SYSTEM AND METHOD FOR LOCAL SAR REDUCTION IN MULTISLICE PARALLEL TRANSMISSION MAGNETIC RESONANCE IMAGING USING SAR HOPPING BETWEEN EXCITATIONS

摘要

Described here are a system and method for designing radio frequency ("RF") pulses for parallel transmission ("pTx") applications, and particularly pTx applications in multislice magnetic resonance imaging ("MRI"). The concept of "SAR hopping" is implemented by framing the concept between slice-selective excitations as a constrained optimization problem that attempts designing multiple pulses simultaneously subject to an overall local SAR constraint. This results in the set of RF waveforms that yield the best excitation profiles for all pulses while ensuring that the local SAR of the average of all pulses is below the regulatory limit imposed by the FDA. Pulses are designed simultaneously while constraining local SAR, global SAR, and peak power, and average power explicitly.