1/35. Integration of preoperative and intraoperative functional brain mapping in a frameless stereotactic environment for lesions near eloquent cortex. Technical note.The authors present a method of incorporating preoperative noninvasive functional brain mapping data into the frameless stereotactic magnetic resonance (MR) imaging dataset used for image-guided resection of brain lesions located near eloquent cortex. They report the use of functional (f)MR imaging and magnetic source (MS) imaging for preoperative mapping of eloquent cortex in difficult cases of brain tumor resection such as those in which there are large expansive masses or in which reoperations are required and the anatomy is distorted from prior treatments. To correlate methods of preoperative and intraoperative mapping localization directly, the authors have developed techniques of importing preoperative MS and fMR imaging data into an image-guided frameless stereotactic computer workstation. The data appear as a seamless overlay on the same preoperative volumetric MR imaging dataset used for stereotactic guidance during the operation. Intraoperatively identified functional locations mapped by cortical stimulation are recorded as digitally registered points. This approach should prove useful in assessing the accuracy and reliability of various preoperative functional brain mapping techniques.- - - - - - - - - - ranking = 1keywords = environment (Clic here for more details about this article) |
2/35. Planning and simulation of neurosurgery in a virtual reality environment.OBJECTIVE: To report our experience with preoperative neurosurgical planning in our stereoscopic virtual reality environment for 21 patients with intra- and extra-axial brain tumors and vascular malformations. methods: A neurosurgical planning system called VIVIAN (Virtual Intracranial Visualization and Navigation) was developed for the Dextroscope, a virtual reality environment in which the operator reaches with both hands behind a mirror into a computer-generated stereoscopic three-dimensional (3-D) object and moves and manipulates the object in real time with natural 3-D hand movements. Patient-specific data sets from multiple imaging techniques (magnetic resonance imaging, magnetic resonance angiography, magnetic resonance venography, and computed tomography) were coregistered, fused, and displayed as a stereoscopic 3-D object. A suite of 3-D tools accessible inside the VIVIAN workspace enabled users to coregister data, perform segmentation, obtain measurements, and simulate intraoperative viewpoints and the removal of bone and soft tissue. RESULTS: VIVIAN was used to plan neurosurgical procedures primarily in difficult-to-access areas, such as the cranial base and the deep brain. The intraoperative and virtual reality 3-D scenarios correlated well. The VIVIAN system substantially contributed to surgical planning by 1) providing a quick and better understanding of intracranial anatomic and abnormal spatial relationships, 2) simulating the craniotomy and the required cranial base bone work, and 3) simulating intraoperative views. CONCLUSION: The VIVIAN system allows users to work with complex imaging data in a fast, comprehensive, and intuitive manner. The 3-D interaction of this virtual reality environment is essential to the efficient assembly of surgically relevant spatial information from the data derived from multiple imaging techniques. The usefulness of the system is highly dependent on the accurate coregistration of the data and the real-time speed of the interaction.- - - - - - - - - - ranking = 1.75keywords = environment (Clic here for more details about this article) |
3/35. Acquired cerebral arteriovenous malformation induced by an anaplastic astrocytoma: an interesting case.High grade gliomas foster an environment rich in angiogenic factors that promote neovascularity. We report a case of a cerebral arteriovenous malformation, which developed in the setting of a high grade astrocytoma. The patient presented with complaints of confusion and left hemiparesis. An initial cerebral angiogram was normal. Repeat angiography six weeks later demonstrated an extremely vascular lesion with arteriovenous shunting involving the right thalamus and occipital lobe. Histopathologic evaluation of open biopsy and autopsy specimens demonstrated a high grade astrocytoma in association with an arteriovenous malformation. Immunohistochemical staining with VEGF was diffusely positive. A possible role for the hyperangiogenic environment of a high grade astrocytoma resulting in the development of an arteriovenous malformation is discussed.- - - - - - - - - - ranking = 0.5keywords = environment (Clic here for more details about this article) |
