Development of a robust diffusion-MR elastography (dMRE) technique to mitigate intravoxel phase dispersion

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Physics

Background:

• Diffusion-magnetic resonance elastography (dMRE) combines diffusion MRI and MRE for simultaneous data acquisition.
• Intravoxel phase dispersion (IVPD) causes signal loss, hindering accurate apparent diffusion coefficient (ADC) calculation in dMRE.

Purpose of the Study:

• To develop and validate a novel dMRE pulse sequence mitigating the effects of IVPD.
• To enhance the accuracy of ADC measurements in dMRE.

Main Methods:

• A new dMRE pulse sequence was introduced and compared with an existing technique.
• Experiments were conducted using a phantom with varying elasticity rods vibrated at 60 Hz.
• ADC and stiffness values were compared against conventional spin-echo (SE) diffusion and SE-MRE.

Main Results:

• Stiffness measurements showed minimal differences between the existing and proposed dMRE techniques.
• The proposed dMRE technique significantly reduced the mean absolute difference (MAD) in ADC values in soft phantom regions compared to the previous method (approx. 2.7x lower).
• The reduced ADC MAD highlights the diminished influence of IVPD with the new technique.

Conclusions:

• The proposed dMRE technique effectively addresses signal loss caused by IVPD.
• This advancement offers a more robust method for simultaneous dMRE and diffusion imaging, improving ADC accuracy.