Neuroimaging clinics of North America
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Neuroimaging Clin. N. Am. · May 2003
ReviewImaging of adults with low back pain in the primary care setting.
The evidence for the diagnostic accuracy of the four main imaging modalities used in low back pain (plain radiographs, CT, MR imaging, radionuclide bone scans) is variable in quality and limits the ultimate conclusions regarding the effectiveness and cost-effectiveness of diagnostic strategies. In addition, the frequent finding of abnormalities in normal adults limits the specificity of all of these tests. Nevertheless, MR imaging is likely in most cases to offer the greatest sensitivity and specificity for systemic diseases, and its performance is superior to that of radiographs and comparable with CT and radionuclide bone scans for most conditions causing neurologic compromise.
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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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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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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."