Unexpected anisotropic behavior of ultrasound attenuation after collagen cross-linking in porcine tendons

Takiuchi, Shin; Marsh, Jon N.; Hall, Christopher S.; Lanza, Gregory M.; Wickline, S.A.

doi:10.1109/ultsym.2001.991947

Cited by 3 publications

(4 citation statements)

References 16 publications

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“…A study by Takiuchi et al [62] suggests that increased protein cross linking resulting from the action of formalin in tendon (∼30% collagen by wet weight) on ultrasonic attenuation shows the same trend as observed in myocardium in which the largest increase occurs for insonification perpendicular to the fibers, and there is a significant overlap in uncertainties at parallel insonification. These results also can be compared to those for skeletal muscle, in which the collagen content is less than that in myocardium (∼0.4-0.8% collagen by wet weight).…”

Section: B Comparison To Other Studiesmentioning

confidence: 74%

Ultrasonic Detection of the Anisotropy of Protein Cross Linking in Myocardium at Diagnostic Frequencies

Baldwin

Yang

Marutyan

et al. 2007

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Increased myocardial stiffness in aging and diabetes that may result in pathologies such as diastolic dysfunction has been attributed, in part, to an increase in cross linking of extracellular matrix proteins such as collagen. With the development of new approaches to cardiovascular therapy, it becomes increasingly important to develop noninvasive approaches for monitoring changes in myocardial cross linking. The objective of this study was to use ultrasound at frequencies used in clinical echocardiography to measure changes in myocardial attenuation resulting from increased cross linking as a function of angle of insonification over a complete rotation. Throughtransmission radiofrequency-based measurements were performed on 36 specimens from 12 freshly excised ovine hearts at room temperature, which were then fixed in formalin to induce protein cross linking prior to repeated measurements. For angles near perpendicular to the myofiber direction, the measured slope of attenuation increased from 0.52 0.07 dB/(cm MHz) (mean one standard deviation) for freshly excised to 0.85 0.08 dB/(cm MHz) for formalin-fixed myocardium. In contrast, results for parallel insonification exhibit considerable overlap (1.88 0.17 for freshly excised and 1.75 0.19 dB/(cm MHz) for formalinfixed myocardium). Results of this study suggest that the response of the extracellular collagenous matrix to changes in cross linking is directionally dependent. The anisotropy of ultrasonic attenuation thus may provide an approach for noninvasive monitoring of the extent and progression of myocardial disease associated with changes in protein cross linking. Accounting for effects due to anisotropy may be essential for the future detection of such changes using ultrasonic attenuation in vivo.

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Section: B Comparison To Other Studiesmentioning

confidence: 74%

Ultrasonic Detection of the Anisotropy of Protein Cross Linking in Myocardium at Diagnostic Frequencies

Baldwin

Yang

Marutyan

et al. 2007

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…Increase in k 1 and k 2 indicates that stronger fibers present in collagen gels with higher GP concentration. Takiuchi et al [62] showed that crosslinking along fibers may happen more often than across fibers. They showed that during the process of fixing tendon samples in formalin, the stiffness along the fibers increased linearly with fixing time.…”

Section: Discussionmentioning

confidence: 99%

Experimental and Modeling Study of Collagen Scaffolds with the Effects of Crosslinking and Fiber Alignment

Chow

Zhang

2011

International Journal of Biomaterials

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Collagen type I scaffolds are commonly used due to its abundance, biocompatibility, and ubiquity. Most applications require the scaffolds to operate under mechanical stresses. Therefore understanding and being able to control the structural-functional integrity of collagen scaffolds becomes crucial. Using a combined experimental and modeling approach, we studied the structure and function of Type I collagen gel with the effects of spatial fiber alignment and crosslinking. Aligned collagen scaffolds were created through the flow of magnetic particles enmeshed in collagen fibrils to mimic the anisotropy seen in native tissue. Inter- and intra- molecular crosslinking was modified chemically with Genipin to further improve the stiffness of collagen scaffolds. The anisotropic mechanical properties of collagen scaffolds were characterized using a planar biaxial tensile tester and parallel plate rheometer. The tangent stiffness from biaxial tensile test is two to three orders of magnitude higher than the storage moduli from rheological measurements. The biphasic nature of collagen gel was discussed and used to explain the mechanical behavior of collagen scaffolds under different types of mechanical tests. An anisotropic hyperelastic constitutive model was used to capture the characteristics of the stress-strain behavior exhibited by collagen scaffolds.

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“…While it is known that fixation does affect absolute values of ultrasonically measured quantities (Baldwin et al 2005a; Bamber et al 1979; Hall et al 2000a; Takiuchi et al 2001; van der Steen et al 1991), the measurements performed in this study focused on relative properties of the heart, which should be largely preserved in fixed myocardium. For this research study, the length of time required for data acquisition (hours) and concerns regarding fresh tissue degradation made the use of fresh tissue impractical, although desirable.…”

Section: Discussionmentioning

confidence: 99%

“…The measurements performed in this study focus on the relative attenuation properties of the left ventricular and right ventricular myocardium. Although formalin fixation can affect the absolute level of attenuation and backscatter parameters (Baldwin et al 2005a; Bamber et al 1979; Hall et al 2000a; Takiuchi et al 2001; van der Steen et al 1991) the relative differences should be largely preserved.…”

Section: Introductionmentioning

confidence: 99%

Measurements of Ultrasonic Attenuation Properties of Midgestational Fetal Pig Hearts

Gibson¹,

Singh²,

Hoffman³

et al. 2009

Ultrasound in Medicine & Biology

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The objectives of this study were to measure the relative attenuation properties of the left and right ventricles in fetal pig hearts and to compare the spatial variation in attenuation measurements with those observed in previously published backscatter measurements. Approximately 1.0 mm thick, short-axis slices of excised, formalin-fixed heart were examined from 15 mid-gestational fetal pigs using a 50-MHz single-element transducer. Measurements of the attenuation properties demonstrate regional differences in the left and right ventricular myocardium that appear consistent with the previously reported regional differences in apparent integrated backscatter measurements of the same fetal pig hearts. For regions of perpendicular insonification relative to the myofiber orientation, the right ventricular free wall showed larger values for the slope of the attenuation coefficient from 30-60 MHz (1.48 ± 0.22 dB/(cm•MHz) (mean ± SD (standard deviation)) and attenuation coefficient at 45 MHz (46.3 ± 7.3 dB/cm (mean ± SD)) than the left ventricular free wall (1.18 ± 0.24 dB/(cm•MHz) and 37.0 ± 7.9 dB/cm (mean ± SD) for slope of attenuation coefficient and attenuation coefficient at 45 MHz, respectively). This attenuation study supports the hypothesis that intrinsic differences in the myocardium of the left and right ventricles exist in fetal pig hearts at mid-gestation.

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Unexpected anisotropic behavior of ultrasound attenuation after collagen cross-linking in porcine tendons

Cited by 3 publications

References 16 publications

Ultrasonic Detection of the Anisotropy of Protein Cross Linking in Myocardium at Diagnostic Frequencies

Ultrasonic Detection of the Anisotropy of Protein Cross Linking in Myocardium at Diagnostic Frequencies

Experimental and Modeling Study of Collagen Scaffolds with the Effects of Crosslinking and Fiber Alignment

Measurements of Ultrasonic Attenuation Properties of Midgestational Fetal Pig Hearts

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