- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Lens-free microscopy for 3D + time acquisitions of 3D cell culture
摘要： Thanks to a novel three-dimensional imaging platform based on lens-free microscopy, it is possible to perform multi-angle acquisitions and holographic reconstructions of 3D cell cultures directly into the incubator. Being able of reconstructing volumes as large as ~5 mm3 over a period of time covering several days, allows us to observe a broad range of migration strategies only present in 3D environment, whether it is single cell migration, collective migrations of cells and dispersal of cells. In addition we are able to distinguish new interesting phenomena, e.g. large-scale cell-to-matrix interactions (>1 mm), fusion of cell clusters into large aggregate (~10,000 μm2) and conversely, total dissociation of cell clusters into clumps of migrating cells. This work on a novel 3D + time lens-free microscopy technique thus expands the repertoire of phenomena that can be studied within 3D cell cultures.
关键词： cell migration,holographic reconstruction,extracellular matrix,3D cell culture,lens-free microscopy
更新于2025-09-23 15:21:01
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Three-dimensional view of out-of-plane artifacts in photoacoustic imaging using a laser-integrated linear-transducer-array probe
摘要： Research on photoacoustic imaging (PAI) using a handheld integrated photoacoustic probe has been a recent focus of clinical translation of this imaging technique. One of the remaining challenges is the occurrence of out-of-plane artifacts (OPAs) in such a probe. Previously, we proposed a method to identify and remove OPAs by axially displacing the transducer array. Here we show that besides the benefit of removing OPAs from the imaging plane, the proposed method can provide a three-dimensional (3D) view of the OPAs. In this work, we present a 3D reconstruction method using axial transducer array displacement. By axially displacing the transducer array, out-of-plane absorbers can be three-dimensionally visualized at an elevation distance of up to the acquired imaging depth. Additionally, OPAs in the in-plane image are significantly reduced. We experimentally demonstrate the method with phantom and in vivo experiments using an integrated PAI probe. We also compare the method with elevational transducer array displacement and take into account the sensitivity of the transducer array in the 3D reconstruction.
关键词： Out-of-plane artifact,Three-dimensional reconstruction,Linear array,Beamforming
更新于2025-09-23 15:21:01
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Sparsity-induced dynamic guided filtering approach for sparse-view data toward low-dose X-ray computed tomography
摘要： Iterative reconstruction (IR) methods that can incorporate filtering or regularization techniques have received widespread attention in many situations. Total variation (TV) regularization has proven to be a powerful tool to suppress streak artifacts and noise for sparse-view computed tomography (CT) reconstruction over 360°. However, with under-sampled projection data from limited-view (e.g., half-view) CT scanning, where the projections are further reduced, the edge structures are partly blurred, and some artifacts (such as blocky artifacts) are not effectively suppressed in TV-based results. To further improve the quality of the reconstructed image, a sparsity-induced dynamic guided image filtering reconstruction (SIDGIFR) method is proposed. Intermediate reconstruction results constrained by total difference minimization are taken as the guidance image to filter the results of projection onto convex sets (POCS) by guided image filtering. In the SIDGIFR algorithm, the guidance image is dynamically updated, which can transfer the important features (such as edge and small details) to the filtered image during the iterative process. To confirm the efficiency and feasibility of the SIDGIFR algorithm, simulated experiments and real data studies are performed. The quantitative evaluation shows that the proposed SIDGIFR method has better performance than other classical iterative reconstruction methods. What’s more, the proposed SIDGIFR algorithm can better preserve the edge structures, and suppress noise and artifacts, than the existing iterative reconstruction methods.
