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BETA
Öberg, Åke
Alternative names
Publications (10 of 72) Show all publications
Johansson, A., Kuiper, J.-H., Sundqvist, T., Persson, F., Speier, C., DAlfonso, D., . . . Öberg, Å. (2012). Spectroscopic Measurement of Cartilage Thickness in Arthroscopy: Ex Vivo Validation in Human Knee Condyles. Arthroscopy: The Journal of Arthroscopy And Related, 28(10), 1513-1523
Open this publication in new window or tab >>Spectroscopic Measurement of Cartilage Thickness in Arthroscopy: Ex Vivo Validation in Human Knee Condyles
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2012 (English)In: Arthroscopy: The Journal of Arthroscopy And Related, ISSN 0749-8063, E-ISSN 1526-3231, Vol. 28, no 10, p. 1513-1523Article in journal (Refereed) Published
Abstract [en]

Purpose: To evaluate the accuracy of articular cartilage thickness measurement when implementing a new technology based on spectroscopic measurement into an arthroscopic camera. Methods: Cartilage thickness was studied by ex vivo arthroscopy at a number of sites (N = 113) in human knee joint osteoarthritic femoral condyles and tibial plateaus, removed from 7 patients undergoing total knee replacement. The arthroscopic image spectral data at each site were used to estimate cartilage thickness. Arthroscopically derived thickness values were compared with reference cartilage thickness as measured by 3 different methods: needle penetration, spiral computed tomography scanning, and geometric measurement after sample slicing. Results: The lowest mean error (0.28 to 0.30 mm) in the regression between arthroscopic and reference cartilage thickness was seen for reference cartilage thickness less than 1.5 mm. Corresponding values for cartilage thickness less than 2.0 and 2.5 mm were 0.32 to 0.40 mm and 0.37 to 0.47 mm, respectively. Cartilage thickness images-created by pixel-by-pixel regression model calculations applied to the arthroscopic images-were derived to demonstrate the clinical use of a camera implementation. Conclusions: On the basis of this investigation on osteoarthritic material, when one is implementing the spectroscopic method for estimating cartilage thickness into an arthroscopic camera, errors in the range of 0.28 to 0.30 mm are expected. This implementation does not, however, influence the fact that the spectral method performs less well in the cartilage thickness region from 1.5 to 2.5 mm and cannot assess cartilage thicker than 2.5 mm. Clinical Relevance: Imaging cartilage thickness directly in the arthroscopic camera video stream could serve as an interesting image tool for in vivo cartilage quality assessment, in connection with cartilage diagnosis, repair, and follow-up.

Place, publisher, year, edition, pages
WB Saunders, 2012
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-85201 (URN)10.1016/j.arthro.2012.03.009 (DOI)000309602500026 ()
Note

Funding Agencies|BioOptico AB||ConMed||

Available from: 2012-11-09 Created: 2012-11-09 Last updated: 2017-12-07
Johansson, A., Sundqvist, T., Kuiper, J.-H. & Öberg, Å. (2011). A spectroscopic approach to imaging and quantification of cartilage lesions in human knee joints. Physics in Medicine and Biology, 56(6), 1865-1878
Open this publication in new window or tab >>A spectroscopic approach to imaging and quantification of cartilage lesions in human knee joints
2011 (English)In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 56, no 6, p. 1865-1878Article in journal (Refereed) Published
Abstract [en]

We have previously described a technology based on diffuse reflectance of broadband light for measuring joint articular cartilage thickness, utilizing that optical absorption is different in cartilage and subchondral bone. This study is the first evaluation of the technology in human material. We also investigated the prospects of cartilage lesion imaging, with the specific aim of arthroscopic integration. Cartilage thickness was studied ex vivo in a number of sites (n = 87) on human knee joint condyles, removed from nine patients during total knee replacement surgery. A reflectance spectrum was taken at each site and the cartilage thickness was estimated using the blue, green, red and near-infrared regions of the spectrum, respectively. Estimated values were compared with reference cartilage thickness values (taken after sample slicing) using an exponential model. Two-dimensional Monte Carlo simulations were performed in a theoretical analysis of the experimental results. The reference cartilage thickness of the investigated sites was 1.60 ± 1.30 mm (mean ± SD) in the range 0–4.2 mm. Highest correlation coefficients were seen for the calculations based on the near-infrared region after normalization to the red region (r = 0.86) and for the green region (r = 0.80).

