title: Time-dependent ultrasound echo changes occur in tendon during viscoelastic testing.
abstract: The viscoelastic behavior of tendons has been extensively studied in vitro. A noninvasive method by which to acquire mechanical data would be highly beneficial, as it could lead to the collection of viscoelastic data in vivo. Our lab has previously presented acoustoelasticity as an alternative ultrasound-based method of measuring tendon stress and strain by reporting a relationship between ultrasonic echo intensity (B mode ultrasound image brightness) and mechanical behavior of tendon under pseudoelastic in vitro conditions [Duenwald, S., Kobayashi, H., Frisch, K., Lakes, R., and Vanderby Jr, R., 2011, "Ultrasound Echo is Related to Stress and Strain in Tendon," J. Biomech., 44(3), pp. 424-429]. Viscoelastic properties of the tendons were not examined in that study, so the presence of time-dependent echo intensity changes has not been verified. In this study, porcine flexor tendons were subjected to relaxation and cyclic testing while ultrasonic echo response was recorded. We report that time- and strain history-dependent mechanical properties during viscoelastic testing are manifested in ultrasonic echo intensity changes. We also report that the patterns of the echo intensity changes do not directly mimic the patterns of viscoelastic load changes, but the intensity changed in a repeatable (and therefore predictable) fashion. Although mechanisms need further elucidation, viscoelastic behavior can be anticipated from echo intensity changes. This phenomenon could potentially lead to a more extensive characterization of in vivo tissue behavior.
authors: Department of Biomedical Engineering, University of Wisconsin, Madison, WI 53706, USA.
authors: Sarah
authors: S
authors: Duenwald-Kuehl
authors: Hirohito
authors: H
authors: Kobayashi
authors: Roderic
authors: R
authors: Lakes
authors: Ray
authors: R
authors: Vanderby
mesh_terms: D000818:Animals; D004548:Elasticity; D008422:Materials Testing / Q000379:methods*; D013314:Stress, Mechanical; D013552:Swine; D013710:Tendons / Q000000981:diagnostic imaging*; D013997:Time Factors; D014463:Ultrasonography; D014783:Viscosity
references: Ultrasound Med Biol. 1998 Sep;24(7):995-1007
references: 9809634
references: J Biomech. 2009 Sep 18;42(13):2210-3
references: 19647261
references: J Orthop Res. 2007 Apr;25(4):458-64
references: 17205554
references: J Orthop Res. 1994 May;12(3):350-6
references: 8207588
references: Eur J Echocardiogr. 2000 Sep;1(3):154-70
references: 11916589
references: J Biomech Eng. 2004 Oct;126(5):651-6
references: 15648818
references: Nature. 1987 Jan 8-14;325(7000):147-9
references: 3808070
references: Breast Cancer Res. 2010;12(6):R104
references: 21122101
references: J Gen Physiol. 1959 Nov 1;43(2):265-83
references: 19873525
references: Med Biol Eng. 1967 Sep;5(5):433-43
references: 6069823
references: J Am Soc Echocardiogr. 1998 Nov;11(11):1013-9
references: 9812093
references: Ann Biomed Eng. 2006 Jun;34(6):1008-18
references: 16783656
references: J Ultrasound Med. 2007 Jun;26(6):807-15
references: 17526612
references: J Clin Endocrinol Metab. 2010 Dec;95(12):5281-8
references: 20881263
references: AJR Am J Roentgenol. 2011 Sep;197(3):532-6
references: 21862792
references: J Orthop Res. 2005 Jan;23(1):67-76
references: 15607877
references: J Acoust Soc Am. 2003 Dec;114(6 Pt 1):3087-91
references: 14714790
references: Ann Biomed Eng. 2004 Feb;32(2):306-12
references: 15008379
references: Ultrason Imaging. 1991 Apr;13(2):111-34
references: 1858217
references: J Acoust Soc Am. 2007 Feb;121(2):879-87
references: 17348512
references: Radiology. 2006 May;239(2):341-50
references: 16484352
references: J Biomech Eng. 1981 Nov;103(4):293-8
references: 7311496
references: Ann Biomed Eng. 2001 Oct;29(10):908-14
references: 11764321
references: Biorheology. 2010;47(1):1-14
references: 20448294
references: Ann Biomed Eng. 2009 Jun;37(6):1131-40
references: 19353269
references: J Biomech. 2011 Feb 3;44(3):424-9
references: 21030024
references: J Magn Reson. 2000 Jun;144(2):217-27
references: 10828190