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- Antonsson, Johan, 1973-
(författare)
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On optical methods for intracerebral measurements during stereotactic and functional neurosurgery : Experimental studies
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Radio frequency (RF) lesioning and deep brain stimulation (DBS) are the two prevailing surgical treatments for movement disorders within the field of stereotactic and functional neurosurgery. For RF-lesioning, a small volume of brain tissue is coagulated and knowledge of the lesion size and growth is of great importance for the safety and outcome of the procedure. This thesis deals with adapting the laser Doppler perfusion monitoring (LDPM) technique for measurements in brain tissue during RF-lesioning. The relation between LDPM signal changes and developed lesion size was investigated. LDPM measurements were evaluated both in vitro (albumin protein solution) and in vivo in the porcine brain during RF-lesioning corresponding to a bilateral thalamotomy in man. The investigated signals from the LDPI measurements can be used for following the lesioning time course and to detect if a lesion was created, both in vitro and in the animal model. For the albumin model, both the total backscattered light intensity and the perfusion signal can be used as markers for estimating the final coagulation size, while in the animal model this conclusion was not statistical verified.Independent on surgical method, RF-lesioning or DBS, intracerebral guidance is an important aspect within stereotactic and functional neurosurgery. To increase the accuracy and precision of reaching the correct target, different methods for intracerebral guidance exist, such as microelectrode recording and impedance methods. In this thesis, the possibility of developing an optical intracerebral guidance method has been investigated. Diffuse reflectance spectroscopy served as technology and all measurements were performed stereotactically in both porcine and human brain. Measurements of white and gray matter showed large differences, with higher reflectivity for white brain matter, both in porcine and in human brain. For the human measurements during DBS-implants, large differences between white matter and functional targets were found. Additionally, differences between native and lesioned porcine brain matter were detected. Both studies support the idea of using diffuse reflectance spectroscopy for developing an intracerebral guidance method.
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- Antonsson, Johan, 1973-
(författare)
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Optical measurements in brain tissue during radio frequency lesioning
- 2004
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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- Dahlström, Örjan, et al.
(författare)
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Clustering as a data mining method in a Web-based system for thoracic surgery
- 2001
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Ingår i: Journal of the Medical Informatics Association. Symposium Supplement. - Washington : Hanley&Belfus. - 1560535369 ; , s. 888-
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Konferensbidrag (refereegranskat)abstract
- Cluster analysis is one way of data mining from large amounts of information. Being able to perform series of analyses, varying clinical criteria and requests, expected results of the clustering might be truly rewarding. Instead of having a few hypotheses prepared and tested, medical experts can be surprised by obtaining a set of hypotheses to further validate and work on.Internet technologies enable a substantial flexibility that can be taken advantage of when implementing a Web-based tool. Division of Medical Informatics together with Linkoping Heart Center of the Linkoping University is developing procedures for multivariate clustering within the Web-based AssistMe1 system.
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- Kircher, Albert, et al.
(författare)
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Knowledge representation forms for data mining methodologies as applied in thoracic surgery
- 2000
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Ingår i: AMIA,2000. - Philadelphia : Hanley & Belfus Inc. - 156053480X ; , s. 428-432
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Konferensbidrag (refereegranskat)abstract
- Typical ways of disseminating and using results of clinical research are scientific journals and reports. Presentation forms are condensed and comprehensible mainly to the experts following the specific topics. A vast amount of information remains unutilized due to the complex form of presenting the knowledge. Subject of this research is to explore possibilities of representation and also visualization of the results obtained using data mining methodologies. The intention is to formulate more than scientific ways to communicate facts that are of interest for the clinicians, medical students and even patients. Internet technologies as already widely established media support knowledge representation forms such as hypertext documents and structured knowledge components. The "Assist Me" decision support system for surgical treatment of cardiac patients integrates several forms of data mining and representation methodologies. We are showing a feasibility study in which scientific outcomes were forwarded to a broad group of potential users.
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- Wårdell, Karin, 1959-, et al.
(författare)
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A laser Doppler system for intracerebral measurements during stereotactic neurosurgery
- 2007
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Ingår i: Engineering in Medicine and Biology Society, 2007. EMBS 2007. - : IEEE. - 9781424407873 - 9781424407880 ; , s. 4083-4086
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Konferensbidrag (refereegranskat)abstract
- A laser Doppler system for intracerebral measurements during stereotactic and functional neurosurgery is presented. The system comprises a laser Doppler perfusion monitor, an optical probe adapted for the Leksellreg stereotactic system and a personal computer with software for acquisition, data analysis and presentation. The software makes it possible to present both the perfusion and the total backscattered light intensity (TLI) in real-time. During intracerebral measurements, the perfusion signal records the tissue's microcirculation whereas the TLI signal may be used to distinguish between grey and white matter. Evaluation of the system has been done during stereotactic neurosurgery in relation to implantation of deep brain stimulation electrodes. Measurements were made along trajectories towards targets in the deep brain structure as well as in pre-calculated target areas. The measurements show that the system has a potential to be used for intracerebral guidance but further evaluation of the technique is needed.
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