Clinical relevance and practical implications of trials of perfusion and angiographic imaging in patients with acute ischaemic stroke: a multicentre cohort imaging study

Background In randomised trials testing treatments for acute ischaemic stroke, imaging markers of tissue reperfusion and arterial recanalisation may provide early response indicators. Objective To determine the predictive value of structural, perfusion and angiographic imaging for early and late clinical outcomes and assess practicalities in three comprehensive stroke centres. Methods We recruited patients with potentially disabling stroke in three stroke centres, performed magnetic resonance (MR) or CT, including perfusion and angiography imaging, within 6h, at 72h and 1month after stroke. We assessed the National Institutes of Health Stroke Scale (NIHSS) score serially and functional outcome at 3months, tested associations between clinical variables and structural imaging, several perfusion parameters and angiography. Results Among 83 patients, median age 71 (maximum 89), median NIHSS 7 (range 1-30), 38 (46%) received alteplase, 41 (49%) had died or were dependent at 3months. Most baseline imaging was CT (76%); follow-up was MR (79%) despite both being available acutely. At presentation, perfusion lesion size varied considerably between parameters (p<0.0001); 40 (48%) had arterial occlusion. Arterial occlusion and baseline perfusion lesion extent were both associated with baseline NIHSS (p<0.0001). Recanalisation by 72h was associated with 1month NIHSS (p=0.0007) and 3month functional outcome (p=0.048), whereas tissue reperfusion, using even the best perfusion parameter, was not (p=0.11, p=0.08, respectively). Conclusion Early recanalisation on angiography appeared to predict clinical outcome more directly than did tissue reperfusion. Acute assessment with CT and follow-up with MR was practical and feasible, did not preclude image analysis, and would enhance trial recruitment and generalisability of results.