Abstract:Conventional magnetic resonance imaging (MRI) scans suffer from limited resolution that prohibits the visualization of microscopic domains thus providing information at coarse length scales. To obtain information at smaller length scales, the MR signal can be sensitized to self-diffusion of water molecules whose motional history is influenced by the local microstructure. After introducing the basics of diffusion-weighted MR, I will discuss how the technique can be employed to address important problems such as mapping neural connectivity in the human brain. Despite the technique's tremendous popularity, most diffusion-weighted MR acquisitions still employ a pulse sequence introduced in 1960s featuring two magnetic field gradient pulses. In the second part of the talk, I will discuss alternative approaches to diffusion sensitization and argue that alternative gradient waveforms could broaden the spectrum of information one can obtain using diffusion-weighted MR. Emphasis will be given to the multiple pulsed field gradient techniques, which could be used to characterize the local microstructural features of the medium without the need to employ strong magnetic field gradients.