BACKGROUND The main clinical manifestation of Alzheimer’s disease(AD)is memory loss,which can be accompanied by neuropsychiatric symptoms at different stages of the disease.Amygdala is closely related to emotion and ...BACKGROUND The main clinical manifestation of Alzheimer’s disease(AD)is memory loss,which can be accompanied by neuropsychiatric symptoms at different stages of the disease.Amygdala is closely related to emotion and memory.AIM To evaluate the diagnostic value of amygdala on structural magnetic resonance imaging(sMRI)for AD.METHODS In this study,22 patients with AD and 26 controls were enrolled.Their amygdala volumes were measured by sMRI and analyzed using an automatic analysis software.RESULTS The bilateral amygdala volumes of AD patients were significantly lower than those of the controls and were positively correlated with the hippocampal volumes.Receiver operating characteristic curve analyses showed that the sensitivity of the left and right amygdala volumes in diagnosing AD was 80.8%and 88.5%,respectively.Subgroup analyses showed that amygdala atrophy was more serious in AD patients with neuropsychiatric symptoms,which mainly included irritability(22.73%),sleep difficulties(22.73%),apathy(18.18%),and hallucination(13.64%).CONCLUSION Amygdala volumes measured by sMRI can be used to diagnose AD,and amygdala atrophy is more serious in patients with neuropsychiatric symptoms.展开更多
Starting with introduction of basic concept of optical coherence tomography(OCT) techniques,this paper focuses on a detailed review of ophthalmic OCT instruments and their clinical applications. As one of the most imp...Starting with introduction of basic concept of optical coherence tomography(OCT) techniques,this paper focuses on a detailed review of ophthalmic OCT instruments and their clinical applications. As one of the most important inventions of ophthalmology instruments,OCT has become a standard imaging tool for daily ophthalmic diagnosis. The imaging capability has been significantly improved during the past ~ 30 years. In this article,several representing systems which have made significant contributions to OCT developments will be reviewed in details. For each system,the system configuration will be discussed first,follow ed by a brief introduction of their clinical applications. The review concludes with discussions on potential directions of OCT developments and expectations for further improvements of OCT imaging capabilities.展开更多
Transforming a scattering medium into a lens for imaging very simple binary objects is possible;however,it remains challenging to image complex grayscale objects,let alone measure 3D continuous distribution objects.He...Transforming a scattering medium into a lens for imaging very simple binary objects is possible;however,it remains challenging to image complex grayscale objects,let alone measure 3D continuous distribution objects.Here,we propose and demonstrate the use of a ground glass diffuser as a scattering lens for imaging complex grayscale fringes,and we employ it to achieve microscopic structured light 3D imaging(MSL3DI).The ubiquitous property of the speckle patterns permits the exploitation of the scattering medium as an ultra-thin scattering lens with a variable focal length and a flexible working distance for microscale object measurement.The method provides a light,flexible,and cost-effective imaging device as an alternative to microscope objectives or telecentric lenses in conventional MSL3DI systems.We experimentally demonstrate that employing a scattering lens allows us to achieve relatively good phase information and robust 3D imaging from depth measurements,yielding measurement accuracy only marginally lower than that of a telecentric lens,typically within approximately 10μm.Furthermore,the scattering lens demonstrates robust performance even when the imaging distance exceeds the typical working distance of a telecentric lens.The proposed method facilitates the application of scattering imaging techniques,providing a more flexible solution for MSL3DI.展开更多
Borehole acoustic reflection logging can provide high resolution images of nearborehole geological structure. However, the conventional seismic migration and imaging methods are not effective because the reflected wav...Borehole acoustic reflection logging can provide high resolution images of nearborehole geological structure. However, the conventional seismic migration and imaging methods are not effective because the reflected waves are interfered with the dominant borehole-guided modes and there are only eight receiving channels per shot available for stacking. In this paper, we apply an equivalent offset migration method based on wave scattering theory to process the acoustic reflection imaging log data from both numerical modeling and recorded field data. The result shows that, compared with the routine post-stack depth migration method, the equivalent offset migration method results in higher stack fold and is more effective for near-borehole structural imaging with low SNR acoustic reflection log data.展开更多
Acoustic reflection imaging in deep water wells is a new application scope for offshore hydrocarbon exploration.Two-dimensional(2 D)geological structure images can be obtained away from a one-dimensional(1 D)borehole ...Acoustic reflection imaging in deep water wells is a new application scope for offshore hydrocarbon exploration.Two-dimensional(2 D)geological structure images can be obtained away from a one-dimensional(1 D)borehole using single-well acoustic reflection imaging.Based on the directivity of dipole source and four-component dipole data,one can achieve the azimuth detection and the three-dimensional(3 D)structural information around the wellbore can be obtained.We first perform matrix rotation on the field fourcomponent data.Then,a series of processing steps are applied to the rotated dipole data to obtain the reflector image.According to the above dipole shear-wave imaging principle,we used four-component cross-dipole logging data from a deviated well in the South China Sea to image geological structures within 50 m of a deviated well,which can delineate the structural configuration and determine its orientation.The configuration of near-borehole bedding boundaries and fault structures from shear-wave imaging results agrees with those from the Inline and Xline seismic profiles of the study area.In addition,the configuration and orientation of the fault structure images are consistent with regional stress maps and the results of the borehole stress anisotropy analysis.Furthermore,the dip azimuth of the bedding boundary images was determined using borehole wall resistivity data.Results of this study indicate that integrating borehole acoustic reflection with seismic imaging not only fills the gap between the two measurement scales but also accurately delineates geological structures in the borehole vicinity.展开更多
Underwater imaging posts a challenge due to the degradation by the absorption and scattering occurred during light propagation as well as poor lighting conditions in water medium Although image filtering techniques ar...Underwater imaging posts a challenge due to the degradation by the absorption and scattering occurred during light propagation as well as poor lighting conditions in water medium Although image filtering techniques are utilized to improve image quality effectively, problems of the distortion of image details and the bias of color correction still exist in output images due to the complexity of image texture distribution. This paper proposes a new underwater image enhancement method based on image struc- tural decomposition. By introducing a curvature factor into the Mumford_Shah_G decomposition algorithm, image details and struc- ture components are better preserved without the gradient effect. Thus, histogram equalization and Retinex algorithms are applied in the decomposed structure component for global image enhancement and non-uniform brightness correction for gray level and the color images, then the optical absorption spectrum in water medium is incorporate to improve the color correction. Finally, the en- hauced structure and preserved detail component are re.composed to generate the output. Experiments with real underwater images verify the image improvement by the proposed method in image contrast, brightness and color fidelity.展开更多
