FLAIR Imaging Serves as a Tissue Clock
Fransisca Indraswari, MD
Aoki J, Sakamoto Y, Suzuki K, Nishi Y, Kutsuna A, Takei Y, et al. Fluid-Attenuated Inversion Recovery May Serve As a Tissue Clock in Patients Treated With Endovascular Thrombectomy. Stroke. 2021;52:2232–2240.
This retrospective study by Aoki et al. investigated the role of fluid-attenuated inversion recovery (FLAIR) sequence in the magnetic resonance imaging (MRI) of the brain as a tool to predict outcome after an endovascular thrombectomy (EVT), regardless of the time of symptom onset. The notion of imaging-based prognostication of clinical outcome has been elucidated in previous trials, e.g., THAWS1 and WAKE UP.2 Similarly, the concept of extending therapeutic window of thrombectomy up to 24 hours based on imaging selection criteria in DAWN3 and DEFUSE3.4 They hypothesized that if the signal change on FLAIR was associated with the clinical outcome after EVT, FLAIR may be able to serve not only as a time clock, but also as a tissue clock.
Patients with acute ischemic stroke treated with EVT were recruited between September 2014 and December 2018. They were divided between FLAIR-positive and FLAIR-negative groups based on the parenchymal change on FLAIR sequence in their MRI brain. The clinical characteristics, imaging findings, EVT parameters, and the intracranial hemorrhage defined as Heidelberg Bleeding Classification ≥1c hemorrhage (parenchymal hemorrhage, intraventricular hemorrhage, subarachnoid hemorrhage, and/or subdural hemorrhage) were compared between the 2 groups. Clinical outcome at 3 months was defined as modified Rankin Scale Score (mRS) with 0-1 being good outcome.