Automated Assessment of DWI-FLAIR Mismatch in Patients with Acute Ischemic Stroke: Added Value to Routine Clinical Practice

BACKGROUND AND PURPOSE: DWI-FLAIR mismatch is used to determine thrombolytic eligibility in patients with acute ischemic stroke (AIS) when time since stroke onset (TSS) is unknown. Commercial software packages have been developed for automated DWI-FLAIR classification. We aimed to use e-Stroke software (Brainomix, Oxford, UK) for automated classification of DWI-FLAIR mismatch in a cohort of patients with AIS and in a comparative analysis with two expert neuroradiologists.

MATERIALS AND METHODS: In this retrospective study, patients with AIS who had MRI and known TSS were included. DWI-FLAIR mismatch was evaluated by two neuroradiologists blinded to TSS and automatically by e-Stroke software. After 4 weeks, the neuroradiologists reevaluated the MRIs, this time equipped with automated predicted e-Stroke results as a computer assisted tool (CAT). Diagnostic performances of e-Stroke software and neuroradiologists were evaluated for prediction of DWI-FLAIR mismatch status.

RESULTS: A total of 157 patients met inclusion criteria. A total of 82 patients (52%) had TSS ≤ 4.5 hours. Using consensus reads, 81 patients (51.5%) had DWI-FLAIR mismatch. The diagnostic accuracy (AUC/sensitivity/specificity) of e-Stroke software for determination of DWI-FLAIR mismatch was 0.72/90.0/53.9. The diagnostic accuracy (AUC/sensitivity/specificity) for neuroradiologist 1 and 2 was 0.76/69.1/84.2 and was 0.82/91.4/73.7 respectively, both significantly (p<0.05) improved to 0.83/79.0/86.8 and 0.89/92.6/85.5 respectively following the use of e-Stroke predictions as CAT. The interrater agreement (K) for determination of DWI-FLAIR status was improved from 0.49 to 0.57 following the use of CAT.

CONCLUSIONS: Automated quantitative approach for DWI-FLAIR mismatch provides comparable results to human experts and can improve diagnostic accuracies of expert neuroradiologists in determination of DWI-FLAIR status.

ABBREVIATIONS: AIS: Acute ischemic stroke; CAT: Computer assisted tool; TSS: Time since stroke onset