| 1. |
- Andersson, Emil, et al.
(författare)
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Facilitating clinically relevant skin tumor diagnostics with spectroscopy-driven machine learning
- 2024
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Ingår i: iScience. - 2589-0042. ; 27:5
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Tidskriftsartikel (refereegranskat)abstract
- In the dawning era of artificial intelligence (AI), health care stands to undergo a significant transformation with the increasing digitalization of patient data. Digital imaging, in particular, will serve as an important platform for AI to aid decision making and diagnostics. A growing number of studies demonstrate the potential of automatic pre-surgical skin tumor delineation, which could have tremendous impact on clinical practice. However, current methods rely on having ground truth images in which tumor borders are already identified, which is not clinically possible. We report a novel approach where hyperspectral images provide spectra from small regions representing healthy tissue and tumor, which are used to generate prediction maps using artificial neural networks (ANNs), after which a segmentation algorithm automatically identifies the tumor borders. This circumvents the need for ground truth images, since an ANN model is trained with data from each individual patient, representing a more clinically relevant approach.
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| 2. |
- Barup, Kerstin, et al.
(författare)
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Multi-disciplinary lidar applications
- 2010
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Ingår i: Laser Applications to Chemical, Security and Environmental Analysis, LACSEA 2010. - 2162-2701. - 9781557528803
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Konferensbidrag (refereegranskat)abstract
- Lidar is a powerful technique normally associated with atmospheric monitoring. However, lidar techniques, also of the laser-induced fluorescence and laser-induced breakdown spectroscopy varieties, provide many new possibilities in unconventional fields including cultural heritage and ecological applications.
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| 3. |
- Berggren, Johanna, et al.
(författare)
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Forehead flap perfusion monitored by laser speckle contrast imaging – importance of flap length and thickness
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Ingår i: JPRAS Open. - 2352-5878.
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Forehead flaps are commonly used in oculoplastic surgery to cover defects after tumor excision. Blood perfusion is vital for flap survival. The aim of this study was to monitor the perfusion in forehead flaps and investigate the impact of flap length and thickness. Methods: Nineteen forehead flaps in patients undergoing direct brow lift were studied. Perfusion was monitored using laser speckle contrast imaging, immediately after raising flaps consisting of epidermis, dermis, and subcutaneous tissue, and after removing the subcutaneous tissue resulting in a thin flap. Results: Perfusion decreased gradually along the length; the mean value being 44% at 5 mm and 26% at 15 mm from the base, in thick flaps. Perfusion was significantly lower in thin flaps, being 13% measured 15 mm from the flap base (p<0.0024). Perfusion was better preserved in thick than in thin flaps. Very low perfusion was observed 16.7 mm (16.0-17.3 mm) from the base in thick flaps, and from 10.2 mm (9.8-10.6 mm) from the base in thin flaps (p<0.0001).Conclusions: Flap thickness is important in maintaining adequate blood perfusion and thus increasing the probability of flap survival. This may be particularly important in long flaps and in patients with impaired microcirculation.
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| 4. |
- Berggren, Johanna V, et al.
(författare)
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Blood Perfusion of Human Upper Eyelid Skin Flaps Is Better in Myocutaneous than in Cutaneous Flaps
- 2022
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Ingår i: Ophthalmic Plastic and Reconstructive Surgery. - 1537-2677. ; 38:2, s. 166-169
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The aim of this study was to monitor blood perfusion in human upper eyelid skin flaps and examine how the perfusion is affected by the thickness of the flap.METHODS: Twenty upper eyelids were dissected as part of a blepharoplasty procedure in patients. The medial end of the blepharoplasty flap remained attached to mimic a flap design often used in reconstruction in the periocular area, a myocutaneous flap in which the blood supply follows the fibers of the orbicularis muscle and is thus parallel to the long axis of the flap. The muscle was thereafter dissected from the flap to create a cutaneous flap. Blood perfusion in the 2 types of flaps was compared using laser speckle contrast imaging.RESULTS: Blood perfusion decreased gradually from the base to the tip of all the flaps. Perfusion was significantly higher in the myocutaneous flaps than in the cutaneous flaps (p < 0.0004): 69% in the myocutaneous flaps and 43% in the cutaneous flaps, measured 5 mm from the base. Blood perfusion was preserved to a greater extent distally in the myocutaneous flaps (minimum value seen at 25 mm) than in the cutaneous flaps (minimum seen at 11 mm).CONCLUSIONS: Blood perfusion was better preserved in myocutaneous flaps, including both skin and the orbicularis oculi muscle, than in cutaneous flaps. This may be of clinical interest in patients with poor microcirculation in which a long flap is required for reconstructive surgery.
