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Background and Purpose: Computed tomographic angiography and magnetic resonance angiography are used increasingly to assess arterial patency in patients with ischemic stroke. We determined which baseline angiography features predict response to intravenous thrombolytics in ischemic stroke using randomized controlled trial data., Methods: We analyzed angiograms from the IST-3 (Third International Stroke Trial), an international, multicenter, prospective, randomized controlled trial of intravenous alteplase. Readers, masked to clinical, treatment, and outcome data, assessed prerandomization computed tomographic angiography and magnetic resonance angiography for presence, extent, location, and completeness of obstruction and collaterals. We compared angiography findings to 6-month functional outcome (Oxford Handicap Scale) and tested for interactions with alteplase, using ordinal regression in adjusted analyses. We also meta-analyzed all available angiography data from other randomized controlled trials of intravenous thrombolytics., Results: In IST-3, 300 patients had prerandomization angiography (computed tomographic angiography=271 and magnetic resonance angiography=29). On multivariable analysis, more extensive angiographic obstruction and poor collaterals independently predicted poor outcome (P<0.01). We identified no significant interaction between angiography findings and alteplase effect on Oxford Handicap Scale (P≥0.075) in IST-3. In meta-analysis (5 trials of alteplase or desmoteplase, including IST-3, n=591), there was a significantly increased benefit of thrombolytics on outcome (odds ratio>1 indicates benefit) in patients with (odds ratio, 2.07; 95% confidence interval, 1.18-3.64; P=0.011) versus without (odds ratio, 0.88; 95% confidence interval, 0.58-1.35; P=0.566) arterial obstruction (P for interaction 0.017)., Conclusions: Intravenous thrombolytics provide benefit to stroke patients with computed tomographic angiography or magnetic resonance angiography evidence of arterial obstruction, but the sample was underpowered to demonstrate significant treatment benefit or harm among patients with apparently patent arteries., Clinical Trial Registration: URL: http://www.isrctn.com. Unique identifier: ISRCTN25765518., (© 2016 The Authors.)

Introduction: CT angiography (CTA) is often used for assessing patients with acute ischaemic stroke. Only limited observer reliability data exist. We tested inter- and intra-observer reliability for the assessment of CTA in acute ischaemic stroke., Methods: We selected 15 cases from the Third International Stroke Trial (IST-3, ISRCTN25765518) with various degrees of arterial obstruction in different intracranial locations on CTA. To assess inter-observer reliability, seven members of the IST-3 expert image reading panel (>5 years experience reading CTA) and seven radiology trainees (<2 years experience) rated all 15 scans independently and blind to clinical data for: presence (versus absence) of any intracranial arterial abnormality (stenosis or occlusion), severity of arterial abnormality using relevant scales (IST-3 angiography score, Thrombolysis in Cerebral Infarction (TICI) score, Clot Burden Score), collateral supply and visibility of a perfusion defect on CTA source images (CTA-SI). Intra-observer reliability was assessed using independently repeated expert panel scan ratings. We assessed observer agreement with Krippendorff's-alpha (K-alpha)., Results: Among experienced observers, inter-observer agreement was substantial for the identification of any angiographic abnormality (K-alpha = 0.70) and with an angiography assessment scale (K-alpha = 0.60-0.66). There was less agreement for grades of collateral supply (K-alpha = 0.56) or for identification of a perfusion defect on CTA-SI (K-alpha = 0.32). Radiology trainees performed as well as expert readers when additional training was undertaken (neuroradiology specialist trainees). Intra-observer agreement among experts provided similar results (K-alpha = 0.33-0.72)., Conclusion: For most imaging characteristics assessed, CTA has moderate to substantial observer agreement in acute ischaemic stroke. Experienced readers and those with specialist training perform best.

Introduction: Endovascular coiling of intracranial aneurysms carries a risk of complications. Early detection and management of complications can improve clinical outcomes. AngioCT is a new imaging technology enabling CT-like images to be generated on a flat-panel digital subtraction angiography system, which can provide immediate "on angio table" identification and thorough assessment of such complications. We prospectively audited its utility during aneurysm coiling in patients following subarachnoid haemorrhage (SAH)., Methods: A prospective series of 44 patients with SAH undergoing endovascular coiling with AngioCT was audited for image quality and the influence of the AngioCT on patient management. In a parallel experimental study, radiation doses were measured and image quality parameters on standard phantoms were established., Results: In all patients, AngioCT provided adequate diagnostic information. In 40.9% of patients, AngioCT was a substantial or major factor in determining the management immediately after coiling. Using a 10-s high-dose acquisition technique, acceptable image quality could be obtained rapidly with a radiation dose just over half that for a conventional CT scan of the head (35 mGy versus approximately 60 mGy). No patient in this series required conventional CT to clarify the AngioCT appearance., Conclusion: AngioCT has many applications in the neurointerventional setting. In particular during coiling, AngioCT provides a rapid way to clarify concerns or identify complications and in some cases was the major factor influencing further patient management immediately after coiling. AngioCT images were judged of adequate quality to be clinically useful in all patients in this series.