Neurological abnormalities identified via neuroimaging are common in patients with Alzheimer’s disease.However,it is not yet possible to easily detect these abnormalities using head computed tomography in the early s...Neurological abnormalities identified via neuroimaging are common in patients with Alzheimer’s disease.However,it is not yet possible to easily detect these abnormalities using head computed tomography in the early stages of the disease.In this review,we evaluated the ways in which modern imaging techniques such as positron emission computed tomography,single photon emission tomography,magnetic resonance spectrum imaging,structural magnetic resonance imaging,magnetic resonance diffusion tensor imaging,magnetic resonance perfusion weighted imaging,magnetic resonance sensitive weighted imaging,and functional magnetic resonance imaging have revealed specific changes not only in brain structure,but also in brain function in Alzheimer’s disease patients.The reviewed literature indicated that decreased fluorodeoxyglucose metabolism in the temporal and parietal lobes of Alzheimer’s disease patients is frequently observed via positron emission computed tomography.Furthermore,patients with Alzheimer’s disease often show a decreased N-acetylaspartic acid/creatine ratio and an increased myoinositol/creatine ratio revealed via magnetic resonance imaging.Atrophy of the entorhinal cortex,hippocampus,and posterior cingulate gyrus can be detected early using structural magnetic resonance imaging.Magnetic resonance sensitive weighted imaging can show small bleeds and abnormal iron metabolism.Task-related functional magnetic resonance imaging can display brain function activity through cerebral blood oxygenation.Resting functional magnetic resonance imaging can display the functional connection between brain neural networks.These are helpful for the differential diagnosis and experimental study of Alzheimer’s disease,and are valuable for exploring the pathogenesis of Alzheimer’s disease.展开更多
Impaired structure and function of the hippocampus is a valuable predictor of progression from amnestic mild cognitive impairment（a MCI） to Alzheimer＇s disease（AD）. As a part of the medial temporal lobe memory sy...Impaired structure and function of the hippocampus is a valuable predictor of progression from amnestic mild cognitive impairment（a MCI） to Alzheimer＇s disease（AD）. As a part of the medial temporal lobe memory system,the hippocampus is one of the brain regions affected earliest by AD neuropathology,and shows progressive degeneration as a MCI progresses to AD. Currently,no validated biomarkers can precisely predict the conversion from a MCI to AD. Therefore,there is a great need of sensitive tools for the early detection of AD progression. In this review,we summarize the specifi c structural and functional changes in the hippocampus from recent a MCI studies using neurophysiological and neuroimaging data. We suggest that a combination of advanced multi-modal neuroimaging measures in discovering biomarkers will provide more precise and sensitive measures of hippocampal changes than using only one of them. These will potentially affect early diagnosis and disease-modifying treatments. We propose a new sequential and progressive framework in which the impairment spreads from the integrity of fibers to volume and then to function in hippocampal subregions. Meanwhile,this is likely to be accompanied by progressive impairment of behavioral and neuropsychological performance in the progression of a MCI to AD.展开更多
The current study aimed to evaluate the susceptibility to regional brain atrophy and its biological mechanism in Alzheimer’s disease(AD).We conducted data-driven meta-analyses to combine 3,118 structural magnetic res...The current study aimed to evaluate the susceptibility to regional brain atrophy and its biological mechanism in Alzheimer’s disease(AD).We conducted data-driven meta-analyses to combine 3,118 structural magnetic resonance images from three datasets to obtain robust atrophy patterns.Then we introduced a set of radiogenomic analyses to investigate the biological basis of the atrophy patterns in AD.Our results showed that the hippocampus and amygdala exhibit the most severe atrophy,followed by the temporal,frontal,and occipital lobes in mild cognitive impairment(MCI)and AD.The extent of atrophy in MCI was less severe than that in AD.A series of biological processes related to the glutamate signaling pathway,cellular stress response,and synapse structure and function were investigated through gene set enrichment analysis.Our study contributes to understanding the manifestations of atrophy and a deeper understanding of the pathophysiological processes that contribute to atrophy,providing new insight for further clinical research on AD.展开更多
A novel carbazole quaternary ammonium compound（abbreviated as T_2） had been synthesized and characterized by ~1H NMR, ^（13）C NMR and Mass spectrometry. The single-crystal structure has been determined by X-ray sin...A novel carbazole quaternary ammonium compound（abbreviated as T_2） had been synthesized and characterized by ~1H NMR, ^（13）C NMR and Mass spectrometry. The single-crystal structure has been determined by X-ray single-crystal diffraction. The electrochemical and two-photon absorption properties of T_2 were systematically studied by cyclic voltammetry and Z-scan determination methods, respectively. The results suggested that T_2 had a good oxidation-reduction and excellent nonlinear optical property. The two-photon absorption（TPA） value has a maximum corresponding to cross section σ = 7963.3 GM（Goeppert-Mayer units） at 700 nm, indicating potential applications in nonlinear optical materials. Furthermore, attributing to the excellent water solubility and low cytotoxicity, the compound was explored on its primary application in biological imaging.展开更多
Hydrocephalus is often treated with a cerebrospinal fluid shunt(CFS) for excessive amounts of cerebrospinal fluid in the brain.However,it is very difficult to distinguish whether the ventricular enlargement is due to ...Hydrocephalus is often treated with a cerebrospinal fluid shunt(CFS) for excessive amounts of cerebrospinal fluid in the brain.However,it is very difficult to distinguish whether the ventricular enlargement is due to hydrocephalus or other causes,such as brain atrophy after brain damage and surgery.The non-trivial evaluation of the consciousness level,along with a continuous drainage test of the lumbar cistern is thus clinically important before the decision for CFS is made.We studied 32 secondary mild hydrocephalus patients with different consciousness levels,who received T1 and diffusion tensor imaging magnetic resonance scans before and after lumbar cerebrospinal fluid drainage.We applied a novel machine-learning method to find the most discriminative features from the multi-modal neuroimages.Then,we built a regression model to regress the JFK Coma Recovery Scale-Revised(CRS-R) scores to quantify the level of consciousness.The experimental results showed that our method not only approximated the CRS-R scores but also tracked the temporal changes in individual patients.The regression model has high potential for the evaluation of consciousness in clinical practice.展开更多
