Yong Liu

Three-dimensional morphological revealing of human placental villi with common obstetric complications via optical coherence tomography

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Placental villi play a vital role in human fetal development, acting as the bridge of material exchange between the maternal and fetal. The abnormal morphology of placental villi is closely related to placental circulation disorder and pregnancy complications. Revealing placental villi three-dimensional (3D) morphology of common obstetric complications and healthy pregnancies provides a new perspective for studying the role of the placenta and its villi in the development of pregnancy diseases. In this study, we established a noninvasive, high-resolution 3D imaging platform via optical coherence tomography to reveal placental villi 3D morphological information of diseased and normal placentae. For the first time, 3D morphologies of placental villous tree structures in common obstetric complications were quantitatively revealed and corresponding 3D information could visualize the morphological characteristics of the placental villous tree from a more intuitive perspective, providing ...

Hybrid-structure network and network comparative study for deep-learning-based speckle-modulating optical coherence tomography

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Optical coherence tomography (OCT), a promising noninvasive bioimaging technique, can resolve sample three-dimensional microstructures. However, speckle noise imposes obvious limitations on OCT resolving capabilities. Here we proposed a deep-learning-based speckle-modulating OCT based on a hybrid-structure network, residual-dense-block U-Net generative adversarial network (RDBU-Net GAN), and further conducted a comprehensively comparative study to explore multi-type deep-learning architectures' abilities to extract speckle pattern characteristics and remove speckle, and resolve microstructures. This is the first time that network comparative study has been performed on a customized dataset containing mass more-general speckle patterns obtained from a custom-built speckle-modulating OCT, but not on retinal OCT datasets with limited speckle patterns. Results demonstrated that the proposed RDBU-Net GAN has a more excellent ability to extract speckle pattern characteristics and remove s...

Depth-resolved transverse-plane motion tracking with configurable measurement features via optical coherence tomography

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Optical coherence tomography (OCT), a promising noninvasive bioimaging technique, has become one of the most successful optical technologies implemented in medicine and clinical practice. Here we report a novel technique of depth-resolved transverse-plane motion tracking with configurable measurement features via optical coherence tomography, termed OCT-MT. Based on OCT circular scanning combined with speckle spatial oversampling, the OCT-MT technique can perform depth-resolved transverse-plane motion tracking. Benefitting from the optical interference and depth-resolved feature, the proposed OCT-MT can reduce the requirements on the input power of the irradiation signal and the surface reflectivity and roughness of the target, when performing motion tracking. Furthermore, OCT-MT can conduct such kind of motion tracking with configurable measurement ranges and resolutions by configuring A-line number per scanning circle, circular scanning radius, and A-line scanning time. The propos...

Single A-Line Method for Fast Sample-Structure-Nondependent Dispersion Compensation of FD-OCT

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Here we proposed a single A-line sample-structure-nondependent (SSNd) dispersion detection and compensation method for Fourier-domain optical coherence tomography (FD-OCT), without need for acquiring and processing B-scan data. A new FD-OCT dispersion mismatch index, based on the line slope of the bright line in the A-line spectrogram, has been presented in the proposed method. With the new dispersion mismatch index, the proposed single A-line method can fast and visually detect the dispersion mismatch states of FD-OCT setup and perform the SSNd dispersion compensation, just using a single A-line. Experimental results of multiple samples demonstrated the advantages and convenience of the proposed method, and also proved that the proposed method can be used to analyze the relation of OCT imaging and optical path difference between the sample and reference arms. ( Read Full Article )

Sm-Net OCT: a deep-learning-based speckle-modulating optical coherence tomography

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Speckle imposes obvious limitations on resolving capabilities of optical coherence tomography (OCT), while speckle-modulating OCT can efficiently reduce speckle arbitrarily. However, speckle-modulating OCT seriously reduces the imaging sensitivity and temporal resolution of the OCT system when reducing speckle. Here, we proposed a deep-learning-based speckle-modulating OCT, termed Sm-Net OCT, by deeply integrating conventional OCT setup and generative adversarial network trained with a customized large speckle-modulating OCT dataset containing massive speckle patterns. The customized large speckle-modulating OCT dataset was obtained from the aforementioned conventional OCT setup rebuilt into a speckle-modulating OCT and performed imaging using different scanning parameters. Experimental results demonstrated that the proposed Sm-Net OCT can effectively obtain high-quality OCT images without the electronic noise and speckle, and conquer the limitations of reducing the imaging sensitiv...