4/35. Registration of functional and anatomical MRI: accuracy assessment and application in navigated neurosurgery.OBJECTIVE: A procedure for acquisition, automated registration, and fusion of functional and anatomical magnetic resonance images is presented. Its accuracy is quantitatively assessed using a publicly available gold standard. A patient case is used to illustrate the technique's clinical usefulness in image-guided neurosurgery. MATERIALS AND methods: Before and after functional MRI (fMRI) acquisition, additional anatomical images were acquired at spatial locations identical to those of the functional images (5-10 slices) for the purpose of voxel-based image registration. Registration accuracy of the anatomical volumes and high-resolution 3D MRI volumes (MP-rage imaging) was quantified using adapted data (8 patients) originating from the Vanderbilt Retrospective Registration Evaluation Project (NIH project 1 R01 NS33926-02). Selecting three subsets of slices from that data (5 slices/6 mm slice distance, 10 slices/3 mm distance, and 10 slices/6 mm distance), the small number of images available from fMRI acquisition was taken into account. Accuracies in registering these sparse data sets were then compared to the accuracy achieved using complete data. For clinical patient data (16 patients), fMRI images were fused with MP-rage images, thereby integrating anatomical images with information about the locations of functional areas. The resulting images were used for planning and navigation during tumor resections using an operating microscope (MKM, Zeiss). RESULTS: Quantitative analysis showed no loss of registration accuracy due to a reduced number of slices, regardless of whether 5 or 10 slices were used. For small-volume coverage in the anatomical images (thickness 24 mm), registration of one patient failed, and this could easily be identified by visual inspection. No failures were experienced when 54 mm was covered. In the clinical environment, all 16 interventions using fused fMRI and MRI data were successful. CONCLUSIONS: Automatic registration of functional and high-resolution anatomical MRI was found to be sufficiently accurate and reliable for use in stereotactic neurosurgery.- - - - - - - - - - ranking = 0.25keywords = environment (Clic here for more details about this article) |
5/35. Secondary parathyroid hyperplasia in tuberous sclerosis: report of a case with large eosinophilic ganglion-like cells similar to those of subependymal giant cell astrocytoma, tubers, and atypical angiomyolipoma.We report a case of secondary parathyroid hyperplasia in a 49-year-old man with tuberous sclerosis. Two parathyroid glands had collections of large, eosinophilic ganglion-like endocrine cells that to our knowledge have not been previously described at this site. These cells are morphologically similar to those of subependymal giant cell astrocytoma, tubers, and atypical angiomyolipoma, all of which may arise in the setting of tuberous sclerosis. These large, eosinophilic ganglion-like cells found in different affected organs appear to be distinctive of tuberous sclerosis. We suggest these large eosinophilic cells arise from a common stem cell precursor that acquires variable phenotypes according to alterations in the cellular microenvironment.- - - - - - - - - - ranking = 0.25keywords = environment (Clic here for more details about this article) |
6/35. Localization of congenital glioblastomas in the Japanese: a case report and review of the literature.We report a rare case of glioblastoma that was definitely congenital. Most congenital glioblastomas arise in the cerebral hemispheres. Four cases of congenital glioblastoma have been reported in the literature from Asian countries, two from japan and the others from korea. Two Japanese cases arose in the cerebello-pontine angle, and a cerebellar hemisphere, respectively. In contrast, both known Korean cases and Euro-American cases arose in cerebral hemispheres. Surprisingly, the parents of the present patient were Korean. When we reviewed the world literature on congenital glioblastomas, we recognized that in Japanese patients this tumor did not tend to occur in a cerebral hemisphere. This deviation of the localization may have biological reasons, such as genetic or environmental factors.- - - - - - - - - - ranking = 0.25keywords = environment (Clic here for more details about this article) |
