This study used an atherosclerotic rabbit model to investigate the feasibility of quantifying adventitial vasa vasorum (VV) via contrast-enhanced ultrasound (CEUS) imaging to identify early atherosclerosis. Recent evidence has linked adventitial VV with atherosclerotic plaque progression and vulnerability. A growth in VV density has been detected preceding intimal thickening and even endothelial dysfunction. In our study, carotid atherosclerosis rabbit models were used, and animals underwent CEUS imaging at the end of the atherosclerotic induction period. Normalized maximal video-intensity enhancement (MVE) was calculated to quantify VV density. After CEUS imaging, animals were euthanized, and their carotids were processed for histopathological analysis following staining for CD31 and VEGF. Adventitial normalized MVE increased as atherosclerosis progressed (p < 0.001), and normalized MVE also progressed, demonstrating a linear correlation with histological findings (r = 0.634, p < 0.001 for VEGF-positive; r = 0.538, p < 0.001 for CD31-positive). Thus, we histologically validated that CEUS imaging can be used to quantify the development of adventitial VV associated with atherosclerosis progression. This method can be used for monitoring the VV to detect early atherosclerosis.