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iterative reconstruction

Caleb J Bashor, James J Collins
Engineering synthetic gene regulatory circuits proceeds through iterative cycles of design, building, and testing. Initial circuit designs must rely on often-incomplete models of regulation established by fields of reductive inquiry-biochemistry and molecular and systems biology. As differences in designed and experimentally observed circuit behavior are inevitably encountered, investigated, and resolved, each turn of the engineering cycle can force a resynthesis in understanding of natural network function...
March 16, 2018: Annual Review of Biophysics
Katsuyuki Taguchi, Toshihide Itoh, Matthew K Fuld, Eric Fournie, Okkyun Lee, Kyo Noguchi
OBJECTIVES: A novel imaging technique ("X-map") has been developed to identify acute ischemic lesions for stroke patients using non-contrast-enhanced dual-energy computed tomography (NE-DE-CT). Using the 3-material decomposition technique, the original X-map ("X-map 1.0") eliminates fat and bone from the images, suppresses the gray matter (GM)-white matter (WM) tissue contrast, and makes signals of edema induced by severe ischemia easier to detect. The aim of this study was to address the following 2 problems with the X-map 1...
March 14, 2018: Investigative Radiology
Nils Große Hokamp, Alexandra Hellerbach, Andreas Gierich, David W Jordan, Veerle Visser-Vandewalle, David Maintz, Stefan Haneder
OBJECTIVES: The aim of this study was to evaluate the reduction of artifacts from deep brain stimulation electrodes (DBS) using an iterative metal artifact reduction algorithm (O-MAR), virtual monoenergetic images (VMI), and both in combination in postoperative spectral detector computed tomography using a dual-layer detector (spectral detector computed tomography [SDCT]) of the head. MATERIAL AND METHODS: Nonanthropomorphic phantoms with different DBS leads were examined on SDCT; in 1 phantom periprocedural bleeding was simulated...
March 14, 2018: Investigative Radiology
John W Garrett, Yinsheng Li, Ke Li, Guang-Hong Chen
PURPOSE: Digital breast tomosynthesis (DBT) has been shown to somewhat alleviate the breast tissue overlapping issues of two dimensional (2D) mammography.However, the improvement in current DBT systems over mammography is still limited.Statistical image reconstruction (SIR) methods have the potential to reduce through-plane artifacts in DBT, and thus may be used to further reduce anatomical clutter. The purpose of this work was to study the impact of SIR on anatomical clutter in the reconstructed DBT image volumes...
March 15, 2018: Medical Physics
D J Murphy, A Aghayev, M L Steigner
Non-invasive cross-sectional imaging techniques play a crucial role in the assessment of the varied manifestations of vascular disease. Vascular imaging encompasses a wide variety of pathology. Designing vascular imaging protocols can be challenging owing to the non-uniform velocity of blood in the aorta, differences in cardiac output between patients, and the effect of different disease states on blood flow. In this review, we provide the rationale behind-and a practical guide to-designing and implementing straightforward vascular computed tomography (CT) and magnetic resonance imaging (MRI) protocols...
March 14, 2018: Insights Into Imaging
Yan Wu, Yaojun Jiang, Xueli Han, Mingyue Wang, Jianbo Gao
Background: To investigate the repeatability and accuracy of quantitative CT (QCT) measurement of bone mineral density (BMD) by low-mAs using iterative model reconstruction (IMR) technique based on phantom model. Methods: European spine phantom (ESP) was selected and measured on the Philips Brilliance iCT Elite FHD machine for 10 times. Data were transmitted to the QCT PRO workstation to measure BMD (mg/cm3 ) of the ESP (L1, L2, L3). Scanning method: the voltage of X-ray tube is 120 kV, the electric current of X-ray tube output in five respective groups A-E were: 20, 30, 40, 50 and 60 mAs...
February 2018: Quantitative Imaging in Medicine and Surgery
Amir Pourmorteza, Noemie Keller, Richard Chen, Albert Lardo, Henry Halperin, Marcus Y Chen, Elliot McVeigh
Resting regional wall motion abnormality (RWMA) has significant prognostic value beyond the findings of computed tomography (CT) coronary angiography. Stretch quantification of endocardial engraved zones (SQUEEZ) has been proposed as a measure of regional cardiac function. The purpose of the work reported here was to determine the effect of lowering the radiation dose on the precision of automatic SQUEEZ assessments of RWMA. Chronic myocardial infarction was created by a 2-h occlusion of the left anterior descending coronary artery in 10 swine (heart rates 80-100, ejection fraction 25-57%)...
March 13, 2018: International Journal of Cardiovascular Imaging
Y R Chai, J J Xing, J B Gao, P J Lü, P Hou, J Liu
Objective: To analyze the effect of preset adaptive statistical iterative reconstruction-V (ASIR-V) on image quality and radiation dose in dual-enhanced abdominal CT and to investigate the optimal ASIR-V in clinic use. Methods: From February 13 to April 30 in 2017, one hundred and eighty patients who received up abdominal CT scan in the First Affiliated Hospital of Zhengzhou University were collected prospectively. All patients underwent arterial phase (AP) and portal venous phase (PVP) enhanced abdominal CT(120 kVp, noise index 10) and were randomly divided into 6 groups according to random number table (A-F, 30 cases in each group)...
