Meeting Banner
Abstract #4247

Mitigate B1+ Inhomogeneity by Slice-Selective Composite Excitation Pulses

Yi-Cheng Hsu1, Ying-Hua Chu2, Thomas Witzel3, I-Liang Chern4, Fa-Hsuan Lin2

1Department of Mathematics, Nnational Taiwan University, Taipei, Taiwan; 2Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan; 3A. A. Martinos Center, Massachusetts General Hospital, Charlestown, MA, United States; 4Department of Mathematics, National Taiwan University, Taipei, Taiwan

To mitigate the B1+ inhomogeneity and to achieve more homogeneous large flip angle in high field MRI, we propose a method of composite excitation pulses, which does not require the refocusing slice selection gradient between two pulses. At 3T MRI, we demonstrate and compare this method to the standard single pulse excitation and a previously reported two-pulse method. We also used the Bloch equation to simulate the magnetization after our two-pulse excitation over a slice FOV to prove that our proposed composite pulses method can also work with slice-selective pulses.

Abstract PDF Presentation Video

Keywords

absolute accordingly achieve achieving amounting amplitude approximation array audience axis better biomedical brain cause causes clinical close closer coil comparing compensate compensation component composite conclude condition consequently contrast decrease dependent design desired diagnosis dielectric difficult dimensional distribution duration dynamics efficiently empirical engineering equation error even excellent excitation excite excited exciting expect fast field freeman frequency furthermore general gradient homogeneity homogeneous hospital human imperfections improve improvement infinite inhomogeneity inhomogeneous inside institute knowledge larger latency leave limited linear lobes loss magnetization makes mathematics maximal medicine mitigate mitigating modified national nominal nonlinear object opposite optimized parallel park phantom polarity predicting previously profile propose proposed pulse pulses radio ramp ranging reduce reduced reduction refocusing remaining reported saline scientists selected selection selective shims shortened simulate simulation simulations simultaneous slew slice spatially spherical spin strength strengths successfully tailored target targeted theory thick transmission transmits transmitted transmitter transverse unchanged uniformity usually waiting wavelength whole