Place, publisher, year, edition, pages
IOP, 2011
National Category
Medical Laboratory and Measurements Technologies
Identifiers
urn:nbn:se:liu:diva-66090 (URN)10.1088/0031-9155/56/6/021 (DOI)000287848600021 ()
Available from: 2011-03-07 Created: 2011-03-03 Last updated: 2017-12-11Bibliographically approved
Johansson, A., Larsby, B., Tamura, T. & Öberg, Å. (2005). Fallförebyggande sensor för äldre. In: Svenska Läkarsällskapets riksstämma, Stockholm 2005. Abstract: . Paper presented at Svenska Läkarsällskapets riksstämma, Stockholm, 30 november - 2 december 2005.
Open this publication in new window or tab >>Fallförebyggande sensor för äldre
2005 (Swedish)In: Svenska Läkarsällskapets riksstämma, Stockholm 2005. Abstract, 2005Conference paper, Oral presentation with published abstract (Other academic)
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-95791 (URN)
Conference
Svenska Läkarsällskapets riksstämma, Stockholm, 30 november - 2 december 2005
Available from: 2013-07-22 Created: 2013-07-22 Last updated: 2013-08-13
Johansson, A., Larsby, B., Tamura, T. & Öberg, Å. (2005). Fallförebyggande sensor för äldre. In: National Medical Convent,2005.
Open this publication in new window or tab >>Fallförebyggande sensor för äldre
2005 (Swedish)In: National Medical Convent,2005, 2005Conference paper, Published paper (Refereed)
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-37677 (URN)37292 (Local ID)37292 (Archive number)37292 (OAI)
Available from: 2009-10-10 Created: 2009-10-10
Johansson, A., Sundqvist, T., Kuiper, J.-H. & Öberg, Å. (2005). IN VITRO Imaging of human cartilage - contrast improvement by optical wavelength selection. In: Nordic Baltic Conference Biomedical Engineering and Medical Physics,2005 (pp. 172). Umeå: IFMBE
Open this publication in new window or tab >>IN VITRO Imaging of human cartilage - contrast improvement by optical wavelength selection
2005 (English)In: Nordic Baltic Conference Biomedical Engineering and Medical Physics,2005, Umeå: IFMBE , 2005, p. 172-Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Umeå: IFMBE, 2005
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-28764 (URN)13941 (Local ID)13941 (Archive number)13941 (OAI)
Available from: 2009-10-09 Created: 2009-10-09
Öberg, Å., Sundqvist, T. & Johansson, A. (2004). Assessment of cartilage thickness utilising reflectance spectroscopy. Medical and Biological Engineering and Computing, 42(1)
Open this publication in new window or tab >>Assessment of cartilage thickness utilising reflectance spectroscopy
2004 (English)In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 42, no 1Article in journal (Refereed) Published
Abstract [en]

A new principle for cartilage layer thickness assessments in joints is presented. It is based on the differences between the absorption spectra of cartilage and subchondral bone (containing blood). High-resolution ultrasound measurements of cartilage thickness were compared with reflection spectroscopy data from the same area of bovine hip joint condyles. A simple mathematical model allowed calculation of thickness and comparison with ultrasound data. The cartilage thickness was changed by being ground in short episodes. For thicker cartilage layers, a high degree of reflection in the 400-600nm wavelength interval was seen. For thinner cartilage layers, the characteristics of the spectra of blood and bone dominated those of cartilage. The mean (±SD) thickness of intact cartilage was 1.21± 0.30 mm (n = 30). In an exponential regression model, spectroscopic estimation of cartilage thickness showed a correlation coefficient of r= 0.69 (n = 182). For thinner cartilage layers (d<0.5mm), the mean model error was 0.19±0.17mm. Results from a bi-layer Monte Carlo simulation supported the assumption of an exponential relationship between spectroscopy data and reference ultrasound data. The conclusion is that optical reflection spectroscopy can be used for cartilage layer thickness assessment.

