Journal
MAGNETIC RESONANCE IN MEDICINE
Volume 79, Issue 5, Pages 2481-2490Publisher
WILEY
DOI: 10.1002/mrm.26911
Keywords
single-voxel magnetic resonance spectroscopy; phase rotation; short echo time
Funding
- Monroy-Marks Career Development Fund
- Carolito Stiftung Fund
- Leona M. and Harry B. Helmsley Charitable Trust
- Sylvia Schaefer Alzheimer's Research Fund
- National Institute of Neurological Disorders and Stroke
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PurposeApplication of phase rotation to the STRESS (=STEAM+PRESS) localization scheme, to shorten echo time, minimize J-coupling dephasing and estimate B1+ inhomogeneity. STRESS (=STEAM+PRESS) simultaneously refocuses and acquires the double spin echo (SE123) and stimulated echo (STE-) pathways, combining PRESS-like signal with lower chemical shift displacement as in STEAM. Phase rotation effectively separates coherence pathways, allows reduction of spoiling gradients moments leading to reduction in echo time. Implementing it in STRESS allows one to individually phase-correct SE123 and STE- prior to combination. Moreover, B1+ inhomogeneity can be assessed by comparing the measured ratio of resonance intensities of SE123 and STE- pathways to the simulated one. MethodsIn vivo spectra were acquired from a single voxel placed in the sensory-motor cortex of 10 healthy volunteers, using phase rotation-STRESS/PRESS/STEAM sequences at 3 T scanner. The phases of each slice-selective pulse were incremented by 1/2/3=22.5 degrees/-45 degrees/45 degrees. ResultsPhase rotation-STRESS showed quantification accuracy (% Cramer Rao lower bounds) and reproducibility (% coefficients of variation) comparable to PRESS and STEAM, in both phantoms and in vivo study. Minimal echo time achieved was 13 ms. ConclusionPhase rotation complements STRESS by reducing echo time, allowing processing of each pathway individually prior to addition and providing B1+ estimation in single voxel proton magnetic resonance spectroscopy. Magn Reson Med 79:2481-2490, 2018. (c) 2017 International Society for Magnetic Resonance in Medicine.
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