T2 relaxation times identify acute ischaemic stroke patients within the thrombolysis treatment window with higher accuracy than T2-weighted signal intensities

Unknown symptom onset time is a common contraindication for thrombolysis of hyperacute ischaemic stroke. MRI may identify patients within the 4.5-hour thrombolysis treatment window, but it is unclear which parameter is most accurate. We compared the ability of hemispheric differences in quantitative T₂ (qT₂), ADC, and signal intensities of DWI, T₂-weighted and T₂-weighted FLAIR images at distinguishing between patients scanned within and beyond 4.5-hours. qT₂ correlated significantly with time from onset (r = .491, p =.003) and had the highest and only significant AUC (0.77, p = .007). These data point to qT₂ as a stroke timer.