Background: The FLAIR hyperintense vessel sign (FHVS) is an established non-contrast MRI marker for large vessel occlusion (LVO) in acute ischemic stroke. However, its role in identifying patients with a favorable perfusion mismatch profile, critical for thrombectomy decision-making, remains uncertain. Similarly, the utility of susceptibility-weighted imaging (SWI) vessel and clot signs in this context is underexplored. Objective: To assess the association between FHVS and MR perfusion mismatch in acute ischemic stroke and to evaluate the diagnostic performance of additional SWI markers—dilated vessel sign, MIP clot sign, and phase clot sign—for LVO and mismatch status for potential thrombectomy. Methods: We retrospectively screened 225 patients who presented with suspected acute ischemic stroke in 2024 and underwent brain MRI. After excluding cases with suboptimal imaging, 175 patients with confirmed acute ischemic stroke were included. This was a blinded study: all imaging markers—including FHVS, SWI dilated vessel sign, SWI MIP clot sign, and SWI phase clot sign—were evaluated blinded to clinical data, perfusion imaging results, and vascular imaging findings. These imaging markers were correlated to quantitative MR perfusion parameters (ischemic core, penumbra, mismatch ratio and volume, and hypoperfusion index) and the presence of LVO on vascular imaging. LVO, rather than thrombectomy, was used as the primary endpoint to avoid bias related to treatment access or clinical status. Results: Among 175 included patients, FHVS demonstrated high diagnostic accuracy for LVO (sensitivity 81.1%, specificity 90.7%). Comparable performance was observed with the SWI dilated vessel sign (74.5%, 86.8%), SWI MIP clot sign (72.9%, 89.2%), and SWI phase clot sign (67.4%, 88.9%). No statistically significant association was found between the presence of FHVS and standard MR perfusion parameters, including core volume, mismatch ratio, mismatch volume, or hypoperfusion index. Conclusions: FHVS and SWI-based vessel signs are reliable non-contrast MRI markers for detecting LVO in acute ischemic stroke. These findings highlight their diagnostic utility in stroke triage, and in the setting of MR perfusion scan variability, these markers can be utilized in identifying thrombectomy-eligible patients Impact: In resource-limited or time-sensitive settings, non-contrast MRI vessel signs may aid in rapid LVO detection without the need for standard MR perfusion imaging.
Brittingham et al. (Thu,) studied this question.