关键词： computed tomography,total variation,iterative reconstruction,total difference,guided image filtering,sparse-view
更新于2025-09-23 15:21:01
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[IEEE 2018 International Conference on 3D Vision (3DV) - Verona (2018.9.5-2018.9.8)] 2018 International Conference on 3D Vision (3DV) - Fusion++: Volumetric Object-Level SLAM
摘要： We propose an online object-level SLAM system which builds a persistent and accurate 3D graph map of arbitrary reconstructed objects. As an RGB-D camera browses a cluttered indoor scene, Mask-RCNN instance segmentations are used to initialise compact per-object Truncated Signed Distance Function (TSDF) reconstructions with object size-dependent resolutions and a novel 3D foreground mask. Reconstructed objects are stored in an optimisable 6DoF pose graph which is our only persistent map representation. Objects are incrementally re?ned via depth fusion, and are used for tracking, relocalisation and loop closure detection. Loop closures cause adjustments in the relative pose estimates of object instances, but no intra-object warping. Each object also carries semantic information which is re?ned over time and an existence probability to account for spurious instance predictions.
关键词： SLAM,object-level mapping,Mask-RCNN,3D reconstruction,RGB-D
更新于2025-09-23 15:21:01
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[IEEE 2018 3rd Russian-Pacific Conference on Computer Technology and Applications (RPC) - Vladivostok (2018.8.18-2018.8.25)] 2018 3rd Russian-Pacific Conference on Computer Technology and Applications (RPC) - Image-Based Navigation of Autonomous Underwater Robot and 3D Reconstruction of Environment
摘要： An approach to solving the problem of navigation an autonomous underwater robot by video stream in the conditions of local maneuvering is described. The approach is based on the using of the visual odometry method by stereo images and a virtual network for coordinate referencing. To increase the accuracy of the calculation of local movements of the robot, an original algorithm for tracing features on images taking into account past frames is proposed. The proposed method for solving the problem of 3D reconstruction of environment objects from images is described also.
关键词： stereo images,autonomous underwater robot,3D reconstruction,visual odometry,navigation
更新于2025-09-23 15:21:01
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Statistical CT reconstruction using region-aware texture preserving regularization learning from prior normal-dose CT image
摘要： In some clinical applications, prior normal-dose CT (NdCT) images are available, and the valuable textures and structure features in them may be used to promote follow-up low-dose CT (LdCT) reconstruction. This study aims to learn texture information from the NdCT images and leverage it for follow-up LdCT image reconstruction to preserve textures and structure features. Specifically, the proposed reconstruction method first learns the texture information from those patches with similar structures in NdCT image, and the similar patches can be clustered by searching context features efficiently from the surroundings of the current patch. Then it utilizes redundant texture information from the similar patches as a priori knowledge to describe specific regions in the LdCT image. The advanced region-aware texture preserving prior is termed as ‘RATP’. The main advantage of the PATP prior is that it can properly learn the texture features from available NdCT images and adaptively characterize the region-specific structures in the LdCT image. The experiments using patient data were performed to evaluate the performance of the proposed method. The proposed RATP method demonstrated superior performance in LdCT imaging compared to the filtered back projection (FBP) and statistical iterative reconstruction (SIR) methods using Gaussian regularization, Huber regularization and the original texture preserving regularization.
关键词： texture preserving,statistical iterative reconstruction,low-dose,a priori image,CT imaging
更新于2025-09-23 15:21:01
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Geometric distortion correction of long-range imaging containing moving objects
摘要： Video sequences of long-range imaging are inevitably affected by optical turbulence, which leads to non-uniform geometric distortion and object position shifts. Restoration of this turbulence-degraded data containing moving objects is a challenging task, which essentially involves in video stabilization and moving objects detection. In this work, a novel method for simultaneously realizing turbulence mitigation and moving objects detection is proposed in such scenarios. We firstly model the turbulent foreground with a specific mixture of Gaussian (MoG) distribution, which is regularized online by the low-rank subspace of background. Furthermore, to well preserve the low-rank property of dynamic background, we embed a transformation operator into the proposed model which makes it much more robust in practical camera jitters or rotation. Finally, a simple mask strategy is used to reconstruct stable frame containing moving objects. Extensive experiments using synthetic and real-life turbulence-degraded data show that the proposed method outperforms other compared approaches in terms of both geometric distortion correction and moving objects preservation.
