Towards a generalization of the MP2RAGE partial volume estimation model to account for B1+ inhomogeneities at 7T

Brain morphometry performed with magnetic resonance (MR) imaging is affected by partial volume (PV) effects when single voxels contain the signal from two different tissues. This paper proposes a generalization of the MP2 RAGE sequence PV estimation model which accounts for transmitted magnetic field $(B1^{+})$ inhomogeneities at 7T. Our simulation experiments demonstrated that the PV estimation error of the proposed model is significantly lower than the error obtained with the same model neglecting $B1^{+}$ inhomogeneities (p<0.0001). The accuracy and precision of the $B1^{+}$ model (acc=92.0%, prec=89.6%) was significantly increased compared to the non $B1^{+}$ model (acc=69.8%, prec=65.4%). This highlights the importance of accounting for $B1^{+}$ inhomogeneities when computing PV on MP2RAGE data, which would otherwise limit the accuracy of brain morphometry at 7T.