Non-contrast CT Matches Advanced Imaging in Late Presentation of Stroke

In patients with proximal anterior circulation occlusion stroke presenting in the extended window, non-contrast computed tomography (CT) had comparable clinical and safety outcomes with patients selected by CT perfusion or magnetic resonance imaging (MRI). This is according to a study published in the JAMA Neurology.

“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, of the department of neurology and radiology at Boston Medical Center. “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 across many stroke centers.

This multinational cohort study included 1604 consecutive patients (median age 70, 52.9% women) with proximal anterior circulation occlusion stroke presenting within six to 24 hours of time last 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.

No difference in 90-day ordinal modified Rankin Scale (mRS) shift , the main outcome, was seen between patients selected by CT compared with CT perfusion (adjusted[a]OR, 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 compared with the MRI group, at 88.9%, 89.5% and 78.9%, respectively (P < .001). No significant differences in symptomatic intracranial hemorrhage or 90-day mortality were observed.

“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, occlusion of the internal carotid or proximal middle cerebral artery, the findings cannot be applied to other patients. Other limitations of the study included the retrospective design and that no independent imaging core laboratory was used, both factors that may introduce bias.