关键词： Image detection systems.,Image reconstruction-restoration,Imaging through turbulent media,Atmospheric turbulence
更新于2025-09-23 15:21:01
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Hand-Held 3-D Reconstruction of Large-Scale Scene With Kinect Sensors Based on Surfel and Video Sequences
摘要： This letter presents a hand-held complex large-scale scene reconstruction method with Kinect sensors based on surfel and video sequences. The feature point method simultaneous localization and mapping (SLAM) is employed to estimate the pose of the camera, and then bundle adjustment by combining 2-D and 3-D feature points is used to optimize camera pose. Also, the surfel model is employed to construct deformation maps for the fusion and optimization of point clouds, and finally, an accurate precise 3-D map can be obtained. The main contribution of this letter is that: 1) by using the SLAM method to obtain camera pose as the initial value of optimization, the problem of insufficient memory and low efficiency of the structure form motion method can be well solved; 2) sparsely textured regions can be reconstructed better by using bundle adjustment by combining 2-D and 3-D feature points; and 3) dense 3-D reconstruction of large scenes can be achieved, and the reconstructed 3-D models are more elaborate. Finally, experimental results show that this proposed method can be applied to a variety of complex large-scale scenes, and can obtain accurate precise 3-D model. This presented 3-D reconstruction method can be widely used in the fields of human–computer interaction, consumer electronics, and virtual reality.
关键词： Kinect sensors,bundle adjustment,3-D reconstruction,surfel
更新于2025-09-23 15:21:01
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[IEEE 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Honolulu, HI, USA (2018.7.18-2018.7.21)] 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Improved Heart Rate Tracking Using Multiple Wrist-type Photoplethysmography during Physical Activities
摘要： Photoplethysmography (PPG) signals collected from wearable sensing devices during physical exercise are easily corrupted by motion artifact (MA), which poses great challenge on heart rate (HR) estimation. This paper proposes a new framework to accurately estimate HR using two leads of PPG signals in combination with accelerometer (ACC) data in the presence of MA. A moving time window is first used to segment PPG signals and ACC signals. Then, MA is attenuated by joint sparse spectrum reconstruction in each time window, where maximum spectrum frequencies of ACC are subtracted from the spectrum frequency of PPG signals. Further, HR for each cleansed PPG is estimated from the frequency with maximum amplitude in the sparse spectrum. The actual HR is determined using spectral band powers calculated from each reconstructed PPG signals. The proposed method was validated using the 2015 IEEE Signal Processing Cup dataset. The average absolute error is 1.15 beats per minutes (BPM) (standard deviation: 2.00 BPM), and the average absolute error percentage is 0.95% (standard deviation: 1.86%). The proposed method outperforms the previously reported work in terms of accuracy.
关键词： accelerometer (ACC),heart rate (HR),motion artifact (MA),joint sparse spectrum reconstruction,Photoplethysmography (PPG)
更新于2025-09-23 15:21:01
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Handbook of Neuro-Oncology Neuroimaging || Positron Emission Tomography (PET) and Single-Photon Emission Computed Tomography (SPECT) Physics
摘要： The purpose of emission tomography is to estimate the distribution of a radiotracer from external measurements of the pattern of photons emerging from the brain. Some of these photons are detected, and certain information about them recorded, by the scanner. These external measurements are termed “projections,” and each measurement in a projection represents, ideally, the sum of radioactivity concentration along a line through the brain. From these measured projection data sets and knowledge of certain aspects of the single-photon emission computed tomography (SPECT) or positron emission tomography (PET) instrument, estimated images of the distribution of radioactivity are mathematically reconstructed. All modern SPECT and PET scanners image the three-dimensional (3D) distribution of radioactivity, either as a stack of two-dimensional (2D) transaxial images or directly as a 3D volume.
关键词： Single-Photon Emission Computed Tomography,Positron Emission Tomography,Image Reconstruction,Radiotracer,SPECT,PET,Radioactivity Distribution,Physics
更新于2025-09-23 15:21:01