Perfusion imaging to select basilar artery occlusion patients eligible for EVT

In the last decade, several randomized clinical trials demonstrated the role of CT perfusion (CTP) in evaluating anterior circulation large vessel occlusion (LVO) patients eligible for endovascular thrombectomy (EVT). 

Dr. Carlo Cereda and co-authors conducted a multicenter, retrospective cohort study and showed that basilar artery occlusion (BAO) patients with limited regions of severe hypoperfusion (Tmax > 10) have a favorable response to EVT. 

Critical Area Perfusions Score to identify BAO patients who could benefit from EVT.

Approximately 15% of acute ischemic strokes are due to LVOs in the vertebral or basilar artery. Even though multiple retrospective studies suggest the potential benefits of EVT in treating patients with BAO, randomized clinical trials have failed to show the benefits of EVT in these patients. 

The criteria to select BAO patients eligible for EVT have not been defined. Standard selection criteria such as ischemic core and penumbra volumes are not applicable. Even a small volume of irreversibly damaged tissue in the midbrain, pons, or thalamus can lead to a poor prognosis. 

The authors hypothesized that BAO patients with fewer regions of severe hypoperfusion (Tmax>10) would respond more favorably to endovascular reperfusion.

This retrospective study included 103 BAO patients who had perfusion imaging before EVT. CT and MR perfusion images were processed using Rapid software. 

A predetermined Critical Area Perfusions Score (CAPS) was used to quantify severe hypoperfusion (Tmax>10) in the:

• Cerebellum (1 point/hemisphere)
• Midbrain and/or thalamus (2 points) 
• Pons (2 points)

A region was considered positive if the Tmax > 10 lesion had a diameter of 6mm or more.  

Patients were divided into two groups, favorable (CAPS ≤ 3) and unfavorable (CAPS>3). 

BAO patients with limited regions of severe hypoperfusion had a favorable response to EVT.

The results showed that BAO patients with ≤ 3 CAPS and limited area of hypoperfusion (Tmax > 10 seconds) had a favorable response to reperfusion following EVT. Reperfused CAPS ≤ 3 patients were more likely to achieve good functional outcomes at 90 days following EVT.

Learn more about our clinically validated, FDA-cleared Rapid CTP and Rapid MRI software.