Abstract #0716

A new approach to time-dependent diffusion: Direct, time-domain measurement of the velocity autocorrelation function

Teddy Xuke Cai¹, Nathan Hu Williamson¹, Rea Ravin¹, Magnus Herbethson², Evren Özarslan³, and Peter Joel Basser¹

¹Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States, ²Department of Mathematics, Linköping University, Linköping, Sweden, ³Department of Biomedical Engineering, Linköping University, Linköping, Sweden

Synopsis

Keywords: Diffusion Modeling, Diffusion Modeling, time-dependent diffusion, velocity autocorrelation

Motivation: Time-dependent diffusion can reveal fine microstructural details, but its quantitative measurement is difficult. Oscillating gradient methods probe a limited range of frequencies, and the recovered spectrum is not straightforward to interpret.

Goal(s): To measure time-dependent diffusion directly via the velocity autocorrelation function (VAF), i.e., half the second derivative of the mean-squared displacement (MSD).

Approach: A double diffusion encoding method and analysis framework provides a semi-quantitative measurement of the VAF. The method is validated using simulations. Proof-of-concept data in ex vivo tissue are also presented.

Results: The estimated VAF agrees with analytical and numerical ground truth. The VAF scaling in tissue indicates barrier-limited exchange.

Impact: Time-dependent diffusion encapsulates diffusion microstructural MRI. The conventional oscillating gradient approach, however, is limited by slew rates and relaxation. We propose a new approach that is semi-quantitative and can access a wide range of times using a longitudinal storage period.

How to access this content:

For one year after publication, abstracts and videos are only open to registrants of this annual meeting. Registrants should use their existing login information. Non-registrant access can be purchased via the ISMRM E-Library.

After one year, current ISMRM & ISMRT members get free access to both the abstracts and videos. Non-members and non-registrants must purchase access via the ISMRM E-Library.

After two years, the meeting proceedings (abstracts) are opened to the public and require no login information. Videos remain behind password for access by members, registrants and E-Library customers.

Click here for more information on becoming a member.