1. In a method for providing an NMR image of a region using a sequence of rf excitations each involving a different field providing an array of received signals which are processed to form projection signals the steps of: exciting the region with an rf inversion pulse following the decay of the received signal; and driving the magnetization in the region back to equilibrium between rf excitations by exciting the region with an rf pulse occurring at the peak of the received spin-echo signal providing a tipping angle of substantially 90.degree..