Abstract
Background:T2 relaxation-based magnetic resonance imaging (MRI) signals may provide onset time for acute ischemic strokes with an unknown onset. The ability of visual and quantitative MRI-based methods in a cohort of hyperacute ischemic stroke patients was studied.Methods:A total of 35 patients underwent 3T (3 Tesla) MRI (<9-hour symptom onset). Diffusion-weighted (DWI), apparent diffusion coefficient (ADC), T1-weighted (T1w), T2-weighted (T2w), and T2 relaxation time (T2) images were acquired. T2-weighted fluid attenuation inversion recovery (FLAIR) images were acquired for 17 of these patients. Image intensity ratios of the average intensities in ischemic and non-ischemic reference regions were calculated for ADC, DWI, T2w, T2 relaxation, and FLAIR images, and optimal image intensity ratio cut-offs were determined. DWI and FLAIR images were assessed visually for DWI/FLAIR mismatch.Results:The T2 relaxation time image intensity ratio was the only parameter with significant correlation with stroke duration (r = 0.49, P = .003), an area under the receiver operating characteristic curve (AUC = 0.77, P < .0001), and an optimal cut-off (T2 ratio = 1.072) that accurately identified patients within the 4.5-hour thrombolysis treatment window with sensitivity of 0.74 and specificity of 0.74. In the patients with the additional FLAIR, areas under the precision-recall-gain curve (AUPRG) and F1 scores showed that the T2 relaxation time ratio (AUPRG = 0.60, F1 = 0.73) performed considerably better than the FLAIR ratio (AUPRG = 0.39, F1 = 0.57) and the visual DWI/FLAIR mismatch (F1 = 0.25).Conclusions:Quantitative T2 relaxation time is the preferred MRI parameter in the assessment of patients with unknown onset for treatment stratification.
Highlights
Unknown time of symptom onset due to “wake-up stroke” or lack of witness is a common contraindication for reperfusion therapies for ischemic stroke.[1,2] Intra-arterial administration of thrombolytic agents is considered safe within 6 hours of onset but is not routine,[3] and patients with large vessel occlusion (LVO) can be considered for mechanical thrombectomy if symptom onset was within the last 24 hours.[4,5] For the many patients without LVO, intravenous (IV) thrombolysis using recombinant tissue plasminogen activator is the only alternative.[5]
magnetic resonance imaging (MRI) may, aid treatment stratification of ischemic stroke patients with unknown symptom onset time by identifying patients who (1) are likely to be within the 4.5-hour IV recombinant tissue plasminogen activator (rtPA) treatment window or (2) have sufficient viable tissue that would suggest they may benefit from reperfusion therapy regardless of onset time.[7,8]
All stroke subtypes were considered for enrolment, including lacunar stroke (LACS), partial anterior stroke (PACS), posterior circulation stroke (POCS), and total anterior circulation stroke (TACS)
Summary
Unknown time of symptom onset due to “wake-up stroke” or lack of witness is a common contraindication for reperfusion therapies for ischemic stroke.[1,2] Intra-arterial administration of thrombolytic agents is considered safe within 6 hours of onset but is not routine,[3] and patients with large vessel occlusion (LVO) can be considered for mechanical thrombectomy if symptom onset was within the last 24 hours.[4,5] For the many patients without LVO, intravenous (IV) thrombolysis using recombinant tissue plasminogen activator (rtPA) is the only alternative.[5]. T2 relaxation-based magnetic resonance imaging (MRI) signals may provide onset time for acute ischemic strokes with an unknown onset. The ability of visual and quantitative MRI-based methods in a cohort of hyperacute ischemic stroke patients was studied
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