| 1. |
- Khodaverdi, Azin, et al.
(author)
-
Optical tuning of copolymer-in-oil tissue-mimicking materials for multispectral photoacoustic imaging
- 2024
-
In: Biomedical Physics Engineering Express. - 2057-1976. ; 10:5
-
Journal article (peer-reviewed)abstract
- OBJECTIVE: The availability of tissue-mimicking materials (TMMs) for manufacturing high-quality phantoms is crucial for standardization, evaluating novel quantitative approaches, and clinically translating new imaging modalities, such as photoacoustic imaging (PAI). Recently, a gel comprising the copolymer styrene-ethylene/butylene-styrene (SEBS) in mineral oil has shown significant potential as TMM due to its optical and acoustic properties akin to soft tissue. We propose using artists' oil-based inks dissolved and diluted in balsam turpentine to tune the optical properties.APPROACH: A TMM was fabricated by mixing a SEBS copolymer and mineral oil, supplemented with additives to tune its optical absorption and scattering properties independently. A systematic investigation of the tuning accuracies and relationships between concentrations of oil-based pigments and optical absorption properties of the TMM across visible and near-infrared wavelengths using collimated transmission spectroscopy was conducted. The photoacoustic spectrum of various oil-based inks was studied to analyze the effect of increasing concentration and depth.MAIN RESULTS: Artists' Oil-based inks dissolved in turpentine proved effective as additives to tune the optical absorption properties of mineral oil SEBS-gel with high accuracy. The TMMs demonstrated long-term stability and suitability for producing phantoms with desired optical absorption properties for PAI studies.SIGNIFICANCE: The findings, including tuning of optical absorption and spectral shape, suggest that this TMM facilitates the development of more sophisticated phantoms of arbitrary shapes. This approach holds promise for advancing the development of PAI, including investigation of the spectral coloring effect. In addition, it can potentially aid in the development and clinical translation of ultrasound optical tomography.
|
|
| 2. |
|
|
| 3. |
- Bengtsson, Alexander, et al.
(author)
-
Characterization and modeling of acousto-optic signal strengths in highly scattering media
- 2019
-
In: Biomedical Optics Express. - 2156-7085. ; 10:11, s. 5565-5584
-
Journal article (peer-reviewed)abstract
- Ultrasound optical tomography (UOT) is an imaging technique based on the acousto-optic effect that can perform optical imaging with ultrasound resolution inside turbid media, and is thus interesting for biomedical applications, e.g. for assessing tissue blood oxygenation. In this paper, we present near background free measurements of UOT signal strengths using slow light filter signal detection. We carefully analyze each part of our experimental setup and match measured signal strengths with calculations based on diffusion theory. This agreement between experiment and theory allows us to assert the deep tissue imaging potential of similar to 5 cm for UOT of real human tissues predicted by previous theoretical studies [Biomed. Opt. Express 8, 4523 (2017)] with greater confidence, and indicate that future theoretical analysis of optimized UOT systems can be expected to be reliable. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
|
|
| 4. |
- Bunke, Josefine, et al.
(author)
-
Extended-wavelength diffuse reflectance spectroscopy for a comprehensive view of blood perfusion and tissue response in human forearm skin
- 2019
-
In: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 124, s. 1-5
-
Journal article (peer-reviewed)abstract
- BACKGROUND: The aim of this study was to investigate the possibility of using extended-wavelength diffuse reflectance spectroscopy (EW-DRS) to measure tissue response related to blood perfusion. The study was performed on a model that we have previously found to be useful for studying techniques for perfusion monitoring following the injection of epinephrine in a local anesthetic in the human forearm.METHODS: Nine healthy subjects were included in the study. Spectroscopy was performed with an EW-DRS system using a combination of two spectrometers to resolve light in the visible (350 nm to 1100 nm) and the near-infrared regions (900 nm to 1700 nm). The change in signal upon the injection of lidocaine (20 mg/ml) + epinephrine (12.5 μg/ml) (LIDO +EPI), compared to a control injection with saline (9 mg/ml), was investigated.RESULTS: Injection of lidocaine + epinephrine (12.5 μg/ml) caused a change in the EW-DRS signal in the wavelength intervals 510 to 610 nm, known to change upon deoxygenation of hemoglobin. When examining the full wavelength range (450 to 1550 nm) a decrease in reflectance upon LIDO +EPI injection was observed, suggesting that the broader spectrum provides more detailed information on the tissue response. The time to stable hypoperfusion was found to be 2.6 min.CONCLUSIONS: EW-DRS appears to be a promising technique for monitoring perfusion, and could provide a useful tool in plastic and reconstructive surgery. The broad spectrum provides detailed information on the molecular changes taking place in the tissue. However, the technique must be thoroughly validated before it can be implemented in clinical practice.
|
|
| 5. |
- Bunke, Josefine, et al.
