Fluid-Attenuated Inversion Recovery May Serve As a Tissue Clock in Patients Treated With Endovascular Thrombectomy

Abstract

Background and Purpose: We investigated whether the signal change on fluid-attenuated inversion recovery (FLAIR) can serve as a tissue clock that predicts the clinical outcome after endovascular thrombectomy (EVT), independently of the onset-to-admission time. Methods: Consecutive patients with acute stroke treated with EVT between September 2014 and December 2018 were enrolled. Based on the parenchymal signal change on FLAIR, patients were classified into FLAIR-negative and FLAIR-positive groups. 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. A modified Rankin Scale score 0 to 1 at 3 months was considered to represent a good outcome. Results: Of the 227 patients with EVT during the study period, 140 patients (62%) were classified into the FLAIR-negative group and 87 (38%) were classified into the FLAIR-positive group. In the FLAIR-negative group, the patients were older ( P =0.011), the onset-to-image time was shorter ( P <0.001), the frequency of cardioembolic stroke was higher ( P =0.006), and the rate of intravenous thrombolysis was higher ( P <0.001) in comparison to the FLAIR-positive group. Although the rate of complete recanalization after EVT did not differ between the 2 groups ( P =0.173), the frequency of both any-intracranial hemorrhage and Heidelberg Bleeding Classification ≥1c hemorrhage were higher in the FLAIR-positive group ( P =0.004 and 0.011). At 3 months, the percentage of patients with a good outcome (FLAIR-negative, 41%; FLAIR-positive, 27%) was significantly related to the FLAIR signal change ( P =0.047), while the onset-to-image time was not significant ( P =0.271). A multivariate regression analysis showed that a FLAIR-negative status was independently associated with a good outcome (odds ratio, 2.10 [95% CI, 1.02–4.31], P =0.044). Conclusions: A FLAIR-negative status may predict the clinical outcome more accurately than the onset-to-admission time, which may support the role of FLAIR as a tissue clock.

Predicting DWI-FLAIR mismatch on NCCT: the role of artificial intelligence in hyperacute decision making

“…The mean age of included subjects was 71.8 ± 12.8 years, 123 (55%) were male, and the baseline NIHSS score was a median of 11 [IQR,[6][7][8][9][10][11][12][13][14][15][16][17][18]. All images were taken in the following order: NCCT -DWI -FLAIR, starting after a median of 139 min after the time of the last known well.…”

“…The safety and efficacy of intravenous thrombolysis based on the DWI-FLAIR mismatch were documented in randomized clinical trials ( 11 , 12 ). A single-center study showed the utility of the DWI-FLAIR mismatch as a case selection for endovascular recanalization treatment ( 10 ). Therefore, DWI-FLAIR mismatch may be considered a tissue clock, beyond the role of a time clock, that may guide the reperfusion treatment.…”

“…The mean age of the study population was 71.8 ± 12.8 years, and 123 (55%) of them were male. The baseline NIHSS score at arrival was a median of 11 [IQR, [6][7][8][9][10][11][12][13][14][15][16][17][18]. 149 (67%) received acute stroke treatment [120 (54%) intravenous thrombolysis and 77 (35%) endovascular recanalization].…”

“…In lieu of the time from onset, which may be an inadequate surrogate for tissue ischemia, the mismatched lesion on the diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) image has been proposed as a means of measuring the extent of individual ischemic brain injury ( 8 , 9 ). Due to the fact that DWI images were more sensitive to early ischemic changes than FLAIR images, the phrase “tissue clock” was coined to describe its potential to use as criteria for thrombolysis ( 10 ). Randomized clinical trials that chose intravenous thrombolysis candidates in unclear onset time based on the diffusion-FLAIR mismatch demonstrated the feasibility and applicability of the tissue clock in acute decision-making ( 11–13 ).…”

Thrombolysis for Acute Wake-Up and Unclear-Onset Strokes with Alteplase at 0.6 mg/kg in Clinical Practice: THAWS2 Study

“…The relatively high percentage of combined mechanical thrombectomy (35%) might be one of the reasons for the preferable outcomes in our patients. Aoki et al [11] recently demonstrated that DWI-FLAIR mismatch was independently associated with mRS 0–1 at 3 months after mechanical thrombectomy. Therefore, MRI-guided selection may also help in selecting candidates for mechanical thrombectomy.…”