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

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

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

METHODS AND MATERIALS: We performed a dynamic 19 F 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 19 F signal-time curve.

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

CONCLUSIONS: Whole-body dynamic 19 F MRI of newly developed 19 FIT-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 19 F MRI using our newly developed compound to investigate major organ kinetics.