51
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Crecea V, Oldenburg AL, Liang X, Ralston TS, Boppart SA. Magnetomotive nanoparticle transducers for optical rheology of viscoelastic materials. OPTICS EXPRESS 2009; 17:23114-22. [PMID: 20052238 PMCID: PMC2883324 DOI: 10.1364/oe.17.023114] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The availability of a real-time non-destructive modality to interrogate the mechanical properties of viscoelastic materials would facilitate many new investigations. We introduce a new optical method for measuring elastic properties of samples which employs magnetite nanoparticles as perturbative agents. Magnetic nanoparticles distributed in silicone-based samples are displaced upon probing with a small external magnetic field gradient and depth-resolved optical coherence phase shifts allow for the tracking of scatterers in the sample with nanometer-scale sensitivity. The scatterers undergo underdamped oscillations when the magnetic field is applied step-wise, allowing for the measurement of the natural frequencies of oscillation of the samples. Validation of the measurements is accomplished using a commercial indentation apparatus to determine the elastic moduli of the samples. This real-time non-destructive technique constitutes a novel way of probing the natural frequencies of viscoelastic materials in which magnetic nanoparticles can be introduced.
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Affiliation(s)
- Vasilica Crecea
- Department of Physics, University of Illinois at Urbana-Champaign, 1110 W. Green St., Urbana, IL 61801, USA
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave., Urbana, IL 61801, USA
| | - Amy L. Oldenburg
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave., Urbana, IL 61801, USA
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 1406 W. Green St., Urbana, IL 61801, USA
| | - Xing Liang
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave., Urbana, IL 61801, USA
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 1406 W. Green St., Urbana, IL 61801, USA
| | - Tyler S. Ralston
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave., Urbana, IL 61801, USA
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 1406 W. Green St., Urbana, IL 61801, USA
| | - Stephen A. Boppart
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave., Urbana, IL 61801, USA
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 1406 W. Green St., Urbana, IL 61801, USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, 1304 West Springfield Avenue, Urbana, IL 61801, USA
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52
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Kennedy BF, Hillman TR, McLaughlin RA, Quirk BC, Sampson DD. In vivo dynamic optical coherence elastography using a ring actuator. OPTICS EXPRESS 2009; 17:21762-72. [PMID: 19997419 DOI: 10.1364/oe.17.021762] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We present a novel sample arm arrangement for dynamic optical coherence elastography based on excitation by a ring actuator. The actuator enables coincident excitation and imaging to be performed on a sample, facilitating in vivo operation. Sub-micrometer vibrations in the audio frequency range were coupled to samples that were imaged using optical coherence tomography. The resulting vibration amplitude and microstrain maps are presented for bilayer silicone phantoms and multiple skin sites on a human subject. Contrast based on the differing elastic properties is shown, notably between the epidermis and dermis. The results constitute the first demonstration of a practical means of performing in vivo dynamic optical coherence elastography on a human subject.
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Affiliation(s)
- Brendan F Kennedy
- School of Electrical, Electronic and Computer Engineering, The University of Western Australia, Crawley, Western Australia, Australia.
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53
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Liang X, Graf BW, Boppart SA. Imaging engineered tissues using structural and functional optical coherence tomography. JOURNAL OF BIOPHOTONICS 2009; 2:643-655. [PMID: 19672880 PMCID: PMC2883316 DOI: 10.1002/jbio.200910048] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
As the field of tissue engineering evolves, there will be an increasingly important need to visualize and track the complex dynamic changes that occur within three-dimensional constructs. Optical coherence tomography (OCT), as an emerging imaging technology applied to biological materials, offers a number of significant advantages to visualize these changes. Structural OCT has been used to investigate the longitudinal development of engineered tissues and cell dynamics such as migration, proliferation, detachment, and cell-material interactions. Optical techniques that image functional parameters or integrate multiple imaging modalities to provide complementary contrast mechanisms have been developed, such as the integration of optical coherence microscopy with multiphoton microscopy to image structural and functional information from cells in engineered tissue, optical coherence elastography to generate images or maps of strain to reflect the spatially-dependent biomechanical properties, and spectroscopic OCT to differentiate different cell types. From these results, OCT demonstrates great promise for imaging and visualizing engineered tissues, and the complex cellular dynamics that directly affect their practical and clinical use.