Fourier-domain optical coherence tomography-guided phototherapeutic keratectomy for the treatment of anterior corneal scarring

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AIM : To evaluate the safety, visual and anatomic outcomes of fourier-domain optical coherence tomography (FD-OCT)-guided excimer laser phototherapeutic keratectomy (PTK) combined with photorefractive keratectomy (PRK) surgery in treating anterior corneal scarring. METHODS : Clinical data of 23 eyes of 21 patients with anterior corneal scarring underwent FD-OCT-guided PTK and PRK from Dec. 2014 to Jul. 2016 were reviewed. Patients were assessed for preoperative and postoperative uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), contrast sensitivity (CS), FD-OCT, corneal topography and colour figures of anterior segments. RESULTS : The preoperative corneal pathologic conditions included viral keratitis (7 patients, 7 eyes), band keratopathy (2 patients, 4 eyes), corneal dystrophy (4 patients, 4 eyes), traumatic corneal disease (2 patients, 2 eyes) and corneal chemical injury (6 patients, 6 eyes). Mean follow-up time was 10.65 (range, 3-19)mo. UCVA (in ...

Detection and compensation of dispersion mismatch for frequency-domain optical coherence tomography based on A-scan’s spectrogram

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Balanced dispersion between reference and sample arms is critical in frequency-domain optical coherence tomography (FD-OCT) to perform imaging with the optimal axial resolution, and the spectroscopic analysis of each voxel in FD-OCT can provide the metric of the spectrogram. Here we revisited dispersion mismatch in the spectrogram view using the spectroscopic analysis of voxels in FD-OCT and uncovered that the dispersion mismatch disturbs the A-scan’s spectrogram and reshapes the depth-resolved spectra in the spectrogram. Based on this spectroscopic effect of dispersion mismatch on A-scan’s spectrogram, we proposed a numerical method to detect dispersion mismatch and perform dispersion compensation for FD-OCT. The proposed method can visually and quantitatively detect and compensate for dispersion mismatch in FD-OCT, with visualization, high sensitivity, and independence from sample structures. Experimental results of tape and mouse eye suggest that this technique can be...

Towards Indicating Human Skin State In Vivo Using Geometry-Dependent Spectroscopic Contrast Imaging

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Skin plays a significant role in human body function and its collagen states change during the human skin ageing process, which affects skin function. We previously reported on geometry-dependent spectroscopic contrast achieved by spectroscopic micro-optical coherence tomography ( S μ OCT), which discovered that transversely oriented and regularly arranged nano-cylinders selectively backscatter the long-wavelength lights and generate spectral centroid (SC) shifts towards the long wavelengths within a spectral window of 700 − 950 nm . Here we further proposed a novel method towards indicating the state of human skin in vivo using geometry-dependent spectroscopic contrast imaging. The proposed method can obtain spectroscopic contrast images of different human skin layers, including the papillary dermis and reticular dermis, and provide a quantitative method towards indicating collagen state in human skin in vivo. Experimental results have shown that the proposed method may po...

Numerical investigation on coherent mid-infrared supercontinuum generation in chalcogenide PCFs with near zero flattened all-normal dispersion profiles

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We present a novel design of all-normal flat near zero dispersion chalcogenide photonics crystal fiber (PCF) for mid-infrared supercontinuum (SC) generation. The proposed PCF with a core made of As<sub>2</sub>Se<sub>3</sub> glass and uniform air holes in the cladding is selectively filled with As<sub>2</sub>S<sub>5</sub> glass. By carefully engineering the PCF with an all-normal flat near zero dispersion profile, the anomalous-dispersion soliton effects are reduced, enabling broadband highly coherent SC generation. We also investigate the impacts of the pulse parameters on the SC generation. Broadband SCs covering 1.4-10μm with perfect coherence is achieved by pumping the 3-cm-long proposed PCF with 100-fs pulses at 3μm. The results provide a potential all-fiber realization of the broadband coherent MIR-SC. ( Read Full Article )

AI for medical imaging goes deep

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An artificial intelligence (AI) using a deep-learning approach can classify retinal images from optical coherence tomography for early diagnosis of retinal diseases and has the potential to be used in other image-based medical diagnoses. ( Read Full Article )

Feasibility of Optical Coronary Tomography in Quantitative Measurement of Coronary Arteries With Lipid-Rich Plaque

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Background: The aim of the present study was to evaluate the feasibility of optical coherence tomography (OCT) for measurement of vessel area in coronary arteries with lipid-rich plaque as compared with intravascular ultrasound (IVUS). Methods and Results: We investigated 80 coronary artery segments with lipid-rich plaque on OCT and non-attenuated plaque on IVUS. According to the lipid arc on OCT, the plaques were classified into 4 groups: group 1, lipid arc ≤90°; group 2, 90°<lipid arc≤180°; group 3, 180°<lipid arc≤270°; group 4, lipid arc >270°. Vessel circular arcs that could not be identified due to OCT signal attenuation were interpolated using an approximating algorithm. OCT-measured vessel area was well-correlated with IVUS-measured vessel area (R=0.834, P<0.001). On Bland-Altman plot, there was a good agreement between OCT-measured vessel area and IVUS-measured vessel area, although mean difference and limits of agreement increase...

