New CT perfusion findings may predict poor outcomes after thrombectomy
CT perfusion imaging may help identify patients at risk of poor functional outcomes after successful endovascular thrombectomy (EVT) for acute ischemic stroke, according to a study that sought to establish a proper imaging definition of the no-reflow phenomenon.
No-reflow occurs when blood flow to brain tissue remains impaired despite successful reopening of an occluded artery. This microvascular dysfunction could be at the root of why some patients experience poor functional recovery even after technically successful EVT treatment. However, a standardized imaging definition of no-reflow has not been established, which can make it difficult to identify vulnerable patients, Tianqi Xu, MD, with the Sydney Brain Center in Australia, and colleagues write in Radiology.
Having a better understanding of which patients meet specified no-reflow criteria could help providers better manage treatment plans. In a bid to define the phenomenon, researchers conducted a secondary analysis of two prospective, multicenter imaging registries. It included patients with acute ischemic stroke who underwent thrombectomy between 2016 and 2022, achieved successful recanalization and received CT or MR perfusion imaging before treatment and then again 24 hours afterward.
The primary cohort included 67 patients, with a median age of 69 years. Researchers evaluated eight perfusion maps and a range of thresholds to determine which imaging findings best identified patients with poor functional outcomes at 90 days, defined as a modified Rankin Scale score greater than 2.
A delay time greater than four seconds on 24-hour perfusion imaging was the strongest predictor of poor outcomes, with an area under the curve of 0.72. Using this threshold, researchers identified no-reflow in 14 patients (or 21%). Poor functional outcomes occurred in 79% of patients classified as having no-reflow, compared to 21% of those without it. What’s more, the odds of a poor outcome were more than 12 times higher in the no-reflow group; that same group also experienced greater infarct growth.
The findings suggest that successful large vessel recanalization does not necessarily mean that tissue-level perfusion has been fully restored.
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In addition to her background in journalism, Hannah also has patient-facing experience in clinical settings, having spent more than 12 years working as a registered rad tech. She began covering the medical imaging industry for Innovate Healthcare in 2021.