Windowed Eigen-Decomposition Algorithm for Motion Artifact Reduction in Optical Coherence Tomography-Based Angiography

Abstract

Optical coherence tomography-based angiography (OCTA) has attracted attention in clinical applications as a non-invasive and high-resolution imaging modality. Motion artifacts are the most seen artifact in OCTA. Eigen-decomposition (ED) algorithms are popular choices for OCTA reconstruction, but have limitations in the reduction of motion artifacts. The OCTA data do not meet one of the requirements of ED, which is that the data should be normally distributed. To overcome this drawback, we propose an easy-to-deploy development of ED, windowed-ED (wED). wED applies a moving window to the input data, which can contrast the blood-flow signals with significantly reduced motion artifacts. To evaluate our wED algorithm, pre-acquired dorsal wound healing data in a murine model were used. The ideal window size was optimized by fitting the data distribution with the normal distribution. Lastly, the cross-sectional and en face results were compared among several OCTA reconstruction algorithms, Speckle Variance, A-scan ED (aED), B-scan ED, and wED. wED could reduce the background noise intensity by 18% and improve PSNR by 4.6%, compared to the second best-performed algorithm, aED. This study can serve as a guide for utilizing wED to reconstruct OCTA images with an optimized window size.

Deep Learning for Motion Artifact-Suppressed OCTA Image Generation from Both Repeated and Adjacent OCT Scans

“…On the other hand, the application of the current fusion method is limited to the suppression of significant motion noise existing in 1~2 frames. When tissue motion is quite violent and causes significant motion artifacts at multiple (>2) consecutive positions, this fusion method may fail to work properly, and more advanced algorithms such as the recently proposed window-based blood flow computation method [51] or bulk motion correction [52] need to be developed to solve this problem.…”

Development of an intraoral handheld optical coherence tomography-based angiography probe for multi-site oral imaging

“…The imaging system used in this study is a lab-built, portable, non-invasive swept-source optical coherence tomography (SSOCT) system with an OCTA function, which was demonstrated in previous studies [27]. This system utilizes a swept-source vertical-cavity surface-emitting laser (SL132120, Thorlabs Inc., Newton, MA, USA) with a center wavelength of 1300 nm, a bandwidth of 100 nm, and a sweeping rate of 200 kHz.…”

“…The resolved element based on the Rayleigh criterion [28] was group 4 element 5, which corresponds to a lateral resolution of 39.38 µm. The scanning protocol employed in this study was the B-M scan, which has been utilized in previous research [27]. Each OCTA scan is composed of numerous A-lines, with each A-line providing structural depth information along the axial axis (Z axis) at a specific location.…”

“…The X galvo mirror can manipulate the laser orientation along the X axis, enabling the acquisition of multiple A-lines that coalesce into a single B-frame. By repeatedly capturing B-frames at the same position, angiography information can be extracted [27]. The Y galvo mirror facilitates the B-M scan on a line-by-line basis, generating a 3D volume dataset encompassing both structural and angiography information.…”

“…A post-processing pipeline was utilized to extract angiography information and visualize vascular networks. Firstly, the interference signals were subjected to the Fourier transform, and then the windowed eigen-decomposition (wED) algorithm [27], which can extract the angiography signals. When selecting layers along the Z axis, the epithelium and lamina propria layers were selected, which contain the vascular information for the tissue, and are widely used in the assessment of oral diseases [16,29].…”