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iterative reconstruction

Jiao Wu, Feilong Cao, Juncheng Yin
A novel multi-morphological representation model for solving the nonlocal similarity-based image reconstruction from compressed measurements is introduced in this paper. Under the probabilistic framework, the proposed approach provides the nonlocal similarity clustering for image patches by using the Gaussian mixture models, and endows a multimorphological representation for image patches in each cluster by using the Gaussians that represent the different features to model the morphological components. Using the simple alternating iteration, the developed piecewise morphological diversity estimation (PMDE) algorithm can effectively estimate the MAP of morphological components, thus resulting in the nonlinear estimation for image patches...
August 16, 2017: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Shuo Chen, Jian Yang, Lei Luo, Yang Wei, Kaihua Zhang, Ying Tai
This paper develops a novel method to address the structural noise in samples for image classification. Recently, regression related classification methods have shown promising results when facing the pixel-wise noise. However, they become weak in coping with the structural noise due to ignoring of relationships between pixels of noise image. Meanwhile, most of them need to implement the iterative process for computing representation coefficients, which leads to the high time consumption. To overcome these problems, we exploit a latent pattern model called Low-Rank Latent Pattern Approximation (LLPA) to reconstruct the test image having structural noise...
August 10, 2017: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Martin H Goodenberger, Nicolaus A Wagner-Bartak, Shiva Gupta, Xinming Liu, Ramon Q Yap, Jia Sun, Eric P Tamm, Corey T Jensen
OBJECTIVE: The purpose of this study was to compare abdominopelvic computed tomography images reconstructed with adaptive statistical iterative reconstruction-V (ASIR-V) with model-based iterative reconstruction (Veo 3.0), ASIR, and filtered back projection (FBP). METHODS AND MATERIALS: Abdominopelvic computed tomography scans for 36 patients (26 males and 10 females) were reconstructed using FBP, ASIR (80%), Veo 3.0, and ASIR-V (30%, 60%, 90%). Mean ± SD patient age was 32 ± 10 years with mean ± SD body mass index of 26...
August 12, 2017: Journal of Computer Assisted Tomography
Yegang Hu, Yicong Lin, Baoshan Yang, Guangrui Tang, Tao Liu, Yuping Wang, Jicong Zhang
In recent years, the source localization technique of magnetoencephalography (MEG) has played a prominent role in cognitive neuroscience and in the diagnosis and treatment of neurological and psychological disorders. However, locating deep brain activities such as in the mesial temporal structures, especially in preoperative evaluation of epilepsy patients, may be more challenging. In this work we have proposed a modified beamforming approach for finding deep sources. First, an iterative spatiotemporal signal decomposition was employed for reconstructing the sensor arrays, which could characterize the intrinsic discriminant features for interpreting sensor signals...
August 11, 2017: Sensors
Yasutaka Fushimi, Tomohisa Okada, Takayuki Kikuchi, Akira Yamamoto, Tsutomu Okada, Takayuki Yamamoto, Michaela Schmidt, Kazumichi Yoshida, Susumu Miyamoto, Kaori Togashi
Compressed sensing (CS) MRI has just been introduced to research areas as an innovative approach to accelerate MRI. CS is expected to achieve higher k-space undersampling by exploiting the underlying sparsity in an appropriate transform domain. MR angiography (MRA) provides high spatial resolution information on arteries; however, a relatively long acquisition time is necessary to cover a wide volume. Reduction of acquisition time by CS for time-of-flight (TOF) MR angiography (Sparse-TOF) is beneficial in clinical examinations; therefore, the clinical validity of Sparse-TOF needs to be investigated...
August 10, 2017: NMR in Biomedicine
Rongrong Ji, Hong Liu, Liujuan Cao, Di Liu, Yongjian Wu, Feiyue Huang
Binary code learning, a.k.a. hashing, has received increasing attention in large-scale visual search. By transforming high-dimensional features to binary codes, the original Euclidean distance is approximated via Hamming distance. More recently, it is advocated that it is the manifold distance, rather than the Euclidean distance, that should be preserved in the Hamming space. However, it retains as an open problem to directly preserve the manifold structure by hashing. In particular, it needs first to build the local linear embedding in the original feature space, and then quantize such embedding to binary codes...