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| 5. |
- Brydegaard, Mikkel, et al.
(författare)
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Realistic Instrumentation Platform for Active and Passive Optical Remote Sensing.
- 2016
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Ingår i: Applied Spectroscopy. - : SAGE Publications. - 1943-3530 .- 0003-7028. ; 70:2, s. 372-385
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Tidskriftsartikel (refereegranskat)abstract
- We describe the development of a novel versatile optical platform for active and passive remote sensing of environmental parameters. Applications include assessment of vegetation status and water quality. The system is also adapted for ecological studies, such as identification of flying insects including agricultural pests. The system is based on two mid-size amateur astronomy telescopes, continuous-wave diode lasers at different wavelengths ranging from violet to the near infrared, and detector facilities including quadrant photodiodes, two-dimensional and line scan charge-coupled device cameras, and a compact digital spectrometer. Application examples include remote Raman-laser-induced fluorescence monitoring of water quality at 120 m distance, and insect identification at kilometer ranges using the recorded wing-beat frequency and its spectrum of overtones. Because of the low cost this developmental platform is very suitable for advanced research projects in developing countries and has, in fact, been multiplied during hands-on workshops and is now being used by a number of groups at African universities.
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| 6. |
- Brydegaard, Mikkel, et al.
(författare)
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Versatile multispectral microscope based on light emitting diodes.
- 2011
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 1089-7623 .- 0034-6748. ; 82:12
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Tidskriftsartikel (refereegranskat)abstract
- We describe the development of a novel multispectral microscope, based on light-emitting diodes, capable of acquiring megapixel images in thirteen spectral bands from the ultraviolet to the near infrared. The system captures images and spectra in transmittance, reflectance, and scattering modes. We present as examples of applications ground truth measurements for remote sensing and parasitology diagnostics. The system is a general purpose scientific instrument that could be used to develop dedicated simplified instruments with optimal bands and mode selection.
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| 7. |
- Bunke, Josefine, et al.
(författare)
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Hyperspectral and Laser Speckle Contrast Imaging for Monitoring the Effect of Epinephrine in Local Anesthetics in Oculoplastic Surgery
- 2022
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Ingår i: Ophthalmic Plastic and Reconstructive Surgery. - 1537-2677. ; 38:5, s. 462-468
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Epinephrine is used in local anesthetics to induce vasoconstriction and thus reduce bleeding and prolong the anesthetic effect. Finding the optimal delay between the administration of the anesthetic and skin incision to ensure vasoconstriction and minimize bleeding is important and has recently become the subject of debate. This is the first study to assess blood perfusion and oxygen saturation (sO2) simultaneously in response to a local anesthetic containing epinephrine in human oculoplastic surgery.METHODS: A local anesthetic consisting of lidocaine and epinephrine (20 mg/ml + 12.5 μg/ml) was injected in the eyelids of 9 subjects undergoing blepharoplasty. The perfusion and sO2 of the eyelids were monitored using laser speckle contrast imaging and hyperspectral imaging, respectively.RESULTS: Laser speckle contrast imaging monitoring showed a decrease in perfusion over time centrally at the site of injection. Half-maximum effect was reached after 34 seconds, and full effect after 115 seconds, determined by exponential fitting. The drop in perfusion decreased gradually further away from the injection site and hypoperfusion was less prominent 4 mm from the injection site, with a spatially dependent half-maximum effect of 231 seconds. Hyperspectral imaging showed only a slight decrease in sO2 of 11 % at the injection site.CONCLUSIONS: The optimal time delay for skin incision in oculoplastic surgery is approximately 2 minutes after the injection of lidocaine with epinephrine. Longer delay does not lead to a further decrease in perfusion. As sO2 was only slightly reduced after injection, the results indicate that the use of epinephrine is safe in the periocular region.
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| 8. |
- Bunke, Josefine, et al.
