Simultaneous Optimization of MP2RAGE T 1 -weighted (UNI) and FLuid And White matter Suppression (FLAWS) brain images at 7T using Extended Phase Graph (EPG) Simulations.

Autor: Dokumacı AS; Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.; London Collaborative Ultra high field System (LoCUS), London, United Kingdom., Aitken FR; Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.; London Collaborative Ultra high field System (LoCUS), London, United Kingdom., Sedlacik J; London Collaborative Ultra high field System (LoCUS), London, United Kingdom.; Radiology Department, Great Ormond Street Hospital for Children, London, United Kingdom., Bridgen P; Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.; London Collaborative Ultra high field System (LoCUS), London, United Kingdom., Tomi-Tricot R; Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.; London Collaborative Ultra high field System (LoCUS), London, United Kingdom.; MR Research Collaborations, Siemens Healthcare Limited, Camberley, United Kingdom., Mooiweer R; Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.; MR Research Collaborations, Siemens Healthcare Limited, Camberley, United Kingdom., Vecchiato K; London Collaborative Ultra high field System (LoCUS), London, United Kingdom.; Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom.; Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom., Wilkinson T; Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.; London Collaborative Ultra high field System (LoCUS), London, United Kingdom., Casella C; London Collaborative Ultra high field System (LoCUS), London, United Kingdom.; Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom., Giles S; Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.; London Collaborative Ultra high field System (LoCUS), London, United Kingdom., Hajnal JV; Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.; London Collaborative Ultra high field System (LoCUS), London, United Kingdom., Malik SJ; Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.; London Collaborative Ultra high field System (LoCUS), London, United Kingdom., O'Muircheartaigh J; London Collaborative Ultra high field System (LoCUS), London, United Kingdom.; Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom.; Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.; MRC Centre for Neurodevelopmental Disorders, King's College London, London, United Kingdom., Carmichael DW; Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.; London Collaborative Ultra high field System (LoCUS), London, United Kingdom.
Jazyk: angličtina
Zdroj: Magnetic resonance in medicine [Magn Reson Med] 2023 Mar; Vol. 89 (3), pp. 937-950. Date of Electronic Publication: 2022 Nov 09.
DOI: 10.1002/mrm.29479
Abstrakt: Purpose: The MP2RAGE sequence is typically optimized for either T 1 -weighted uniform image (UNI) or gray matter-dominant fluid and white matter suppression (FLAWS) contrast images. Here, the purpose was to optimize an MP2RAGE protocol at 7 Tesla to provide UNI and FLAWS images simultaneously in a clinically applicable acquisition time at <0.7 mm isotropic resolution.
Methods: Using the extended phase graph formalism, the signal evolution of the MP2RAGE sequence was simulated incorporating T 2 relaxation, diffusion, RF spoiling, and B 1 + variability. Flip angles and TI were optimized at different TRs (TR MP2RAGE ) to produce an optimal contrast-to-noise ratio for UNI and FLAWS images. Simulation results were validated by comparison to MP2RAGE brain scans of 5 healthy subjects, and a final protocol at TR MP2RAGE  = 4000 ms was applied in 19 subjects aged 8-62 years with and without epilepsy.
Results: FLAWS contrast images could be obtained while maintaining >85% of the optimal UNI contrast-to-noise ratio. Using TI 1 /TI 2 /TR MP2RAGE of 650/2280/4000 ms, 6/8 partial Fourier in the inner phase-encoding direction, and GRAPPA factor = 4 in the other, images with 0.65 mm isotropic resolution were produced in <7.5 min. The contrast-to-noise ratio was around 20% smaller at TR MP2RAGE  = 4000 ms compared to that at TR MP2RAGE  = 5000 ms; however, the 20% shorter duration makes TR MP2RAGE  = 4000 ms a good candidate for clinical applications example, pediatrics.
Conclusion: FLAWS and UNI images could be obtained in a single scan with 0.65 mm isotropic resolution, providing a set of high-contrast images and full brain coverage in a clinically applicable scan time. Images with excellent anatomical detail were demonstrated over a wide age range using the optimized parameter set.
(© 2022 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)
Databáze: MEDLINE
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