Cerebrovascular ultrasonography: Technique and common pitfalls
ABSTRACT Although the clinical features in some patients with cerebrovascular ischemia may be ill defined, majority of the patients present with focal neurological deficits caused by an arterial occlusion, and the clinical presentations are usually referable to the involved arterial territory. Therefore, vascular imaging constitutes an important component of the diagnostic workup. Cervical duplex ultrasonography of carotid and vertebral arteries is employed to evaluate the extracranial vasculature while transcranial Doppler provides important information about intracranial hemodynamic changes in cerebrovascular ischemia. These two components of cerebrovascular ultrasonography are fast and reproducible, and can be performed at the bedside. They provide real-time information about the status of cervico-cranial arterial patency and various hemodynamic alterations, including collateral flow. The information obtained from cerebrovascular ultrasonography is useful for diagnostic as well as prognostic purposes. Furthermore, it can be used to monitor cerebral blood flow for extended periods and aid in decision making for various interventions. The hemodynamic information obtained from cerebrovascular ultrasonography helps in determining the underlying mechanisms of brain ischemia, and is complementary to the clinical examination and other imaging modalities.We describe the technique of performing cervical duplex sonography, diagnostic criteria for arterial stenosis, characterizing plaque morphology, measuring intima-media thickness and various pitfalls while performing the test.
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ABSTRACT: The ability to maintain cerebral parenchymal perfusion during states of acute or chronic ischemic insult depends largely on the capacity of the cerebral collateral circulation. Perfusion techniques, including perfusion-CT and arterial spin labeling, may not only describe the overall status of the collateral network, but can also quantify the pathophysiologic collateral reserve, which is occult to conventional imaging techniques. The following review details advanced imaging modalities capable of resolving pathophysiologic collateral circulation in a functional and dynamic manner, with regards to the evaluation of both acute ischemic penumbra and chronic cerebral vascular reserve. Specifically, the applications of perfusion-CT, arterial spin labeling MRI techniques, and transcranial Doppler are reviewed in the context of collateral circulation with emphasis on perfusion techniques and proposed clinical utility.Journal of Neuroradiology 01/2013; 41(4). DOI:10.1016/j.neurad.2013.11.002 · 1.13 Impact Factor
Annals of Indian Academy of Neurology 07/2013; 16(3):454. DOI:10.4103/0972-2327.116943 · 0.51 Impact Factor