| 1. |
- Antonsson, Johan, et al.
(författare)
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Diffuse reflectance spectroscopy measurements for tissue type discrimination during deep brain stimulation
- 2008
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Ingår i: Journal of neural engineering. - : IOP Publishing. - 1741-2560 .- 1741-2552. ; 5:2, s. 185-190
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Tidskriftsartikel (refereegranskat)abstract
- Diffuse reflectance spectroscopy as a method for improving intracerebral guidance during functional neurosurgery has been investigated. An optical probe was developed for measurements during stereotactic and functional neurosurgery in man. The aim of the study was to investigate the spectral differences between white and grey matter and between white matter and functional targets. Diffuse reflectance spectroscopy measurements in ten patients were recorded at incremental steps towards and in three different functional targets (STN, GPi and Zi). The recorded spectra along the trajectory were sorted into white or grey matter, based on preoperative MRI images or the recorded spectral shape and intensity. The difference between tissue types was calculated as a quotient. Significant intensity differences between white and grey matter were found to be at least 14% (p < 0.05) and 20% (p < 0.0001) for MRI and spectral-sorted data respectively. The reflectance difference between white matter and the functional targets of GPi was higher than for STN and Zi. The results indicate that diffuse reflectance spectroscopy has a potential to be developed to a suitable complement to other intracerebral guidance methods.
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| 2. |
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| 3. |
- Wårdell, Karin, et al.
(författare)
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Intracerebral microvascular measurements during deep brain stimulation implantation using laser doppler perfusion monitoring
- 2007
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Ingår i: Stereotactic and Functional Neurosurgery. - : S. Karger. - 1011-6125 .- 1423-0372. ; 85:6, s. 279-286
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to investigate if laser Doppler perfusion monitoring (LDPM) can be used in order to differentiate between gray and white matter and to what extent microvascular perfusion can be recorded in the deep brain structures during stereotactic neurosurgery. An optical probe constructed to fit in the Leksell® Stereotactic System was used for measurements along the trajectory and in the targets (globus pallidus internus, subthalamic nucleus, zona incerta, thalamus) during the implantation of deep brain stimulation leads (n = 22). The total backscattered light intensity (TLI) reflecting the grayness of the tissue, and the microvascular perfusion were captured at 128 sites. Heartbeat-synchronized pulsations were found at all perfusion recordings. In 6 sites the perfusion was more than 6 times higher than the closest neighbor indicating a possible small vessel structure. TLI was significantly higher (p < 0.005) and the perfusion significantly lower (p < 0.005) in positions identified as white matter in the respective MRI batch. The measurements imply that LDPM has the potential to be used as an intracerebral guidance tool.
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| 4. |
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| 5. |
- 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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| 6. |
- Antonsson, Johan, et al.
(författare)
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Optical measurements during experimental stereotactic radiofrequency lesioning
- 2006
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Ingår i: Stereotactic and Functional Neurosurgery. - : S. Karger. - 1011-6125 .- 1423-0372. ; 84:2-3, s. 118-124
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate in vivo a laser Doppler measurement system in porcine brain tissue during thermal lesioning. A 2-mm monopolar radiofrequency lesioning electrode was equipped with optical fibers in order to monitor the lesioning procedure. Laser Doppler and backscattered light intensity signals were measured along the electrode trajectory and during bilateral lesioning in the central gray (70, 80 and 90°C, n = 14). The time course of the coagulation process could be followed by optical recordings. Two separate groups of tissue were identified from the intensity signals. The changes in the perfusion levels in both groups displayed significant changes (p < 0.05, n = 48) at all temperature settings, while backscattered light intensity was significant for only one group at the different temperatures (p < 0.05, n = 39). These results indicate that optical measurements correlate with lesion development in vivo. The study also indicates that it is possible to follow the lesioning process intra-operatively.
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| 7. |
- Antonsson, Johan, et al.
(författare)
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Radio frequency electrode system for optical lesion size estimation in functional neurosurgery
- 2005
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Ingår i: Journal of Biomedical Optics. - : SPIE - International Society for Optical Engineering. - 1083-3668 .- 1560-2281. ; 10:3, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 8. |
- Hansson, Bengt Göran, et al.
(författare)
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Strong Association between Infection With Human Papillomavirus and Oral and Oropharyngeal Squamous Cell Carcinoma : A Population-based Case-control Study in Southern Sweden
- 2005
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Ingår i: Acta Oto-Laryngologica. - : Informa UK Limited. - 0001-6489 .- 1651-2251. ; 125:12, s. 1337-1344
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- CONCLUSIONS: The results of this study demonstrate a strong association between infection with high-risk types of human papillomavirus (HPV) and oral and oropharyngeal squamous cell carcinoma (OOSCC), suggesting that high-risk HPV types play a key role in car-cinogenesis. The estimated proportion of OOSCC cases attributable to HPV infection was 35%. OBJECTIVE: HPV appears to have an aetiological role in OOSCC, despite the fact that the reported prevalences of HPV in both OOSCC patients and healthy individuals have varied widely. We aimed to investigate the presence and spectrum of both high- and low-risk HPVs in all consecutive cases of OOSCC in a Swedish healthcare region over a 3-year period and in population-based, matched healthy controls. MATERIAL AND METHODS: A total of 131 patients with OOSCC were studied. Samples taken from the surface of the tumour and from the tonsillar fossa using cotton-tipped swabs were investigated, together with exfoliated cells collected using a mouthwash. Tonsillar fossa and mouthwash specimens were collected in the same way from 320 matched controls. All samples were tested for HPV DNA by nested polymerase chain reaction using the primer pairs MY09/MY11 and GP5 + /GP6+, and in positive cases the HPV type was determined by DNA sequencing. RESULTS: Infection with high-risk HPV was shown to be a strong risk factor for OOSCC (OR = 63; 95% CI 14-480). Forty-seven (36%) of the cancer patients had > or =1 specimen that was positive for a high-risk HPV type (81% of which were HPV 16), while only 3 (0.94%) of the controls were positive for a high-risk HPV type. Seven (5.3%) of the cancer patients and 13 (4.1%) of the controls were positive for any of the mucosal, mucocutaneous or cutaneous low-risk HPV types.
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| 9. |
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| 10. |
- Linton, Johan, 1966, et al.
(författare)
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Arkitekturens ordning
- 2008
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Ingår i: Psykoanalytisk Tid/Skrift. - 1650-7398.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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