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Background and Purpose: Transient ischemic attack may rarely reveal an intracranial artery occlusion. We analyzed acute magnetic resonance imaging (MRI) patterns and early outcome after reperfusion therapy in these cases.Method: Clinical and imaging data were taken retrospectively from our comprehensive stroke center registry. Two MRI patterns were determined. Pattern A: full mismatch with negative diffusion-weighted imaging (DWI) and perfusion defect. Pattern B: large mismatch with positive DWI and perfusion defect. MRI-derived collateral flow maps were automatically generated from the raw of dynamic susceptibility contrast MRI. Patients were treated either by recombinant tissue plasminogen activator (rtPA) alone or in combination with mechanical thrombectomy.Results: From October 1, 2010 to May 15, 2016, 1,019 patients were admitted and treated by t-PA within 4.5 hours of stroke onset of them; 14 had a transient ischemic attack (TIA) within the 6 hours preceding MRI. Perfusion imaging was performed in 11 patients. An arterial occlusion was found in all of them, 11 patients had a distal anterior circulation occlusion, whereas 3 patients (21%) had a proximal occlusion. According to MRI, 6 patients showed pattern A, whereas 5 patients had pattern B. Good collaterals were observed in 10 patients (6 patients with grade 3 and 4 patients with grade 4), whereas 1 patient had poor collaterals (grade 2). The day 1 National Institutes of Health Stroke Scale median was 0. Modified Rankin Scale median at 3 months was 0.Conclusion: TIAs may reveal acute intracranial artery occlusion. Acute MRI may able to assist in therapeutic decision. [ABSTRACT FROM AUTHOR]

BSTRACT PURPOSE [ABSTRACT FROM AUTHOR]

BACKGROUND/PURPOSE Leptomeningeal collateral volume flow has not been previously quantified. Quantitative magnetic resonance angiography (QMRA) can determine flow in the large vessels of the intracranial circulation. METHODOLOGY We reviewed consecutive QMRA studies performed between December 1, 2004 and August 30, 2005, for cases showing asymmetrically higher flow in a posterior cerebral artery (PCA) just distal to the origin of the posterior communicating artery ipsilateral to a hemodynamic middle cerebral artery (MCA) or internal carotid artery lesion. The mean, range, and standard deviation (SD) of the flow rate in the PCAs, MCAs, and PCA ipsilateral-contralateral difference were calculated. Ipsilateral and contralateral PCA flow rates were compared using the Student's t-test. RESULT Sixteen studies met selection criteria. Mean age was 52 years (range 21-79) and 9 were female. MCA flow was below QMRA detection limits in 6 studies. Mean measurable ipsilateral MCA flow reduction was 84 mL/min (range 9-147, SD 51.4). Mean ipsilateral PCA flow was 118 mL/min (range 72-206, SD 38.5) and mean contralateral PCA flow was 68 mL/min (range 35-144, SD 30.5, P < .001); mean difference was 50 mL/min (range 10-93, SD 24.3). CONCLUSION Leptomeningeal collateral flow can be assessed with QMRA and may be substantial. [ABSTRACT FROM AUTHOR]