Comparison of vascular response between everolimus-eluting stent and bare metal stent implantation in ST-segment elevation myocardial infarction assessed by optical coherence tomography

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Aims The long-term safety of second-generation everolimus-eluting stents (EESs) in ST-segment elevation myocardial infarction (STEMI) remains unclear. The aim of this study was to evaluate the late vascular response after stent implantation in STEMI between EES and bare-metal stent (BMS) by using optical coherence tomography (OCT). Methods and results A prospective OCT examination was performed in 102 patients at 10 months after stent implantation for treatment of STEMI. A total of 1253 frames with 12 772 struts in 61 EESs and 776 frames with 8594 struts in 41 BMSs were analysed. There were no significant differences in the percentage of uncovered struts (2.1 ± 2.8 vs. 1.7 ± 2.7%, P = 0.422) and malapposed struts (0.7 ± 1.3 vs. 0.6 ± 1.2%, P = 0.756) between EES and BMS. The frequency of intra-stent thrombus was comparable between the two stents (13 vs. 10%, P = 0.758). The mean neointimal thickness was smaller in EES compared with BMS (104 ± 39 vs...

Comparison of longitudinal geometric measurement in human coronary arteries between frequency-domain optical coherence tomography and intravascular ultrasound

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Previous studies have demonstrated the higher accuracy of frequency-domain optical coherence tomography (FD-OCT) for quantitative measurements in comparison with intravascular ultrasound (IVUS). However, those analyses were based on the cross-sectional images. The aim of this study was to assess the accuracy of FD-OCT for longitudinal geometric measurements of coronary arteries in comparison with IVUS. Between October 2011 and March 2012, we performed prospective FD-OCT and IVUS examinations in consecutive 77 patients who underwent percutaneous coronary intervention with single stent. Regression analysis and Bland-Altman analysis revealed an excellent correlation between the FD-OCT-measured stent lengths and IVUS-measured stent lengths (r = 0.986, p < 0.001; mean difference = -0.51 mm). There was an excellent agreement between the actual stent lengths and the FD-OCT-measured stent lengths (r = 0.993, p < 0.001) as well as between the actual stent lengths and the IVUS-measured ...

Assessment by Optical Coherence Tomography of Stent Struts Across Side Branch – Comparison of Bare-Metal Stents and Drug-Eluting Stents –

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Late stent thrombosis (LST) after drug-eluting stent (DES) implantation is a major clinical problem that has not been fully explained. Incomplete neointimal coverage of stent struts is an important morphometric predictor of LST, which may be associated with impaired healing and the absence of full coverage of struts at branch-point ostia. Optical coherence tomography (OCT) was performed to compare 3 types of stents placed across side branches. Methods and Results: At 9-month follow-up, the neointimal coverage of the struts of 58 stents across a side branch was measured by OCT (bare metal (BMS), n=20; sirolimus-eluting (SES), n=23; paclitaxel-eluting (PES), n=15). According to the diameter ratio of side branch to main vessel, the side branches were classified as either large (ratio >0.33) or small (ratio ≤0.33). BMS had the lowest frequency of uncovered struts (29.4%) and the greatest neointimal thickness on the struts (123±33µm). Neointimal thickness on the struts was less for SES t...

Clinical Classification and Plaque Morphology Determined by Optical Coherence Tomography in Unstable Angina Pectoris

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Unstable angina pectoris (UAP) is categorized with the Braunwald classification. However, the association of clinical presentation and plaque structure/function has not yet been elucidated in relation to cause. We used optical coherence tomography to investigate this relation. One hundred fifteen patients with primary UAP were categorized according to the Braunwald classification. Patients with class I UAP had the highest frequency of ulcers without fibrous cap disruption (p = 0.003) and the smallest minimum lumen area (class I, median 0.70 mm2, quartiles 1 to 3 0.42 to 1.00; class II, 1.80 mm2, 1.50 to 2.50; class III, 2.31 mm2, 1.21 to 3.00; p ( Read Full Article )


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