Stroke is commonly caused by thromboembolic events originating from a ruptured carotid plaque. Histological studies have shown that plaque rupture potential is related to plaque composition rather than degree of stenosis. The use of Acoustic Radiation Force Impulse (ARFI) ultrasound imaging has enabled assessment of carotid plaque composition and structure. In particular, a previous study has shown that ARFI-derived peak displacement (PD) can differentiate between soft (intraplaque hemorrhage/necrotic core) and stiff (collagen/calcium) plaque components with high sensitivity and specificity. However, PD showed low performance for distinguishing between soft and between stiff features. This study evaluates an alternative ARFI-derived parameter, variance of acceleration (VoA), for intraplaque feature delineation. This study analyzed 20 carotid plaques imaged in vivo in patients undergoing carotid endarterectomy (CEA). After imaging, CEA specimens were harvested for histological validation. VoA was statistically significantly different (Wilcoxon, p < 0.01) between all examined plaque features, including between intraplaque hemorrhage and necrotic core and between collagen and calcium. Results suggest that VoA analysis improves ARFI discrimination between soft and between stiff carotid plaque components that are related to vulnerability for rupture.