What is the role of MRI in the diagnosis of vertebrobasilar stroke?

Updated: Mar 03, 2020
  • Author: Vladimir Kaye, MD; Chief Editor: Stephen Kishner, MD, MHA  more...
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Answer

Answer

MRI is more sensitive than CT in the identification of ischemia (since bone does not degrade the image). Newer techniques, including flow suppression and the production of diffusion-weighted and perfusion-weighted images, make MRI a very powerful tool for the exclusion of intraparenchymal hemorrhage or edema and for the identification of early and potentially reversible ischemia. [14, 15, 20, 21, 22]

MRI and magnetic resonance angiography (MRA) are very helpful in finding occult lesions, such as demyelinating plaques, tumors, vertebrobasilar dolichoectasia, or dissection. [23, 24, 25] MRA has a sensitivity of up to 97% and a specificity of up to 98% when used to identify vertebrobasilar occlusion.

A limitation of MRA is its tendency to overestimate the degree of stenosis. This overestimation occurs because the production of a vessel's image in MRA is a based on a flow-related phenomenon; hence, the presence of severe stenosis with significant flow compromise may result in poor visualization of a vessel and cause the MRA image to resemble vascular occlusion.


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