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Rejmstad, Peter
Publications (8 of 8) Show all publications
Rejmstad, P., Johansson, J. D., Haj-Hosseini, N. & Wårdell, K. (2017). A method for monitoring of oxygen saturation changes in brain tissue using diffuse reflectance spectroscopy. Journal of Biophotonics, 10(3), 446-455
Open this publication in new window or tab >>A method for monitoring of oxygen saturation changes in brain tissue using diffuse reflectance spectroscopy
2017 (English)In: Journal of Biophotonics, ISSN 1864-063X, E-ISSN 1864-0648, Vol. 10, no 3, p. 446-455Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2017
Keywords
oxygenation, diffuse reflectance spectroscopy, hemoglobin, optical phantom, human brain
National Category
Other Medical Engineering
Identifiers
urn:nbn:se:liu:diva-127362 (URN)10.1002/jbio.201500334 (DOI)000398216200012 ()27094015 (PubMedID)
Note

Funding agencies: Swedish Childhood Cancer Foundation; Swedish Research Council [621-2010-4216, 621-2013-6078]

Available from: 2016-04-22 Created: 2016-04-22 Last updated: 2017-04-20Bibliographically approved
Rejmstad, P., Åkesson, G., Åneman, O. & Wårdell, K. (2016). A laser Doppler system for monitoring of cerebral microcirculation: implementation and evaluation during neurosurgery. Medical and Biological Engineering and Computing, 54(1), 123-131
Open this publication in new window or tab >>A laser Doppler system for monitoring of cerebral microcirculation: implementation and evaluation during neurosurgery
2016 (English)In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, ISSN 0140-0118, Vol. 54, no 1, p. 123-131Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to adapt and evaluate laser Doppler perfusion monitoring (LDPM) together with custom designed brain probes and software for continuous recording of cerebral microcirculation in patients undergoing neurosurgery. The LDPM system was used to record perfusion and backscattered light (TLI). These parameters were displayed together with the extracted heart rate (HR), pulsatility index (PI) and signal trends from adjustable time intervals. Technical evaluation was done on skin during thermal provocation. Clinical measurements were performed on ten patients undergoing brain tumour surgery. Data from 76 tissue sites were captured with a length varying between 10 s to 15 min. Statistical comparisons were done using Mann-Whitney tests. Grey and tumour tissue could be separated from white matter using the TLI-signal (p < 0.05). The perfusion was significantly higher in grey and tumour tissue compared to white matter (p < 0.005). LDPM was successfully used as an intraoperative tool for monitoring local blood flow and additional parameters linked to cerebral microcirculation (perfusion, TLI, heart rate and PI) during tumour resection. The systems stability opens up for studies in the postoperative care of patients with e.g. traumatic brain injury or subarachnoid haemorrhage.

Place, publisher, year, edition, pages
Springer Berlin/Heidelberg, 2016
Keywords
Microcirculation, Brain tumour Laser Doppler perfusion monitoring (LDPM), Pulsatility index (PI), Neurosurgery
National Category
Medical Laboratory and Measurements Technologies
Identifiers
urn:nbn:se:liu:diva-120632 (URN)10.1007/s11517-015-1332-5 (DOI)000371437900010 ()26105147 (PubMedID)
Funder
Swedish Research Council, 6212-010-4216
Available from: 2015-08-20 Created: 2015-08-20 Last updated: 2017-12-04Bibliographically approved
Wårdell, K., Hemm-Ode, S., Rejmstad, P. & Zsigmond, P. (2016). High-Resolution Laser Doppler Measurements of Microcirculation in the Deep Brain Structures: A Method for Potential Vessel Tracking.. Stereotactic and Functional Neurosurgery, 94(1), 1-9
Open this publication in new window or tab >>High-Resolution Laser Doppler Measurements of Microcirculation in the Deep Brain Structures: A Method for Potential Vessel Tracking.
2016 (English)In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 94, no 1, p. 1-9Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Laser Doppler flowmetry (LDF) can be used to measure cerebral microcirculation in relation to stereotactic deep brain stimulation (DBS) implantations.

OBJECTIVE: To investigate the microcirculation and total light intensity (TLI) corresponding to tissue grayness in DBS target regions with high-resolution LDF recordings, and to define a resolution which enables detection of small vessels.

METHODS: Stereotactic LDF measurements were made prior to DBS implantation with 0.5-mm steps in the vicinity to 4 deep brain targets (STN, GPi, Vim, Zi) along 20 trajectories. The Mann-Whitney U test was used to compare the microcirculation and TLI between targets, and the measurement resolution (0.5 vs. 1 mm). The numbers of high blood flow spots along the trajectories were calculated.

RESULTS: There was a significant difference (p < 0.05) in microcirculation between the targets. High blood flow spots were present at 15 out of 510 positions, 7 along Vim and GPi trajectories, respectively. There was no statistical difference between resolutions even though both local blood flow and TLI peaks could appear at 0.5-mm steps.

CONCLUSIONS: LDF can be used for online tracking of critical regions presenting blood flow and TLI peaks, possibly relating to vessel structures and thin laminas along stereotactic trajectories.

