MRI Physics

Principal Investigator: Marcin Jankiewicz

Field inhomogeneities are one of the most common and fundamental problems in MRI, as they corrupt the quality and hence the practical use of MR images and spectra. We have analysed composite waveform performance for a wide range of field inhomogeneities and conclude that performance is highly dependent on the inhomogeneity as well as the desired % error in achieved flip-angle (FA). Our findings result in a practical quantification of performance of composite waveforms giving insight into realistic and clinically realizable alternatives to existing and underperforming imaging sequences.

We have shown how a class of B1 excitation pulses, generated with Shinnar-Le Roux (SLR) algorithm improves the performance of a FLASH (spoiled gradient echo) sequence. This sequence, in its original form, is used in almost every MR experiment, including structural imaging, spectroscopy and diffusion tensor imaging. Principal Investigator: We have presented results of in-vivo experiments utilizing a train (a composite waveform) of SLR pulses with a simultaneous slice-selection or slice-selective realization of adiabatic BIR-4. Limited time penalty (short repetition time) opens new avenues for applications in challenging imaging scenarios and applications.