August 2, 2017: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Qiang Zhou, Niyun Zhou, Hong-Wei Wang
As single particle cryo-electron microscopy has evolved to a new era of atomic resolution, sample heterogeneity still imposes a major limit to the resolution of many macromolecular complexes, especially those with continuous conformational flexibility. Here, we describe a particle segmentation algorithm towards solving structures of molecules composed of several parts that are relatively flexible with each other. In this algorithm, the different parts of a target molecule are segmented from raw images according to their alignment information obtained from a preliminary 3D reconstruction and are subjected to single particle processing in an iterative manner...
2017: Biophysics Reports
Yu Chen, Zihao Wang, Jingrong Zhang, Lun Li, Xiaohua Wan, Fei Sun, Fa Zhang
Electron tomography (ET) plays an important role in studying in situ cell ultrastructure in three-dimensional space. Due to limited tilt angles, ET reconstruction always suffers from the "missing wedge" problem. With a validation procedure, iterative compressed-sensing optimized NUFFT reconstruction (ICON) demonstrates its power in the restoration of validated missing information for low SNR biological ET dataset. However, the huge computational demand has become a major problem for the application of ICON...
2017: Biophysics Reports
Tatiana Latychevskaia, Flavio Wicki, Conrad Escher, Hans-Werner Fink
While imaging individual atoms can routinely be achieved in high resolution transmission electron microscopy, visualizing the potential distribution of individually charged adsorbates leading to a phase shift of the probing electron wave is still a challenging task. Low-energy electrons (30 - 250 eV) are sensitive to localized potential gradients. We employed low-energy electron holography to acquire in-line holograms of individual charged impurities on free-standing graphene. By applying an iterative phase retrieval reconstruction routine we recover the potential distribution of the localized charged impurities present on free-standing graphene...
July 29, 2017: Ultramicroscopy
Liang Xu, Rongchang Chen, Yiming Yang, Biao Deng, Guohao Du, Honglan Xie, Tiqiao Xiao
Monochromatic-beam-based dynamic X-ray computed microtomography (CT) was developed to observe evolution of microstructure inside samples. However, the low flux density results in low efficiency in data collection. To increase efficiency, reducing the number of projections should be a practical solution. However, it has disadvantages of low image reconstruction quality using the traditional filtered back projection (FBP) algorithm. In this study, an iterative reconstruction method using an ordered subset expectation maximization-total variation (OSEM-TV) algorithm was employed to address and solve this problem...
July 31, 2017: Journal of X-ray Science and Technology
Lars Kasper, Maria Engel, Christoph Barmet, Maximilian Haeberlin, Bertram J Wilm, Benjamin E Dietrich, Thomas Schmid, Simon Gross, David O Brunner, Klaas E Stephan, Klaas P Pruessmann
We report the deployment of spiral acquisition for high-resolution structural imaging at 7T. Long spiral readouts are rendered manageable by an expanded signal model including static off-resonance and B0 dynamics along with k-space trajectories and coil sensitivity maps. Image reconstruction is accomplished by inversion of the signal model using an extension of the iterative non-Cartesian SENSE algorithm. Spiral readouts up to 25 ms are shown to permit whole-brain 2D imaging at 0.5 mm in-plane resolution in less than a minute...
July 31, 2017: NeuroImage
Dengjiang Wang, Weifang Zhang, Xiangyu Wang, Bo Sun
This study presents a novel monitoring method for hole-edge corrosion damage in plate structures based on Lamb wave tomographic imaging techniques. An experimental procedure with a cross-hole layout using 16 piezoelectric transducers (PZTs) was designed. The A0 mode of the Lamb wave was selected, which is sensitive to thickness-loss damage. The iterative algebraic reconstruction technique (ART) method was used to locate and quantify the corrosion damage at the edge of the hole. Hydrofluoric acid with a concentration of 20% was used to corrode the specimen artificially...
November 12, 2016: Materials
Zijing Dong, Fuyixue Wang, Xiaodong Ma, Erpeng Dai, Zhe Zhang, Hua Guo
PURPOSE: To develop a new approach to correct for physiological and macroscopic motion in multishot, interleaved echo-planar diffusion imaging. THEORY: This work built on the previous SPIRiT (iterative self-consistent parallel imaging reconstruction) based reconstruction for physiological motion correction in multishot diffusion-weighted imaging to account for macroscopic motion. In-plane rotation, translation correction, data rejection, and weighted combination are integrated in SPIRiT-based reconstruction to correct for ghosting artifacts, blurring, altered b-matrix, and residual artifacts caused by motion...
