During 2008-2009 significant progress was made in a number of areas. A new 32 channel detector for 7T MRI was tested and evaluated and shown to lead to a 20% improved sensitivity. Comparison with simulations showed that this performance now approaches the maximum theoretically achievable with the current technology. Future efforts may include cooling of the detector elements. Improved techniques for homogenizing the Bo field were developed and shown to be significantly more robust than previous techniques. Also, improved techniques were developed to measure transverse relaxation parameters. A project to improve B1 uniformity based on multi-channel excitation was continued with a focus to more accurately control the individual channels. Measurements on realistic head phantoms have indicated that the method is effective in reducing spatial B1 variations;nevertheless, additional technology may be needed to achieve the uniformity required for specific applications. A new scanner platform currently being purchased will facilitate this.
| Gudino, Natalia; de Zwart, Jacco A; Duan, Qi et al. (2018) Optically controlled on-coil amplifier with RF monitoring feedback. Magn Reson Med 79:2833-2841 |
| Liu, Jiaen; de Zwart, Jacco A; van Gelderen, Peter et al. (2018) Effect of head motion on MRI B0 field distribution. Magn Reson Med 80:2538-2548 |
| van Gelderen, Peter; Jiang, Xu; Duyn, Jeff H (2017) Rapid measurement of brain macromolecular proton fraction with transient saturation transfer MRI. Magn Reson Med 77:2174-2185 |
| Jiang, Xu; van Gelderen, Peter; Duyn, Jeff H (2017) Spectral characteristics of semisolid protons in human brain white matter at 7 T. Magn Reson Med 78:1950-1958 |
| Gudino, Natalia; Duan, Qi; de Zwart, Jacco A et al. (2016) Optically controlled switch-mode current-source amplifiers for on-coil implementation in high-field parallel transmission. Magn Reson Med 76:340-9 |
| Duan, Qi; Nair, Govind; Gudino, Natalia et al. (2015) A 7T spine array based on electric dipole transmitters. Magn Reson Med 74:1189-97 |
| van Gelderen, Peter; Mandelkow, Hendrik; de Zwart, Jacco A et al. (2015) A torque balance measurement of anisotropy of the magnetic susceptibility in white matter. Magn Reson Med 74:1388-96 |
| Duan, Qi; Duyn, Jeff H; Gudino, Natalia et al. (2014) Characterization of a dielectric phantom for high-field magnetic resonance imaging applications. Med Phys 41:102303 |
| Duyn, Jeff H (2014) Frequency shifts in the myelin water compartment. Magn Reson Med 71:1953-5 |
| Duyn, Jeff H; Barbara, Thomas M (2014) Sphere of Lorentz and demagnetization factors in white matter. Magn Reson Med 72:1-3 |
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