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Affiliation(s)
- Xing Liang
- Department of Electrical and Computer Engineering, Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Benedikt W. Graf
- Department of Electrical and Computer Engineering, Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Stephen A. Boppart
- Departments of Electrical and Computer Engineering, Bioengineering, and Internal Medicine, Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
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54
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Liang X, Orescanin M, Toohey KS, Insana MF, Boppart SA. Acoustomotive optical coherence elastography for measuring material mechanical properties. OPTICS LETTERS 2009; 34:2894-6. [PMID: 19794759 PMCID: PMC2883315 DOI: 10.1364/ol.34.002894] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Acoustomotive optical coherence elastography (AM-OCE), a dynamic and internal excitation optical coherence elastography technique, is reported. Acoustic radiation force was used for internal mechanical excitation, and spectral-domain optical coherence tomography was used for detection. Mechanical properties of gelatin tissue phantoms were measured by AM-OCE and verified using rheometry results. Measured mechanical properties including shear moduli and shear damping parameters of the gelatin samples double when their polymer concentration increases from 3% to 4%. Spectral analysis was also performed on the acquired data, which improved the processing speed by a factor of 5 compared with a least-square fitting approach. Quantitative measurement, microscale resolution, and remote excitation are the main features of AM-OCE, which make the technique promising for measuring biomechanical properties.
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Affiliation(s)
- Xing Liang
- Department of Electrical and Computer Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 North Mathews, Urbana, Illinois 61801, USA
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55
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Georgakoudi I, Rice WL, Hronik-Tupaj M, Kaplan DL. Optical spectroscopy and imaging for the noninvasive evaluation of engineered tissues. TISSUE ENGINEERING PART B-REVIEWS 2009; 14:321-40. [PMID: 18844604 DOI: 10.1089/ten.teb.2008.0248] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Optical spectroscopy and imaging approaches offer the potential to noninvasively assess different aspects of the cellular, extracellular matrix, and scaffold components of engineered tissues. In addition, the combination of multiple imaging modalities within a single instrument is highly feasible, allowing acquisition of complementary information related to the structure, organization, biochemistry, and physiology of the sample. The ability to characterize and monitor the dynamic interactions that take place as engineered tissues develop promises to enhance our understanding of the interdependence of processes that ultimately leads to functional tissue outcomes. It is expected that this information will impact significantly upon our abilities to optimize the design of biomaterial scaffolds, bioreactors, and cell systems. Here, we review the principles and performance characteristics of the main methodologies that have been exploited thus far, and we present examples of corresponding tissue engineering studies.
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Affiliation(s)
- Irene Georgakoudi
- Biomedical Engineering Department, Tufts University, Medford, Massachusetts 02155, USA.
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56
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Ahmad A, Adie SG, Chaney EJ, Sharma U, Boppart SA. Cross-correlation-based image acquisition technique for manually-scanned optical coherence tomography. OPTICS EXPRESS 2009; 17:8125-36. [PMID: 19434144 PMCID: PMC2883319 DOI: 10.1364/oe.17.008125] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We present a novel image acquisition technique for Optical Coherence Tomography (OCT) that enables manual lateral scanning. The technique compensates for the variability in lateral scan velocity based on feedback obtained from correlation between consecutive A-scans. Results obtained from phantom samples and biological tissues demonstrate successful assembly of OCT images from manually-scanned datasets despite non-uniform scan velocity and abrupt stops encountered during data acquisition. This technique could enable the acquisition of images during manual OCT needle-guided biopsy or catheter-based imaging, and for assembly of large field-of-view images with hand-held probes during intraoperative in vivo OCT imaging.
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Affiliation(s)
- Adeel Ahmad
- Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 405 N. Mathews Avenue, Urbana, IL 61801
| | - Steven G. Adie
- Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 405 N. Mathews Avenue, Urbana, IL 61801
| | - Eric J. Chaney
- Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 405 N. Mathews Avenue, Urbana, IL 61801
| | - Utkarsh Sharma
- Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 405 N. Mathews Avenue, Urbana, IL 61801
| | - Stephen A. Boppart
- Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 405 N. Mathews Avenue, Urbana, IL 61801
- Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, Department of Bioengineering, Department of Medicine, University of Illinois at Urbana-Champaign, 405 N. Mathews Avenue, Urbana, IL 61801
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57
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Adie SG, Kennedy BF, Armstrong JJ, Alexandrov SA, Sampson DD. Audio frequency in vivo optical coherence elastography. Phys Med Biol 2009; 54:3129-39. [PMID: 19420415 DOI: 10.1088/0031-9155/54/10/011] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We present a new approach to optical coherence elastography (OCE), which probes the local elastic properties of tissue by using optical coherence tomography to measure the effect of an applied stimulus in the audio frequency range. We describe the approach, based on analysis of the Bessel frequency spectrum of the interferometric signal detected from scatterers undergoing periodic motion in response to an applied stimulus. We present quantitative results of sub-micron excitation at 820 Hz in a layered phantom and the first such measurements in human skin in vivo.
