image: Flow chart showing the processing steps of the Deconv-RPM method. is the acquired OCT frame (B-scan), where x is the B-scan direction, z is the depth direction. For simplicity, r represents any of the coordinates x or z in the case of B-scan and x, y or z for C-scan. N is the number of B-scans. In step 1, an iterative Richardson-Lucy deconvolution is performed to produce a deconvolved image . In step 2, numerical random phase masks are modulated on the , which is the Fourier space representations of. For B-scan, 1-D FFT ℱ and IFFT ℱ-1 are operated along the rows first and then the columns. obeys the normal distribution with a mean of 0. andare the pixel indices in spatial domain and Fourier domain, respectively. An average of the normalized modulated images results in a final image. For C-scan, we repeat steps 1 and 2 along the y direction in step 3.
Credit: OEA
A new publication from Opto-Electronic Advances, 10.29026/oes.2024.230020 discusses revolutionizing OCT imaging.
Deconvolution, an essential method widely employed in various optical imaging modalities such as fluorescence microscopy, has been less practical in Optical Coherence Tomography (OCT) due to significant challenges. In OCT imaging, the primary issue with deconvolution arises from noise-induced ringing artifacts that degrade image quality. Overcoming this obstacle is critical for harnessing the full potential of deconvolution in OCT. This research addresses this challenge head-on, innovatively mitigating the effects of noise and effectively reducing ringing artifacts. This breakthrough revitalizes the use of deconvolution in OCT, significantly enhancing image clarity and details. The successful application of deconvolution in OCT marks a pivotal advancement, not only improving diagnostic accuracy in medical imaging but also paving the way for new applications across various fields of optical imaging. The impact of this development is substantial, offering a powerful tool for better understanding and interpreting complex biological structures.
This article focuses on resolving the issue of noise-induced artifacts in OCT images caused by deconvolution methods. The primary goal of this study was to improve the clarity of OCT images by overcoming the limitations of traditional deconvolution method. To achieve this, the authors proposed the integration of random phase modulation with deconvolution, an approach aimed at effectively minimizing ringing artifacts. This would enhance the quality of OCT imaging.
The novel technique, referred to as Deconv-RPM, incorporates the iterative Richardson-Lucy deconvolution algorithm with the numerical synthesis of random phase masks (Fig. 1). This integration has shown to significantly reduce the full width at half-maximum (FWHM) in OCT images, leading to images that are clearer and possess greater detail.
The method was remarkably successful in improving the visualization of cellular-level details in various samples, including ex vivo nonkeratinized epithelial cells and in vivo moving blood cells (Fig. 2). This represented a considerable enhancement over traditional OCT imaging.
The Deconv-RPM method has paved the way for advanced biomedical applications of OCT. By offering more accurate and detailed images, it has potential applications in a range of fields, from medical diagnostics to biological research. This advancement is a game-changer in OCT imaging, providing a new tool for researchers and clinicians.
Keywords: deconvolution / random phase masks / deblurring
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Dr Ge received B.S. in Optical information science and technology in 2008, and Ph.D in Synchrotron radiation and its applications in 2013, from University of Science and Technology of China. He took postdoc training at the Chinese university of Hong Kong between 2013 to 2015 and Nanyang Technological University between 2015 to 2021, respectively. He joined the School of Science at SYSU as an Assistant Professor in 2022. His research interests are mainly focused on developing computational imaging models and building interferometric imaging instruments for various imaging applications.
Dr Liu received B.Eng in Precision Instrument in 2001, and M. Eng. in Optical Engineering in 2004, from Tianjin University, China. He received PhD in Graduate Programme in Bioengineering (GPBE) in 2008 from School of Medicine, National University of Singapore. From 2008-2011, he received his postdoctoral training in Wellman Center in Photomedicine, Harvard Medical School (HMS) and Massachusetts General Hospital (MGH) where he developed and established a new generation of OCT technology termed micro-Optical Coherence Tomography (µOCT). Dr Liu was promoted as an Instructor in Dermatology at HMS before he joined the School of Electrical and Electronic Engineering and School of Chemical and Biomedical Engineering at NTU as a Nanyang Assistant Professor in 2012. His research interests are mainly focused on development and validation of non-invasive, cellular and sub-cellular resolution imaging methods for disease diagnosis and life science research.
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Ge X, Chen S, Lin K et al. Deblurring, artifact-free optical coherence tomography with deconvolution-random phase modulation. Opto-Electron Sci 3, 230020 (2024). doi: 10.29026/oes.2024.230020