A novel contrast medium detects increased permeability of rat injured carotid arteries in magnetic resonance T2 mapping imaging.

Aim: Aim of this study was to directly detect increased permeability of vascular lesions by magnetic resonance imaging.Methods: A novel contrast medium with a mean hydrodynamic diameter of 100 nm was prepared from monodispersed iron colloids incorporated into micelles of block copolymers composed of polyethylene glycol and polyamino acid. T2 mapping was applied to differentiate the minimal shortening of T2 relaxation time in balloon-injured rat carotid arteries.Results: The novel contrast medium accumulated in deendothelialized arteries. T2 relaxation times of injured and uninjured arteries were 50.6 ± 9.5 ms and 26.9 ± 2.4 ms, respectively (the mean ± SD, p< 0.01, n=5). The novel contrast medium, but not commercially available contrast media, shortened the T2 relaxation time of the injured artery to 35.5 ± 9.7 ms (p< 0.01, n=4).Conclusion: A novel iron contrast medium enhanced the lesions with increased permeability. The contrast medium in combination with T2 mapping may be useful to detect unstable atherosclerotic plaques.