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- Title
Improving T<sub>2</sub>-weighted imaging at high field through the use of k<sub>T</sub>-points.
- Authors
Eggenschwiler, Florent; O'Brien, Kieran R.; Gruetter, Rolf; Marques, José P.
- Abstract
Purpose At high magnetic field strengths ( B0 ≥ 3 T), the shorter radiofrequency wavelength produces an inhomogeneous distribution of the transmit magnetic field. This can lead to variable contrast across the brain which is particularly pronounced in T2-weighted imaging that requires multiple radiofrequency pulses. To obtain T2-weighted images with uniform contrast throughout the whole brain at 7 T, short (2-3 ms) 3D tailored radiofrequency pulses (kT-points) were integrated into a 3D variable flip angle turbo spin echo sequence. Methods The excitation and refocusing 'hard' pulses of a variable flip angle turbo spin echo sequence were replaced with kT-point pulses. Spatially resolved extended phase graph simulations and in vivo acquisitions at 7 T, utilizing both single channel and parallel-transmit systems, were used to test different kT-point configurations. Results Simulations indicated that an extended optimized k-space trajectory ensured a more homogeneous signal throughout images. In vivo experiments showed that high quality T2-weighted brain images with uniform signal and contrast were obtained at 7 T by using the proposed methodology. Conclusion This work demonstrates that T2-weighted images devoid of artifacts resulting from B1+ inhomogeneity can be obtained at high field through the optimization of extended kT-point pulses. Magn Reson Med 71:1478-1488, 2014. © 2013 Wiley Periodicals, Inc.
- Publication
Magnetic Resonance in Medicine, 2014, Vol 71, Issue 4, p1478
- ISSN
0740-3194
- Publication type
Academic Journal
- DOI
10.1002/mrm.24805