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  • 1
    Electronic Resource
    Electronic Resource
    Enhanced magnetic resonance imaging of the rat brain using a stereotaetic device with a small head coil: Technical note (1995)
    Springer
    Acta neurochirurgica 133 (1995), S. 87-92 
    Details
    ISSN: 0942-0940
    Keywords: MRI ; rat, brain ; stereotactic atlas ; Gamma Knife
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A stereotactic device (SDM) was developed for performing consistent magnetic resonance imaging (MRI) of the rat brain. The SDM was developed by adapting a radiofrequency transmit/receive head coil of 4.4 cm inner diameter (quadrature birdcage head coil), and utilizing partial acrylic construction for the positioning elements. The small head coil provides improved resolution and accuracy of the image, while the stereotactic holder permits repeatable and accurate imaging of identified brain structures. This system provides several advantages over existing experimental MRI devices. The SDM ensures that the head is always placed in the center of the coil in a uniform fashion. Standardized positioning of the skull optimizes image quality and provides a consistent orientation of the brain. In addition, a widely-utilized coordinate system described by Paxinos and Watson can be employed to assist in the identification of structures and to facilitate surgical planning. The SDM is compatible with a recently-developed stereotactic device for radiosurgery with the Gamma Knife, thus permitting the planning and performance of experimental radiosurgery using the same coordinate system. The SDM also provides the ability to perform MRI and radiosurgery at different times, thus avoiding the need for prolonged anesthesia during an experimental study. Finally, the SDM allows repeated MRI of the same, identifiable positions in the brain during longitudinal experimental studies. The utility of this device is demonstrated here by examining the time course of cerebral damage that evolved within a radiosurgical focus after gamma irradiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01404955
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  • 2
    Electronic Resource
    Electronic Resource
    Stereotactic laser-guided approach to distal middle cerebral artery aneurysms (1995)
    Springer
    Acta neurochirurgica 132 (1995), S. 138-144 
    Details
    ISSN: 0942-0940
    Keywords: Stereotactic surgery ; mycotic aneurysm ; laser guidance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The Steiner-Lindquist laser intra-operative guidance method is described and its application in the surgical treatment of mycotic aneurysm is presented. Three illustrative cases of distal middle cerebral artery aneurysms are reported. The authors argue that all ruptured mycotic aneurysms should be treated surgically. The laserguided stereotactic approach is presented as simple, flexible and reliable method to improve safety and accuracy of the operation in these cases. In our experience it compares favorably with previously described stereotactic techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01404862
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Accuracy of an experimental stereotactic system for MRI-based Gamma Knife irradiation in the rat (1996)
    Springer
    Acta neurochirurgica 138 (1996), S. 1103-1108 
    Details
    ISSN: 0942-0940
    Keywords: Gamma Knife ; MRI ; Stereotactic atlas ; rat ; stereotactic device
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Stereotactic devices for experimental Gamma Knife irradiation and magnetic resonance imaging (MRI) have recently been developed for experimental studies using rats [6, 7]. The present study examined the accuracy of these devices using the following two approaches. In the first approach, Gamma Knife irradiation was performed using the stereotactic device with targets based on a standard stereotactic atlas. Gadolinium-enhanced T1-weighted magnetic resonance imaging was performed using the MRI stereotactic device. Animals were then sacrificed after Evans blue injection, and the rat brain was sliced using an attachment to the stereotactic device. The center coordinates of the gadolinium-enhanced area from the MRI and Evans blue-stained area from the tissue sections were obtained using a computer-assisted image analysis system. These coordinates were compared with the target coordinates planned from the stereotactic atlas. In the second approach, a thermoluminescence dosimeter was implanted in the rat brain. Stereotactic MRI was performed using the stereotactic MRI device, and the coordinates of the implant were obtained. Gamma Knife irradiation was then performed at this target using the stereotactic device. The absorbed dose was measured and compared with the planning dose. These experiments demonstrated a spatial error of 0.6 mm (standard error ± 0.07) between Gamma Knife irradiation based on a comparison of the atlas coordinates and the lesion, and a spatial error of 1.0 mm (standard error ± 0.13) based on a comparison of the stereotactic MR images and the lesion. Gamma Knife irradiation based on MR images using the stereotactic device demonstrated a maximum error of 10% in absorbed dose at the target center. Together, the stereotactic devices for Gamma Knife irradiation and magnetic resonance imaging provide useful tools for Gamma Knife research in an animal model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01412315
