Intra-arterial thrombus visualized on T2*gradient echo imaging in acute ischemic stroke
ABSTRACT MR signal loss related to arterial thrombosis leading to vascular susceptibility artifacts (VSA) has recently been reported on gradient echo images. The time course and sensitivity of VSA in acute stroke patients has been scarcely investigated. The aim of this study was to assess the frequency and course of VSA in acute stroke patients, to compare its sensitivity to distinct features of arterial occlusion as detected on FLAIR images or on CT scan.
Twenty-nine patients were scanned from 45 min to 6 h after stroke onset using identical MR parameters. All had an acute ischemic lesion identified on diffusion-weighted images, 25 had an occlusion of MCA or PCA confirmed by magnetic resonance angiography.
VSA was detected in 22/25 patients having an occluded artery at the time of MRI examination. Flair disclosed a hyperintense vessel in all of these 25 cases, but CT scan revealed a hyperdense artery in only 15 cases. Follow-up studies showed that VSA can vanish or disappear after partial recanalization. When the artery remains occluded, VSA can decrease, disappear or increase in the next hours, possibly related to structural modifications of the thrombus with time. Most occlusions were due to cardiac and arterial emboli or to intracranial extension of carotid occlusion.
VSA are frequent in the first hours of MCA or PCA occlusion in acute stroke patients. The sensitivity of VSA appears lower than the arterial hyperintensity on FLAIR images but higher than the hyperdense artery sign on CT scan. The extent and intensity of VSA can change with recanalization or structural modifications of the thrombus.
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ABSTRACT: Hyperintense vessels (HV) on fluid-attenuated inversion recovery imaging are frequently observed in acute ischemic stroke patients. However, the exact mechanism and clinical implications of this sign have not yet been clearly defined. The features of HV and its relevance to other imaging factors are presented here. Prominence and location of HV were documented in 52 consecutive patients with middle cerebral artery (MCA) territory infarction, before treatment with IV recombinant tissue plasminogen activator. Pretreatment ischemic lesion volume, perfusion lesion volume, and vessel occlusion were determined in addition to recanalization status and ischemic lesion volume on follow-up imaging. NIH Stroke Scale (NIHSS) was used as a measure of clinical severity. HV distal to arterial occlusion was observed in 73% of patients; more frequent in proximal than distal MCA occlusion patients. Among the 38 patients with proximal MCA occlusion, initial perfusion lesion volume was comparable among patients with different grade distal HV. However, patients with more prominent distal HV had smaller initial, 24-hour, and subacute ischemic lesion volumes and lower initial NIHSS scores. The presence of distal hyperintense vessels before thrombolytic treatment is associated with large diffusion-perfusion mismatch and smaller subacute ischemic lesion volumes in patients with proximal middle cerebral artery occlusion. DWI = diffusion-weighted imaging; FLAIR = fluid-attenuated inversion recovery; GRE = gradient recalled echo; HV = hyperintense vessels; MCA = middle cerebral artery; MRA = magnetic resonance angiography; MTT = mean transit time; NIHSS = NIH Stroke Scale; PWI = perfusion-weighted imaging; rt-PA = recombinant tissue plasminogen activator; TE = echo time; TI = inversion time; TIMI = thrombolysis in myocardial infarction; TR = repetition time.Neurology 03/2009; 72(13):1134-9. DOI:10.1212/01.wnl.0000345360.80382.69 · 8.30 Impact Factor
- Clinical Neuroradiology 03/2009; 19(1):20-30. · 1.62 Impact Factor
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ABSTRACT: Acute stroke imaging has developed from intraarterial angiography and native, unenhanced CT to highly elaborated tools with the access to a variety of pathophysiological variables ahead of therapy. Despite enduring unresolved problems, we can now obtain a comprehensive view on the individual patient's disease and act fast and specifically under consideration of chances and risks of different therapies. The stroke neuroradiologist is the decisive partner of engaged clinical disciplines and should own a leading role in future acute stroke trials. Weighing the different modalities against each other, there is an established advantage of acute stroke MRI over CT based on diffusion-weighted imaging and the possibility to obtain even more functional information on stroke pathophysiology.Clinical Neuroradiology 04/2009; 19(1):20-30. DOI:10.1007/s00062-009-8030-3 · 1.38 Impact Factor