Is Non-contrast CT a Viable Option for Assessing Patients with Late Stroke Presentation for Mechanical Thrombectomy?

In a recent multinational study involving over 1,600 patients presenting with proximal anterior circulation occlusion stroke in the extended window, researchers found that the use of non-contrast computed tomography (CT) to determine candidacy for mechanical thrombectomy had similar clinical and safety outcomes in comparison to CT perfusion or magnetic resonance imaging (MRI).

“To our knowledge, this is the largest multicenter study to date assessing selection of patients in the extended time window with non-contrast CT compared with CT perfusion or MRI,” wrote Thanh N. Nguyen, MD, the director of interventional neurology/neuroradiology at Boston Medical Center and a professor of neurology, neurosurgery, and radiology at the Boston University School of Medicine. “These findings suggest non-contrast computed tomography alone may be used as an alternative to advanced imaging in selecting patients with late-presenting large-vessel occlusion for mechanical thrombectomy.”

Advanced imaging with MRI or CT perfusion is currently recommended in the American Stroke Association and European Stroke Organization guidelines for the selection of patients with large-vessel occlusion stroke who present within six to 24 hours from symptom onset. However, access to acute MRI or CT perfusion is not readily available or performed in many stroke centers.

This multinational cohort study, published in JAMA Neurology, included 1,604 consecutive patients (median age of 70) with proximal anterior circulation occlusion stroke who presented within six to 24 hours of the last time they were seen well. Patients presented from January 2014 to December 2020 and were followed for 90 days from stroke onset. The researchers compared the clinical and safety outcomes of 534 patients selected for mechanical thrombectomy by non-contrast CT with 752 patients selected by CT perfusion and 318 patients selected by MRI in the extended time window.

The study authors found no difference in the 90-day ordinal modified Rankin Scale (mRS) shift between patients selected by CT compared with CT perfusion (adjusted odds ratio (aOR), 0.95 [95% CI, 0.77-1.17]; P = .64) or CT versus MRI (aOR, 0.95 [95% CI, 0.8-1.13]; P = .55). For the secondary outcomes, the rates of 90-day functional independence were similar between patients selected by CT and CT perfusion, but lower in patients selected by MRI than CT. Successful reperfusion was more common in the CT and CT perfusion groups (88.9 percent and 89.5 percent respectively) compared with the MRI group at 78.9 percent. No significant differences in symptomatic intracranial hemorrhage or 90-day mortality were observed, according to the study.

“These findings have the potential to widen the indication for treating patients in the extended window using a simpler and more widespread non-contrast CT–only paradigm,” the authors wrote.

The authors noted that since the study was limited to patients with baseline mRS scores of 0 to 2 and occlusion of the internal carotid or proximal middle cerebral artery, the findings cannot be extrapolated to other patients. Other reported limitations of the study included the retrospective design and not using an independent imaging core laboratory, factors that may have led to patient selection bias.