Noncontact quantitative biomechanical characterization of cardiac muscle using shear wave imaging optical coherence tomography

Abstract

Abstract:We report on a quantitative optical elastographic method based on shear wave imaging optical coherence tomography (SWI-OCT) for biomechanical characterization of cardiac muscle through noncontact elasticity measurement. The SWI-OCT system employs a focused air-puff device for localized loading of the cardiac muscle and utilizes phasesensitive OCT to monitor the induced tissue deformation. Phase information from the optical interferometry is used to reconstruct 2-D depth-resolved shear wave propagation inside the muscle tissue. Cross-correlation of the displacement profiles at various spatial locations in the propagation direction is applied to measure the group velocity of the shear waves, based on which the Young's modulus of tissue is quantified. The quantitative feature and measurement accuracy of this method is demonstrated from the experiments on tissue-mimicking phantoms with the verification using uniaxial compression test. The experiments are performed on ex vivo cardiac muscle tissue from mice with normal and genetically altered myocardium. Our results indicate this optical elastographic technique is useful as a noncontact tool to assist the cardiac muscle studies. shear wave propagation using phase-sensitive optical coherence tomography for dynamic elastography," Opt. Lett. 39(4), 838-841 (2014). 33. C. Li, G. Guan, Z. Huang, M. Johnstone, and R. K. Wang, "Noncontact all-optical measurement of corneal elasticity," Opt. Lett. 37(10), 1625-1627 (2012). 34. C. Li, G. Guan, R. Reif, Z. Huang, and R. K. Wang, "Determining elastic properties of skin by measuring surface waves from an impulse mechanical stimulus using phase-sensitive optical coherence tomography," J. R. Soc. Interface 9(70), 831-841 (2012). 35. X. Liang and S. A. Boppart, "Biomechanical properties of In vivo human skin from dynamic optical coherence elastography," IEEE Trans. Biomed. Eng. 57(4), 953-959 (2010). 36.

Assessing mechanical properties of tissue phantoms with non-contact optical coherence elastography and Michelson interferometric vibrometry

“…The time t for the wave to propagate from a reference measurement position to each location was obtained by cross-correlation analysis. The elastic wave velocity, c, was then obtained by the inverse slope of the linear fit of the propagation distances, Δd, to the elastic wave propagation delays, Δt [42]. Since the tissue-mimicking agar phantoms can be treated as an isotropic homogeneous elastic material, the Young's modulus [43], E, was estimated by [23,40,44]:…”

Optical coherence elastography – OCT at work in tissue biomechanics [Invited]

“…Point dynamic loading is attractive as a source of shear waves, and an attractive noncontact localized method is the micro-air puff developed and applied extensively by the Larin group [45, 57, 63, 81, [97][98][99][100][101][102][103][104][105][106][107][108][109][110][111][112][113][114][115][116], mainly to the cornea, but also to skin [108,116], cardiac and skeletal muscles [104], cartilage [101,106], fat and soft tissue tumors [97], and kidneys [112]. Similar to ARF-based excitation, an air puff can deliver a localized and well-controlled impulse stimulus, which can be accompanied by measurement of the tissue displacement or measurement of the air puff-induced elastic wave.…”

“…The elastic wave velocity can be calculated from the ratio of the propagation distance to the time delay, which is usually obtained through the cross-correlation of the OCE-measured local axial displacement profiles along the wave propagation path (see Fig. 8(g)) [104,180]. As indicated by Eq.…”

“…We note in passing that axial (depth) resolution of shear wavebased OCE methods is limited, in theory, to the OCT axial resolution (typically on the order of 7-15 μm), but the practical limits have yet to be comprehensively investigated. (15) [112], fat and soft tissue tumors [97], and muscle [104], to relatively hard tissues such as cartilage [101,106] and tendons [86]. In common with OCT, as described in this Special Issue, ophthalmology is a major application of OCE, where relatively low-scattering tissues, such as the cornea, allow imaging elastic waves at relatively high SNR.…”

Longitudinal shear wave imaging for elasticity mapping using optical coherence elastography

“…Benefiting from the micrometer spatial resolution and millimeter penetration of optical coherence tomography (OCT), optical coherence elastography (OCE) based on the shear wave measurement has shown promising results in biomedical studies, including blood coagulation assessment, 8 ocular elasticity assessment, 4,9 and cardiac muscle measurement. 10 In an OCE application, an excitation from a force source, such as an ultrasonic transducer, 11-15 an airpuff device, 9 and a piezo-transducer (PZT), 16 is commonly applied to induce vibration, and OCT is used to detect the displacement and visualize the shear wave. Using shear wave elastography, the shear modulus is quantified by tracking the shear wave propagation.…”