264 Scientific Programme 22. European Stroke Conference © 2013 S. Karger AG, Basel 13 Vascular imaging High-Resolution MRI in the Investigation of Intracranial Stenosis: Preliminary Experience B.P.L. Chan1, Y. Kusuma2, V.K. Sharma3, H.L. Teoh4, R.C.S. Seet5, C.L.H. Chen6, K.H. Chuang7 Division of Neurology, National University Hospital, Singapore, SINGAPORE1, Division of Neurology, National University Hospital, Singapore, SINGAPORE2, Division of Neurology, Nation-al University Hospital, Singapore, SINGAPORE3, Division of Neurology, National University Hos-pital, Singapore, SINGAPORE4, Division of Neurology, National University Hospital, Singapore, SINGAPORE5, Department of Pharmacology, National University of Singapore, Singapore, SIN-GAPORE6, Singapore Bioimaging Consortium, A*STAR, Singapore, SINGAPORE7 Objective: High-resolution dark-blood MRI (HR-MRI) imaging has recently been introduced for investigation of intracranial stenosis. We aim to study the usefulness of the various HR-MRI sequences compared to time-of-flight MRA (TOF-MRA) in a group of stroke patients with intracranial stenosis. Methods: Consecutive patients with ischaemic stroke or TIA presented to a teaching hospital in Singapore were recruited into a long-term follow-up study and underwent MRI of the brain including TOF-MRA with a 3T scanner at the convalescent stage. T2 and T1 3-dimentional HR-MRI were per-formed in all subjects and post-contrast T1 HR-MRI was performed in subjects with normal renal function. Findings: Out of 111 patients, intracranial stenosis was the stroke aetiology in 28 (mean age: 57.5 years, 18 were male) who underwent study MRI at a mean of 109 days after stroke onset. Sites of stenosis/ occlusion include 11 M1, 8 ICA, 4 VA and 5 BA. HR-MRI was not evaluable in one patient and needed to be repeated in another due to movement artefacts. Compared to TOF-MRA, HR-MRI pro-vided better information on plaque morphology and/or extent in 23 cases, led to reclassification of the severity of stenosis in 8 cases, revealed additional tandem stenoses in 4 cases, and demonstrated significant plaque enhancement in 16 of 21 cases when gadolinium was given. T2 HR-MRI was ei-ther equal or superior but never inferior to T1 in the study of intracranial stenosis due to better tissue contrast, whereas T1 vessel wall hyperintensity suggestive of possible intraplaque haemorrhage was only found in 2 cases. Conclusion: HR-MRI is a promising technique that can reveal potentially useful information in the majority of patients with stroke due to intracranial stenosis. However, further technological advance to over-come the current limitations of long acquisition time, suboptimal resolution and restricted brain cov-erage is required before adoption of this technique into routine clinical practice. 12 Vascular imaging Prevalence and prognosis of symptomatic intracranial and extracranial posterior circulation stenosis in TIA and non-disabling stroke: a population-based study U.G. Schulz1, W. Kueker2, L. Li3, P.M. Rothwell4 Oxford Vascular Study Stroke Prevention Research Unit, Nuffield Department of Clinical Neurosciences, Oxford Uni-versity, Oxford, UNITED KINGDOM1, Department of Neuroradiology, John Radcliffe Hospital, Oxford, UNITED KINGDOM2, Stroke Prevention Research Unit, Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, UNITED KINGDOM3, Stroke Prevention Research Unit, Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, UNITED KING-DOM4 BACKGROUND: Previous studies have reported a high risk of recurrence after posterior circulation TIA or stroke, which is presumed to be due to a relatively high prevalence of atheromatous stenosis in the vertebrobasilar (VB) arteries. Interventional treatment of stenosis is possible, but more data on the prevalence and natural history of posterior circulation stenosis are required to inform trial de-sign. METHODS: Consecutive patients with posterior circulation TIA or non-disabling ischaemic stroke underwent MRI-brain and MR-angiography in a population-based study (Oxford Vascular Study). Detailed baseline clinical and imaging data were collected and patients were followed up at 1, 6 and 12 months. Clinically significant arterial stenosis was arbitrarily defined as ≥50%. RE-SULTS: Of 306 patients (61% men, mean SD age 69 12 years), 66 (22%) had posterior circu-lation occlusive disease, of whom 24 (36%) had ≥50% extracranial stenosis, 15 (23%) had ≥50% intracranial stenosis, 9 (14%) had an isolated vessel occlusion, and 18 (27%) had multiple lesions. Patients with intracranial stenosis were more likely to have multiple lesions or multi-vessel involve-ment than patients with extracranial disease (65% vs 32%, p=0.01). One year risk of recurrent stroke was higher in patients with ≥50% VB-stenosis vs those without (12% vs 5%, p=0.038), and higher in patients with intracranial than extracranial disease (16% vs 8%, p=0.05). CONCLUSION: In this cohort, the risk of recurrent stroke and the prevalence of complex multi-vessel disease differed be-tween patients with intra- and extracranial posterior circulation stenosis. These differences may in-fluence the risk and benefits of intervention and should be taken account of in treatment trials.
Karger_ESC London_2013
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