Hemodynamic and Geometrical Parameters Associated with Carotid Artery Stenosis: A Cross-Sectional Study Using 4D Flow MRI and CFD

Purpose Carotid geometry and local hemodynamics are closely associated with atherosclerosis, yet how anatomy and disturbed flow jointly mark disease presence and relate to pro-atherogenic flow in still-non-stenosed bifurcations remains unresolved. This study quantifies the cross-sectional association between three-dimensional carotid bifurcation geometry and pro-atherogenic flow and identifies anatomical biomarkers for non-invasive risk stratification. Methods Geometric analyses included 346 carotid bifurcations, comprising 240 stenosed and 106 non-stenosed bifurcations. Patient-specific CFD was performed in 176 bifurcations: 101 stenosed and 75 non-stenosed. Eight geometric descriptors, including a new offset flow divider capturing bifurcation apex asymmetry, and four ICA bulb hemodynamic indices (TAWSS, OSI, RRT, BFI) were extracted; logistic and linear regression assessed the association of geometry with (i) stenosis presence and (ii) pro-atherogenic flow. Results Bifurcation angle, ICA angle, tortuosity, and offset flow divider were significantly elevated in stenosed bifurcations (all $$p<0.001$$ p < 0.001 ); a four-feature geometric model showed moderate discrimination between stenosed and non-stenosed bifurcations (cross-validated AUROC=0.767 AUROC = 0.767 ). The post-stenotic expansion ratio was more strongly associated with local flow disturbance than the degree of luminal narrowing. In non-stenosed bifurcations, multivariable geometric models explained 49 to $$60%$$ 60 % of the variance in the flow-normalized low-TAWSS, elevated-OSI, and elevated-RRT outcomes, with bulb area and area ratio providing the largest independent contributions, indicating that geometric variation is strongly associated with candidate pro-atherogenic flow patterns even in the absence of detectable luminal narrowing. Conclusions Carotid geometry carries two complementary signals: markers of disease presence (bifurcation angle, ICA angle) and candidate anatomical substrates of pro-atherogenic flow in still-non-stenosed bifurcations (bulb area, area ratio). Together with the post-stenotic expansion ratio, these geometric features define a compact, image-derivable set of candidate biomarkers for future early carotid risk stratification.