Preliminary study about the relationship between degree of internal carotid artery stenosis, wall shear stress on MR angiography and 18F-FDG uptake on PET/CT

1622 Purpose: Internal carotid artery stenosis is a well-known risk factor of ischemic stroke. However, with improvement in vascular imaging, not just degree of internal carotid artery stenosis but also the vulnerability of plaque is an important contributory factor in stroke. The purpose of this preliminary study was to evaluate the relationship between degree of internal carotid artery stenosis, the wall shear stress (WSS) by computational fluid dynamics (CFD) on MR angiography and 18F-FDG uptake of the plaque on PET/CT. Methods and Materials: A total of 40 carotid arteries in 20 patients with carotid atherosclerotic disease were examined with MR angiography and 18F-FDG PET/CT. Luminal diameter at the site of maximal narrowing and diameter of normal distal internal carotid artery where the artery walls are parallel were measured. Degree of internal carotid artery stenosis (%) was calculated according to the North American Symptomatic Carotid Endarterectomy Trial (NASCET) method. The 3D geometry of internal carotid artery was reconstructed based on 3D TOF-MRA data using commercially available software (Ziostation 2), and then CFD analysis was performed using commercially available software (Hemoscope v2.1.1). The maximum WSS (WSSmax) was measured by the color bar of analyzed images. 18F-FDG uptake in carotid artery plaque was quantified using maximum standardized uptake value (SUVmax). Results: The mean (±SD) degree of internal carotid artery stenosis was 31.18±28.28 %. The mean (±SD) WSSmax was 61.43±85.09 Pa. The mean (±SD) SUVmax was 2.61±1.18. There was a significant correlation between WSSmax and degree of internal carotid artery stenosis (ρ = 0.813, p < 0.001). There was a significant correlation between WSSmax and the SUVmax of 18F-FDG PET/CT (ρ = 0.6, p < 0.001). There was a significant correlation between WSSmax and carotid artery stenosis rate (ρ = 0.489, p = 0.001). The p value between WSS and 18F-FDG uptake was lower than that between degree of internal carotid artery stenosis and 18F-FDG uptake. Conclusions: These preliminary results indicated that there were significant correlations between degree of internal carotid artery stenosis, WSS and 18F-FDG uptake in patients with carotid artery stenosis. Furthermore, the relationship between WSS and 18F-FDG uptake was higher than that between degree of internal carotid artery stenosis and 18F-FDG uptake.