7/35. Intracranial neurothekeoma--a rare parenchymal nerve sheath myxoma of the middle cranial fossa.Neurothekeomas are rare, benign nerve sheath tumors, usually arising from cutaneous nerves in the head and neck region. So far, only 4 cases of the intracranial counterpart have been reported and these were located in the posterior fossa, sellar and parasellar region. We report here the first case of neurothekeoma located deep inside the brain parenchyma. Histologically, the tumor had lobular appearance with bland morphology in spite of cellular pleomorphism, myxoid background and variable S-100 positivity, characteristics of neurothekeomas. The schwannian origin was further confirmed ultrastructurally by demonstrating basal lamina and Luse bodies. Because of its benign nature, the lesion does not need postoperative radiotherapy. Histogenesis of neurothekeoma arising in the parenchyma remains enigmatic. The probable cell of origin could be the Schwann cell or perineurial cell of the nerve twigs around the blood vessels or by extreme differentiation of the precursor cell resting in a suitable microenvironment to the schwannian phenotype.- - - - - - - - - - ranking = 0.25keywords = environment (Clic here for more details about this article) |
8/35. Analysis and 3D reconstruction of heterogeneity in malignant brain tumors: an interdisciplinary case study using a novel computational visualization approach.OBJECTIVE: To explore how a multidisciplinary approach, combining modern visualization and image processing techniques with innovative experimental studies, can augment the understanding of tumor development. STUDY DESIGN: We analyzed histologic sections of a microscopic brain tumor and reconstructed these slices into a 3D representation. We processed these slices to: (1) identify tumor boundaries, (2) isolate proliferating tumor cells, and (3) segment the tumor into regions based on the density of proliferating cells. We then reconstructed the 3D shape of the tumor using a constrained deformable surface approach. RESULTS: This novel method allows the analyst to (1) see specific properties of histologic slices in the 3D environment with animation, (2) switch 2D "views" dynamically, and (3) see relationships between the 3D structure and structure on a plane. CONCLUSION: Using this method to analyze a specific "case," we were also able to shed light on the limitations of a widely held assumption about the shape of expanding microscopic solid tumors as well as find more indications that such tumors behave as adaptive biosystems. Implications of these case study results, as well as future applications of the method for tumor biology research, are discussed.- - - - - - - - - - ranking = 0.25keywords = environment (Clic here for more details about this article) |
9/35. Environmental tilt illusion as the only symptom of a thalamic astrocytoma.A 14-year-old girl experienced two episodes of environmental tilt illusion. During both episodes, which lasted less than 1 minute, she perceived all objects within view as rotated 45 degrees clockwise. There were no auras, accompanying symptoms, or sequelae. Neuro-ophthalmic examination findings were normal except for a right relative afferent pupil defect (RAPD). Imaging disclosed a cystic mass in the left posterior thalamus with compression of the brachium of the left superior colliculus. Stereotactic biopsy revealed a pilocytic astrocytoma. This is the first case documenting environmental tilt illusion as an isolated symptom of a thalamic lesion. Disruption of vestibular connections between the posterior thalamus and the posterior parietal cortex may be the cause of this visual perceptive disorder.- - - - - - - - - - ranking = 0.5keywords = environment (Clic here for more details about this article) |
10/35. Intracranial extramedullary hematopoiesis associated with pilocytic astrocytoma: a case report.Intracranial EMH is only occasionally found in primary brain tumors (mostly hemangioblastomas) and, to our knowledge, this is the first case of EMH associated with an astrocytoma. Intracranial extramedullary hematopoiesis (EMH) is described in a 29-year-old man with a recurrent pilocytic astrocytoma in the tectal region. Special stains confirmed the identities of erythroid, myeloid and megakaryocytic cells. The patient had no evidence of a predisposing bone marrow disorder or systemic EMH. Although the presence of multinucleated and blastic cells associated with a low-grade brain neoplasm is unusual, recognition of hematopoietic lineages allows EMH to be readily identified. Another tumor resection after a year of follow-up confirmed the absence of malignant progression in this recurrent astrocytoma. The small number of cases describing intracranial EMH in the absence of systemic hematologic abnormalities are correlated with the findings in this case. The low incidence of intracranial EMH indicates that cells with hematopoietic potential are seldom exposed to a supportive microenvironment within the central nervous system. However, intracranial EMH should be included as a potential, ancillary diagnosis when considering brain lesions. This may be particularly true if medical therapies involving growth factors or stem cells are found to promote hematopoiesis.- - - - - - - - - - ranking = 0.25keywords = environment (Clic here for more details about this article) |
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