Neuroimaging clinics of North America
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Neuroimaging Clin. N. Am. · Feb 2003
ReviewHydrovenous disorders in pediatric intracranial arteriovenous fistula.
High-flow AVFs are a challenging problem in the pediatric age group. Venous occlusive changes develop as part of the dynamic response to these fistulas. The development of adequate venous collateral flow circumvents the destructive sequelae of longstanding venous hypertension. ⋯ Venous hypertension interferes with CSF resorption, resulting in increased brain water. Ventriculomegaly and tonsillar prolapse commonly develop and are reversible if therapeutic intervention is done in a timely fashion. If left untreated, chronic venous ischemic changes develop, which result in delay in important developmental milestones.
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Neuroimaging Clin. N. Am. · Feb 2003
ReviewRadiologic findings and clinical significance of venous compartment of brain arteriovenous shunts.
The venous compartment of brain AVS is closely related to the development of various clinical consequences, including hemorrhage, seizure, and neurologic deficit. Therefore, understanding the venous etiology of the clinical symptoms and the imaging characteristics of partial or complete venous outlet thrombosis is critical for the proper management of patients with brain AVSs.
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Neuroimaging Clin. N. Am. · Feb 2003
ReviewVenous congestive encephalopathy related to cranial dural arteriovenous fistulas.
Cranial DAVFs present with a wide spectrum of clinical findings from pulsatile tinnitus alone to intracranial hemorrhage and NHND. The neurologic sequelae are a consequence of venous hypertension and venous congestion. DAVFs with CVR can present with or develop a VCE that can be recognized on MR imaging as a diffuse T2 hyperintensity in the deep white matter of the cerebral or cerebellar hemispheres. ⋯ The telltale sign on MR imaging is the plethora of prominent pial vessels on the surface of the brain that are the engorged cortical veins participating in the cortical venous reflux. Selective angiography is critical for the accurate assessment of the CVR. DAVFs with CVR require prompt treatment, either endovascular alone or a combination of endovascular treatment and surgery.
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Neuroimaging Clin. N. Am. · Nov 2002
ReviewImportance of hypoxia in the biology and treatment of brain tumors.
The resistance of gliomas to treatment with radiation and antineoplastic drugs may result in part from the effects of the extensive, severe hypoxia that is present in these tumors. It is clear that brain tumors contain extensive regions in which the tumor cells are subjected to unphysiological levels of hypoxia. Hypoxic cells are resistant to radiation. ⋯ During the past 50 years, many attempts have been made to circumvent the therapeutic resistance induced by hypoxia, by improving tumor oxygenation, by using oxygen-mimetic radiosensitizers, by adjuvant therapy with drugs that are preferentially toxic to hypoxic cells, by using hyperthermia, or by devising radiation sources and regimens that are less affected by hypoxia. Past clinical trials have provided tantalizing suggestions that the outcome of therapy can be improved by many of these approaches, but none has yet produced a significant, reproducible improvement in the therapeutic ratio, which would be needed for any of these approaches to become the standard therapy for these diseases. Several ongoing clinical trials are addressing other, hopefully better regimens; it will be interesting to see the results of these studies.
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Neuroimaging Clin. N. Am. · Nov 2002
ReviewAnti-angiogenic agents for the treatment of brain tumors.
It is accepted that novel therapeutic approaches are needed for the majority of patients with malignant brain tumors. The vascularity of many primary brain tumors and the encouraging preclinical studies suggest that antiangiogenic agents have the potential to become an important component of multimodality treatment of patients with brain tumors. The understanding of the biology of angiogenesis is improving rapidly, offering the hope for more specific vascular targeting of brain tumor neovasculature. Neuroimaging techniques evaluating the angiogenic process and the impact of antiangiogenic agents will be an important tool for the rapid development of these novel therapeutic agents.