The traditional information hiding methods embed the secret information by modifying the carrier,which will inevitably leave traces of modification on the carrier.In this way,it is hard to resist the detection of steg...The traditional information hiding methods embed the secret information by modifying the carrier,which will inevitably leave traces of modification on the carrier.In this way,it is hard to resist the detection of steganalysis algorithm.To address this problem,the concept of coverless information hiding was proposed.Coverless information hiding can effectively resist steganalysis algorithm,since it uses unmodified natural stego-carriers to represent and convey confidential information.However,the state-of-the-arts method has a low hidden capacity,which makes it less appealing.Because the pixel values of different regions of the molecular structure images of material(MSIM)are usually different,this paper proposes a novel coverless information hiding method based on MSIM,which utilizes the average value of sub-image’s pixels to represent the secret information,according to the mapping between pixel value intervals and secret information.In addition,we employ a pseudo-random label sequence that is used to determine the position of sub-images to improve the security of the method.And the histogram of the Bag of words model(BOW)is used to determine the number of subimages in the image that convey secret information.Moreover,to improve the retrieval efficiency,we built a multi-level inverted index structure.Furthermore,the proposed method can also be used for other natural images.Compared with the state-of-the-arts,experimental results and analysis manifest that our method has better performance in anti-steganalysis,security and capacity.展开更多
The prediction of fundus fluorescein angiography(FFA)images from fundus structural images is a cutting-edge research topic in ophthalmological image processing.Prediction comprises estimating FFA from fundus camera im...The prediction of fundus fluorescein angiography(FFA)images from fundus structural images is a cutting-edge research topic in ophthalmological image processing.Prediction comprises estimating FFA from fundus camera imaging,single-phase FFA from scanning laser ophthalmoscopy(SLO),and three-phase FFA also from SLO.Although many deep learning models are available,a single model can only perform one or two of these prediction tasks.To accomplish three prediction tasks using a unified method,we propose a unified deep learning model for predicting FFA images from fundus structure images using a supervised generative adversarial network.The three prediction tasks are processed as follows:data preparation,network training under FFA supervision,and FFA image prediction from fundus structure images on a test set.By comparing the FFA images predicted by our model,pix2pix,and CycleGAN,we demonstrate the remarkable progress achieved by our proposal.The high performance of our model is validated in terms of the peak signal-to-noise ratio,structural similarity index,and mean squared error.展开更多
Irritable bowel syndrome(IBS)is a common clinical label for medically unexplained gastrointestinal symptoms,recently described as a disturbance of the microbiota-gut-brain axis.Despite decades of research,the pathophy...Irritable bowel syndrome(IBS)is a common clinical label for medically unexplained gastrointestinal symptoms,recently described as a disturbance of the microbiota-gut-brain axis.Despite decades of research,the pathophysiology of this highly heterogeneous disorder remains elusive.However,a dramatic change in the understanding of the underlying pathophysiological mechanisms surfaced when the importance of gut microbiota protruded the scientific picture.Are we getting any closer to understanding IBS’etiology,or are we drowning in unspecific,conflicting data because we possess limited tools to unravel the cluster of secrets our gut microbiota is concealing?In this comprehensive review we are discussing some of the major important features of IBS and their interaction with gut microbiota,clinical microbiota-altering treatment such as the low FODMAP diet and fecal microbiota transplantation,neuroimaging and methods in microbiota analyses,and current and future challenges with big data analysis in IBS.展开更多
Mesial temporal lobe epilepsy(mTLE),the most common type of focal epilepsy,is associated with functional and structural brain alterations.Machine learning(ML)techniques have been successfully used in discriminating mT...Mesial temporal lobe epilepsy(mTLE),the most common type of focal epilepsy,is associated with functional and structural brain alterations.Machine learning(ML)techniques have been successfully used in discriminating mTLE from healthy controls.However,either functional or structural neuroimaging data are mostly used separately as input,and the opportunity to combine both has not been exploited yet.We conducted a multimodal ML study based on functional and structural neuroimaging measures.We enrolled 37 patients with left mTLE,37 patients with right mTLE,and 74 healthy controls and trained a support vector ML model to distinguish them by using each measure and the combinations of the measures.For each single measure,we obtained a mean accuracy of 74%and 69%for discriminating left mTLE and right mTLE from controls,respectively,and 64%when all patients were combined.We achieved an accuracy of 78%by integrating functional data and 79%by integrating structural data for left mTLE,and the highest accuracy of 84%was obtained when all functional and structural measures were combined.These findings suggest that combining multimodal measures within a single model is a promising direction for improving the classification of individual patients with mTLE.展开更多
Searching for effective biomarkers is one of the most challenging tasks in the research ？eld of Autism Spectrum Disorder（ASD）. Magnetic resonance imaging（MRI） provides a non-invasive and powerful tool for investi...Searching for effective biomarkers is one of the most challenging tasks in the research ？eld of Autism Spectrum Disorder（ASD）. Magnetic resonance imaging（MRI） provides a non-invasive and powerful tool for investigating changes in the structure, function, maturation,connectivity, and metabolism of the brain of children with ASD. Here, we review the more recent MRI studies in young children with ASD, aiming to provide candidate biomarkers for the diagnosis of childhood ASD. The review covers structural imaging methods, diffusion tensor imaging, resting-state functional MRI, and magnetic resonance spectroscopy. Future advances in neuroimaging techniques, as well as cross-disciplinary studies and largescale collaborations will be needed for an integrated approach linking neuroimaging, genetics, and phenotypic data to allow the discovery of new, effective biomarkers.展开更多