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Affiliation(s)
- Steven G Adie
- Optical+Biomedical Engineering Laboratory, School of Electrical, Electronic & Computer Engineering, The University of Western Australia, Crawley, Western Australia, Australia
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58
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Zheng K, Rupnick MA, Liu B, Brezinski ME. Three Dimensional OCT in the Engineering of Tissue Constructs: A Potentially Powerful Tool for Assessing Optimal Scaffold Structure. ACTA ACUST UNITED AC 2009; 2:8-13. [PMID: 19997536 DOI: 10.2174/1875043500902010008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Optical Coherence Tomography (OCT) provides detailed, real-time information on the structure and composition of constructs used in tissue engineering. The focus of this work is the OCT three-dimensional assessment of scaffolding architecture and distribution of cells on it. PLGA scaffolds were imaged in two and three-dimensions, both seeded and unseeded with cells. Then two types of scaffolds were reconstructed in three dimensions. Both scaffolding types were examined at three different seeding densities. The importance of three-dimensional assessments was evident, particularly with respect to porosity and identification of asymmetrical cell distribution.
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Affiliation(s)
- K Zheng
- Department of Orthopedic Surgery, Brigham & Women's Hospital, Boston, MA
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59
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Liang X, Oldenburg AL, Crecea V, Chaney EJ, Boppart SA. Optical micro-scale mapping of dynamic biomechanical tissue properties. OPTICS EXPRESS 2008; 16:11052-65. [PMID: 18648419 PMCID: PMC2883328 DOI: 10.1364/oe.16.011052] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Accepted: 07/03/2008] [Indexed: 05/18/2023]
Abstract
Mechanical forces such as adhesion, shear stress and compression play crucial roles in tissue growth, patterning and development. To understand the role of these mechanical stimuli, it is of great importance to measure biomechanical properties of developing, engineered, and natural tissues. To enable these measurements on the micro-scale, a novel, dynamic, non-invasive, high-speed optical coherence elastography (OCE) system has been developed utilizing spectral-domain optical coherence tomography (OCT) and a mechanical wave driver. Experimental results of OCE on silicone phantoms are in good agreement with those obtained from a standardized indentation method. Using phase-resolved imaging, we demonstrate OCE can map dynamic elastic moduli of normal and neoplastic ex vivo human breast tissue with a sensitivity of 0.08%. Spatial micro-scale mapping of elastic moduli of tissue offers the potential for basic science and clinical investigations into the role biomechanics play in health and disease.
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Affiliation(s)
- Xing Liang
- Department of Electrical and Computer Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N. Mathews Avenue, Urbana, IL 61801, USA
| | - Amy L. Oldenburg
- Department of Electrical and Computer Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N. Mathews Avenue, Urbana, IL 61801, USA
| | - Vasilica Crecea
- Department of Physics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N. Mathews Avenue, Urbana, IL 61801, USA
| | - Eric J. Chaney
- Department of Electrical and Computer Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N. Mathews Avenue, Urbana, IL 61801, USA
| | - Stephen A. Boppart
- Department of Electrical and Computer Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N. Mathews Avenue, Urbana, IL 61801, USA
- Corresponding author:
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60
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Rice WL, Firdous S, Gupta S, Hunter M, Foo CWP, Wang Y, Kim HJ, Kaplan DL, Georgakoudi I. Non-invasive characterization of structure and morphology of silk fibroin biomaterials using non-linear microscopy. Biomaterials 2008; 29:2015-24. [PMID: 18291520 DOI: 10.1016/j.biomaterials.2007.12.049] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Accepted: 12/22/2007] [Indexed: 11/17/2022]
Abstract
Designing biomaterial scaffolds remains a major challenge in tissue engineering. Key to this challenge is improved understanding of the relationships between the scaffold properties and its degradation kinetics, as well as the cell interactions and the promotion of new matrix deposition. Here we present the use of non-linear spectroscopic imaging as a non-invasive method to characterize not only morphological, but also structural aspects of silkworm silk fibroin-based biomaterials, relying entirely on endogenous optical contrast. We demonstrate that two photon excited fluorescence and second harmonic generation are sensitive to the hydration, overall beta sheet content and molecular orientation of the sample. Thus, the functional content and high resolution afforded by these non-invasive approaches offer promise for identifying important connections between biomaterial design and functional engineered tissue development. The strategies described also have broader implications for understanding and tracking the remodeling of degradable biomaterials under dynamic conditions both in vitro and in vivo.
