We used six Watanabe heritable hyperlipidemic (WHHL) rabbits obtained from the Institute for Experimental Animals at Kobe University, Hyogo, Japan. Each was 9-12 months old and weighed approximately 3 kg. At this age, WHHL rabbits harbor active plaque formations in the aortic wall. 28 They were divided into two equal groups and injected intravenously with 0.8 mmol iron (Fe)/kg (dose 3) of D-or DM-USPIO. Gadolinium-enhanced magnetic resonance angiography (MRA) scans were obtained before and 5 days after the injection. For each MRI session, the rabbits were fully anesthetized with ketamine (Ketalar; Daiichi Sankyo, Tokyo, Japan), at 25 mg/kg body weight, and medetomidine (Domitor; Nippon Zenyaku Kogyo, Koriyama, Fukushima, Japan), at 0.1 mg/kg body weight, then injected intravenously with 2 mL gadopentetate dimeglumine (Magnevist ® ; Bayer Health Care Japan), diluted in 10 mL saline.