ID-OCTA: OCT angiography based on inverse SNR and decorrelation features

Li, Huakun; Liu, Kaiyuan; Yao, Lin; Deng, Xiaofeng; Zhang, Ziyi; Peng, Li

doi:10.1142/s1793545821300019

Cited by 15 publications

(3 citation statements)

References 79 publications

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“…The inverse process of the proposed PRSMC method can be used for motion estimation via optimization, and the measurement accuracy can be improved by eliminating the phase error introduced by the change of local speckle patterns. In OCTA, complex-value-based algorithms possess higher motion contrast, but their performance is susceptible to phase error due to bulk motion [44, 45], which can be well suppressed with the PRSMC method. Furthermore, our proposed approach may also be beneficial for complex-value-based averaging techniques [46] and computational adaptive optics (such as numerical refocusing [27] and aberration correction [47, 48]), where the phase stability is crucial for their implementation.…”

Section: Discussionmentioning

confidence: 99%

Phase-Restoring Subpixel Image Registration: Enhancing Motion Detection Performance in Fourier-domain Optical Coherence Tomography

Tan

Pandiyan

et al. 2022

Preprint

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Phase-sensitive Fourier-domain optical coherence tomography (FD-OCT) enables label-free imaging of cellular movements in vivo with detection sensitivity down to the nanometer scale. Due to this high sensitivity, it is widely employed in various emerging functional imaging modalities such as optoretinography (ORG), optical coherence elastography (OCE), and optical coherence tomography angiography (OCTA). However, achieving shot-noise limited detection sensitivity remains a major challenge for in-vivo measurements where the sample is constantly affected by vascular pulsation, breathing, eye and head motion, and other involuntary movements. Here, we propose a phase-restoring subpixel motion correction (PRSMC) method for post-hoc image registration in FD-OCT. Based on a generalized FD-OCT model, this method enables translational shifts of OCT images by arbitrary displacements while accurately restoring physically meaningful phase components, both with subpixel precision. With the sample movements estimated from averaged Doppler shift or normalized cross-correlation, we reconstructed the OCT images by correcting the axial displacement in the spectrum (k) domain and the lateral displacement in the spatial frequency domain, respectively. We validated our method in simulations, phantom experiments, and in-vivo optoretinogram imaging, where the advantages over conventional approaches for both amplitude stability and phase accuracy were demonstrated. Our approach significantly reduces the motion-induced phase error (MIPE) when imaging moving samples, achieving systematic phase sensitivities close to the shot-noise regime.

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Section: Discussionmentioning

confidence: 99%

Phase-Restoring Subpixel Image Registration: Enhancing Motion Detection Performance in Fourier-domain Optical Coherence Tomography

Tan

Pandiyan

et al. 2022

Preprint

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“…The mathematical expression of the classifier infers that a larger kernel size improves the performance of the classifier by decreasing the distribution std in the IDa space. However, enlarging the spatial kernel degrades the spatial resolution, while enlarging the temporal kernel increases the imaging time (37). Therefore, an appropriate kernel size should be selected by trading off between the classification accuracy, spatial resolution, and imaging time.…”

Section: Ida-octa Algorithmmentioning

confidence: 99%

Endoscopic optical coherence tomography angiography using inverse SNR-amplitude decorrelation features and electrothermal micro-electro-mechanical system raster scan

