Hyperintense vessels on FLAIR: A useful non-invasive method for assessing intracerebral collaterals

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Abstract

Objective

This study was aimed to evaluate relationship between hyperintense vessels (HV) on fluid-attenuated inversion recovery (FLAIR) and artery steno-occlusion related intracerebral collaterals.

Materials and methods

A total of 233 patients with 260 atherosclerotic lesions in the M1 segment of the middle cerebral artery (MCA) were examined with FLAIR and digital subtraction angiography (DSA). HV were graded as 0, 1, 2 and 3 by its distributions in the MCA territory. Grade 0 indicated no HV; Grade 1 indicated the HV limited in Sylvian fissure; Grade 2 indicated the HV limited in Sylvian fissure and the temporal-occipital junction; Grade 3 indicated the HV extended to frontal-parietal lobes. Collateral blood flows were classified by DSA results. The relationship between HV grades and patterns of collateral flows was analyzed.

Results

HV were observed in 76 out of 260 hemispheres. For patients with Grade 1 HV, most of their collateral flows (80.8%) were antegrade; for patients with Grade 2, the retrograde leptomeningeal flows were commonly manifested as anterior cerebral artery to MCA (75%); for patients with Grade 3 HV, most of the retrograde leptomeningeal flows were manifested as posterior cerebral artery to MCA (81.8%). As the grade HV increased, the frequency of retrograde leptomeningeal collateral from ACA to MCA decreased (100% to 75% and to 18.2%), and increased (0% to 25% and to 81.8%) for the retrograde leptomeningeal collateral via PCA to MCA (P < 0.001).

Conclusions

The HV could assess non-invasively intracerebral collaterals in patients with steno-occlusive lesions of M1 segment of MCA.

Introduction

Hyperintense vessels (HV) on fluid-attenuated inversion recovery (FLAIR) MR images refer to focal hyperintension. HV can be frequently observed near the cerebral surface along the cortical sulci in patients with ischemic stroke [1], [2], [3], [4]. Although HV have non-invasively diagnostic value for intracerebral artery steno-occlusive lesion [2], the influence of degree of stenosis on the presence of HV is unclear. A recent study revealed that HV are associated with slow collateral blood flow in the setting of acute ischemic stroke [5], though the correlation of the location of HV with the patterns of collaterals is still unclear.

Atherosclerotic steno-occlusive disease in the M1 segment of the middle cerebral artery (MCA) can recruit the different patterns of collaterals, including the low grade of leptomeningeal retrograde collateral from anterior cerebral artery (ACA) to MCA and the high grade of leptomeningeal retrograde collateral from posterior cerebral artery (PCA) to MCA [6], [7]. These patterns of collaterals may provide a setting helping to understand the underlying mechanism of HV. In this study, we aimed to investigate the relationship between the location of HV and these patterns of collaterals by contemporaneously comparing findings on FLAIR images with digital subtraction angiography (DSA) in the setting of patients with atherosclerotic steno-occlusive disease in M1 segment of MCA.

Section snippets

Subjects

A total of 233 consecutive patients with atherosclerotic steno-occlusive lesions in M1 segment of the MCA were inclused as subjects, of which 57 were diagnosed with transient ischemic attacks (TIA), and 176 with cerebral infarctions (CI). These patients were retrieved from the Nanjing Stroke Registry Program (NSRP) between January 2004 and April 2010. The detailed profile of NSRP has been previously published elsewhere [8]. Inclusion criteria included: (1) initial presence of transient or

Results

A total of 233 patients (age, 59.4 ± 10.8 years) with symptomatic atherosclerotic steno-occlusive lesions of the M1 segment were included. There were 16 of these patients presented with ischemic lesions in bilateral hemispheres, so the total number of the symptomatic hemispheres were 249 (TIA, n = 59; CI, n = 190). There were 11 asymptomatic steno-occlusive lesions in the M1 segment, number of M1 steno-occlusive lesions were 260. Because 8 patients were observed the HV in the bilateral territories of

Discussion

In this study, we retrospectively selected patients, who were initially diagnosed as atherosclerotic steno-occlusive lesions in the M1 segment according to patients’ clinical characteristics, magnetic resonance angiogram and/or T2 weighted MR imaging (detecting the steno-occlusive lesions of the horizontal portion of MCA at the level of basal cistern). To achieve revascularization of the M1 segment by angioplasty and stenting, these patients were further performed with standard DAS.

This study

Conclusion

This study indicated that the HV show up at a degree of M1 stenosis of greater than or equal to 90%, and more importantly, the location of HV are indicators of the different patterns of collaterals. The HV could assess non-invasively the patterns of collaterals in patients with steno-occlusive lesions in the M1 segment of MCA.

Acknowledgements

This study was supported by Natural Science Foundation of China (NSFC #30870848 to GX and NSFC #30870847 to XL).

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1

These two authors contributed equally to this work.

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