Counteracting RF inhomogeneity on the upper legs at 3T using strongly modulating pulses
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چکیده
Introduction: Strongly modulating pulses (SMP) [1] have been used to homogenize tissue flip angle (FA) on upper legs at 3 T. The muscle and fat tissues were discriminated in the pulse design algorithm via their resonance frequencies to achieve different flip angles. For a given TR, by implementing the respective nominal Ernst angles of the two different tissues in a spoiled gradient recalled echo (GRE) sequence, a higher signal for both tissues in addition to a better signal uniformity can be in principle obtained. After measuring the B1 and ΔB0 maps to generate the corresponding 2D histogram, a strongly modulating pulse with Ernst angles of 19° (for muscle) and 37° (for fat) was designed (TR=80 ms [2]). The pulse was then inserted in a GRE sequence and its performance was compared with the one of a strong hard pulse with nominal flip angle equal to 19°. Measurements of the FA when using the SMP were also performed to confirm the theory.
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تاریخ انتشار 2008