulation analysis of source-detector position for percutaneously measured O2-gas signal in a three-dimensional preterm infant lung
- 2018
-
Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X. ; 11:11
-
Tidskriftsartikel (refereegranskat)abstract
- Further improvements in the clinical care of our most vulnerable patients-preterm infants-are needed. Novel diagnostic and surveillance tools facilitate such advances. The GASMAS technique has shown potential to become a tool to, noninvasively, monitor gas in the lungs of preterm infants, by placing a laser source and a detector on the chest wall skin. It is believed that this technology will become a valuable clinical diagnostic tool for monitoring the lung function of these patients. Today, the technology is, for this application, in an early stage and further investigations are needed. In the present study, a three-dimensional computer model of the thorax of an infant is constructed, from a set of CT images. Light transport simulations are performed to provide information about the position dependence of the laser- and detector probe on the thorax of the infant. The result of the simulations, based on the study method and the specified model used in this work, indicates that measurement geometries in front and on the side of the lung are favorable in order to obtain a good gas absorption signal.
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| 48. |
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| 49. |
- Pohling, C., et al.
(författare)
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Chemical imaging of lignocellulosic biomass by CARS microscopy
- 2014
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X. ; 7:1-2, s. 126-134
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Tidskriftsartikel (refereegranskat)abstract
- Chemical and structural composition of wood biomass is studied by label-free and chemically specific Coherent Anti-Stokes Raman Scattering (CARS) microscopy. A concept developed for assignment and semi-quantitative imaging of sample components; cellulose, hemicellulose, and lignin; by multiplex CARS microspectroscopy and subsequent data analysis is presented. Specific imaging without fluorescence backround is achieved an order of magnitude faster compared with conventional Raman microscopy. Laser polarization control yield information on molecular arrangement in wood fibers. Narrowband CARS excitation of single vibrations allows for three-dimensional volume imaging. Thus, CARS microscopy has potential as an important instrument for characterization of lignocellulosic materials.
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| 50. |
- Sterenborg, Henricus J. C. M., et al.
(författare)
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Clinical Biophotonics
- 2011
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X. ; 4:10, s. 665-666
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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