Abstract
Elastography provides a powerful tool for histopathological identification and clinical diagnosis based on information from tissue stiffness. Benefiting from high resolution, three-dimensional (3D), and noninvasive optical coherence tomography (OCT), optical micro-elastography has the ability to determine elastic properties with a resolution of ~10 μm in a 3D specimen. The shear wave velocity measurement can be used to quantify the elastic modulus. However, in current methods, shear waves are measured near the surface with an interference of surface waves. In this study, we developed acoustic radiation force (ARF) orthogonal excitation optical coherence elastography (ARFOE-OCE) to visualize shear waves in 3D. This method uses acoustic force perpendicular to the OCT beam to excite shear waves in internal specimens and uses Doppler variance method to visualize shear wave propagation in 3D. The measured propagation of shear waves agrees well with the simulation results obtained from finite element analysis (FEA). Orthogonal acoustic excitation allows this method to measure the shear modulus in a deeper specimen which extends the elasticity measurement range beyond the OCT imaging depth. The results show that the ARFOE-OCE system has the ability to noninvasively determine the 3D elastic map.
Highlights
The measurement of resonant frequency in response to an external force provides quantitative assessment of the elastic modulus in tissues[20]
We previously developed an ARFOE-optical coherence elastography (OCE) system using the Doppler variance method where the acoustic force is perpendicular to the OCT detection beam[15]
We demonstrated that the shear modulus of a sample as deep as at least 7.5 mm, which is beyond the OCT detection range, can be quantified
Summary
The measurement of resonant frequency in response to an external force provides quantitative assessment of the elastic modulus in tissues[20]. The mapping of the biomechanical properties of tissue is limited to OCT imaging depth To overcome these limitations, we previously developed an ARFOE-OCE system using the Doppler variance method where the acoustic force is perpendicular to the OCT detection beam[15]. Only one-dimensional (1D) shear wave propagating along the OCT beam was detected, and the map of the shear modulus in a two-dimensional (2D) plane requires point-by-point scans of the samples. The vibration generated by the acoustic force is perpendicular to the OCT detection direction, and the shear wave propagates from the ARF focus to the surrounding medium. The Doppler variance method, which is sensitive to the displacement perpendicular to the OCT beam direction, is applied to the 500 A-lines for visualization of vibration at each position.
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call