Phase-Resolved Optical Coherence Elastography: An Insight into Tissue Displacement Estimation
Ana Batista,
Pedro Serranho,
Mário J. Santos,
Carlos Correia,
José P. Domingues,
Custódio Loureiro,
João Cardoso,
Sílvia Barbeiro,
Miguel Morgado,
Rui Bernardes
Affiliations
Ana Batista
Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, 3000-548 Coimbra, Portugal
Pedro Serranho
Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, 3000-548 Coimbra, Portugal
Mário J. Santos
Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Coimbra, 3004-531 Coimbra, Portugal
Carlos Correia
Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, 3000-548 Coimbra, Portugal
José P. Domingues
Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, 3000-548 Coimbra, Portugal
Custódio Loureiro
Department of Physics, Faculty of Science and Technology, University of Coimbra, 3004-531 Coimbra, Portugal
João Cardoso
Department of Physics, Faculty of Science and Technology, University of Coimbra, 3004-531 Coimbra, Portugal
Sílvia Barbeiro
Department of Mathematics, CMUC, University of Coimbra, 3004-531 Coimbra, Portugal
Miguel Morgado
Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, 3000-548 Coimbra, Portugal
Rui Bernardes
Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, 3000-548 Coimbra, Portugal
Robust methods to compute tissue displacements in optical coherence elastography (OCE) data are paramount, as they play a significant role in the accuracy of tissue elastic properties estimation. In this study, the accuracy of different phase estimators was evaluated on simulated OCE data, where the displacements can be accurately set, and on real data. Displacement (∆d) estimates were computed from (i) the original interferogram data (Δφori) and two phase-invariant mathematical manipulations of the interferogram: (ii) its first-order derivative (Δφd) and (iii) its integral (Δφint). We observed a dependence of the phase difference estimation accuracy on the initial depth location of the scatterer and the magnitude of the tissue displacement. However, by combining the three phase-difference estimates (Δdav), the error in phase difference estimation could be minimized. By using Δdav, the median root-mean-square error associated with displacement prediction in simulated OCE data was reduced by 85% and 70% in data with and without noise, respectively, in relation to the traditional estimate. Furthermore, a modest improvement in the minimum detectable displacement in real OCE data was also observed, particularly in data with low signal-to-noise ratios. The feasibility of using Δdav to estimate agarose phantoms’ Young’s modulus is illustrated.
