Abdelkader, Omar

Background: Carotid stenosis has been associated with stroke and cognitive impairment. It remains unclear if hypometablism, a marker for neurodegeneration, may be in the mechanistic pathway in the association between carotid stenosis and cognitive decline. This study aims to investigate whether patients with carotid stenosis exhibit reduced cerebral glucose metabolism, using 18-FDG PET imaging as a sensitive measure of brain’s glucose metabolism. Methods: We have identified 138 patients from one health care system who underwent 18-FDG PET imaging and had extracranial carotid imaging (doppler ultrasound/CT angiography/MR angiography) within 1 year of PET scan. Severity of carotid stenosis was defined using NASCET criteria as <50% (mild), 50-69% (moderate), >70% (high-grade). Cerebral glucose metabolism was quantified by measuring standardized uptake value ratio (SUVR) after normalizing to pons in 12 different regions of interest (ROI). Hypometabolism was defined using the cutoff of SUVR <1.41. SUVR and hypometabolism measures were compared across severity of carotid stenosis. Results: Of 138 patients identified, 54 were excluded due to indeterminant ipsilateral hemisphere status. Mild, moderate and severe stenosis was present in 86.9%, 4.8%, 8.3%, respectively. The analysis revealed a numerically reduced cerebral glucose metabolism in patients with moderate to severe carotid stenosis compared to control subjects (Table 1). The most pronounced decrease in FDG uptake was observed in regions supplied by the affected carotid artery, particularly the ipsilateral cortical areas. There was a numerically increased risk of hypometabolism with increasing carotid stenosis: Adjusted odds of hypometabolism ipsilateral to the carotid stenosis were 2.90, 5.56 across patients with moderate and high-grade carotid stenosis in sensorimotor cortex (trend-P=0.095). These findings were consistent across different regions supplied by the stenotic carotid artery but attenuated in territories supplied by unaffected posterior arteries (Table 2). Conclusions: FDG-PET imaging demonstrates reduced glucose metabolism in patients with carotid stenosis, suggesting that cerebral hypoperfusion may contribute to the metabolic disturbances observed in these patients. These results underscore the importance of early detection and management of carotid stenosis to mitigate potential cerebral metabolic deficits and the associated risk of dementia and ischemic stroke.