Keywords
BITES
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-22157 (URN)10.1007/BF02351004 (DOI)1267 (Local ID)1267 (Archive number)1267 (OAI)
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13
Sundberg, M., Peebo, M., Öberg, Å., Lundquist, P.-G. & Strömberg, T. (2004). Diffuse reflectance spectroscopy of the human tympanic membrane in otitis media. Physiological Measurement, 25(6), 1473-1483
Open this publication in new window or tab >>Diffuse reflectance spectroscopy of the human tympanic membrane in otitis media
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2004 (English)In: Physiological Measurement, ISSN 0967-3334, Vol. 25, no 6, p. 1473-1483Article in journal (Refereed) Published
Abstract [en]

We have investigated if features in the diffuse reflectance spectra from in vivo spectroscopic measurements of the tympanic membrane could aid the diagnosis of otitis media in children. Diffuse reflectance spectroscopy, in the visible wavelength range, was used in 15 ears from children with otitis media with effusion before and after myringotomy and in 15 healthy ears as a reference. Two previously published erythema detection algorithms yielded numerical quantities of haemoglobin content. With a combination of the algorithms, induced erythema (after myringotomy) was distinguished from healthy ears using Student's t-test (p < 0.01). Otitis media with mucous effusion was distinguished from (1) otitis media with serous effusion, (2) induced erythema and (3) healthy ears, (p < 0.05) using Student's t-test for independent groups and the paired t-test for dependent groups. Our results imply that reflectance spectroscopy is a promising technique to be used for the diagnosis of otitis media.

Keywords
diffuse reflectance spectroscopy, otitis media, tympanic membrane, erythema
National Category
Medical Laboratory and Measurements Technologies
Identifiers
urn:nbn:se:liu:diva-13009 (URN)10.1088/0967-3334/25/6/012 (DOI)
Available from: 2008-03-20 Created: 2008-03-20 Last updated: 2013-11-13
Sundberg, M., Borga, M., Knutsson, H., Johansson, A., Strömberg, T. & Öberg, Å. (2004). Fibre-optic array for curvature assessment: application in otitis diagnosis. Medical & Biological Engineering & Computing, 42(2), 245-252
Open this publication in new window or tab >>Fibre-optic array for curvature assessment: application in otitis diagnosis
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2004 (English)In: Medical & Biological Engineering & Computing, ISSN 0140-0118, Vol. 42, no 2, p. 245-252Article in journal (Refereed) Published
Abstract [en]

A contact-free sensor consisting of two parallel optical-fibre arrays was designed to assess surface shapes of diffusely scattering media. By sequentially illuminating objects using one fibre array and detecting the diffusely back-scattered photons by the other, a source-detector intensity matrix was formed, where the matrix element (i, j) was the intensity at detector j when light source i was excited. Experimental data from convex and concave polyacetal plastic surfaces were recorded. A mathematical model was used for simulating source-detector intensity matrices for the surfaces analysed in the experiments. Experimental results from the system were compared with the theoretically expected results provided by the mathematical model. The shape and relative amplitude showed similar behaviour in the experiments and simulations. A convex/concave discriminator index D, representing the detected intensity difference between two source-detector separations, was defined. The relative dynamic range of D, defined as the difference between the maximum and the minimum divided by the mean of the index, was 1.37 for convex surfaces and 0.68 for concave surfaces, at a measuring distance of 4.5mm. The index D was positive for convex surfaces and negative for concave surfaces, which showed that the system could distinguish between convex and concave surfaces, an important result for the diagnosis of otitis media.

