While Phosphorous (31P) MRS (I) has been promising in experimental and clinical settings since the early 70s, it has been beset by prohibitively lower sensitivity, limited spectral-spatial resolution, and prolonged acquisition. This manuscript and proceedings of the annual scientific meeting of ISMRM in 2022 (REF1) and 2023 (REF2) demonstrate that our novel acquisition strategy, the novel Rosette Trajectory for fast and flexible MR(S)I contrast (Shen et al. 2023 (REF3), later we renamed it as PETALUTE after the translation to the preclinical scanners of 7T and 9.4T), enables operator-independent (1) rapid acquisition (~7 minutes), (2) reconstruction, and (3) processing pipeline, resulting in phosphorous metabolite ratio maps (10 x 10 x 10 mm3) of the whole brain. In response to the “Repeat it with Me” challenge organized by the Reproducible Research study group of ISMRM, we demonstrated the power of this technique in 5 healthy volunteers at three different institutions with different experimental setups (2nd Place: UTE 31P 3D Rosette MRSI Reproducibility Team, REF4). Since the proposed acquisition/reconstruction/processing pipeline was operator/scanner/coil-independent, the Reproducer sub-teams successfully replicated the findings of the original proceeding in 2022 (REF1). As part of this challenge, we provided some MATLAB scripts and k-space data to reproduce some of the results described in this manuscript. The software and data can be downloaded from https://purr.purdue.edu/projects/ismrm31pmrsi. These results will likely be of broad interest across clinical settings since the proposed acquisition strategy is not specific to any region, nuclei, or magnetic field and is operator-independent. This study's resolution and signal-to-noise ratios permit the metabolite maps in an experimentally and clinically feasible timeframe at 3 Tesla and 7T. REF1 Bozymski B, Shen X, Ozen AC, Ibey S, Chiew M, Thomas A, Dydak U, Emir UE. Ultra-Short Echo Time 31P 3D MRSI at 3T with Novel Rosette k-space Trajectory. Proceedings 30th Scientific Meeting, International Society for Magnetic Resonance in Medicine, 2022. REF2 Farley N, Bozymski B, Dydak U, Emir UE*. Fast 3D 31P MRSI Using Novel Rosette Petal Trajectory at 3T with x4 Accelerated Compressed Sensing. Proceedings 31st Scientific Meeting, International Society for Magnetic Resonance in Medicine, 2023. REF3 Shen X, Özen AC, Sunjar A, Ilbey S, Sawiak S, Shi R, Chiew M, Emir UE. Ultrashort T2 components imaging of the whole brain using 3D dual-echo UTE MRI with rosette k-space pattern. Magnetic Resonance in Medicine. 2023;89(2):508–521. REF4 https://challenge.ismrm.org/2023-24-reproducibility-challenge/results-22-23/

1. Multi-site Ultrashort
Echo Time 3D
Phosphorous MRSI
repeatability using
novel Rosette
Trajectory
(PETALUTE)
*S.A. and A.R.C. contributed equally to this work.
1 Institute of Neuroradiology, University Hospital Frankfurt, Goethe University,
Frankfurt/Main, Germany
2 University Cancer Center Frankfurt (UCT), Frankfurt/Main, Germany
3 Frankfurt Cancer Institute (FCI), Frankfurt/Main, Germany
4 Department of Clinical Engineering, Haukeland University Hospital, Bergen, Norway
5 Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway
6 Radiology and biomedical imaging, University of California San Francisco, CA, USA
Physical Sciences, Sunnybrook Research Institute, Toronto, Canada
7 Department of Medical Biophysics, University of Toronto, Toronto, Canada
8 Physical Sciences, Sunnybrook Research Institute, Toronto, Canada
9 Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
10 Department of Radiology, Medical Physics, Medical Center-University of Freiburg, Faculty of Medicine,
University of Freiburg, Freiburg, Germany.
11 Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.
12 Department of Psychology, University of Cambridge, Cambridge, UK.
13 Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA.
14 School of Health Sciences, Purdue University, West Lafayette, Indiana, USA.

2. PETALUTE
• While Phosphorous (31P) MRS (I) has been promising in experimental and clinical settings since the early 70s, it has
been beset by prohibitively lower sensitivity, limited spectral-spatial resolution, and prolonged acquisition. This
manuscript and proceedings of the annual scientific meeting of ISMRM in 2022 (REF1) and 2023 (REF2) demonstrate
that our novel acquisition strategy, the novel Rosette Trajectory for fast and flexible MR(S)I contrast (Shen et al. 2023
(REF3), later we renamed it as PETALUTE after the translation to the preclinical scanners of 7T and 9.4T), enables
operator-independent (1) rapid acquisition (~7 minutes), (2) reconstruction, and (3) processing pipeline, resulting in
phosphorous metabolite ratio maps (10 x 10 x 10 mm3) of the whole brain.
• In response to the “Repeat it with Me” challenge organized by the Reproducible Research study group of ISMRM,
we demonstrated the power of this technique in 5 healthy volunteers at three different institutions with different
experimental setups (2nd Place: UTE 31P 3D Rosette MRSI Reproducibility Team, REF4). Since the proposed
acquisition/reconstruction/processing pipeline was operator/scanner/coil-independent, the Reproducer sub-teams
successfully replicated the findings of the original proceeding in 2022 (REF1). As part of this challenge, we provided
some MATLAB scripts and k-space data to reproduce some of the results described in this manuscript. The software
and data can be downloaded from https://purr.purdue.edu/projects/ismrm31pmrsi.
• These results will likely be of broad interest across clinical settings since the proposed acquisition strategy is not
specific to any region, nuclei, or magnetic field and is operator-independent. This study's resolution and signal-to-
noise ratios permit the metabolite maps in an experimentally and clinically feasible timeframe at 3 Tesla and 7T.

