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

MethodsA 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 s and a final resolution of 10 x 10 x 10 mm3 in 9 min. 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.

ResultsThis 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, PME, and the mean CoV of ATP/PCr resulted in below %20.

ConclusionWe 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.