Localizing the Excitation to Reduce Scan Time Using Nonlinear Gradient Fields

Emre Kopanoglu¹, ², Ugur Yilmaz¹, ², Burak Akin², Volkan Acikel¹, ², Ergin Atalar¹, ²

For numerous applications, the region of interest is merely a portion of the imaged volume. Conventional one-dimensional RF pulses have relatively low SAR, but they cannot excite local regions and therefore causes long scan times. Although small volumes can be excited using multi-dimensional excitation pulses, such pulses are long and/or have relatively high SAR. It is shown that, using gradient fields with nonlinear variation in space, excitation regions can be confined in three dimensions without increasing pulse duration and SAR. In this abstract we show that a 60% decrease in required phase-encoding steps is obtained while imaging the occipital lobe of the brain. Initial in-vivo results are presented.