Treatment with a FXI inhibitor reduced VCAM-1 expression at the inflamed vessel wall surface in the setting of hyperlipidemia. We used a noninvasive ultrasound-based molecular imaging technique to measure VCAM-1 expression at the vessel wall surface as a marker of local activation in NHPs on a high-fat diet (n = 5) treated with a FXI function–blocking antibody. Data are presented as box and whisker plots showing the background subtracted video intensity for control and VCAM-1-targeted microbubbles (A). Systemic activation was determined by measuring the circulating levels of VCAM-1 (sVCAM-1) in both NHPs on a standard chow diet (lean) and NHPs on a high-fat diet (obese) treated with a FXI function–blocking antibody (B). Statistical analyses were conducted using a Wilcoxon test, an unpaired t-test, or a Friedman test with a Dunn’s post-hoc test. Statistical significance is indicated by an asterisk for P < .05. Data are shown as mean ± SEM. F, factor; NHP, nonhuman primate; VCAM-1, vascular cell adhesion molecule 1.