Early-phase 18F-AV-45 PET Imaging can Detect Crossed Cerebellar Diaschisis Following Carotid Artery Stenosis and Cerebral Hypoperfusion

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 (pl0.0001, r=0.5731). The AI of cerebellar perfusion was negatively correlated to that of cerebral perfusion (pl0.0001, r=-0.8751). Multiple linear regression showed the cerebral AI (pl0.0001) 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.