New Developments and Applications of the MP2RAGE Sequence - Focusing the Contrast and High Spatial Resolution R1 Mapping
Figure 6
Transverse and coronal slices of: (a) Uncorrected R1 maps using protocol ii-B; (b,c) Uncorrected R1 maps using using protocol ii-A with two different head and dielectric pad positions; (e) Corrected R1 maps using protocol ii-B; (f,g) Corrected R1 maps using using protocol ii-A with two different head and dielectric pad positions; (e,h) B1+ maps corresponding to the two different head and dielectric pad positions; R1 maps are shown in a short range from 0.75 to 0.95 s−1 to emphasize the sensitivity of the R1 maps to the B1 in-homogeneity, and the success of its correction.
Arrows point out regions of increased difference between in the B1+ maps that have clear implications on the uncorrected high resolution R1 maps. Blue arrows point out white matter fibber bundles with increased R1 values with respect to the remaining white matter. Red arrows point out regions of significant R1 differences from the ground truth prior to the B1+ correction, which are successfully corrected. The white arrow points out a region of very low B1+ field where the adiabatic condition was not reached and hence the R1 values are largely overestimated and not possible to correct with the proposed methodology.