An experimental measurement was performed us- ing time-resolved particle image velocimetry （TRPIV） to in- vestigate the spatial topological character of coherent struc- tures in wall-bounded turbulence of polymer ad...An experimental measurement was performed us- ing time-resolved particle image velocimetry （TRPIV） to in- vestigate the spatial topological character of coherent struc- tures in wall-bounded turbulence of polymer additive solu- tion. The fully developed near-wall turbulent flow fields with and without polymer additives at the same Reynolds number were measured by TRPIV in a water channel. The compar- isons of turbulent statistics confirm that due to viscoelastic structure of long-chain polymers, the wall-normal velocity fluctuation and Reynolds shear stress in the near-wall region are suppressed significantly. Furthermore, it is noted that such a behavior of polymers is closely related to the decease of the motion of the second and forth quadrants, i.e., the ejection and sweep events, in the near-wall region. The spa- tial topological mode of coherent structures during bursts has been extracted by the new mu-level criteria based on locally averaged velocity structure function. Although the general shapes of coherent structures are unchanged by polymer additives, the fluctuating velocity, velocity gradient, velocity strain rate and vorticity of coherent structures during burst events are suppressed in the polymer additive solution com- pared with that in water. The results show that due to the polymer additives the occurrence and intensity of coherent structures are suppressed, leading to drag reduction.展开更多
Nature has shown us that the microstructure of the skin of fast-swimming sharks in the ocean can reduce the skin friction drag due to the well-known shark-skin effect.In the present study,the effect of shark-skin-insp...Nature has shown us that the microstructure of the skin of fast-swimming sharks in the ocean can reduce the skin friction drag due to the well-known shark-skin effect.In the present study,the effect of shark-skin-inspired riblets on coherent vortex structures in a turbulent boundary layer（TBL） is investigated.This is done by means of tomographic particle image velocimetry（TPIV） measurements in channel fl ws over an acrylic plate of drag-reducing riblets at a friction Reynolds number of 190.The turbulent fl ws over drag-reducing riblets are verifie by a planar time-resolved particle image velocimetry（TRPIV） system initially,and then the TPIV measurements are performed.Two-dimensional（2D） experimental results with a dragreduction rate of around 4.81% are clearly visible over triangle riblets with a peak-to-peak spacing s＋of 14,indicating from the drag-reducing performance that the buffer layer within the TBL has thickened;the logarithmic law region has shifted upward and the Reynolds shear stress decreased.A comparison of the spatial topological distributions of the spanwise vorticity of coherent vortex structures extracted at different wall-normal heights through the improved quadrant splitting method shows that riblets weaken the amplitudesof the spanwise vorticity when ejection（Q2） and sweep（Q4） events occur at the near wall,having the greatest effect on Q4 events in particular.The so-called quadrupole statistical model for coherent structures in the whole TBL is verified Meanwhile,their spatial conditional-averaged topological shapes and the spatial scales of quadrupole coherent vortex structures as a whole in the overlying turbulent fl w over riblets are changed,suggesting that the riblets dampen the momentum and energy exchange between the regions of near-wall and outer portion of the TBL by depressing the bursting events（Q2 and Q4）,thereby reducing the skin friction drag.展开更多
Characterizing the trajectory of the healthy aging brain and exploring age-related structural changes in the brain can help deepen our understanding of the mechanism of brain aging.Currently,most structural magnetic r...Characterizing the trajectory of the healthy aging brain and exploring age-related structural changes in the brain can help deepen our understanding of the mechanism of brain aging.Currently,most structural magnetic resonance imaging literature explores brain aging merely from the perspective of morphological features,which cannot fully utilize the grayscale values containing important intrinsic information about brain structure.In this study,we propose the construction of two-dimensional horizontal visibility graphs based on the pixel intensity values of the gray matter slices directly.Normalized network structure entropy(NNSE)is then introduced to quantify the overall heterogeneities of these graphs.The results demonstrate a decrease in the NNSEs of gray matter with age.Compared with the middle-aged and the elderly,the larger values of the NNSE in the younger group may indicate more homogeneous network structures,smaller differences in importance between nodes and thus a more powerful ability to tolerate intrusion.In addition,the hub nodes of different adult age groups are primarily located in the precuneus,cingulate gyrus,superior temporal gyrus,inferior temporal gyrus,parahippocampal gyrus,insula,precentral gyrus and postcentral gyrus.Our study can provide a new perspective for understanding and exploring the structural mechanism of brain aging.展开更多
Background:Fear of negative evaluation(FNE),referring to negative expectation and feelings toward other people’s social evaluation,is closely associated with social anxiety that plays an important role in our social ...Background:Fear of negative evaluation(FNE),referring to negative expectation and feelings toward other people’s social evaluation,is closely associated with social anxiety that plays an important role in our social life.Exploring the neural markers of FNE may be of theoretical and practical significance to psychiatry research(e.g.,studies on social anxiety).Methods:To search for potentially relevant biomarkers of FNE in human brain,the current study applied multivariate relevance vector regression,a machine-learning and data-driven approach,on brain morphological features(e.g.,cortical thickness)derived from structural imaging data;further,we used these features as indexes to predict self-reported FNE score in each participant.Results:Our results confirm the predictive power of multiple brain regions,including those engaged in negative emotional experience(e.g.,amygdala,insula),regulation and inhibition of emotional feeling(e.g.,frontal gyrus,anterior cingulate gyrus),and encoding and retrieval of emotional memory(e.g.,posterior cingulate cortex,parahippocampal gyrus).Conclusions:The current findings suggest that anxiety represents a complicated construct that engages multiple brain systems,from primitive subcortical mechanisms to sophisticated cortical processes.展开更多
基金Supported by The Young Talents Fund of the Second Hospital of Shandong University,No.2018YT16Rongxiang Regenerative Medicine Foundation of Shandong University,No.2019SDRX-09.
文摘BACKGROUND The main clinical manifestation of Alzheimer’s disease(AD)is memory loss,which can be accompanied by neuropsychiatric symptoms at different stages of the disease.Amygdala is closely related to emotion and memory.AIM To evaluate the diagnostic value of amygdala on structural magnetic resonance imaging(sMRI)for AD.METHODS In this study,22 patients with AD and 26 controls were enrolled.Their amygdala volumes were measured by sMRI and analyzed using an automatic analysis software.RESULTS The bilateral amygdala volumes of AD patients were significantly lower than those of the controls and were positively correlated with the hippocampal volumes.Receiver operating characteristic curve analyses showed that the sensitivity of the left and right amygdala volumes in diagnosing AD was 80.8%and 88.5%,respectively.Subgroup analyses showed that amygdala atrophy was more serious in AD patients with neuropsychiatric symptoms,which mainly included irritability(22.73%),sleep difficulties(22.73%),apathy(18.18%),and hallucination(13.64%).CONCLUSION Amygdala volumes measured by sMRI can be used to diagnose AD,and amygdala atrophy is more serious in patients with neuropsychiatric symptoms.
