Neuroimaging clinics of North America
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Spinal dural AVFs, the most common type of spinal arteriovenous malformations, are symptomatic because of venous hypertension and congestion. This has been referred to as venous congestive myelopathy. The typical MRI findings that reflect venous congestive myelopathy include peripheral T2 hypointensity that outlines a T2 hyperintensity within a swollen spinal cord. ⋯ Contrast-enhanced MRA has become instrumental in localizing the site of these fistulas. Spinal epidural AVFs and the perimedullary spinal cord AVFs may also present with a congestive myelopathy and have similar findings on MRI. Angiography remains the gold standard for characterization of the angioarchitecture of spinal vascular malformations. [figure: see text] Multidisciplinary treatment planning is mandatory and requires knowledge of the natural history of these vascular lesions.
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Vascular anomalies involving both intra- and extra-cranial structures are more common than previously thought. It is important to evaluate the brain and its coverings carefully when imaging cervicofacial vascular malformations. Scientific knowledge regarding developmental mechanisms responsible for blood vessel formation is increasing rapidly and, hopefully, will contribute to better understanding of these clinical and imaging "patterns."
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Neuroimaging Clin. N. Am. · Feb 2003
ReviewImaging and anatomy of the normal intracranial venous system.
The intracranial venous system is a complex three-dimensional structure that is often asymmetric and considerably more variable than the arterial anatomy. The traditional approach has been to evaluate venous phase of catheter angiography. ⋯ MR angiography, and especially Gd-enhanced 3D MRA, has recently emerged and offers excellent visualization of venous morphology from multiple orientations. An overview of the current non-invasive MRA methods and their applications has been provided during depiction of normal venous anatomy.
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Cavernous malformations are commonly being recognized on CT and MR imaging in both asymptomatic and symptomatic patients. The diagnosis of CMs can often be made on MR imaging based on the characteristic morphology of the subacute and chronic blood products. An atypical appearance of a CM in the setting of a recent hemorrhage requires follow-up imaging to confirm the diagnosis. Deep CMs have a significant clinical event rate that justifies close follow up or surgical treatment if possible.
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Sinus thrombosis in children is increasingly recognized; however, the diagnosis is still frequently missed. Children may have an increased incidence of this disorder compared with adults, and neonates are at greatly increased risk compared with older children. Childhood CSVT carries significant long-term sequelae that include death or neurologic deficits in nearly 50% of cases. ⋯ Among the most significant current and future developments in childhood CSVT is the evolution of accurate, noninvasive and economical neuroimaging techniques. The latter techniques have the potential to increase the detection rate of childhood CSVT, improve our understanding of the pathophysiology and define important subgroups of patients who best respond to treatment. An international interest in childhood CSVT is developing and, in the next decade, will enable the necessary multi-national clinical trials to provide evidence-based treatments and decrease the adverse outcomes.