What is the role of MRI and MRA in the workup of basilar artery thrombosis?

Updated: Jan 11, 2019
  • Author: Salvador Cruz-Flores, MD, MPH, FAHA, FCCM, FAAN, FACP, FANA; Chief Editor: Helmi L Lutsep, MD  more...
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Answer

Magnetic resonance imaging (MRI) and MR angiography (MRA) are more sensitive than CT scanning for identifying ischemia and vascular occlusion. [6]

Gradient echo technique, with its higher sensitivity for identifying blood, and diffusion/perfusion-weighted images, with their higher sensitivity for identifying ischemia and hypoperfusion, make MRI a more powerful tool for the treatment of patients with basilar artery occlusion. (See the image below.) [11]

Diffusion-weighted MRI images showing a right cere Diffusion-weighted MRI images showing a right cerebellar infarct.

Helpful findings include lesions that suggest microbleeds, tumors, vertebral/basilar dolichoectasia, and vertebral/basilar dissections.

MRA can identify vertebral/basilar occlusion with sensitivity of as high as 97% and a specificity of 98%. (See the image below.)

Magnetic resonance angiography demonstrating the a Magnetic resonance angiography demonstrating the absence of flow in the vertebrobasilar system.

MRA has limitations, however, because it frequently overestimates the degree of stenosis. Severe stenosis may resemble vascular occlusion. This occurs because the image of the vessel with MRA is a flow-related phenomenon; therefore, severe stenosis with significant flow compromise may result in poor visualization of the vessel.


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