Radial PC-bSSFP 4D Flow MRI at 0.6T

Motivation: Phase-contrast balanced steady-state free precession enables the simultaneous acquisition of structural cine images and flow quantification, reducing total scan time. Goal(s): Full coverage 3D PC-bSSFP for simultaneous cine and flow quantification using a free-running radial approach. Approach: A wobbling Archimedian spiral (WASP) 3D radial trajectory was implemented on a prototype 0.6T system, utilizing added bipolar velocity-encoding gradients and referenceless velocity quantification. Results: 3D PC-bSSFP velocity quantification compared well to 2D PC-GRE reference, showing a small velocity underestimation, and producing cine-contrast magnitude images which enabled retrospective reslicing to any cine view. Impact: Referenceless radial cine 3D phase-contrast balanced steady-state free precession (PC-bSSFP) enables simultaneous full coverage cine images and flow quantification during free-breathing. This method is particularly well suited for lower-field systems, taking advantage of relaxed sequence restrictions at lower field strengths.