3. References
• REF1 Bozymski B, Shen X, Ozen AC, Ibey S, Chiew M,
Thomas A, Dydak U, Emir UE. Ultra-Short Echo Time 31P 3D
MRSI at 3T with Novel Rosette k-space Trajectory. Proceedings
30th Scientific Meeting, International Society for Magnetic
Resonance in Medicine, 2022.
• REF2 Farley N, Bozymski B, Dydak U, Emir UE*. Fast 3D 31P
MRSI Using Novel Rosette Petal Trajectory at 3T with x4
Accelerated Compressed Sensing. Proceedings 31st Scientific
Meeting, International Society for Magnetic Resonance in
Medicine, 2023.
• REF3 Shen X, Özen AC, Sunjar A, Ilbey S, Sawiak S, Shi R,
Chiew M, Emir UE. Ultrashort T2 components imaging of the
whole brain using 3D dual-echo UTE MRI with rosette k-space
pattern. Magnetic Resonance in Medicine. 2023;89(2):508–
521.
• REF4 https://challenge.ismrm.org/2023-24-reproducibility-
challenge/results-22-23/

4. Figure 1
• The detailed pulse diagram illustrates
achieving an acquisition delay of 65 μs from
the center of the RF pulse. ADC event starts
ten us after the RF pulse. Readout gradients
switch on after 6 ADC points (30 μs). The
total delay for readout gradients from the
end of the RF pulse is 40 μs.

5. Figure 2
• (A) The detailed k-space diagram
illustrates the repetition of the same petal
every 480 μs to achieve a spectral
bandwidth of 2.083kHz. (B) A
representative k-space data was acquired
from a uniform phantom of inorganic
phosphate. Only the first 16 repeats were
illustrated for an average of 1444 petals.
(C) An illustration of the 3D rosette k-space
design with different acceleration factors
(AF1, AF2, and AF4).

6. Figure 3
• Extracted in vivo spectra (blue) from 15
voxels of a 5x3 grid with LCModel fit (black)
for AF1, AF2, and AF4. The location of the
5x3 was illustrated as a yellow box on the
first-time point of FID images.

7. Figure 4 • Mean (solid line) and ± standard deviation (shade)
of 31P MRS mean spectra (magenta) and LCModel
baseline estimations (blue) in each ROI from all
subjects for different AFs. Each column separated by
black lines indicates different sites.

8. FIGURE 5
• Metabolite ratios (PCr/ATP and PME/PDE), spectral quality metrics (SNRLCModel and Linewidth
(LW)LCModel), and corresponding inter-subject CoVs maps for all AFs for sites 1. Maps are overlaid
on the Montreal Neurological Institute-152 (MNI) template. Voxels resulting in a CoV higher than
100 % were masked for each map.

9. Figure 6
• Metabolite ratios (PCr/ATP and PME/PDE), spectral quality metrics (SNRLCModel and Linewidth
(LW)LCModel), and corresponding inter-subject CoVs maps for all AFs for sites 3. Maps are overlaid
on the Montreal Neurological Institute-152 (MNI) template. Voxels resulting in a CoV higher than
100 % were masked for each map.

10. FIGURE 7
• The mean metabolite
ratios (PCr/ATP and
PME/PDE) and spectral
quality metrics (SNRLCModel
and Linewidth(LW)LCModel)
for each ROI across
subjects for each site and
AFs.

11. Figure 8
• The mean inter-subject CoVs
of metabolite ratios(PCr/ATP
and PME/PDE) and spectral
quality metrics(SNRLCModel and
Linewidth(LW)LCModel) for each
ROI across subjects for each
site and AFs.

12. Figure 1S
The control file used in the
LCModel analysis.

13. Figure 2S
• Gray (orange) and white
matter ROI masks for
surface (Site 1) and volume
coils (Site 2) overlaid on the
Montreal Neurological
Institute-152 template. The
interactive AFNI view,
showing slices and spectra
graphs, was used to
visualize the final result
spectra.

14. Site 1
Site 2
Site 3
5 subjects and 3
averages for each
subject at each site.
Gaussian
Filtering and
Line
broadening
Zero -filling
Zero-order
phase
correction
Mean of 3
measurements
Compressed
Sensing
Reconstruction
LCModel
Analysis
Register to MNI
Template
METABOLITE MAPS IN
MNI SPACE

15. Figure 3S
The workflow of
post‐processing steps

16. Figure 4S • The mean zero-order phase estimations of the LCModel
analysis for each ROI across subjects for each site and AF.

17. Figure 5S
The mean CRLB for each
ROI across subjects for
each site and AF.

18. References
• REF1 Bozymski B, Shen X, Ozen AC, Ibey S, Chiew
M, Thomas A, Dydak U, Emir UE. Ultra-Short Echo
Time 31P 3D MRSI at 3T with Novel Rosette k-space
Trajectory. Proceedings 30th Scientific Meeting,
International Society for Magnetic Resonance in
Medicine, 2022.
• REF2 Farley N, Bozymski B, Dydak U, Emir UE*.
Fast 3D 31P MRSI Using Novel Rosette Petal
Trajectory at 3T with x4 Accelerated Compressed
Sensing. Proceedings 31st Scientific Meeting,
International Society for Magnetic Resonance in
Medicine, 2023.
• REF3 Shen X, Özen AC, Sunjar A, Ilbey S, Sawiak
S, Shi R, Chiew M, Emir UE. Ultrashort T2
components imaging of the whole brain using 3D
dual-echo UTE MRI with rosette k-space pattern.
Magnetic Resonance in Medicine. 2023;89(2):508–
521.
• REF4 https://challenge.ismrm.org/2023-24-
reproducibility-challenge/results-22-23/