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Fast B1 mapping based on interleaved-three-flip-angle (ITFA) excitation
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10.1118/1.4824151
/content/aapm/journal/medphys/40/11/10.1118/1.4824151
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/40/11/10.1118/1.4824151
View: Figures

Figures

Image of FIG. 1.
FIG. 1.

The proposed ITFA pulse sequence that incorporates interleaved-three-flip-angle excitation RF pulses.

Image of FIG. 2.
FIG. 2.

Isoratio plots of R, R with noise, and R with respect to α and T. (a) (α, β = 1.5α, γ = 2α) and (b) (α, β = 1.2α, γ = 1.4α).

Image of FIG. 3.
FIG. 3.

The magnitude of the minimum of {S, S, S} with respect to α and T. (a) (α, β = 1.5α, γ = 2α) and (b) (α, β = 1.2α, γ = 1.4α).

Image of FIG. 4.
FIG. 4.

The RMS B estimation errors under three different noise levels. (a) All the three flip angles (α,β,γ) are near the optimal flip angles. (b) Some of (α,β,γ) are far from the optimal flip angles.

Image of FIG. 5.
FIG. 5.

The RMS B estimation errors on the (β, γ) space when the nominal flip angle of α is 25°. (a) T is 735 ms. (b) T is 1190 ms. (c) T is 2400 ms. (d) The mean values of RMS B estimation errors from (a) to (c). The red circle indicates the optimal flip angles determined by the minimization over the given T range.

Image of FIG. 6.
FIG. 6.

The RMS B estimation errors with respect to T under three different noise levels when the nominal flip angles are (25°, 70°, 80°).

Image of FIG. 7.
FIG. 7.

The human-brain-mimicking phantom. The phantom has six compartments (from regions 1 to 6) which have T/T values similar to the ones of brain tissues at 3T.

Image of FIG. 8.
FIG. 8.

The flip angle maps of the phantom obtained with DAM, ITFA, and AFI methods, and the T-map of the phantom.

Image of FIG. 9.
FIG. 9.

The average RMS B estimation errors at the six compartments of the phantom in ITFA and AFI B mappings. The estimation errors were computed from 10 repeated experiments of ITFA and AFI on the phantom.

Image of FIG. 10.
FIG. 10.

The flip angle maps on the human head obtained with the DAM, ITFA, and AFI methods. The scan times of ITFA and AFI were the same.

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/content/aapm/journal/medphys/40/11/10.1118/1.4824151
2013-10-10
2014-04-17
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Fast B1 mapping based on interleaved-three-flip-angle (ITFA) excitation
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/40/11/10.1118/1.4824151
10.1118/1.4824151
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