(författare)
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Photoacoustic imaging for the monitoring of local changes in oxygen saturation following an adrenaline injection in human forearm skin
- 2021
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Ingår i: Biomedical Optics Express. - 2156-7085. ; 12:7, s. 4084-4096
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Tidskriftsartikel (refereegranskat)abstract
- Clinical monitoring of blood oxygen saturation (sO2) is traditionally performed using optical techniques, such as pulse oximetry and diffuse reflectance spectroscopy (DRS), which lack spatial resolution. Photoacoustic imaging (PAI) is a rapidly developing biomedical imaging technique that is superior to previous techniques in that it combines optical excitation and acoustic detection, providing a map of chromophore distribution in the tissue. Hitherto, PAI has primarily been used in preclinical studies, and only a few studies have been performed in patients. Its ability to measure sO2 with spatial resolution during local vasoconstriction after adrenaline injection has not yet been investigated. Using PAI and spectral unmixing we characterize the heterogeneous change in sO2 after injecting a local anesthetic containing adrenaline into the dermis on the forearm of seven healthy subjects. In comparison to results obtained using DRS, we highlight contrasting results obtained between the two methods arising due to the so-called ‘window effect’ caused by a reduced blood flow in the superficial vascular plexus. The results demonstrate the importance of spatially resolving sO2 and the ability of PAI to assess the tissue composition in different layers of the skin.
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| 9. |
- Dagar, Janardan, et al.
(författare)
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Alkali Salts as Interface Modifiers in n-i-p Hybrid Perovskite Solar Cells
- 2019
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Ingår i: Solar RRL. - : Wiley. - 2367-198X. ; 3:9
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Tidskriftsartikel (refereegranskat)abstract
- After demonstration of a 23% power conversion efficiency, a high operational stability is the next most important scientific and technological challenge in perovskite solar cells (PSCs). A potential failure mechanism is tied to a bias-induced ion migration, which causes current–voltage hysteresis and a decay in the device performance over time. Herein, alkali salts are shown to mitigate hysteresis and stabilize device performance in n-i-p hybrid planar PSCs. Different alkali salts of potassium chloride, iodide, and nitrate as well as sodium chloride and iodide are deposited from aqueous solution onto the n-type contact, based on SnO2, prior to deposition of the perovskite absorber Cs0.05(FA0.83MA0.17)0.95Pb(I0.83Br0.17)3. Introduction of potassium-based alkali salts suppresses the current–voltage hysteresis and stabilizes the operational device stability at the maximum power point. This is attributed to the suppression of hole trapping at the n-type selective transport layer (SnO2)/perovskite interface observed by surface photovoltage spectroscopy, which is interpreted to reduce interfacial recombination and improve charge carrier extraction. The best and most stable performance of 19% is achieved using potassium nitrate as the interface modifier. Devices with higher and more stable performance exhibit substantially lower current transients, analyzed during maximum power point tracking.
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| 10. |
- Dagar, Janardan, et al.
(författare)
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Compositional and Interfacial Engineering Yield High-Performance and Stable p-i-n Perovskite Solar Cells and Mini-Modules
- 2021
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Ingår i: ACS applied materials & interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 13:11, s. 13022-13033
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Tidskriftsartikel (refereegranskat)abstract
- Through the optimization of the perovskite precursor composition and interfaces to selective contacts, we achieved a p-i-n-type perovskite solar cell (PSC) with a 22.3% power conversion efficiency (PCE). This is a new performance record for a PSC with an absorber bandgap of 1.63 eV. We demonstrate that the high device performance originates from a synergy between (1) an improved perovskite absorber quality when introducing formamidinium chloride (FACl) as an additive in the "triple cation" Cs0.05FA0.79MA0.16PbBr0.51I2.49 (Cs-MAFA) perovskite precursor ink, (2) an increased open-circuit voltage, VOC, due to reduced recombination losses when using a lithium fluoride (LiF) interfacial buffer layer, and (3) high-quality hole-selective contacts with a self-assembled monolayer (SAM) of [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz) on ITO electrodes. While all devices exhibit a high performance after fabrication, as determined from current-density voltage, J-V, measurements, substantial differences in device performance become apparent when considering longer-term stability data. A reduced long-term stability of devices with the introduction of a LiF interlayer is compensated for by using FACl as an additive in the metal-halide perovskite thin-film deposition. Optimized devices maintained about 80% of the initial average PCE during maximum power point (MPP) tracking for >700 h. We scaled the optimized device architecture to larger areas and achieved fully laser patterned series-interconnected mini-modules with a PCE of 19.4% for a 2.2 cm2 active area. A robust device architecture and reproducible deposition methods are fundamental for high performance and stable large-area single junction and tandem modules based on PSCs.
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