Late 2011, the new human 11.7T MRI was installed at NIH and preliminary test were performed on brain samples. Initial results showed excellent image quality and indicated successful system integration and stability. Unfortunately, acoustic noise level testing resulted in a quench of the magnet, causing some apparent internal damage. For this reason, the system had to be sent back to the factory in England for inspection and repairs. It is anticipated that reinstallation will not occur prior to early 2013. At the same time, the new 7T human MRI became fully operational with a complete set of pulse sequence translated from the prior 7T. During 2011-2012, two methods were developed that will greatly facilitate scanning at 7T and will also impact future use of 11.7T. The first method dealt with mapping of the transmit B1 field, which is required for many imaging applications. A rapid and accurate method was developed and made available for general use. The second method improves the B1 excitation field by manipulating B0 shims, and this method was demonstrated, published, and patented. This method is expected to be particularly valuable at 11.7T, where the generation of uniform B1 fields is the most challenging. In parallel with the high field developments, AMRI also worked on functional MRI (fMRI) acquisition and analysis methods to improve the study of brain function. Specifically, a improved method for the concurrent acquisition of EEG and fMRI signals was developed submitted for publication. This methods provides an improved suppression of interference artifacts in the EEG signals and is expected to facilitate our research towards revealing the origin and riole of spontaneous brain activity. In addition, a novel method for analysis of fMRI spontaneous activity was developed based on the avalanche hypothesis. The methods allows the identification of networks not revealed with conventional methods such as independent component analysis or correlation analysis, and may therefore be valuable for interpretation of spontaneous activity and its relationship to structural connectivity.

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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
Duyn, Jeff H; Barbara, Thomas M (2014) Sphere of Lorentz and demagnetization factors in white matter. Magn Reson Med 72:1-3
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
Liu, Xiao; Duyn, Jeff H (2013) Time-varying functional network information extracted from brief instances of spontaneous brain activity. Proc Natl Acad Sci U S A 110:4392-7
Liu, Xiao; Chang, Catie; Duyn, Jeff H (2013) Decomposition of spontaneous brain activity into distinct fMRI co-activation patterns. Front Syst Neurosci 7:101
Sati, Pascal; van Gelderen, Peter; Silva, Afonso C et al. (2013) Micro-compartment specific T2* relaxation in the brain. Neuroimage 77:268-78

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