文摘Starting with introduction of basic concept of optical coherence tomography(OCT) techniques,this paper focuses on a detailed review of ophthalmic OCT instruments and their clinical applications. As one of the most important inventions of ophthalmology instruments,OCT has become a standard imaging tool for daily ophthalmic diagnosis. The imaging capability has been significantly improved during the past ~ 30 years. In this article,several representing systems which have made significant contributions to OCT developments will be reviewed in details. For each system,the system configuration will be discussed first,follow ed by a brief introduction of their clinical applications. The review concludes with discussions on potential directions of OCT developments and expectations for further improvements of OCT imaging capabilities.
基金supported by the National Natural Science Foundation of China(Grant Nos.62275188 and 62505216)the Central Guidance on Local Science and Technology Development Fund(Grant No.YDZJSX2024D019)+1 种基金the International Scientific and Technological Cooperative Project in Shanxi Province(Grant No.202104041101009)the Natural Science Foundation of Shanxi Province of China through Research Project(Grant No.20210302123195).
文摘Transforming a scattering medium into a lens for imaging very simple binary objects is possible;however,it remains challenging to image complex grayscale objects,let alone measure 3D continuous distribution objects.Here,we propose and demonstrate the use of a ground glass diffuser as a scattering lens for imaging complex grayscale fringes,and we employ it to achieve microscopic structured light 3D imaging(MSL3DI).The ubiquitous property of the speckle patterns permits the exploitation of the scattering medium as an ultra-thin scattering lens with a variable focal length and a flexible working distance for microscale object measurement.The method provides a light,flexible,and cost-effective imaging device as an alternative to microscope objectives or telecentric lenses in conventional MSL3DI systems.We experimentally demonstrate that employing a scattering lens allows us to achieve relatively good phase information and robust 3D imaging from depth measurements,yielding measurement accuracy only marginally lower than that of a telecentric lens,typically within approximately 10μm.Furthermore,the scattering lens demonstrates robust performance even when the imaging distance exceeds the typical working distance of a telecentric lens.The proposed method facilitates the application of scattering imaging techniques,providing a more flexible solution for MSL3DI.
基金supported by the National Natural Science Foundation of China (Grant No.50674098)the 863 Program (Grant No.2006AA06Z207 & 2006AA06Z213)the 973 Program (Grant No.2007CB209601)
文摘Borehole acoustic reflection logging can provide high resolution images of nearborehole geological structure. However, the conventional seismic migration and imaging methods are not effective because the reflected waves are interfered with the dominant borehole-guided modes and there are only eight receiving channels per shot available for stacking. In this paper, we apply an equivalent offset migration method based on wave scattering theory to process the acoustic reflection imaging log data from both numerical modeling and recorded field data. The result shows that, compared with the routine post-stack depth migration method, the equivalent offset migration method results in higher stack fold and is more effective for near-borehole structural imaging with low SNR acoustic reflection log data.
基金supported by the National Natural Science Foundation of China(Nos.41804124,41774138,41804121,41604109)China Academy of Sciences Strategic Leading Science and Technology Project(Grant Nos.XDA14020304,XDA14020302)+2 种基金Shandong Provincial Natural Science Foundation,China(No.ZR2019BD039)Shandong Province Postdoctoral Innovation Project(No.201901011)China Postdoctoral Science Foundation(Grant Nos.2019T120615,2018M632745)
文摘Acoustic reflection imaging in deep water wells is a new application scope for offshore hydrocarbon exploration.Two-dimensional(2 D)geological structure images can be obtained away from a one-dimensional(1 D)borehole using single-well acoustic reflection imaging.Based on the directivity of dipole source and four-component dipole data,one can achieve the azimuth detection and the three-dimensional(3 D)structural information around the wellbore can be obtained.We first perform matrix rotation on the field fourcomponent data.Then,a series of processing steps are applied to the rotated dipole data to obtain the reflector image.According to the above dipole shear-wave imaging principle,we used four-component cross-dipole logging data from a deviated well in the South China Sea to image geological structures within 50 m of a deviated well,which can delineate the structural configuration and determine its orientation.The configuration of near-borehole bedding boundaries and fault structures from shear-wave imaging results agrees with those from the Inline and Xline seismic profiles of the study area.In addition,the configuration and orientation of the fault structure images are consistent with regional stress maps and the results of the borehole stress anisotropy analysis.Furthermore,the dip azimuth of the bedding boundary images was determined using borehole wall resistivity data.Results of this study indicate that integrating borehole acoustic reflection with seismic imaging not only fills the gap between the two measurement scales but also accurately delineates geological structures in the borehole vicinity.
基金supported by the National Natural Science Foundation of China (Grant Nos.60772058 and 61271406)
文摘Underwater imaging posts a challenge due to the degradation by the absorption and scattering occurred during light propagation as well as poor lighting conditions in water medium Although image filtering techniques are utilized to improve image quality effectively, problems of the distortion of image details and the bias of color correction still exist in output images due to the complexity of image texture distribution. This paper proposes a new underwater image enhancement method based on image struc- tural decomposition. By introducing a curvature factor into the Mumford_Shah_G decomposition algorithm, image details and struc- ture components are better preserved without the gradient effect. Thus, histogram equalization and Retinex algorithms are applied in the decomposed structure component for global image enhancement and non-uniform brightness correction for gray level and the color images, then the optical absorption spectrum in water medium is incorporate to improve the color correction. Finally, the en- hauced structure and preserved detail component are re.composed to generate the output. Experiments with real underwater images verify the image improvement by the proposed method in image contrast, brightness and color fidelity.
基金This work was supported by the Science and Technology Support Plan of Guizhou Province of China,No.QianKeHe-Zhicheng[2020]4Y129(to HB)the Scientific Research Foundation of Guizhou Health Committee of China,No.gzwkj2017-1-022(to HB)the Scientific Research Project of Guizhou Traditional Chinese Medicine Bureau of China,No.QZYY-2018-044(to HB).
