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Front Neurol. 2014 Dec 5;5:254. doi: 10.3389/fneur.2014.00254. eCollection 2014.

Impact of Severe Extracranial ICA Stenosis on MRI Perfusion and Diffusion Parameters in Acute Ischemic Stroke.

Author information

1
Department of Computational Neuroscience, University Medical Center Hamburg-Eppendorf , Hamburg , Germany.
2
Department of Neurology, University Medical Center Hamburg-Eppendorf , Hamburg , Germany.
3
Department of Medical Biometrics and Epidemiology, University Medical Center Hamburg-Eppendorf , Hamburg , Germany.
4
Department of Diagnostic and Interventional Neuroradiology, University Medical Center Hamburg-Eppendorf , Hamburg , Germany.
5
Department of Computational Neuroscience, University Medical Center Hamburg-Eppendorf , Hamburg , Germany ; Department of Diagnostic and Interventional Neuroradiology, University Medical Center Hamburg-Eppendorf , Hamburg , Germany.

Abstract

PURPOSE:

The aim of this study was to investigate the impact of a coexisting internal carotid artery (ICA) stenosis on lesion volumes as well as diffusion and perfusion parameters in acute ischemic stroke resulting from middle cerebral artery (MCA) occlusion.

MATERIAL AND METHODS:

Magnetic resonance imaging data of 32 patients with MCA occlusion with or without additional ICA stenosis imaged within 4.5 h of symptom onset were analyzed. Both groups consisted of 16 patients. Acute diffusion lesions were semi-automatically segmented in apparent diffusion coefficient (ADC) MRI datasets. Perfusion maps of cerebral blood volume (CBV), cerebral blood flow, mean transit time and T max were calculated using perfusion-weighted MRI datasets. Tissue-at-risk (TAR) volumes were generated by subtracting the ADC lesion from the hypoperfusion lesion defined by T max >6 s. Median ADC and perfusion parameter values were extracted separately for the diffusion lesion and TAR and used for statistical analysis.

RESULTS:

No significant differences were found between the groups regarding the diffusion lesion and TAR volumes. Statistical analysis of diffusion and perfusion parameters revealed CBV as the only parameter with a significant difference (p = 0.009) contributing a small effect (η(2) = 0.11) to the group comparison with higher CBV values for the patient group with a coexisting ICA stenosis, while no significant effects were found for the other diffusion and perfusion parameters analyzed.

CONCLUSION:

The results of this study suggest that a coexisting ICA stenosis does not have a strong effect on tissue status or perfusion parameters in acute stroke patients except for a moderate elevation of CBV. This may reflect improved collateral circulation or ischemic preconditioning in patients with a pre-existing proximal stenosis balancing impaired perfusion from the stenosis.

KEYWORDS:

brain ischemia; diffusion; internal carotid artery stenosis; magnetic resonance imaging; perfusion

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