Sweep Imaging with Fourier Transformation (SWIFT)

A radically new method to accomplish magnetic resonance imaging (MRI), called sweep imaging with Fourier transformation (SWIFT), was proposed in 2006. SWIFT stands alone from any other MRI techniques due to its unique image acquisition protocol (pulse sequence), which involves exciting spins with a frequency-swept pulse and simultaneously acquiring the spins' signals. This chapter presents an introduction to SWIFT, along with its variations and applications. In its most basic form, SWIFT executes a swept RF excitation while nearly simultaneously acquiring the spins' signal. To encode spatial information, this process is performed in the presence of a field gradient. The RF power deposition of FM pulses applied in the presence of field gradients can be significantly reduced by modulating the amplitude of those gradients. Presently, fully functioning SWIFT sequences have been implemented only on research scanners.