Multi-site Ultrashort Echo Time 3D Phosphorous MRSI repeatability using novel Rosette Trajectory (PETALUTE)

Purpose: This study aims 1) to implement an operator-independent acquisition, reconstruction, and processing pipeline using a novel rosette k-space pattern for UTE 31P 3D MRSI and 2) to evaluate the clinical applicability and replicability at different experimental setups. Methods: A multicenter repeatability study was conducted for the novel UTE 31P 3D Rosette MRSI at three institutions with different experimental setups. Non-localized 31P MRSI data of 5 healthy subjects at each site were acquired with an acquisition delay of 65 microseconds and a final resolution of 10 x 10 x 10 mm3 in 9 minutes. Spectra were quantified using the LCModel package. The potential acceleration was achieved using compressed sensing on retrospectively undersampled data. Reproducibility at each site was evaluated using the inter-subject coefficient of variance. Results: This novel acquisition and advanced processing techniques yielded high-quality spectra and enabled the detection of the critical brain metabolites at three different sites with different hardware specifications. In vivo feasibility with an acceleration factor of 4 in 6.75 min resulted in a mean Cramer-Rao lower bounds below 20% for PCr, ATPs, and PME, and the mean CoV of ATP/PCr resulted in below 20%. Conclusion We demonstrated that UTE 31P 3D Rosette MRSI acquisition, combined with compressed sensing and LCModel analysis, allows patient-friendly, operator-independent, high-resolution 31P MRSI to be acquired at clinical setups. ### Competing Interest Statement The authors have declared no competing interest.