Publication Citation (NIST authors in bold)
Authors:	Madsen, E. L., Frank, G. R., Hobson, M. A., Lin-Gibson, S. , Hall, T. J., Jiang, J. , Stiles, T. A.
Title:	INSTRUMENT FOR DETERMINING THE COMPLEX SHEAR MODULUS OF SOFT-TISSUE-LIKE MATERIALS FROM 10 TO 300 Hz
Published:	September 15, 2009
Abstract:	Accurate determination of the complex shear modulus of soft-tissue-like materials in the 10 to 300 Hz frequency range is very important to researchers in MR Elastography and Acoustic Radiation Force Impulse (ARFI) imaging. A variety of instruments for making such measurements have been reported, but none of them are not easily reproduced, and none have been tested to conform to causality via the Kramers-Krong (K-K) relations. Assessment of their reported measurements implies that none satisfy the K-K relations. A promising linear oscillation instrument described in a brief report by Arbogast et al (1997), operates between 20 and 160 Hz, but results also appear to violate the K-K relations. We have produced a similar instrument with our own version of the electronic components and have also accounted for instrumental effects on the data reduction, which is not addressed in Arbogast et al. The improved instrument has been shown to conform to an accurate approximation of the K-K relations over the 10 to 300 Hz range. The K-K approximation is based on the Weichert mechanical circuit model. A complete description of the improved instrument is given, facilitating replication in other labs.
Citation:	Physics in Medicine and Biology
Volume:
Issue:
Keywords:	shear modulus, gel, high frequency, Kramers-Kronig relations
Research Area:	Biomaterials;
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