Late Window Imaging Selection for Endovascular Therapy of Large Vessel Occlusion Stroke: An International Survey

Abstract

BACKGROUND Current stroke guidelines recommend advanced imaging (computed tomography [CT] perfusion or magnetic resonance imaging) prior to endovascular therapy (EVT) in patients with late presentation of large vessel occlusion. Adherence to guidelines may be constrained by resources or timely access to imaging. We sought to understand the factors which influence late window imaging selection for EVT candidates with large vessel occlusion. METHODS We conducted an international survey from January to May 2022. The questions aimed to identify advanced imaging and treatment decisions based on access to imaging, time delays, and simulated patient scenarios. RESULTS There were 3000 invited participants and 1506 respondents, the majority (89.6%) from comprehensive stroke centers in high‐income countries. Neurointerventionalists comprised 31.8% and noninterventionalists 68.2% of respondents. Overall, 70.7% reported routine use of advanced imaging for late EVT selection, and 63.6% reported its usage in every case. There was greater availability of advanced imaging in comprehensive stroke centers versus primary stroke centers (67.0% versus 33.7%; P <0.0001), and high‐ versus low‐middle income countries (70.5% versus 44.5%; P <0.0001). When presented with a late window patient, 41.6% would complete CT perfusion or magnetic resonance imaging prior to EVT, 25.4% would perform CT perfusion or magnetic resonance imaging prior to IVT and EVT, and 25.8% would refer to EVT without advanced imaging. If advanced imaging was not readily available, 70.1% would refer a patient to EVT based on CT in the late window. Additional time delay within 20 minutes to obtain advanced imaging was considered acceptable in 77.7% of respondents. CONCLUSION Current guidelines for imaging late window EVT candidates are inconsistent with imaging decisions by physicians. Most respondents consider an imaging delay of greater than 20 minutes unacceptable. Access to advanced imaging was greater in comprehensive stroke centers and high‐income countries. In the case of limited access most respondents would consider EVT based on CT only.

Neuroimaging of Acute Ischemic Stroke: Multimodal Imaging Approach for Acute Endovascular Therapy

“…77,78 Perfusion imaging was used in two of the early window LVO trials 79,80 but became more widespread after the release of the DAWN and DEFUSE-3 trial results which used perfusion for selection of patients for thrombectomy versus medical management. 12 When added to unenhanced imaging, perfusion imaging can facilitate the diagnosis and triage of AIS in several ways. Perfusion imaging can enable the detection of distal and posterior circulation vessel steno-occlusive disease using the Tmax maps.…”

“…120 The adoption of NCCT and CTA-based imaging selection for the 6-to 24-hour time window would also have implications for stroke systems of care because this simplified imaging paradigm can be used at centers that lack CTP and acute phase MRI capabilities to triage patients for EVT without the need for implementing perfusion imaging. 12,121 While this would expand access, it may not identify all patients who could benefit from EVT. ASPECTS has limited correlation with lesion volume and many patients with low ASPECTS can have relatively small ischemic core volumes and would be eligible for treatment using a mismatch paradigm.…”

“…Perfusion imaging was used in two of the early window LVO trials [ 79 , 80 ] but became more widespread after the release of the DAWN and DEFUSE-3 trial results which used perfusion for selection of patients for thrombectomy versus medical management [ 12 ].…”

“…[6][7][8][9][10] Other guidelines, such as from the Society of Vascular and Interventional Neurology, have not been as stringent. 11 However, advanced imaging is not widely available, particularly in low-or middle-income countries and primary stroke centers, 12 and is potentially associated with treatment delay and increased cost. 13,14 In addition, there is a lack of standardized imaging protocols and a variety of qualitative and quantitative (automated) methods for assessing cerebral perfusion in AIS.…”

Acute and Interventional Treatments

“…For instance, post-treatment infarct volumes in the EVT group (median 28 mL, interquartile range, 6-87 mL) suggest most patients would have met the DEFUSE 3 eligibility criterion of pretreatment ischemic core <70 mL. Meanwhile, the optimal choice of imaging selection approach for late-window patients may depend on availability of imaging resources 8 and how important specificity is for the system of care where you practice.…”