Place, publisher, year, edition, pages
S. Karger, 2016
Keywords
Deep brain stimulation · Laser Doppler flowmetry ·Stereotactic neurosurgery · Microcirculation · Navigation
National Category
Biomedical Laboratory Science/Technology Neurology
Identifiers
urn:nbn:se:liu:diva-124691 (URN)10.1159/000442894 (DOI)000373869900001 ()26795207 (PubMedID)
Note

Funding agencies:  Swedish Research Council [621-2013-6078]; Parkinson Foundation at Linkoping University; Swiss National Science Foundation [205321-135285]

Available from: 2016-02-10 Created: 2016-02-10 Last updated: 2017-11-30Bibliographically approved
Wårdell, K., Rejmstad, P., Hemm-Ode, S., Richter, J. & Zsigmond, P. (2014). Microvascular Blood Flow in the Deep Brain Structures - Laser Doppler Measurements during DBS-implantations. In: Movement Disorders 2014, Volym 29, Suppl 1 :1271: . Paper presented at 18th International Congress of Parkinson's Disease and Movement Disorders, June 8-12 2014, Stockholm, Sweden.
Open this publication in new window or tab >>Microvascular Blood Flow in the Deep Brain Structures - Laser Doppler Measurements during DBS-implantations
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2014 (English)In: Movement Disorders 2014, Volym 29, Suppl 1 :1271, 2014Conference paper, Poster (with or without abstract) (Other academic)
National Category
Other Medical Engineering
Identifiers
urn:nbn:se:liu:diva-107592 (URN)
Conference
18th International Congress of Parkinson's Disease and Movement Disorders, June 8-12 2014, Stockholm, Sweden
Available from: 2014-06-17 Created: 2014-06-17 Last updated: 2017-02-03Bibliographically approved
Rejmstad, P. & Wårdell, K. (2014). Oxygen saturation algorithms based on diffuse reflectance spectroscopy. In: : . Paper presented at International Conference on Laser Applications in Life Sciences (LALS 2014), June 29 - July 2, 2014, Ulm, Germany. Ulm
Open this publication in new window or tab >>Oxygen saturation algorithms based on diffuse reflectance spectroscopy
2014 (English)Conference paper, Poster (with or without abstract) (Other academic)
Place, publisher, year, edition, pages
Ulm: , 2014
National Category
Other Medical Engineering
Identifiers
urn:nbn:se:liu:diva-109315 (URN)
Conference
International Conference on Laser Applications in Life Sciences (LALS 2014), June 29 - July 2, 2014, Ulm, Germany
Available from: 2014-08-12 Created: 2014-08-12 Last updated: 2017-02-13Bibliographically approved
Wårdell, K., Zsigmond, P., Rejmstad, P., Åneman, O. & Hillman, J. (2013). Combined laser Doppler and reflectance spectroscopy measurements during brain surgery. In: : . Paper presented at Computer Assisted Radiology and Surgery Heidelberg (pp. 96-97).
Open this publication in new window or tab >>Combined laser Doppler and reflectance spectroscopy measurements during brain surgery
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2013 (English)Conference paper, Oral presentation with published abstract (Other academic)
National Category
Other Medical Engineering
Identifiers
urn:nbn:se:liu:diva-97363 (URN)
Conference
Computer Assisted Radiology and Surgery Heidelberg
Available from: 2013-09-10 Created: 2013-09-10 Last updated: 2017-02-03Bibliographically approved
Rejmstad, P., Åkesson, G., Hillman, J. & Wårdell, K. (2012). A laser Doppler system for monitoring of intracerebral microcirculation. Conf Proc IEEE Eng Med Biol Soc., 1988-1991
Open this publication in new window or tab >>A laser Doppler system for monitoring of intracerebral microcirculation
2012 (English)In: Conf Proc IEEE Eng Med Biol Soc., ISSN 1557-170X, p. 1988-1991Article in journal (Refereed) Published
Abstract [en]

A two-channel standard laser Doppler perfusion monitor has been adapted for intracerebral measurements. Software developed in Labview makes it possible to present the microvascular perfusion, total light intensity (TLI), heart rate and trend curves in real-time during surgery. A custom-made optical probe was designed in order to enable easy fixation during brain surgery. The constructed brain probe was evaluated and compared to a standard probe. Both probes presented similar feasibility when used for the skin recordings. In addition, evaluation was done in one patient in relation to tumor resection. Stable perfusion and TLI signals were immediately recorded when the probe was positioned in cerebral tissue. Movement artifacts were clearly seen when the probe was moved to a new site. Recordings in cortex and tumor border showed higher perfusion and lower TLI compared to measurements in subcortical white matter. The calculated heart rate estimate agreed well with the noted value from the electrocardiographic patient monitoring system.                                                                                                                                                      

Place, publisher, year, edition, pages
IEEE, 2012
National Category
Medical Engineering
Identifiers
urn:nbn:se:liu:diva-86150 (URN)10.1109/EMBC.2012.6346346 (DOI)000313296502058 ()23366307 (PubMedID)978-1-4244-4119-8 (ISBN)e-978-1-4244-4120-4 (ISBN)978-1-4577-1787-1 (ISBN)
Funder
Swedish Research Council
Available from: 2012-12-07 Created: 2012-12-07 Last updated: 2017-02-03Bibliographically approved
Rejmstad, P., Åkesson, G., Hillman, J. & Wårdell, K. (2012). Intracerebral perfusion monitoring by laser Doppler flowmetry, Medicinteknikdagarna. In: : . Paper presented at Medicinteknikdagarns (MTD). Lund
Open this publication in new window or tab >>Intracerebral perfusion monitoring by laser Doppler flowmetry, Medicinteknikdagarna
2012 (English)Conference paper, Published paper (Other academic)
Place, publisher, year, edition, pages
Lund: , 2012
National Category
Medical Engineering
Identifiers
urn:nbn:se:liu:diva-81378 (URN)
Conference
Medicinteknikdagarns (MTD)
Available from: 2012-09-12 Created: 2012-09-12 Last updated: 2017-02-03Bibliographically approved
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