Patients with large-vessel occlusion stroke who were referred from primary stroke centers for consideration of mechanical thrombectomy often had lengthy intervals between initial computed tomography and computed tomography angiography in a regional retrospective audit.
Researchers reviewed 200 consecutive patients referred from 18 primary stroke centers in South-East England to a London comprehensive stroke center between January 2022 and March 2023. After 21 patients with missing computed tomography or computed tomography angiography timing data were excluded, the referring-center analysis included 179 patients.
Eligible patients had acute large-vessel occlusion ischemic stroke and met the referral network’s criteria for mechanical thrombectomy. These criteria incorporated time from stroke onset or last known well, occlusion location, imaging findings, National Institutes of Health Stroke Scale score, Alberta Stroke Program Early CT Score, premorbid modified Rankin Scale score, and the presence of life-limiting illness.
The primary measure was the interval from computed tomography to computed tomography angiography at the referring hospital. Because no official CT-to-CTA target has been established, the researchers classified intervals of 5 minutes or less as “excellent” and 10 minutes or less as “adequate.” They based these operational definitions on recommendations supporting computed tomography and computed tomography angiography during the same imaging session and broader stroke-imaging time goals.
The mean CT-to-CTA interval at referring centers was 62 minutes, and the median was 55 minutes. At the comprehensive stroke center, the mean and median intervals were 1 minute among 155 patients with complete data. The researchers reported a very large difference between settings, with Hedges’ g = 3. However, the comparison involved unmatched patient groups and was not adjusted for differences between the referring and receiving settings.
Among patients who underwent multimodal imaging at a referring center, approximately 55% received computed tomography angiography within 10 minutes of the initial computed tomography. The remaining 45% had intervals longer than 10 minutes. Among patients in that latter group, 80% waited at least 30 minutes and 30% waited at least 60 minutes.
For hospital-level comparisons, the researchers excluded centers that referred fewer than eight patients. Among the 11 remaining primary stroke centers, one had a mean interval of 5 minutes or less and four had a mean interval of 10 minutes or less. When hospitals were evaluated by median performance, three had a median interval of 5 minutes or less and six had a median interval of 10 minutes or less.
In separate unadjusted analyses, the researchers reported no statistically significant differences in CT-to-CTA intervals according to in-hours vs out-of-hours presentation, receipt of intravenous thrombolysis, or baseline National Institutes of Health Stroke Scale score.
The researchers also surveyed participating centers in late 2024 and early 2025 to identify perceived barriers to same-session vascular imaging. The survey had a 21% response rate, and all respondents were consultants.
Reported technical barriers included difficulty registering patients while they remained on a prehospital pathway, lack of computed tomography perfusion capability, and limited out-of-hours computed tomography angiography reporting. Organizational barriers included competition for scanner access, limited availability of stroke specialists outside regular working hours, a lack of financial incentives for thrombectomy referral, growing service demand, financial pressures, and concerns about Sentinel Stroke National Audit Programme methodology. Educational barriers included inconsistent awareness of the role of computed tomography angiography in identifying thrombectomy candidates and uneven implementation of the National Optimal Stroke Imaging Pathway.
In their discussion, the researchers argued that performance measures focused on door-to-thrombolysis time could inadvertently discourage same-session computed tomography angiography, which may add several minutes before thrombolysis while helping identify patients with large-vessel occlusion.
The findings should be interpreted as a regional workflow audit rather than evidence that shortening CT-to-CTA time improves thrombectomy delivery or patient outcomes. An additional consideration is that the cohort included only patients who were referred and considered eligible for thrombectomy. Patients whose large-vessel occlusion was not recognized or who were not referred would not have been captured.
Other limitations included the retrospective design, small and uneven hospital samples, missing timing data, lack of adjustment for patient- and hospital-level factors, and the low survey response rate. The study also did not measure time to referral, transfer, groin puncture, reperfusion, or functional recovery.
The researchers characterized CT-to-CTA time as a potential target for pathway improvement and suggested that additional registry-based research could help determine how the timing of vascular imaging affects treatment and outcomes.
Disclosures: The study received no specific grant funding. Pervinder Bhogal, PhD, reported consulting or advisory relationships with Cerenovus, Balt USA, Vesalio, Phenox, and Brainomix and travel reimbursement from Perflow Medical. The researchers reported using ChatGPT-3.5 to initiate the writing process and summarize or shorten text, after which they reviewed and edited the manuscript and accepted responsibility for its content.
Source: British Journal of Radiology
