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

@entity1 @entity64 @entity2500 @entity850 @entity385
PURPOSE: The aim of this study was to investigate the impact of a coexisting internal carotid artery (ICA) @entity850 on lesion volumes as well as diffusion and perfusion parameters in acute @entity385 resulting from @entity2500 . MATERIAL AND METHODS: Magnetic resonance imaging data of 32 @entity1 with @entity2500 with or without additional ICA @entity850 imaged within 4.5   h of symptom onset were analyzed. Both groups consisted of 16 @entity1 . 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 (  (2)   =   0.11) to the group comparison with higher CBV values for the @entity1 group with a coexisting ICA @entity850 , 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 @entity850 does not have a strong effect on tissue status or perfusion parameters in @entity64 @entity1 except for a moderate elevation of CBV. This may reflect improved collateral circulation or ischemic preconditioning in @entity1 with a pre-existing proximal @entity850 balancing impaired perfusion from the @entity850 .
