Image Inhomogeneity Correction in Human Brain at High Field by B1+ and B1- Maps

Hidehiro Watanabe¹, Nobuhiro Takaya¹, Fumiyuki Mitsumori¹

We propose a correction method of image inhomogeneity at high field. The inhomogeneity is originated from B₁^- and measurable B₁⁺. We confirmed that a ratio map of B₁^- to B₁⁺ (ρ) has a similar spatial pattern throughout human various brains from experimental results. The ratio map ρ in human brain was calculated from B₁⁺ maps and images obtained with adiabatic pulses. Then, B₁^- was calculated by ρ B₁⁺. Homogeneous intensity was achieved in the corrected images by B₁⁺ and B₁^-. Water fractions in gray and white matters obtained from corrected M₀ image were in good agreement with reported values.