Diffusion-Weighted DESS Protocol Optimization for Simultaneous Mapping of the Mean Diffusivity, Proton Density and Relaxation Times at 3 Tesla

    loading  Checking for direct PDF access through Ovid

Abstract

Purpose:

To design a general framework for the optimization of an MRI protocol based on the the diffusion-weighted dual-echo steady-state (DW-DESS) sequence, enabling quantitative and simultaneous mapping of proton density (PD), relaxation times Symbol and Symbol and diffusion coefficient D.

Methods:

A parameterization of the DW-DESS sequence minimizing the Cramér-Rao lower bound of each parameter estimate was proposed and tested in a phantom experiment. An extension of the protocol was implemented for brain imaging to return the rotationally invariant mean diffusivity (MD).

Results:

In an NiCl2-doped agar gel phantom wherein Symbol ms, the parameter estimation errors were below 3% for PD and Symbol and below 7% for Symbol and D while the measured signal-to-noise ratio always exceeded 20. In the human brain, the in vivo parametric maps obtained were overall in reasonable agreement with gold standard measurements, despite a broadening of the distributions due to physiological motion.

Conclusion:

Within the optimization framework presented here, DW-DESS images can be quantitatively interpreted to yield four intrinsic parameters of the tissue. Currently, the method is limited by the sensitivity of the DW-DESS sequence in terms of physiological motion.

Related Topics

    loading  Loading Related Articles