Spin-Echo S = k  (1-exp(-TR/T1)) exp(-TE/T2) Inversion Recovery (180-90) S = k  (1-2exp(-TI/T1)+exp(-TR/T1)) Inversion Recovery (180-90-180) S = k  (1-2exp(-TI/T1)+exp(-TR/T1)) exp(-TE/T2) Gradient Recalled Echo S = k  (1-exp(-TR/T1)) Sin exp(-TE/T2*) / (1 -Cos exp(-TR/T1))