Article

Lee, K. Y. et al. Distal hyperintense vessels on FLAIR: an MRI marker for collateral circulation in acute stroke? Neurology 72, 1134-1139

Section on Stroke Diagnostics and Therapeutics, National Institute of Neurological Disorders and Stroke, 10 Center Drive, Room B1D733, Bethesda, MD 20892-1063, USA.
Neurology (Impact Factor: 8.29). 03/2009; 72(13):1134-9. DOI: 10.1212/01.wnl.0000345360.80382.69
Source: PubMed

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.

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    • "Vascular occlusion can also be indirectly assessed from collaterality circulation from linear FLAIR hyperintensities Figure 12. ''Susceptibility Vessel Sign'' or SVS: magnetic susceptibility artefact on the T2* images in the proximal segment of the right middle cerebral artery due to a thrombus. (or FLAIR vascular hyperintensities, FVH) (Fig. 13) that can be seen in the subarachnoid spaces [40]. The FVH are seen in arterial occlusion and represent hemodynamic disturbances. "
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    • "Vascular occlusion can also be indirectly assessed from collaterality circulation from linear FLAIR hyperintensities Figure 12. ''Susceptibility Vessel Sign'' or SVS: magnetic susceptibility artefact on the T2* images in the proximal segment of the right middle cerebral artery due to a thrombus. (or FLAIR vascular hyperintensities, FVH) (Fig. 13) that can be seen in the subarachnoid spaces [40]. The FVH are seen in arterial occlusion and represent hemodynamic disturbances. "
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    • "Furthermore, they are reported to reflect collateral circulation and diffusion-perfusion mismatch on MRI [4,5,13,14]. However, controversy exists regarding the clinical implication of FHVs for acute severity of stroke and the functional outcome [5,7,10,15,16,17]. "
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    ABSTRACT: Fluid-attenuated inversion recovery hyperintense vessels (FHVs) are known to reflect stagnant or slow blood flow within the cerebral artery. FHVs are frequently observed in patients with acute cerebral infarction accompanied by arterial occlusion or significant stenosis of the anterior cerebral circulation. However, FHVs have not been studied in the context of posterior cerebral circulation. Thus, we investigated the prevalence of FHVs and its clinical significance in patients with acute posterior cerebral artery (PCA) territory infarction. In this retrospective study, consecutive patients with PCA territory infarction who underwent MRI within 1 week after symptom onset were enrolled. Two neurologists who were blinded to the angiographic findings read the images and determined the presence of FHVs. Afterwards, FHVs were graded according to the extent (subtle or prominent) and location (proximal or distal) of the hyperintense vessels. Neurologic deficits of the patients were assessed by the National Institutes of Health Stroke Scale (NIHSS) upon admission and after 5 days. The clinical outcome between patient groups based on FHVs grading was compared using the NIHSS. Among the patients with PCA occlusion, infarction volume on the diffusion-weighted image was compared between the two groups with and without distal FHVs. FHVs were observed in 25 of the 87 patients (28.7%) with PCA territory infarction and in 65.7% of the 35 patients with significant arterial stenosis (10 patients) or occlusion (25 patients) in the posterior cerebral circulation. Among the 18 patients with PCA occlusion, the NIHSS score was significantly improved in patients with distal FHVs compared to the others (2.00 ± 2.18 vs. 0.56 ± 1.01, p = 0.04). The infarction volume was smaller in the distal FHV group than in the others (8.3 ± 8.7 vs. 16.8 ± 17.6 ml), but the difference was not statistically significant. FHVs are detected in patients with PCA territory infarction, especially in those with an occlusive lesion in the PCA. FHVs can be used as an imaging marker of PCA occlusion. Although this study showed a better clinical improvement in patients with distal FHVs, further study is needed to elucidate the clinical meaning of FHVs in PCA infarction.
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