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Optical measurements in brain tissue during radio frequency lesioning
Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
2004 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Radio frequency (RF) lesioning is a well well-known procedure within the field of stereotactic neurosurgery, commonly used for the treatment of movement disorders. During the intervention, an RF-electrode is inserted into the deeper parts of the brain, where a small volume of malfunctioning brain tissue will be coagulated. This procedure is irreversible, as a result, the size and position of the created lesion is crucial in order to avoid unwanted side effects. In this thesis a further development of the RF-technology is presented in order to follow a lesioning process and to estimate the created lesion size. Software, electronics, fiber optics and an RF-electrode equipped with optical fibers was developed and evaluated.

Diffuse reflectance spectroscopy measurements at 450-800 nm in the central gray of porcine brain have been performed with the developed RF-electrode. Measurements of white and gray brain matter showed a large reflectance difference in the investigated wavelength interval, with higher reflectivity for white brain matter. Reflectance differences between native and coagulated, white and gray brain matter were also found .

In-vitro laser Doppler perfusion monitoring measurements at 633 nm have also been performed in a newly designed flow model. An albumin solution with added glass microspheres was placed on top of a revolving disc. The motion of the liquid surrounding the electrode tip simulated a perfusion situation. Changes in both laser Doppler perfusion and total backscattered light intensity signals were collected during the creation of different sized coagulations. The volume, width and length of the created coagulations are correlated to the measured signal changes in-vitro, where larger coagulations displayed larger signal changes. The laser Doppler perfusion and backscattered light intensity signals can be used to follow the lesioning time course and estimate the developed lesion size in-vitro.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 2004. , 33 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1114
Series
LiU-TEK-LIC, 43
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-22099Local ID: 1192ISBN: 91-85295-29-9 (print)OAI: oai:DiVA.org:liu-22099DiVA: diva2:242412
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2013-11-13
List of papers
1. In-vivo reflection spectroscopy measurements in pig brain during stereotactic surgery
Open this publication in new window or tab >>In-vivo reflection spectroscopy measurements in pig brain during stereotactic surgery
2003 (English)In: Biophotonics West: Biomedical Optics, 2003, Vol. 4958, 242-250 p.Conference paper, Published paper (Refereed)
Abstract [en]

Radiofrequency (RF) lesioning in the human brain is a commonsurgical therapy for relieving severe pain as well as formovement disorders such as Parkinsonia. During the procedure a smallelectrode is introduced by stereotactic means towards a target arealocalized by CT or MRI. An RF-current is applied throughthe electrode tip when positioned in the target area. Thetissue in the proximity of the tip is heated bythe current and finally coagulated.The overall aim of this studywas to improve the RF-technique and its ability to estimatelesion size by means of optical methods. Therefore, the opticaldifferences between white and gray matter, as well as lesionedand unlesioned tissue were investigated. Reflection spectroscopy measurements in therange of 450-800 nm were conducted on fully anesthetized pigsduring stereotactic RF-lesioning (n=6). Light from a tungsten lamp wasguided to the electrode tip through optical fibers, inserted alonga 2 mm in diameter monopolar RF-electrode. Measurements were performedin steps of 0-10 mm from the target in eachhemisphere towards the entry point of the skull. In thecentral gray of the porcine brain measurements were performed bothbefore and after the creation of a lesion. A totalof 55 spectra were collected during this study. Correlation totissue type was done using post-operative MR-images. The spectral signaturefor white and gray matter differs significantly for the entirespectral range of 450-800 nm. Pre- and post-lesioning reflection spectroscopyshowed the largest differences below 600 and above 620 nm,which implies that lasers within this wavelength range may beuseful for in-vivo measurements of tissue optical changes during RF-lesioning.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-14234 (URN)10.1117/12.476131 (DOI)
Available from: 2007-01-26 Created: 2007-01-26 Last updated: 2017-02-22Bibliographically approved
2. Radio frequency electrode system for optical lesion size estimation in functional neurosurgery
Open this publication in new window or tab >>Radio frequency electrode system for optical lesion size estimation in functional neurosurgery
2005 (English)In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 10, no 3, 1-6 p.Article in journal (Refereed) Published
Abstract [en]

Radiofrequency(RF) lesioning in the human brain is one possible surgicaltherapy for severe pain as well as movement disorders. Oneobstacle for a safer lesioning procedure is the lack ofsize monitoring. The aim of this study was to investigateif changes in laser Doppler or intensity signals could beused as markers for size estimation during experimental RF lesioning.A 2 mm in diameter monopolar RF electrode was equippedwith optical fibers and connected to a digital laser Dopplersystem. The optical RF electrode's performance was equal to astandard RF electrode with the same dimensions. An albumin solutionwith scatterers was used to evaluate the intensity and laserDoppler signal changes during lesioning at 70, 80, and 90 °C.Significant signal changes were found for these three different clotsizes, represented by the temperatures (p<0.05,  n=10). The volume, width, andlength of the created coagulations were correlated to the intensitysignal changes (r=0.88, n=30, p<0.0001) and to the perfusion signalchanges (r=0.81, n=30, p<0.0001). Both static and Doppler-shifted light canbe used to follow the lesioning procedure as well asbeing used for lesion size estimation during experimental RF lesioning.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2005
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:liu:diva-14232 (URN)10.1117/1.1924615 (DOI)000235127400040 ()16229664 (PubMedID)2-s2.0-24144476322 (Scopus ID)
Available from: 2007-01-26 Created: 2007-01-26 Last updated: 2017-12-13Bibliographically approved

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Antonsson, Johan

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