August 3, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Nikita Cobetto, Carl-Éric Aubin, Stefan Parent, Soraya Barchi, Isabelle Turgeon, Hubert Labelle
BACKGROUND: Recent studies showed that finite element model (FEM) combined to CAD/CAM improves the design of braces for the conservative treatment of adolescent idiopathic scoliosis (AIS), using 2D measurements from in-brace radiographs. We aim to assess the immediate effectiveness on curve correction in all three planes of braces designed using CAD/CAM and numerical simulation compared to braces designed with CAD/CAM only. METHODS: SRS standardized criteria for bracing were followed to recruit 48 AIS patients who were randomized into two groups...
2017: Scoliosis and Spinal Disorders
Patricia Leutz-Schmidt, Oliver Weinheimer, Bertram J Jobst, Julien Dinkel, Jürgen Biederer, Hans-Ulrich Kauczor, Michael U Puderbach, Mark O Wielpütz
OBJECTIVES: To evaluate the influence of exposure parameters and raw-data-based iterative reconstruction (IR) on computer-aided segmentation and quantitative analysis of the tracheobronchial tree on multidetector computed tomography (MDCT). MATERIAL AND METHODS: 10 porcine heart-lung-explants were mounted inside a dedicated chest phantom. MDCT was performed at 120kV and 80kV with 120, 60, 30 and 12 mAs each. All scans were reconstructed with filtered back projection (FBP) or IR, resulting in a total of 160 datasets...
2017: PloS One
Jiabei Zheng, Jeffrey A Fessler, Heang-Ping Chan
This paper describes a new image reconstruction method for digital breast tomosynthesis (DBT). The new method incorporates detector blur into the forward model. The detector blur in DBT causes correlation in the measurement noise. By making a few approximations that are reasonable for breast imaging, we formulated a regularized quadratic optimization problem with a data-fit term that incorporates models for detector blur and correlated noise (DBCN). We derived a computationally efficient separable quadratic surrogate (SQS) algorithm to solve the optimization problem that has a non-diagonal noise covariance matrix...
July 27, 2017: IEEE Transactions on Medical Imaging
Yeo-Jin Jeong, Ki Seok Choo, Kyung Jin Nam, Ji Won Lee, Jin You Kim, Hyuk Jae Jung, Soo Jin Lim
Background Computed tomography venography (CTV) at low kVp using model-based iterative reconstruction (MBIR) can enhance vascular enhancement with noise reduction. Purpose To evaluate image qualities and radiation doses of CTV at 80 kVp using MBIR and a small iodine contrast media (CM) dose and to compare these with those of CTV performed using a conventional protocol. Material and Methods Sixty-five patients (mean age = 58.1 ± 7.2 years) that underwent CTV for the evaluation of deep vein thrombosis (DVT) and varicose veins were enrolled in this study...
January 1, 2017: Acta Radiologica
S B Nam, D W Jeong, K S Choo, K J Nam, J-Y Hwang, J W Lee, J Y Kim, S J Lim
AIM: To compare the image quality of computed tomography angiography (CTA) reconstructed by sinogram-affirmed iterative reconstruction (SAFIRE) with that of advanced modelled iterative reconstruction (ADMIRE) in children with congenital heart disease (CHD). MATERIAL AND METHODS: Thirty-one children (8.23±13.92 months) with CHD who underwent CTA were enrolled. Images were reconstructed using SAFIRE (strength 5) and ADMIRE (strength 5). Objective image qualities (attenuation, noise) were measured in the great vessels and heart chambers...
July 29, 2017: Clinical Radiology
Minghuan Zhang
This paper presents a method for formation flight and collision avoidance of multiple UAVs. Due to the shortcomings such as collision avoidance caused by UAV's high-speed and unstructured environments, this paper proposes a modified tentacle algorithm to ensure the high performance of collision avoidance. Different from the conventional tentacle algorithm which uses inverse derivation, the modified tentacle algorithm rapidly matches the radius of each tentacle and the steering command, ensuring that the data calculation problem in the conventional tentacle algorithm is solved...
2017: PloS One
T Humphries, J Winn, A Faridani
Recent work in CT image reconstruction has seen increasing interest in the use of total variation (TV) and related penalties to regularize problems involving reconstruction from undersampled or incomplete data. Superiorization is a recently proposed heuristic which provides an automatic procedure to 'superiorize' an iterative image reconstruction algorithm with respect to a chosen objective function, such as TV. Under certain conditions, the superiorized algorithm is guaranteed to find a solution that is as satisfactory as any found by the original algorithm with respect to satisfying the constraints of the problem; this solution is also expected to be superior with respect to the chosen objective...
August 1, 2017: Physics in Medicine and Biology
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