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  • 4
    Electronic Resource
    Electronic Resource
    Histological changes in the normal rat brain after gamma irradiation (1996)
    Springer
    Acta neurochirurgica 138 (1996), S. 451-459 
    Details
    ISSN: 0942-0940
    Keywords: Radiosurgery ; Gamma Knife ; radiation necrosis ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Radiation-induced changes in the parietal cortex of Wistar rats were observed at various time points after gamma surgery. Maximum dosages of 50, 75, and 120 Gy were given at the iso-center of the radiation using a 4-mm collimator. Conventional histochemical and immunocytochemical analyses, and computer-assisted videomicroscopy were utilized to examine perfusion-fixed brain tissue. Irradiation at a dosage of 50 Gy elicited morphological changes of astrocytes in the parietal cortex at 3 months. Vasodilatation became obvious at 12 months; fibrin deposition was observed in the dilated capillary wall. Neither leakage of Evans Blue from the vasculature into the tissue nor necrosis was observed across the 12 month observation period. Irradiation at a dosage of 75 Gy resulted in morphological changes of astrocytes within 1 month. Dilatation of vessels and capillary thickening were observed at 3 months. Evans Blue leakage and necrosis were observed at 4 months after 75 Gy irradiation. At this time, the walls of arterioles became thickened by subintimal accumulation of fibrin and hyaline substance; this sometimes resulted in occlusion of the lumen. Significant hemispheric swelling was observed at 4 months. Irradiation at a dosage of 120 Gy elicited changes in astrocytic morphology within 3 days. Evans Blue leakage into the tissue was observed by 3 weeks. Vasodilatation became marked at this time point and rarefaction was observed in the irradiated cortex. Necrosis was observed at 4 weeks, however, no significant swelling was observed. Taken together, these findings demonstrate time-dependent and dosage-dependent changes in normal cerebral tissue after Gamma Knife irradiation. These results provide a basis for gauging the impact of gamma surgery in regions of eloquent tissue. An enhanced understanding of the cellular responses to radiosurgery will contribute to developing and evaluating future applications for gamma surgery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01420308
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  • 5
    Electronic Resource
    Electronic Resource
    Occlusion of the anterior cerebral artery after gamma knife irradiation in a rat (1996)
    Springer
    Acta neurochirurgica 138 (1996), S. 983-991 
    Details
    ISSN: 0942-0940
    Keywords: Gamma Knife ; radiosurgery ; artery ; arteriosclerosis ; vasculitis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The anterior cerebral artery of rats was irradiated at the level of the circle of Willis by Gamma Knife with a maximum dose of 25, 50, or 100 Gy. Occlusion of the anterior cerebral artery was observed in one rat which was followed for 20 months after irradiation of 100 Gy. Cerebral infarction was found at the midline-frontal region and the cingulate gyrus. Arterial wall thickening with fibrosis, splitting of the internal elastic membrane, luminal organized thrombus, and migration of smooth muscle cells into the thrombus were observed. In the anterior cerebral artery, thrombus formation seemed to occur after the endothelial injury and this may play a prominent role for occlusion. In small arteries, various changes were observed in the irradiated tissue. These included fibrosis and thrombus, thickened smooth muscle layer, lymphocytic infiltration, and thickening of vessel wall with fibrosis and fibrinous thrombosis with leakage of fibrin into the surrounding tissue after different doses of radiation and at different observation times. These changes were comparable to the ordinary vascular response to injury including healing vasculitis and arteriosclerosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01411289
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  • 6
    Electronic Resource
    Electronic Resource
    A paedriatic patient with meningioma arising from the cavernous sinus wall (1997)
    Springer
    Acta neurochirurgica 139 (1997), S. 259-260 
    Details
    ISSN: 0942-0940
    Keywords: Cavernous sinus ; meningioma ; paedriatic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01844762
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