Storing phase information in the longitudinal direction: Experimental verification of double diffusion encoding with stimulated echoes applied to closed pores

When applying double diffusion encoding (DDE) to arbitrarily shaped closed pores, non-vanishing imaginary parts in the diffusion signal arise, which allow determining the average shape of the pores in the considered volume element. Key limitations in such experiments are the available gradient strength and reaching the diffusion long-time limit restricted by T2 decay. When incorporating stimulated echoes into DDE-sequences, the slower T1 relaxation can be exploited to reach the long-time limit in larger pores demanding lower gradient strengths. We present experimental verification that phase information can be stored in longitudinal magnetization direction thus preserving complex signals under application of stimulated echoes.