Estimation of effective b-value for a diffusion-weighted double-echo steady-state sequence with bipolar gradients

Area of Science:

• Magnetic Resonance Imaging
• Diffusion Weighted Imaging
• Medical Physics

Background:

• Diffusion-weighted double-echo steady-state (dwDESS) MRI offers distortion-free and motion-insensitive diffusion-weighted images (DWI).
• Clinical adoption is limited by the lack of a method to determine the effective b-value for dwDESS sequences.

Purpose of the Study:

• To adapt a signal model for dwDESS MRI with bipolar diffusion gradients.
• To enable the explicit calculation of an effective b-value (b') for dwDESS DWI.

Main Methods:

• Adapted a previously described signal model for dwDESS sequences with bipolar diffusion gradients.
• Evaluated the model using phantom examinations on a 1.5 T clinical MRI system.
• Compared experimental results with theoretical predictions and standard EPI-DWI sequences.

Main Results:

• The adapted signal model accurately described experimental results for dwDESS MRI.
• The effective b-value (b') was successfully estimated.
• Apparent diffusion coefficient (ADC) values derived from b' (ADC') aligned with conventional ADC measurements.

Conclusions:

• The developed method effectively calculates the b-value for dwDESS MRI.
• This facilitates accurate ADC' quantification, supporting clinical translation.
• dwDESS MRI shows promise for reliable diffusion measurements free from geometric distortions.