Study of kinetics of ¹⁹F-MRI using a fluorinated imaging agent (¹⁹FIT) on a 3T clinical MRI system

To use ¹⁹F imaging tracer (¹⁹FIT-27) to evaluate kinetics in major organs.

Kinetics studies using proton MRI are difficult because of low concentration of ¹⁹FIT-27 protons relative to background water protons. Because there is no background source of ¹⁹F NMR in a biological body, ¹⁹F may be an ideal nucleus to directly trace ¹⁹FIT-27. However, there are several challenges for reliable ¹⁹F MR imaging and spectroscopy, particularly with clinical whole-body MRI systems, which include low concentrations and long ¹⁹F T₁.

We performed a dynamic ¹⁹F MRI study on mice at a 3T whole-body MRI system using a homemade transmit/receive (Tx/Rx) switch and a Tx/Rx volume RF coil. We used a newly developed fluorine imaging agent, which has 27 identical fluorine atoms with identical chemical shift, a relatively short T₁, and high hydrophilicity. Basic kinetics parameters were estimated from the ¹⁹F signal-time curve.

Resultant fluorine images show fairly high spatial (3 × 3 × 3 mm³) and temporal resolutions. Biodistribution and kinetics of ¹⁹FIT-27 are obtained via ¹⁹F images for major uptake organs.

Whole-body dynamic ¹⁹F MRI of newly developed ¹⁹FIT-27 in mice was obtained with fairly high spatial and temporal resolutions on a 3T clinical MRI system. The present study demonstrates the feasibility of ¹⁹F MRI using our newly developed compound to investigate major organ kinetics.