Multi-shot Echo Planar Imaging for accelerated Cartesian MR Fingerprinting: an alternative to conventional spiral MR Fingerprinting

Purpose: To develop an accelerated Cartesian MRF implementation using a multi-shot EPI sequence for rapid simultaneous quantification of T1 and T2 parameters.
Methods: The proposed Cartesian MRF method involved the acquisition of highly subsampled MR images using a 16-shot EPI
readout. A linearly varying flip angle train was used for rapid, simultaneous T1 and T2 quantification. The results were compared
to a conventional spiral MRF implementation. The acquisition time per slice was 8 s and this method was validated on two different
phantoms and three healthy volunteer brains in vivo.
Results: Joint T1 and T2 estimations using the 16-shot EPI readout are in good agreement with the spiral implementation using
the same acquisition parameters (deviation less than 4% for T1 and less than 6% for T2). The T1 and T2 values also agree with the
conventional values previously reported in the literature. The visual qualities of fine brain structures in the multi-parametric maps
generated by multi-shot EPI-MRF and Spiral-MRF implementations were comparable.
Conclusion: The multi-shot EPI-MRF method generated accurate quantitative multi-parametric maps similar to conventional
Spiral-MRF. This multi-shot approach achieved considerable k-space subsampling and comparatively short TRs in a similar manner
to spirals and therefore provides an alternative for performing MRF using an accelerated Cartesian readout; thereby increasing the
potential usability of MRF