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Affiliation(s)
- William L Rice
- Biomedical Engineering Department, Tufts University, 4 Colby Street, Room 229, Medford, MA 02155, USA
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61
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62
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Abstract
Viscoelastic properties of soft tissues and hydropolymers depend on the strength of molecular bonding forces connecting the polymer matrix and surrounding fluids. The basis for diagnostic imaging is that disease processes alter molecular-scale bonding in ways that vary the measurable stiffness and viscosity of the tissues. This paper reviews linear viscoelastic theory as applied to gelatin hydrogels for the purpose of formulating approaches to molecular-scale interpretation of elasticity imaging in soft biological tissues. Comparing measurements acquired under different geometries, we investigate the limitations of viscoelastic parameters acquired under various imaging conditions. Quasi-static (step-and-hold and low-frequency harmonic) stimuli applied to gels during creep and stress relaxation experiments in confined and unconfined geometries reveal continuous, bimodal distributions of respondance times. Within the linear range of responses, gelatin will behave more like a solid or fluid depending on the stimulus magnitude. Gelatin can be described statistically from a few parameters of low-order rheological models that form the basis of viscoelastic imaging. Unbiased estimates of imaging parameters are obtained only if creep data are acquired for greater than twice the highest retardance time constant and any steady-state viscous response has been eliminated. Elastic strain and retardance time images are found to provide the best combination of contrast and signal strength in gelatin. Retardance times indicate average behavior of fast (1-10 s) fluid flows and slow (50-400 s) matrix restructuring in response to the mechanical stimulus. Insofar as gelatin mimics other polymers, such as soft biological tissues, elasticity imaging can provide unique insights into complex structural and biochemical features of connectives tissues affected by disease.
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Affiliation(s)
| | - Jie Liu
- University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Michael F. Insana
- University of California, Davis, CA, and University of Illinois at Urbana-Champaign, 405 North Mathews, Room 4247, Urbana, IL 61801, e-mail:
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63
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Bagnaninchi PO, Yang Y, Zghoul N, Maffulli N, Wang RK, Haj AJE. Chitosan microchannel scaffolds for tendon tissue engineering characterized using optical coherence tomography. ACTA ACUST UNITED AC 2007; 13:323-31. [PMID: 17518566 DOI: 10.1089/ten.2006.0168] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Tendon tissue engineering requires the generation of a uniaxially orientated collagen type I matrix with several organization scales that confer mechanical functionality upon the tendon. A combination of factors in a dose- and time-dependent manner, such as growth factors and mechanical environment, may be the key to an in vitro-engineered tendon. To define the progress of tissue development within a scaffold, on-line systems need to be applied to monitor the newly generated matrix. To address this challenge, we designed a new porous chitosan scaffold with microchannels (diameter: 250 microm), which allows primary porcine tenocytes to proliferate in a bundle-like structure. The cell proliferation and extracellular matrix (ECM) production within the microchannels were successfully assessed under sterile conditions using optical coherence tomography (OCT). A semi-quantitative method that calculated the microchannel occupation ratio (the degree of cell proliferation and tissue turnover based on the total backscattered intensity in the microchannels) was developed. We further investigated the effect of different culture conditions on tendon cell matrix formation. Using a perfusion bioreactor, we demonstrated how fluid flow can increase (p < 1e(3)) ECM production within the microchannels significantly more than static culture. Our study illustrates how using a guiding scaffold in combination with the fast and non-destructive assessment of the microstructure using OCT allows discrimination between the parameters affecting the production and the organization of the ECM.
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Affiliation(s)
- P O Bagnaninchi
- Institute of Science and Technology in Medicine, Keele University, Stoke-On-Trent, United Kingdom
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64
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Abstract
Techniques are being developed to image viscoelastic features of soft tissues from time-varying strain. A compress-hold-release stress stimulus commonly used in creep-recovery measurements is applied to samples to form images of elastic strain and strain retardance times. While the intended application is diagnostic breast imaging, results in gelatin hydrogels are presented to demonstrate the techniques. The spatiotemporal behaviour of gelatin is described by linear viscoelastic theory formulated for polymeric solids. Measured creep responses of polymers are frequently modelled as sums of exponentials whose time constants describe the delay or retardation of the full strain response. We found the spectrum of retardation times tau to be continuous and bimodal, where the amplitude at each tau represents the relative number of molecular bonds with a given strength and conformation. Such spectra indicate that the molecular weight of the polymer fibres between bonding points is large. Imaging parameters are found by summarizing these complex spectral distributions at each location in the medium with a second-order Voigt rheological model. This simplification reduces the dimensionality of the data for selecting imaging parameters while preserving essential information on how the creeping deformation describes fluid flow and collagen matrix restructuring in the medium. The focus of this paper is on imaging parameter estimation from ultrasonic echo data, and how jitter from hand-held force applicators used for clinical applications propagate through the imaging chain to generate image noise.
