MR coronary angiography in pigs with Intraarterial injections of a hyperpolarized 13C substance

A new diagnostic application of a water-soluble contrast medium (CM) based on the hyperpolarization of a C-13 substance is introduced. The degree of polarization achieved is > 30%, which is about a factor of 10(5) higher than the thermal equilibrium polarization level at 1.5 T. Imaging of hyperpolarized (HP) CM during a cardiac interventional MRI procedure was studied. Catheters were positioned in the left and right coronary arteries of pigs. A coil tuned to C-13 was used for nonproton imaging. The HP-C-13 CM (similar to 5 ml, 0.5 M, similar to 30% polarization) was injected during projection imaging using a fully balanced steady-state free precession (SSFP) pulse sequence with and without cardiac gating. The contrast agent-filled catheter was clearly visible during the procedure. The coronary arteries were well depicted and the signal-to-noise ratios (SNRs) were in the range of 10-40. The use of HP-C-13 CM may provide a new diagnostic procedure for interventional MRI.