文摘Neurological abnormalities identified via neuroimaging are common in patients with Alzheimer’s disease.However,it is not yet possible to easily detect these abnormalities using head computed tomography in the early stages of the disease.In this review,we evaluated the ways in which modern imaging techniques such as positron emission computed tomography,single photon emission tomography,magnetic resonance spectrum imaging,structural magnetic resonance imaging,magnetic resonance diffusion tensor imaging,magnetic resonance perfusion weighted imaging,magnetic resonance sensitive weighted imaging,and functional magnetic resonance imaging have revealed specific changes not only in brain structure,but also in brain function in Alzheimer’s disease patients.The reviewed literature indicated that decreased fluorodeoxyglucose metabolism in the temporal and parietal lobes of Alzheimer’s disease patients is frequently observed via positron emission computed tomography.Furthermore,patients with Alzheimer’s disease often show a decreased N-acetylaspartic acid/creatine ratio and an increased myoinositol/creatine ratio revealed via magnetic resonance imaging.Atrophy of the entorhinal cortex,hippocampus,and posterior cingulate gyrus can be detected early using structural magnetic resonance imaging.Magnetic resonance sensitive weighted imaging can show small bleeds and abnormal iron metabolism.Task-related functional magnetic resonance imaging can display brain function activity through cerebral blood oxygenation.Resting functional magnetic resonance imaging can display the functional connection between brain neural networks.These are helpful for the differential diagnosis and experimental study of Alzheimer’s disease,and are valuable for exploring the pathogenesis of Alzheimer’s disease.
基金supported by the National Natural Science Foundation of China (91332000,81171021,and 91132727)the Key Program for Clinical Medicine and Science and Technology,Jiangsu Provence,China ( BL2013025 and BL2014077)
文摘Impaired structure and function of the hippocampus is a valuable predictor of progression from amnestic mild cognitive impairment（a MCI） to Alzheimer＇s disease（AD）. As a part of the medial temporal lobe memory system,the hippocampus is one of the brain regions affected earliest by AD neuropathology,and shows progressive degeneration as a MCI progresses to AD. Currently,no validated biomarkers can precisely predict the conversion from a MCI to AD. Therefore,there is a great need of sensitive tools for the early detection of AD progression. In this review,we summarize the specifi c structural and functional changes in the hippocampus from recent a MCI studies using neurophysiological and neuroimaging data. We suggest that a combination of advanced multi-modal neuroimaging measures in discovering biomarkers will provide more precise and sensitive measures of hippocampal changes than using only one of them. These will potentially affect early diagnosis and disease-modifying treatments. We propose a new sequential and progressive framework in which the impairment spreads from the integrity of fibers to volume and then to function in hippocampal subregions. Meanwhile,this is likely to be accompanied by progressive impairment of behavioral and neuropsychological performance in the progression of a MCI to AD.
基金Science and Technology Innovation 2030 Major Projects(2022ZD0211600)Fundamental Research Funds for the Central Universities(2021XD-A03)+3 种基金National Natural Science Foundation of China(81871438 and 82102018)Data collection and sharing for this project were supported by the National Natural Science Foundation of China(61633018,81571062,81400890,81471120,81701781,and 81901101)Data collection and sharing for this project were funded by the Alzheimer’s Disease Neuroimaging Initiative(ADNI)(National Institutes of Health Grant U01 AG024904)DOD ADNI(Department of Defense award number W81XWH-12-2-0012)。
文摘The current study aimed to evaluate the susceptibility to regional brain atrophy and its biological mechanism in Alzheimer’s disease(AD).We conducted data-driven meta-analyses to combine 3,118 structural magnetic resonance images from three datasets to obtain robust atrophy patterns.Then we introduced a set of radiogenomic analyses to investigate the biological basis of the atrophy patterns in AD.Our results showed that the hippocampus and amygdala exhibit the most severe atrophy,followed by the temporal,frontal,and occipital lobes in mild cognitive impairment(MCI)and AD.The extent of atrophy in MCI was less severe than that in AD.A series of biological processes related to the glutamate signaling pathway,cellular stress response,and synapse structure and function were investigated through gene set enrichment analysis.Our study contributes to understanding the manifestations of atrophy and a deeper understanding of the pathophysiological processes that contribute to atrophy,providing new insight for further clinical research on AD.
基金Supported by the National Natural Science Foundation of China(21271004,51372003,21271003,51432001,21101001)the Natural Science Foundation of Anhui Province(1308085MB24)Scientific Innovation Team Foundation of Educational Commission of Anhui Province(KJ2012A025,2006KJ007TD)
文摘A novel carbazole quaternary ammonium compound（abbreviated as T_2） had been synthesized and characterized by ~1H NMR, ^（13）C NMR and Mass spectrometry. The single-crystal structure has been determined by X-ray single-crystal diffraction. The electrochemical and two-photon absorption properties of T_2 were systematically studied by cyclic voltammetry and Z-scan determination methods, respectively. The results suggested that T_2 had a good oxidation-reduction and excellent nonlinear optical property. The two-photon absorption（TPA） value has a maximum corresponding to cross section σ = 7963.3 GM（Goeppert-Mayer units） at 700 nm, indicating potential applications in nonlinear optical materials. Furthermore, attributing to the excellent water solubility and low cytotoxicity, the compound was explored on its primary application in biological imaging.
基金supported by the National Natural Science Foundation of China (81571025 and 81702461)the National Key Research and Development Program of China (2018YFC0116400)+6 种基金the International Cooperation Project from Shanghai Science Foundation (18410711300)Shanghai Science and Technology Development Funds (16JC1420100)the Shanghai Sailing Program (17YF1426600)STCSM (19QC1400600, 17411953300)the Shanghai Pujiang Program (19PJ1406800)the Shanghai Municipal Science and Technology Major Project (No.2018SHZDZX01) and ZJlabthe Interdisciplinary Program of Shanghai Jiao Tong University。
文摘Hydrocephalus is often treated with a cerebrospinal fluid shunt(CFS) for excessive amounts of cerebrospinal fluid in the brain.However,it is very difficult to distinguish whether the ventricular enlargement is due to hydrocephalus or other causes,such as brain atrophy after brain damage and surgery.The non-trivial evaluation of the consciousness level,along with a continuous drainage test of the lumbar cistern is thus clinically important before the decision for CFS is made.We studied 32 secondary mild hydrocephalus patients with different consciousness levels,who received T1 and diffusion tensor imaging magnetic resonance scans before and after lumbar cerebrospinal fluid drainage.We applied a novel machine-learning method to find the most discriminative features from the multi-modal neuroimages.Then,we built a regression model to regress the JFK Coma Recovery Scale-Revised(CRS-R) scores to quantify the level of consciousness.The experimental results showed that our method not only approximated the CRS-R scores but also tracked the temporal changes in individual patients.The regression model has high potential for the evaluation of consciousness in clinical practice.
