What imaging modalities are used to diagnose vertebrobasilar insufficiency (VBI)?

From the Guidelines

Magnetic resonance angiography (MRA) is the preferred initial imaging modality for suspected vertebrobasilar insufficiency (VBI), with computed tomography angiography (CTA) serving as a reasonable alternative. When evaluating a patient with symptoms suggestive of VBI such as dizziness, vertigo, visual disturbances, or ataxia, imaging should be performed promptly to assess the vertebral and basilar arteries. MRA provides excellent visualization of vascular structures without radiation exposure, though it may be contraindicated in patients with certain implants or severe claustrophobia, as noted in the 2024 study by 1. CTA offers faster acquisition times and can be used in emergency settings or for patients unable to undergo MRI.

Key Considerations for Imaging

• MRA allows for evaluation of the course and luminal caliber of the arteries, as well as detection of luminal filling defects, which may include thrombus, embolus, atherosclerotic plaque, dissection flap, or vascular web, as discussed in the 2024 study by 1.
• The sensitivity, specificity, and accuracy of MRA for detecting vertebral artery origin stenosis were shown to be as high as 97%, 98%, and 93%, respectively, in a study comparing MRA to digital subtraction angiography, cited in 1.
• CTA has the highest reported sensitivity (100%) for detecting vertebral artery dissection, followed by MRA (77%) and Doppler US (71%), as mentioned in the study by 1.

Imaging Modalities and Their Uses

• MRA is preferred for its excellent visualization of vascular structures without radiation exposure.
• CTA is a reasonable alternative, offering faster acquisition times and suitability for emergency settings or patients unable to undergo MRI.
• Doppler ultrasonography of the vertebral arteries may be used as a screening tool but has limitations in visualizing the intracranial portions of the vertebrobasilar system.
• Conventional digital subtraction angiography remains the gold standard for confirmation of clinically suspected VBI or vertebral artery dissection, despite its invasive nature, as noted in the studies by 1.

Clinical Decision Making

Imaging findings that suggest VBI include stenosis, occlusion, dissection, or significant atherosclerotic disease of the vertebral or basilar arteries. These imaging studies help guide appropriate management decisions, including medical therapy with antiplatelets or anticoagulants, or in severe cases, consideration of endovascular or surgical interventions, as discussed in the studies by 1.

From the Research

Imaging Modalities for Vertebrobasilar Insufficiency

• Magnetic Resonance Angiography (MRA) is a widely studied and effective method for identifying and localizing occlusions and stenosis in both neck and intracranial great vessels 2, 3.
• MRA can be used as a screening examination for estimating vertebrobasilar blood flow and provides helpful information for diagnosing Vertebrobasilar Insufficiency (VBI) 3.
• Magnetic Resonance Imaging (MRI) can be recommended to diagnose VBI, providing information on both blood vessel disorder and ischemic changes in the brain 4.
• Noninvasive modalities such as ultrasound, multislice computed tomographic angiography, and MRA are constantly improving and playing an increasingly important role in diagnosing vertebral artery pathology in clinical practice 5.
• Two-dimensional quantification flow can be used as a noninvasive but indirect method to investigate the influence of several factors on the hemodynamics of VBI 6.

Diagnostic Testing

• Arteriography is considered the most important exam to diagnose VBI, but its inherent risks should be taken into consideration 2.
• Transcranial Doppler ultrasound is another diagnostic testing option for VBI, but its effectiveness is not as well-established as MRA 2.
• Vertebrobasilar deprivation testing is also available, but its use is not as common as MRA or arteriography 2.

Key Findings

• The most frequent cause of hemodynamic changes leading to VBI is atherosclerosis 2.
• The main clinical symptoms of VBI are dizziness, vertigo, headaches, vomit, diplopia, blindness, ataxia, imbalance, and weakness in both sides of the body 2.
• MRA is the most specific diagnostic testing modality for VBI, with a high sensitivity and specificity for detecting occlusions and stenosis in the vertebral and basilar arteries 3, 6.