Relaxation-selective magnetic resonance imaging

The Bloch equations with T-2 relaxation can be inverted in closed form with respect to T-2, using inverse scattering theory. Hence, radio frequency pulses can be calculated that cause a final magnetization response that is any desired function of T-2, provided that function is physically realizable (however, there are strong constraints on what is physically realizable). A useful subclass of such pulses are 'dressing' pulses, which store the magnetization on the z-axis, with magnitude a given function of T-2. This enables spins to be selectively nulled according to their T-2- this is demonstrated by obtaining a relaxation-selective image of a phantom. (C) 1999 Elsevier Science B.V. All rights reserved.