基金This work is supported,in part,by the National Natural Science Foundation of China under grant numbers U1536206,U1405254,61772283,61602253,61672294,61502242in part,by the Jiangsu Basic Research Programs-Natural Science Foundation under grant numbers BK20150925 and BK20151530+1 种基金in part,by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)fundin part,by the Collaborative Innovation Center of Atmospheric Environment and Equipment Technology(CICAEET)fund,China.
文摘The traditional information hiding methods embed the secret information by modifying the carrier,which will inevitably leave traces of modification on the carrier.In this way,it is hard to resist the detection of steganalysis algorithm.To address this problem,the concept of coverless information hiding was proposed.Coverless information hiding can effectively resist steganalysis algorithm,since it uses unmodified natural stego-carriers to represent and convey confidential information.However,the state-of-the-arts method has a low hidden capacity,which makes it less appealing.Because the pixel values of different regions of the molecular structure images of material(MSIM)are usually different,this paper proposes a novel coverless information hiding method based on MSIM,which utilizes the average value of sub-image’s pixels to represent the secret information,according to the mapping between pixel value intervals and secret information.In addition,we employ a pseudo-random label sequence that is used to determine the position of sub-images to improve the security of the method.And the histogram of the Bag of words model(BOW)is used to determine the number of subimages in the image that convey secret information.Moreover,to improve the retrieval efficiency,we built a multi-level inverted index structure.Furthermore,the proposed method can also be used for other natural images.Compared with the state-of-the-arts,experimental results and analysis manifest that our method has better performance in anti-steganalysis,security and capacity.
基金supported in part by the Gusu Innovation and Entrepreneurship Leading Talents in Suzhou City,grant numbers ZXL2021425 and ZXL2022476Doctor of Innovation and Entrepreneurship Program in Jiangsu Province,grant number JSSCBS20211440+6 种基金Jiangsu Province Key R&D Program,grant number BE2019682Natural Science Foundation of Jiangsu Province,grant number BK20200214National Key R&D Program of China,grant number 2017YFB0403701National Natural Science Foundation of China,grant numbers 61605210,61675226,and 62075235Youth Innovation Promotion Association of Chinese Academy of Sciences,grant number 2019320Frontier Science Research Project of the Chinese Academy of Sciences,grant number QYZDB-SSW-JSC03Strategic Priority Research Program of the Chinese Academy of Sciences,grant number XDB02060000.
文摘The prediction of fundus fluorescein angiography(FFA)images from fundus structural images is a cutting-edge research topic in ophthalmological image processing.Prediction comprises estimating FFA from fundus camera imaging,single-phase FFA from scanning laser ophthalmoscopy(SLO),and three-phase FFA also from SLO.Although many deep learning models are available,a single model can only perform one or two of these prediction tasks.To accomplish three prediction tasks using a unified method,we propose a unified deep learning model for predicting FFA images from fundus structure images using a supervised generative adversarial network.The three prediction tasks are processed as follows:data preparation,network training under FFA supervision,and FFA image prediction from fundus structure images on a test set.By comparing the FFA images predicted by our model,pix2pix,and CycleGAN,we demonstrate the remarkable progress achieved by our proposal.The high performance of our model is validated in terms of the peak signal-to-noise ratio,structural similarity index,and mean squared error.
基金Supported by the Spanish Ministry of Science and Innovation(MICINN,Spain),No.AGL2017-88801-P(to Sanz Y)the Miguel Server grant from the Spanish"Carlos III"Health Institute(ISCIII),No.CP19/00132(to Benitez-Paez A)+2 种基金The Norwegian Research Council(Funding Postdoc Position for Bharath Halandur Nagaraja),No.FRIMEDBIO276010and Helse Vest’s Research Funding,No.HV912243and ERC H2020-MSCA-IF-2019,No.895219(to Haleem N).
文摘Irritable bowel syndrome(IBS)is a common clinical label for medically unexplained gastrointestinal symptoms,recently described as a disturbance of the microbiota-gut-brain axis.Despite decades of research,the pathophysiology of this highly heterogeneous disorder remains elusive.However,a dramatic change in the understanding of the underlying pathophysiological mechanisms surfaced when the importance of gut microbiota protruded the scientific picture.Are we getting any closer to understanding IBS’etiology,or are we drowning in unspecific,conflicting data because we possess limited tools to unravel the cluster of secrets our gut microbiota is concealing?In this comprehensive review we are discussing some of the major important features of IBS and their interaction with gut microbiota,clinical microbiota-altering treatment such as the low FODMAP diet and fecal microbiota transplantation,neuroimaging and methods in microbiota analyses,and current and future challenges with big data analysis in IBS.
基金This study was supported by the National Natural Science Foundation of China(Nos.81501452,81621003,81761128023,81220108031,and 81227002)the Program for Innovative Research Team in University(PCSIRT,No.IRT16R52)of China+1 种基金the Scholar Professorship Award(No.T2014190)of Chinathe CMB Distinguished Professorship Award(No.F510000/G16916411)administered by the Institute of International Education.
文摘Mesial temporal lobe epilepsy(mTLE),the most common type of focal epilepsy,is associated with functional and structural brain alterations.Machine learning(ML)techniques have been successfully used in discriminating mTLE from healthy controls.However,either functional or structural neuroimaging data are mostly used separately as input,and the opportunity to combine both has not been exploited yet.We conducted a multimodal ML study based on functional and structural neuroimaging measures.We enrolled 37 patients with left mTLE,37 patients with right mTLE,and 74 healthy controls and trained a support vector ML model to distinguish them by using each measure and the combinations of the measures.For each single measure,we obtained a mean accuracy of 74%and 69%for discriminating left mTLE and right mTLE from controls,respectively,and 64%when all patients were combined.We achieved an accuracy of 78%by integrating functional data and 79%by integrating structural data for left mTLE,and the highest accuracy of 84%was obtained when all functional and structural measures were combined.These findings suggest that combining multimodal measures within a single model is a promising direction for improving the classification of individual patients with mTLE.
