Fast abdominal magnetic resonance elastography with simultaneous encoding of three-dimensional displacements

Area of Science:

• Medical Imaging
• Biophysics
• Magnetic Resonance Imaging

Background:

• Three-dimensional (3D) magnetic resonance elastography (MRE) offers superior accuracy over 2D MRE but suffers from lengthy acquisition times.
• Longer scan durations in 3D MRE can lead to patient motion, potentially compromising the accuracy of shear modulus estimation.

Purpose of the Study:

• To introduce and evaluate a novel short-sample interval modulation (short-SLIM) technique for accelerating abdominal 3D MRE acquisition.
• To assess the performance of short-SLIM in reducing scan time while maintaining the accuracy of MRE measurements compared to conventional methods.

Main Methods:

• The study employed two phantom studies (homogeneous and rod-embedded) and in vivo liver imaging in three volunteers.
• Performance was compared between conventional spin-echo echo-planar (SE-EPI) MRE, conventional SLIM, and the proposed short-SLIM technique.
• Quantitative analysis included measuring amplitude and shear modulus, assessing robustness to reduced phase-to-noise ratio, and evaluating complex wave pattern performance.

Main Results:

• Phantom studies demonstrated minimal differences in mean amplitude and shear modulus between conventional MRE and short-SLIM, even with varying vibration power.
• Elastogram patterns and mean shear modulus in the rod-embedded phantom remained consistent across conventional SLIM and short-SLIM.
• In vivo liver imaging showed only minor variations between the different acquisition techniques, indicating comparable diagnostic quality.

Conclusions:

• The short-SLIM technique effectively reduces 3D MRE acquisition time by a factor of 2.25 without sacrificing accuracy.
• Short-SLIM provides comparable MRE results to conventional methods, enhancing shear modulus estimation accuracy by mitigating patient motion.
• This accelerated approach holds promise for improving the clinical utility of abdominal 3D MRE.