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- Markenroth Bloch, Karin, et al.
(författare)
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Benefits, Challenges and Applications of Ultra-High Field Magnetic Resonance
- 2021. - 1
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Ingår i: Advanced Neuro MR Techniques and Applications. - 9780128224793 - 9780128224953 ; 4, s. 533-571
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Bokkapitel (refereegranskat)abstract
- Human ultra-high field (UHF) MR at 7T and above has been on a rapid rise since the first installations in the 1990s, motivated by the opportunities created by SNR gains and contrast changes. Research efforts were for long focused mainly on technological developments to cope with the challenges posed by UHF. This has brought 7T MR neuroimaging to maturity and into an application dominated realm, further accelerated by the availability of clinically certified commercial 7T systems. This chapter aims to give an overview of UHF MR in a neuroimaging context by first providing an overview of the basic physical motivations for going to higher fields. It will then describe the challenges and limitations of working at higher field strengths, and outline some of the currently available solutions. This chapter also provides a discussion of the potentials of UHF by highlighting some of the neuro applications that benefit from UHF.
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| 2. |
- Helms, Gunther, et al.
(författare)
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Quantitative multi-parametric MRI measurements
- 2021
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Ingår i: Advanced Neuro MR Techniques and Applications. - 9780128224793 ; , s. 451-465
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Quantitative multi-parametric MRI measurements provide reproducible metrics of the MR properties of water to characterize brain tissue. The available parameters are determined by the acquisition protocols. These commonly utilize multiple spin-echo sequences, steady-state sequences of gradient-recalled echoes at variable flip angles or echo-planar images, besides novel non-repetitive acquisitions. Water from different environments at dimensions smaller than the voxel, such as myelin water, can be detected by adapted biophysical models (e.g., SyMRI or mcDESPOT) yielding estimates of the corresponding fractional volumes for segmentation. Multi-parametric MRI measurements can be used to simulate bias-free synthetic images for a wide range of pulse sequences. Due to their specific sensitivity, the MR parameters provide information on the main drivers of contrast in brain tissue, chiefly myelin and iron, or can be used as biomarkers.
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