Benchtop-MRI for in vivo imaging using a macromolecular contrast agent based on hydroxyethyl starch (HES).

Magnetic resonance imaging (MRI) is a powerful non-invasive diagnostic tool in the clinical setting. However, the wide spread use of small animal MRI instruments for preclinical research purposes has been limited by the need for strong magnets operating in the range of 4.7-11.7T. To obtain such strong and homogenous magnetic fields, superconducting electromagnets cooled with liquid helium are used, which highly increases the costs for research studies. Here we report on the use of a pilot 0.5T benchtop MRI (BT-MRI) operating with a permanent magnet and designed for in vivo imaging of mice. It was used to evaluate a novel macromolecular MRI contrast agent based on a Gd-chelate of hydroxyethyl starch (Gd-HES). Images obtained by the BT-MRI showed the high contrast enhancement of Gd-HES, its longevity in the circulation, as well as its utility for tumor diagnosis, urography and angiography. These results demonstrate the potential of the new BT-MRI as a useful research tool, as well as that of Gd-HES as a new MRI contrast agent.