Susceptibility-Induced Distortion Correction in Hyperpolarized Echo Planar Imaging


Purpose: Echo planar imaging is an attractive rapid imaging readout that can image hyperpolarized compounds in vivo. By alternating the sign of the phase encoding gradient waveform, spatial offsets arising from uncertain frequency shifts can be determined. We show here that blip-reversed echo planar imaging can also be used to correct for susceptibility and $B_0$ inhomogeneity effects that would otherwise produce image-domain distortion in the heart. Methods: Previously acquired blip-reversed cardiac 3D-Spectral-Spatial echo planar imaging volumetric timecourses of hyperpolarized [1-$^{13}$C]pyruvate were distortion corrected by a deformation field estimated by reconstructing signal-to-noise ratio (SNR)- weighted progressively subsampled temporally summed images of each metabolite. Results: Reconstructing blip-reversed data as proposed produced volumetric timecourses that overlaid with proton reference images more consistently than without such corrections. Conclusion: The method proposed may form an attractive method to correct for image-domain distortions in hyperpolarized echo planar imaging experiments.

In Magnetic Resonance in Medicine