Interpretation of DW‐NMR data: Dependence on experimental conditions

This review examines the effect of experimental conditions on the data obtainable from diffusion weighted NMR experiments. The origin and forms of the Stejskal‐Tanner experiment are presented, and the relative merits of bipolar to monopolar diffusion weighting gradient pulses are discussed, as are those of spin‐echo and stimulated‐echo weighting schemes. The short pulse Stejskal‐Tanner experiment as required for q‐space imaging is described. Criteria for successful diffusion weighted imaging are given, and current strategies for diffusion weighted imaging are evaluated against these. The range of biological objects accessible to diffusion weighted NMR is summarized, together with the associated experimental limitations. In the final section the dependence of diffuson weighted NMR data on diffusion time and b‐value range is examined, and the relationship between apparent restricted diffusion and the size of the extracellular space is demonstrated.