Rapid determination of the RF pulse flip angle and spin-lattice relaxation time for materials imaging.
For samples with T1s longer than 10s, calibration of the RF probe and a measurement of T1 can be very time-consuming. A technique is proposed for use in imaging applications where one wishes to rapidly obtain information about the RF flip angle and sample T1 prior to imaging. The flip angle measurement time is less than 1s for a single scan. Prior knowledge of the RF flip angle is not required for the measurement of T1. The resulting time savings in measuring the values of flip angle and T1 are particularly significant in the case of samples with very long T1 and short T2*. An imaging extension of the technique provides RF flip angle mapping without the need for incrementing the pulse duration, i.e., RF mapping can be performed at fixed RF amplifier output.
Mastikhin
Igor V
IV
Department of Physics, MRI Centre, University of New Brunswick, P.O. Box 4400, Fredericton, E3B 5A3, Canada. mast@unb.ca