Spectral CT parameters of perivascular adipose tissue as non-invasive biomarkers for identifying symptomatic carotid atherosclerosis

Abstract Objectives To evaluate the association between computed tomography (CT) spectral parameters of perivascular adipose tissue (PVAT) and carotid plaque composition, and to assess their value for identifying symptomatic plaques. Materials and methods In this study, 306 consecutive patients with computed tomography angiography (CTA)-confirmed carotid atherosclerosis who underwent head and neck spectral CT angiography were analyzed. Quantitative plaque parameters and PVAT spectral metrics were extracted. Correlations between quantitative plaque parameters and PVAT spectral indices were analyzed, and logistic regression was used to identify independent predictors of symptomatic plaques. Diagnostic performance was evaluated by generating receiver operating characteristic (ROC) curves. Results Compared with asymptomatic patients, symptomatic carotid plaques showed higher PVAT effective atomic number ( Z eff) and iodine concentration (IC) but lower fat fraction (FF) (all p < 0.05). Z eff and IC correlated positively with fibrous fatty and necrotic core volumes, whereas FF correlated negatively with necrotic core volume (all p < 0.001). In multivariable models, Z eff, IC, FF, and virtual monoenergetic image attenuation at 70 keV (CT 70keV ) were independently associated with symptomatic plaques (all p < 0.05). CT 70keV and FF performed best for identifying symptomatic plaques (AUC 0.857 and 0.820). The AUC increased from 0.716 for stenosis severity alone to 0.821 after the addition of necrotic core volume, and further to 0.897 and 0.916 after the addition of FF and CT 70keV , respectively. Conclusion Spectral CT-derived PVAT parameters differ between symptomatic and asymptomatic carotid atherosclerosis and are associated with plaque composition, providing complementary noninvasive information for identifying symptomatic plaques. Key Points Question: Can spectral CT-derived PVAT parameters improve noninvasive identification of symptomatic carotid atherosclerosis beyond luminal stenosis? Findings: PVAT spectral parameters differed between symptomatic and asymptomatic plaques, and adding FF or CT 70keV improved diagnostic performance. Critical relevance statement: spectral parameters of carotid PVAT differ significantly between symptomatic and asymptomatic carotid atherosclerosis and are associated with plaque components.