1Radiology,
Leiden University Medical Center, Leiden, Netherlands, Zuid-Holland,
Netherlands; 2Philips Research Laboratories, Hamburg, Germany
High resolution B1+ mapping techniques in the brain at high field often show residual structure from, in particular, the ventricles. This can be partially explained by the high contrast in electrical conductivity of CSF with respect to white and grey matter, in addition to long relaxation time-related effects. This factor should be considered when assessing the accuracy of various B1+ mapping sequences.