(author)
-
Hyperspectral and Laser Speckle Contrast Imaging for Monitoring the Effect of Epinephrine in Local Anesthetics in Oculoplastic Surgery
- 2022
-
In: Ophthalmic Plastic and Reconstructive Surgery. - 1537-2677. ; 38:5, s. 462-468
-
Journal article (peer-reviewed)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.
|
|
| 6. |
- Bunke, Josefine, et al.
(author)
-
Photoacoustic imaging for the monitoring of local changes in oxygen saturation following an adrenaline injection in human forearm skin
- 2021
-
In: Biomedical Optics Express. - 2156-7085. ; 12:7, s. 4084-4096
-
Journal article (peer-reviewed)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.
|
|
| 7. |
- Chaudhry, Nadia, et al.
(author)
-
Breast Cancer Diagnosis Using Extended-Wavelength–Diffuse Reflectance Spectroscopy (EW-DRS) : Proof of Concept in Ex Vivo Breast Specimens Using Machine Learning
- 2023
-
In: Diagnostics. - 2075-4418. ; 13:19, s. 1-12
-
Journal article (peer-reviewed)abstract
- This study aims to investigate the feasibility of using diffuse reflectance spectroscopy (DRS) to distinguish malignant breast tissue from adjacent healthy tissue, and to evaluate if an extended-wavelength range (450–1550 nm) has an advantage over the standard wavelength range (450–900 nm). Multivariate statistics and machine learning algorithms, either linear discriminant analysis (LDA) or support vector machine (SVM) are used to distinguish the two tissue types in breast specimens (total or partial mastectomy) from 23 female patients with primary breast cancer. EW-DRS has a sensitivity of 94% and specificity of 91% as compared to a sensitivity of 40% and specificity of 71% using the standard wavelength range. The results suggest that DRS can discriminate between malignant and healthy breast tissue, with improved outcomes using an extended wavelength. It is also possible to construct a simple analytical model to improve the diagnostic performance of the DRS technique.
|
|
| 8. |
- Dahlstrand, Ulf, et al.
(author)
-
Extended-wavelength diffuse reflectance spectroscopy with a machine-learning method for in vivo tissue classification
- 2019
-
In: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 14:10
-
Journal article (peer-reviewed)abstract
- OBJECTIVES: An extended-wavelength diffuse reflectance spectroscopy (EWDRS) technique was evaluated for its ability to differentiate between and classify different skin and tissue types in an in vivo pig model.MATERIALS AND METHODS: EWDRS recordings (450-1550 nm) were made on skin with different degrees of pigmentation as well as on the pig snout and tongue. The recordings were used to train a support vector machine to identify and classify the different skin and tissue types.RESULTS: The resulting EWDRS curves for each skin and tissue type had a unique profile. The support vector machine was able to classify each skin and tissue type with an overall accuracy of 98.2%. The sensitivity and specificity were between 96.4 and 100.0% for all skin and tissue types.CONCLUSION: EWDRS can be used in vivo to differentiate between different skin and tissue types with good accuracy. Further development of the technique may potentially lead to a novel diagnostic tool for e.g. non-invasive tumor margin delineation.
|
|
| 9. |
- Eager, David, et al.
(author)
-
Beyond velocity and acceleration : Jerk, snap and higher derivatives
- 2016
-
In: European Journal of Physics. - : IOP Publishing. - 0143-0807 .- 1361-6404. ; 37:6
-
Journal article (peer-reviewed)abstract
- The higher derivatives of motion are rarely discussed in the teaching of classical mechanics of rigid bodies; nevertheless, we experience the effect not only of acceleration, but also of jerk and snap. In this paper we will discuss the third and higher order derivatives of displacement with respect to time, using the trampolines and theme park roller coasters to illustrate this concept. We will also discuss the effects on the human body of different types of acceleration, jerk, snap and higher derivatives, and how they can be used in physics education to further enhance the learning and thus the understanding of classical mechanics concepts.
|
|
| 10. |
- Enestarre, Carina, et al.
(author)
-
The Library Treasure Hunt: Reach for the Stars. Introducing First Year Students to the Landscape of Scientific Information
- 2015
-
In: ASP Conference Series. - 9781583818688 - 9781583818695 ; 492, s. 248-253
-
Conference paper (other academic/artistic)abstract
- One important task for the librarians at Physics and Astronomy Library at Lund University is to teach the students about the library and its resources. The traditional lectures and tours of the library just weren’t working. The library competes with many other introductory activities, such as general orientation, and social events. The aim of the Treasure Hunt is to present the library in a useful and amusing way for new students at the start of their studies. Divided into small groups, the students carry out various tasks at stations in the participating libraries. The hunt takes about two hours and a treasure (a goody bag) waits for them at the end. The evaluations show that the treasure hunt is highly appreciated by the students. They become familiar with the librarians and get to know essential aspects of the library resources. The treasure hunt is important in the students’ later studies as it paves the way for further development of their information retrieval skills. A crucial factor to success of the Treasure Hunt is the cooperation of committed teachers. A challenge for the future is to have the Treasure Hunt integrated in all courses as a compulsory element.
|
|
