Abstract

Background: Carotid artery stenosis (CAS) may induce cerebral hypoperfusion. Early-phase ¹⁸F-Florbetapir (AV-45/Amyvid, ¹⁸F-AV-45) positron emission tomography (PET) imaging can provide perfusion-like property (pAV-45) for the estimation of cerebral blood flow (CBF). Supra-tentorial lesions may cause decreased blood flow and metabolism in the contralateral cerebellum known as crossed cerebellar diaschisis (CCD).

Objective: The aim was to study the occurrence of CCD after CAS using pAV-45 PET.

Methods: Eleven healthy controls and 21 patients with unilateral CAS were studied. All subjects underwent ¹⁸F-AV-45 PET imaging and arterial spin labeling (ASL) CBF magnetic resonance perfusion imaging. The pAV-45 and ASL CBF values were first correlated. Then, cerebral and cerebellar hypoperfusion volume was analyzed. The cerebral and cerebellar perfusion asymmetry indices (AIs) were calculated from the pAV-45 standard uptake value ratios (SUVRs) of bilateral cerebral and cerebellar cortices, respectively.

Results: We found that pAV-45 SUVR was significantly correlated to ASL CBF (p<0.0001, r=0.5731). The AI of cerebellar perfusion was negatively correlated to that of cerebral perfusion (p<0.0001, r=-0.8751). Multiple linear regression showed the cerebral AI (p<0.0001) and hypoperfusion volume (p=0.02) but not the infarction severity and CAS degree significantly correlated to cerebellar AI. If the lower limit of 95% confidence interval of cerebellar AI in healthy controls was set as cut-off for positive CCD, the occurrence of CCD correlated to infarction severity in CAS patients (p=0.03).

Conclusion: Our results suggest pAV-45 is reliable to study CBF change. Under unilateral CAS, cerebral AI and hypoperfusion severity may determine the occurrence of CCD.

Keywords: Carotid stenosis, positron emission tomography, magnetic resonance imaging, crossed cerebellar diaschisis, carotid artery stenosis, stroke.