Conical readouts in free-running 3D bSSFP imaging

Motivation: The 3D radial golden angle phyllotaxis pattern integrated into the Free Running framework, supports 5D imaging of the heart during free breathing and without the need for an ECG or navigators. However, it inherently oversample low k-space frequencies with sparser coverage at the periphery of k-space. Goal(s): Our proposed approach relies on the same phyllotaxis pattern but substitutes the radial readout with spiral sections, enhancing high-frequency sampling, and reduces the overall number of radial readouts needed. Approach: We formulated the cone equations to account for un-aliasing and hardware limitations and validated our method by simulating bSSFP acquisition. Results: We obtained improved image quality. Impact: 3D spirals span a broader extent of k-space compared to radial readouts and allow for a higher sampling density at the periphery of k-space. This may help support higher spatial resolution, reduced noise, and improved image quality.