Yao¹,

Li²,

Liu³

et al. 2022

Quant Imaging Med Surg

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Background: Angiogenesis is closely associated with tumor development and progression. Endoscopic optical coherence tomography angiography (OCTA) enables rapid inspection of mucosal 3D vasculature of inner organs in the early-stage tumor diagnosis; however, it is limited by instabilities of the optical signal and beam scanning.Methods: In the phase-unstable swept source OCTA (SS-OCTA), amplitude decorrelation was used to compute the motion-induced changes as motion contrast. The influence of the random noise-induced amplitude fluctuations on decorrelation was characterized as a function of inverse signal-to-noise ratio (SNR) with a multi-variate time series (MVTS) model and statistical analysis. Then, the noise-induced decorrelation artifacts in static tissue regions were eliminated by applying a flow mask based on the statistical relation between inverse SNR (iSNR) and amplitude decorrelation (IDa), which was named IDa-OCTA. In addition, a distal stepwise raster scan was realized with a low-voltage electrothermal micro-electro-mechanical system (ET-MEMS)-based catheter for endoscopic imaging, whereby the stable and repeatable B-scans at each step suppressed the decorrelation noise induced by the spatial mismatch between paired scans.Results: The derived IDa relation was validated through numerical simulation and flow phantom experiments. In vivo human buccal mucosa imaging was performed to demonstrate the endoscopic IDa-OCTA imaging. In this, the subsurface structure and vasculature were visualized in a rapid and depth-resolved manner. Conclusions:The rapid 3D vasculature visualization realized by the endoscopic IDa-OCTA improves the diagnosis of early tumors in internal organs.

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“…Optical coherence tomography (OCT) [12][13][14] is a noninvasive, interferometric imaging modality that enables in vivo volumetric imaging of the anterior [15] and posterior segments [16] of the eye. Based on the principle that stationary tissue usually produces a nearly constant reflection or scattering, whereas blood cells produce OCT signals that change over time, the OCT-based angiography (OCTA) method has been developed to provide rapid and depth-resolved visualization of tissue microvasculature (such as micro-scale capillaries or microaneurysms) using the motion contrast between two or more consecutive OCT B-scans at the same position with a delay of milliseconds [17][18][19][20][21][22]. OCTA was initially used to assess posterior ocular diseases associated with vasculatures in the retina, choroid, and optical nerve head [16,[23][24][25], and it was very recently applied to evaluate anterior-segment vasculature imaging [26,27].…”

Section: Introductionmentioning

confidence: 99%

Design of 1300 nm spectral domain optical coherence tomography angiography system for iris microvascular imaging

Lan

Hu³

et al. 2021

J. Phys. D: Appl. Phys.

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Developing a high-resolution non-invasive optical coherence tomography angiography (OCTA) method for iris vasculature imaging is essential for diagnosing a wide range of ocular pathologies. However, the current iris-OCTA devices are still limited in imaging quality and penetration depth for dark-colored eyes ranging from brown to dark brown. A spectral domain iris-OCTA system is presented in this paper incorporating a 1300 nm wavelength for deeper tissue penetration, a linear-wavenumber spectrometer for better detection sensitivity, and an iris scan objective lens for better optical focusing across the entire iris over a 12 × 12 mm2 scan field. The −6 dB fall-off range is ∼3 mm, and the maximum sensitivity fall-off is −28.57 dB at 6.94 mm. The axial resolution is 15.1 ± 3.2 μm. The 40 mm focal-length iris scan objective is optimized based on the ocular parameters from 100 Asian participants’ left eyes, and it has a diffraction-limited lateral resolution (14.14 μm) for the iris, in general. OCT distortions were calibrated based on the average ocular parameters, and the maximum residual distortions in both the lateral and axial directions were <0.1 mm (2.0%) for all of the eyes. A pilot study on a constricted pupil was performed to demonstrate high-contrast, wide-field en face iris microvascular imaging by either a horizontal or vertical fast-scan protocol in a dark brown eye. The iris vessels are radially aligned, and each vessel is more visible when it has an angle of ∼65°–90° with respect to the fast-scan direction. A new circular fast-scan protocol could improve image quality for better visualization of the iris features or integration with image-registration algorithms and an eye-tracking system for eye-motion compensation.

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ID-OCTA: OCT angiography based on inverse SNR and decorrelation features

Cited by 15 publications

References 79 publications

Phase-Restoring Subpixel Image Registration: Enhancing Motion Detection Performance in Fourier-domain Optical Coherence Tomography

Phase-Restoring Subpixel Image Registration: Enhancing Motion Detection Performance in Fourier-domain Optical Coherence Tomography

Endoscopic optical coherence tomography angiography using inverse SNR-amplitude decorrelation features and electrothermal micro-electro-mechanical system raster scan

Design of 1300 nm spectral domain optical coherence tomography angiography system for iris microvascular imaging

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