Relaxation-selective magnetic resonance imaging

The Bloch equations with T2 relaxation can be inverted in closed form with respect to T2, using inverse scattering theory. Hence, radio frequency pulses can be calculated that cause a final magnetization response that is any desired function of T2, provided that function is physically realizable (however, there are strong constraints on what is physically realizable). A useful subclass of such pulses are `dressingʹ pulses, which store the magnetization on the z-axis, with magnitude a given function of T2. This enables spins to be selectively nulled according to their T2 – this is demonstrated by obtaining a relaxation-selective image of a phantom.