Removing air-tissue artifacts in phase images by modulating the air susceptibility
نویسندگان
چکیده
x10 Figure 1 Sagittal slices of a phantom (1 row) and sagittal and axial slices of two subjects (2 and3 row) representing the: (a) frequency shift maps, Δω, as measured from the multiple echo before oxygen modulation; (b) frequency shift map attributed to oxygen, Δωoxy (difference between Δω at minimum and maximum oxygen concentration, multiplied by 10 facilitate visualization); (c) frequency shift map before oxygen modulation corrected with polynomials corresponding to first and second order shimm terms; (d) field map as measured from the multiple echo before oxygen modulation corrected with polynomials corresponding to first and second order shimm terms and Δωoxy. On the right it is possible to visualize the good correlation between the measured oxygen fraction (green triangles) and the amplitude of the multiplicative factor (blue circles) needed to cancel the spatial inhomogeneities from the original frequency shift maps. Removing air-tissue artifacts in phase images by modulating the air susceptibility
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