Rapid MRI by SWIFT

From Iibis

Djaudat Idiyatullin, Ph.D., guest lecturer

University of Minnesota, Center for MRI Research

A novel fast and quiet method MRI called SWIFT (SWeep Imaging with Fourier Transformation) creates new opportunities for imaging in medicine and materials science. In SWIFT, time-domain signals are acquired in a time-shared manner during a swept radiofrequency excitation of the nuclear spins. With negligible time between excitation and signal acquisition, new possibilities exist for imaging objects consisting of spins with extremely fast transverse relaxation rates, such as macromolecules, semi-solids, and quadrupolar nuclei. The field gradient used for spatial-encoding is not pulsed on and off, but rather is stepped in orientation in an incremental manner, which results in low acoustic noise. This unique acquisition method is expected to be relatively insensitive to sample motion, which is important for imaging live objects. Additionally, the frequency-swept excitation distributes the signal energy in time and thus dynamic range requirements for proper signal digitization are reduced compared with conventional MRI. For demonstration, in– vitro and in- vivo images of a solid- like and soft tissues will be presented.