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Affiliation(s)
- M Sridhar
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA
| | - J Liu
- Department of Bioengineering, University of Illinois, Urbana-Champaign, IL 61801, USA, E-mail:
| | - M F Insana
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA
- Department of Bioengineering, University of Illinois, Urbana-Champaign, IL 61801, USA, E-mail:
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65
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van Soest G, Mastik F, de Jong N, van der Steen AFW. Robust intravascular optical coherence elastography by line correlations. Phys Med Biol 2007; 52:2445-58. [PMID: 17440245 DOI: 10.1088/0031-9155/52/9/008] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We present a new method for intravascular optical coherence elastography, which is robust against motion artefacts. It employs the correlation between adjacent lines, instead of subsequent frames. Pressure to deform the tissue is applied synchronously with the line scan rate of the optical coherence tomography (OCT) instrument. The viability of the method is demonstrated with a simulation study. We find that the root mean square (rms) error of the displacement estimate is 0.55 microm, and the rms error of the strain is 0.6%. It is shown that high-strain spots in the vessel wall, such as observed at the sites of vulnerable atherosclerotic lesions, can be detected with the technique.
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Affiliation(s)
- Gijs van Soest
- Department of Biomedical Engineering, Thorax Center, Erasmus MC, PO Box 2040, NL-3000 CA Rotterdam, The Netherlands.
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66
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Bagnaninchi P, Yang Y, Zghoul N, Maffulli N, Wang R, Haj AE. Chitosan Micro-Channel Scaffolds for Tendon Tissue Engineering Characterized Using Optical Coherence Tomography. ACTA ACUST UNITED AC 2007. [DOI: 10.1089/ten.2007.13.ft-335] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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67
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Pancrazio JJ, Wang F, Kelley CA. Enabling tools for tissue engineering. Biosens Bioelectron 2006; 22:2803-11. [PMID: 17240132 DOI: 10.1016/j.bios.2006.12.023] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2006] [Revised: 11/20/2006] [Accepted: 12/20/2006] [Indexed: 12/14/2022]
Abstract
Tissue engineering is a multidisciplinary field that combines engineering, physical sciences, biology, and medicine to restore or replace tissues and organs functions. In this review, enabling tools for tissue engineering are discussed in the context of four key areas or pillars: prediction, production, performance, and preservation. Prediction refers to the computational modeling where the ability to simulate cellular behavior in complex three-dimensional environments will be essential for design of tissues. Production refer imaging modalities that allow high resolution, non-invasive monitoring of the development and incorporation of tissue engineered constructs. Lastly, preservation includes biochemical tools that permit cryopreservation, vitrification, and freeze-drying of cells and tissues. Recent progress and future perspectives for development in each of these key areas are presented.
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Affiliation(s)
- Joseph J Pancrazio
- NIH/National Institute for Neurological Disorders and Stroke, 6001 Executive Blvd, Bethesda, MD 20892, United States.
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68
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Kirkpatrick SJ, Wang RK, Duncan DD. OCT-based elastography for large and small deformations. OPTICS EXPRESS 2006; 14:11585-97. [PMID: 19529578 DOI: 10.1364/oe.14.011585] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We present two approaches to speckle tracking for optical coherence tomography (OCT)-based elastography, one appropriate for small speckle motions and the other for large, rapid speckle motions. Both approaches have certain advantages over traditional cross-correlation based motion algorithms. We apply our algorithms to quantifying the strain response of a mechanically inhomogeneous, bi-layered polyvinyl alcohol tissue phantom that is subjected to either small or large dynamic compressive forces while being imaged with a spectral domain OCT system. In both the small and large deformation scenarios, the algorithms performed well, clearly identifying the two mechanically disparate regions of the phantom. The stiffness ratio between the two regions was estimated to be the same for the two scenarios and both estimates agreed with the expected stiffness ratio based on earlier mechanical testing. No single numerical approach is appropriate for all cases and the experimental conditions dictate the proper choice of speckle shift algorithm for OCT-based elastography studies.
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