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Quantitative shear wave magnetic resonance elastography: comparison to a dynamic shear material test.
Stacie I Ringleb1, Qingshan Chen, David S Lake
1Biomechanics Laboratory, Division of Orthopedic Research, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
Magnetic Resonance in Medicine
|April 22, 2005
Summary
Magnetic resonance elastography (MRE) quantifies tissue stiffness by imaging mechanical waves. This study found most MRE algorithms accurately measure shear stiffness compared to dynamic mechanical analysis, except for phase gradient at high concentrations.
Area of Science:
- Biomedical Engineering
- Medical Imaging
- Rheology
Background:
- Magnetic resonance elastography (MRE) is a non-invasive MRI technique for in vivo tissue stiffness quantification.
- Previous validation of MRE primarily used static mechanical compression tests.
- Dynamic mechanical analysis (DMA) offers a more direct comparison for MRE's dynamic shear modulus measurements.
Purpose of the Study:
- To compare the accuracy of various MRE inversion algorithms against DMA for shear stiffness measurement.
- To evaluate MRE's performance across a range of agarose gel concentrations.
Main Methods:
- Agarose gels (1.5-3.5% concentration) were tested using MRE with five inversion algorithms (manual, local frequency, phase gradient, direct inversion, matched filter).
- Shear stiffness measurements from MRE were compared to gold-standard dynamic mechanical analysis (DMA).
Main Results:
- Most MRE inversion algorithms showed good correlation with DMA measurements.
- The phase gradient inversion algorithm significantly overestimated shear modulus in higher concentration gels (3-3.5% agar).
Conclusions:
- MRE is a viable technique for in vivo shear stiffness measurement when appropriate inversion algorithms are used.
- Algorithm selection is crucial for accurate MRE results, particularly in stiffer tissues.