Robust motion tracking based on adaptive speckle decorrelation analysis of OCT signal

Abstract

Speckle decorrelation analysis of optical coherence tomography (OCT) signal has been used in motion tracking. In our previous study, we demonstrated that cross-correlation coefficient (XCC) between Ascans had an explicit functional dependency on the magnitude of lateral displacement (δx). In this study, we evaluated the sensitivity of speckle motion tracking using the derivative of function XCC(δx) on variable δx. We demonstrated the magnitude of the derivative can be maximized. In other words, the sensitivity of OCT speckle tracking can be optimized by using signals with appropriate amount of decorrelation for XCC calculation. Based on this finding, we developed an adaptive speckle decorrelation analysis strategy to achieve motion tracking with optimized sensitivity. Briefly, we used subsequently acquired Ascans and Ascans obtained with larger time intervals to obtain multiple values of XCC and chose the XCC value that maximized motion tracking sensitivity for displacement calculation. Instantaneous motion speed can be calculated by dividing the obtained displacement with time interval between Ascans involved in XCC calculation. We implemented the above-described algorithm in real-time using graphic processing unit (GPU) and demonstrated its effectiveness in reconstructing distortion-free OCT images using data obtained from a manually scanned OCT probe. The adaptive speckle tracking method was validated in manually scanned OCT imaging, on phantom as well as in vivo skin tissue.

Does group velocity always reflect elastic modulus in shear wave elastography?

“…Similar to speckle tracking in ultrasound to detect shear waves, 34 , 35 PhS-OCT can be used to detect motion by analyzing the differential signal between successive A-scans at a single location following an applied load. 5 , 36 – 41 The displacement term is defined as the change in scatterer position between scans and is more appropriately reported by the depth-resolved vertical component (along ) of vibration speed: 5 , 15 , 33 where is the scan rate, is the optical phase difference between successive scans, is the optical wavelength, and is the medium refractive index.…”

Ultrathin lensed fiber-optic probe for optical coherence tomography

“…Details about the system can be found in our previous publications [15]. The system used a superluminescent diode as light source (SLD1325 Thorlabs, 100 nm bandwidth, corresponding to a 7.4 μm axial resolution) and a CMOS InGaAs camera (SUI1024LDH2, Goodrich).…”

Quantitative optical coherence elastography based on fiber-optic probe for in situ measurement of tissue mechanical properties

“…Based on the stiffness of the probe shaft and the imaging speed of our OCT system, the system can theoretically quantify force with a 12,000 N/s derivative. It is possible to adaptively choose Ascans for Doppler phase analysis to improve the robustness in deformation tracking, in a way similar to adaptive speckle tracking method we developed before for lateral motion tracking [28].…”

“…The SD OCT engine was described in detail in our previous publications [28]. Briefly, a superluminescent diode (SLD1325 Thorlabs, 100nm bandwidth, corresponding to a 7.4 μm axial resolution) is used as light source and interference signal is detected by a CMOS InGaAs camera (SUI1024LDH2, Goodrich).…”