Keywords
Diffuse reflection, Optical imaging, Otitis media, Surface shape identification
National Category
Medical Laboratory and Measurements Technologies
Identifiers
urn:nbn:se:liu:diva-13008 (URN)10.1007/BF02344638 (DOI)
Available from: 2008-03-20 Created: 2008-03-20 Last updated: 2014-10-08
Öberg, Å., Spelman, F. A. & Togawa, T. (2004). Introduction. In: P. Å. Öberg, Tatsuo Togawa, Francis A. Spelman (Ed.), Sensors in Medicine and Health Care: . Weinheim, Germany: WileyVCH Verlag
Open this publication in new window or tab >>Introduction
2004 (Swedish)In: Sensors in Medicine and Health Care / [ed] P. Å. Öberg, Tatsuo Togawa, Francis A. Spelman, Weinheim, Germany: WileyVCH Verlag , 2004, p. -420Chapter in book (Other academic)
Abstract [en]

Due to remarkable developments in the field of sensors along with miniaturization, sophisticated microsensors are part of many aspects of 21st century medicine and health care. Turning sensory inputs of all kinds into defined electrical signals that can be  interpreted and acted upon by both stationary and portable medicne  equipment as well as implants, sensors find many applications monitoring blood pressure, heart rates, glucose levels and many other parameters by which human health can be evaluated.        

They also serve as key components in modern imaging equipment as well as operating equipment for minimally invasive surgery,catheters and other applications.        

Taken as a whole, Sensors Applications covers all major fields  of application for commercial sensors, as well as their  manufacturing techniques and major types. Strong emphasis is placedon microsensors, microsystems and integrated electronic sensor  packages rather than bulk equipment. Each of the individual volumes is tailored to the needs and queries of readers from the relevant branches of industry and research.

Place, publisher, year, edition, pages
Weinheim, Germany: WileyVCH Verlag, 2004
Series
Sensor Applications ; Volume 3
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-22448 (URN)1670 (Local ID)3-527-29556-9 (ISBN)978-3-5272-9556-2 (ISBN)1670 (Archive number)1670 (OAI)
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2013-10-31Bibliographically approved
Öberg, Å. (2004). Optical sensors in medical care. In: Åke Öberg; Tatsuo Togawa and Francis A Spelman (Ed.), Sensors in Medicine and Health Care: (pp. 15-44). Weinheim, Germany: WileyVCH Verlag
Open this publication in new window or tab >>Optical sensors in medical care
2004 (English)In: Sensors in Medicine and Health Care / [ed] Åke Öberg; Tatsuo Togawa and Francis A Spelman, Weinheim, Germany: WileyVCH Verlag , 2004, p. 15-44Chapter in book (Other academic)
Abstract [en]

Due to remarkable developments in the field of sensors along with miniaturization, sophisticated microsensors are part of many aspects of 21st century medicine and health care. Turning sensory inputs of all kinds into defined electrical signals that can be  interpreted and acted upon by both stationary and portable medicne  equipment as well as implants, sensors find many applications monitoring blood pressure, heart rates, glucose levels and many other parameters by which human health can be evaluated.         

They also serve as key components in modern imaging equipment as well as operating equipment for minimally invasive surgery,catheters and other applications.         

Taken as a whole, Sensors Applications covers all major fields  of application for commercial sensors, as well as their  manufacturing techniques and major types. Strong emphasis is placedon microsensors, microsystems and integrated electronic sensor  packages rather than bulk equipment. Each of the individual volumes is tailored to the needs and queries of readers from the relevant branches of industry and research.

Place, publisher, year, edition, pages
Weinheim, Germany: WileyVCH Verlag, 2004
Series
Sensors Applications ; Volume 3
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-22447 (URN)1669 (Local ID)3-527-29556-9 (ISBN)978-3-5272-9556-2 (ISBN)1669 (Archive number)1669 (OAI)
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2013-10-31Bibliographically approved
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