文摘Searching for effective biomarkers is one of the most challenging tasks in the research ？eld of Autism Spectrum Disorder（ASD）. Magnetic resonance imaging（MRI） provides a non-invasive and powerful tool for investigating changes in the structure, function, maturation,connectivity, and metabolism of the brain of children with ASD. Here, we review the more recent MRI studies in young children with ASD, aiming to provide candidate biomarkers for the diagnosis of childhood ASD. The review covers structural imaging methods, diffusion tensor imaging, resting-state functional MRI, and magnetic resonance spectroscopy. Future advances in neuroimaging techniques, as well as cross-disciplinary studies and largescale collaborations will be needed for an integrated approach linking neuroimaging, genetics, and phenotypic data to allow the discovery of new, effective biomarkers.
基金supported by the National Natural Science Foundation of China(11272233)National Key Basic Research and Development Program(2012CB720101)2012 opening subjects of The State Key Laboratory of Nonlinear Mechanics(LNM),Institute of Mechanics,Chinese Academy of Sciences
文摘An experimental measurement was performed us- ing time-resolved particle image velocimetry （TRPIV） to in- vestigate the spatial topological character of coherent struc- tures in wall-bounded turbulence of polymer additive solu- tion. The fully developed near-wall turbulent flow fields with and without polymer additives at the same Reynolds number were measured by TRPIV in a water channel. The compar- isons of turbulent statistics confirm that due to viscoelastic structure of long-chain polymers, the wall-normal velocity fluctuation and Reynolds shear stress in the near-wall region are suppressed significantly. Furthermore, it is noted that such a behavior of polymers is closely related to the decease of the motion of the second and forth quadrants, i.e., the ejection and sweep events, in the near-wall region. The spa- tial topological mode of coherent structures during bursts has been extracted by the new mu-level criteria based on locally averaged velocity structure function. Although the general shapes of coherent structures are unchanged by polymer additives, the fluctuating velocity, velocity gradient, velocity strain rate and vorticity of coherent structures during burst events are suppressed in the polymer additive solution com- pared with that in water. The results show that due to the polymer additives the occurrence and intensity of coherent structures are suppressed, leading to drag reduction.
基金supported by the National Natural Science Foundation of China (Grants 11332006,11272233,and 11411130150)the foundation from the China Scholarship Council (CSC) (Grant 201306250092)the Foundation Project for Outstanding Doctoral Dissertations of Tianjin University
文摘Nature has shown us that the microstructure of the skin of fast-swimming sharks in the ocean can reduce the skin friction drag due to the well-known shark-skin effect.In the present study,the effect of shark-skin-inspired riblets on coherent vortex structures in a turbulent boundary layer（TBL） is investigated.This is done by means of tomographic particle image velocimetry（TPIV） measurements in channel fl ws over an acrylic plate of drag-reducing riblets at a friction Reynolds number of 190.The turbulent fl ws over drag-reducing riblets are verifie by a planar time-resolved particle image velocimetry（TRPIV） system initially,and then the TPIV measurements are performed.Two-dimensional（2D） experimental results with a dragreduction rate of around 4.81% are clearly visible over triangle riblets with a peak-to-peak spacing s＋of 14,indicating from the drag-reducing performance that the buffer layer within the TBL has thickened;the logarithmic law region has shifted upward and the Reynolds shear stress decreased.A comparison of the spatial topological distributions of the spanwise vorticity of coherent vortex structures extracted at different wall-normal heights through the improved quadrant splitting method shows that riblets weaken the amplitudesof the spanwise vorticity when ejection（Q2） and sweep（Q4） events occur at the near wall,having the greatest effect on Q4 events in particular.The so-called quadrupole statistical model for coherent structures in the whole TBL is verified Meanwhile,their spatial conditional-averaged topological shapes and the spatial scales of quadrupole coherent vortex structures as a whole in the overlying turbulent fl w over riblets are changed,suggesting that the riblets dampen the momentum and energy exchange between the regions of near-wall and outer portion of the TBL by depressing the bursting events（Q2 and Q4）,thereby reducing the skin friction drag.
基金Project supported by the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20190736)the Young Scientists Fund of the National Natural Science Foundation of China(Grant Nos.81701346 and 61603198)Qinglan Team of Universities in Jiangsu Province(Jiangsu Teacher Letter[2020]10 and Jiangsu Teacher Letter[2021]11).
文摘Characterizing the trajectory of the healthy aging brain and exploring age-related structural changes in the brain can help deepen our understanding of the mechanism of brain aging.Currently,most structural magnetic resonance imaging literature explores brain aging merely from the perspective of morphological features,which cannot fully utilize the grayscale values containing important intrinsic information about brain structure.In this study,we propose the construction of two-dimensional horizontal visibility graphs based on the pixel intensity values of the gray matter slices directly.Normalized network structure entropy(NNSE)is then introduced to quantify the overall heterogeneities of these graphs.The results demonstrate a decrease in the NNSEs of gray matter with age.Compared with the middle-aged and the elderly,the larger values of the NNSE in the younger group may indicate more homogeneous network structures,smaller differences in importance between nodes and thus a more powerful ability to tolerate intrusion.In addition,the hub nodes of different adult age groups are primarily located in the precuneus,cingulate gyrus,superior temporal gyrus,inferior temporal gyrus,parahippocampal gyrus,insula,precentral gyrus and postcentral gyrus.Our study can provide a new perspective for understanding and exploring the structural mechanism of brain aging.
基金This work was supported by the National Natural Science Foundation of China(Nos.31900757,32071083 and 32020103008)the Major Program of the Chinese National Social Science Foundation(No.17ZDA324)the Youth Innovation Promotion Association,CAS(No.2019088).
文摘Background:Fear of negative evaluation(FNE),referring to negative expectation and feelings toward other people’s social evaluation,is closely associated with social anxiety that plays an important role in our social life.Exploring the neural markers of FNE may be of theoretical and practical significance to psychiatry research(e.g.,studies on social anxiety).Methods:To search for potentially relevant biomarkers of FNE in human brain,the current study applied multivariate relevance vector regression,a machine-learning and data-driven approach,on brain morphological features(e.g.,cortical thickness)derived from structural imaging data;further,we used these features as indexes to predict self-reported FNE score in each participant.Results:Our results confirm the predictive power of multiple brain regions,including those engaged in negative emotional experience(e.g.,amygdala,insula),regulation and inhibition of emotional feeling(e.g.,frontal gyrus,anterior cingulate gyrus),and encoding and retrieval of emotional memory(e.g.,posterior cingulate cortex,parahippocampal gyrus).Conclusions:The current findings suggest that anxiety represents a complicated construct that engages multiple brain systems,from primitive subcortical mechanisms to sophisticated cortical processes.
