Serial in vivo MRI documents arterial remodeling in experimental atherosclerosis

Background-Arterial remodeling in response to atherosclerosis may be outwar d (positive) or inward (negative) and is an important mechanism in the clin ical manifestations of atherosclerosis and restenosis after percutaneous co ronary interventions. Postmortem and intravascular ultrasound studies of ar terial remodeling do not allow serial and noninvasive data to be obtained. Ln a rabbit model of atherosclerosis, we sought to validate MRI as a new to ol for documentation of arterial remodeling. Methods and Results-Watanabe heritable hyperlipidemic rabbits underwent ser ial MRI at baseline and 6 months after aortic balloon denudation. The lumen area had a small but significant (P=0.006) increase, from 4.36+/-0.16 to 4 .89+/-0.12 mm(2). There was a large, significant (P<0.0001) increase in the outer wall area, from 7.96+/-0.19 to 10.46+/-0.19 mm(2). The vessel wall a rea (a marker of atherosclerotic burden) increased significantly (P<0.0001) , from 3.61+/-0.07 to 5.57+/-0.09 mm(2). Thus, the increase in atherosclero tic burden over time was completely accounted for by positive arterial remo deling. The subgroup used for histopathological validation confirmed a sign ificant (P<0.0001) agreement between histopathology and MRI for assessment of all 3 parameters. Conclusions-MRI can provide serial and noninvasive data about the arterial wall, allowing assessment of arterial remodeling in this rabbit model. Thus , MRI appears to be a useful tool for the investigation of arterial remodel ing both in native atherosclerosis and after percutaneous coronary interven tion.