Instrument for determining the complex shear modulus of soft-tissue-like materials from 10 to 300 Hz

Area of Science:

• Biomedical Engineering
• Materials Science
• Medical Imaging

Background:

• Accurate complex shear modulus determination is crucial for MR elastography and ARFI imaging.
• Existing instruments lack reproducibility and validation via Kramers-Kronig (K-K) relations.
• Previous instruments operated in limited frequency ranges and were not fully validated.

Purpose of the Study:

• To develop and validate a novel instrument for measuring the complex shear modulus of soft tissues.
• To ensure the instrument's measurements conform to the Kramers-Kronig (K-K) relations.
• To facilitate replication of the measurement technique in other laboratories.

Main Methods:

• Developed a linear oscillation instrument with custom electronic components.
• Accounted for instrumental effects in data reduction.
• Validated measurements against a calibrated commercial rheometer and K-K relations using the Weichert mechanical circuit model.

Main Results:

• The improved instrument operates accurately in the 10-300 Hz frequency range.
• Measurements demonstrated conformity to an accurate approximation of the K-K relations.
• Optimal sample thickness was identified for agreement with commercial rheometers.

Conclusions:

• The developed instrument provides reproducible and validated measurements of soft tissue viscoelasticity.
• The instrument's adherence to K-K relations ensures accurate data for MR elastography and ARFI imaging.
• The detailed description facilitates widespread adoption and further research.