March 6, 2018: Zhonghua Yi Xue za Zhi [Chinese medical journal]
Dominik Zinsser, Roy Marcus, Ahmed E Othman, Fabian Bamberg, Konstantin Nikolaou, Thomas Flohr, Mike Notohamiprodjo
BACKGROUND:  For years, the number of performed CT examinations has been rising. At the same time, computed tomography became more dose efficient. The aim of this article is to give an overview about the state of the art in dose reduction in CT and to highlight currently available tools in dose management. METHOD:  By performing a literature research on Pubmed regarding dose reduction in CT, relevant articles were identified and analyzed. RESULTS AND CONCLUSION:  Technical innovations with individual adaptation of tube current and voltage as well as iterative image reconstruction enable a considerable dose reduction with preserved image quality...
March 13, 2018: RöFo: Fortschritte Auf Dem Gebiete der Röntgenstrahlen und der Nuklearmedizin
Shuying Huang, Jun Sun, Yong Yang, Yuming Fang, Pan Lin, Yue Que
Single-image super-resolution (SR) reconstruction via sparse representation has recently attracted broad interest. It is known that a low-resolution (LR) image is susceptible to noise or blur due to the degradation of the observed image, which would lead to a poor SR performance. In this paper, we propose a novel robust edge-preserving smoothing SR (REPS-SR) method in the framework of sparse representation. An EPS regularization term is designed based on gradient-domain-guided filtering to preserve image edges and reduce noise in the reconstructed image...
June 2018: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Jose Luis Martínez Fuentes, Ignacio Moreno
A new technique for encoding the amplitude and phase of diffracted fields in digital holography is proposed. It is based on a random spatial multiplexing of two phase-only diffractive patterns. The first one is the phase information of the intended pattern, while the second one is a diverging optical element whose purpose is the control of the amplitude. A random number determines the choice between these two diffractive patterns at each pixel, and the amplitude information of the desired field governs its discrimination threshold...
March 5, 2018: Optics Express
A P Konijnenberg, W M J Coene, H P Urbach
A noise-robust extension of iterative phase retrieval algorithms that does not need to assume a noise model is proposed. It works by adapting the intensity constraints using the reconstructed object. Using a proof-of-principle ptychographic experiment with visible light and a spatial light modulator to create an object, the proposed method is tested and it compares favorably to the Extended Ptychographic Iterative Engine (ePIE) with reduced step size. The method is general, so it can also be applied to other iterative reconstruction schemes such as phase retrieval using focus variation...
March 5, 2018: Optics Express
Ximing Ren, Peter W R Connolly, Abderrahim Halimi, Yoann Altmann, Stephen McLaughlin, Istvan Gyongy, Robert K Henderson, Gerald S Buller
A CMOS single-photon avalanche diode (SPAD) quanta image sensor is used to reconstruct depth and intensity profiles when operating in a range-gated mode used in conjunction with pulsed laser illumination. By designing the CMOS SPAD array to acquire photons within a pre-determined temporal gate, the need for timing circuitry was avoided and it was therefore possible to have an enhanced fill factor (61% in this case) and a frame rate (100,000 frames per second) that is more difficult to achieve in a SPAD array which uses time-correlated single-photon counting...
March 5, 2018: Optics Express
Yannick Berker, Joel S Karp, Volkmar Schulz
The use of scattered coincidences for attenuation correction of positron emission tomography (PET) data has recently been proposed. For practical applications, convergence speeds require further improvement, yet there exists a trade-off between convergence speed and the risk of non-convergence. In this respect, a maximum-likelihood gradient-ascent (MLGA) algorithm and a two-branch back-projection (2BP), which was previously proposed, were evaluated. Methods: MLGA was combined with the Armijo step size rule; and accelerated using conjugate gradients, Nesterov's momentum method, and data subsets of different sizes...
September 2017: IEEE Transactions on Radiation and Plasma Medical Sciences
Trixi von Schlippenbach, Peter J Oefner, Wolfram Gronwald
Non-uniform sampling (NUS) allows the accelerated acquisition of multidimensional NMR spectra. The aim of this contribution was the systematic evaluation of the impact of various quantitative NUS parameters on the accuracy and precision of 2D NMR measurements of urinary metabolites. Urine aliquots spiked with varying concentrations (15.6-500.0 µM) of tryptophan, tyrosine, glutamine, glutamic acid, lactic acid, and threonine, which can only be resolved fully by 2D NMR, were used to assess the influence of the sampling scheme, reconstruction algorithm, amount of omitted data points, and seed value on the quantitative performance of NUS in1 H,1 H-TOCSY and1 H,1 H-COSY45 NMR spectroscopy...
March 9, 2018: Scientific Reports
Jun Yu, Zhengxiang Shen, Pengfeng Sheng, Xiaoqiang Wang, Charles J Hailey, Zhanshan Wang
The nested grazing incidence telescope can achieve a large collecting area in x-ray astronomy, with a large number of closely packed, thin conical mirrors. Exploiting the surface metrological data, the ray tracing method used to reconstruct the shell surface topography and evaluate the imaging performance is a powerful tool to assist iterative improvement in the fabrication process. However, current two-dimensional (2D) ray tracing codes, especially when utilized with densely sampled surface shape data, may not provide sufficient accuracy of reconstruction and are computationally cumbersome...
March 1, 2018: Applied Optics
Julien Fade, Estéban Perrotin, Jérôme Bobin
We propose an original concept of compressive sensing (CS) polarimetric imaging based on a digital micromirror (DMD) array and two single-pixel detectors, without using any polarizer. The polarimetric sensitivity of the proposed setup is due to the tiny difference in Fresnel's coefficients of reflecting mirrors, which is exploited here to form an original reconstruction problem including a CS problem and a source-separation task. We show that a two-step approach, tackling each problem successively, is outperformed by a dedicated combined reconstruction method, which is demonstrated in this paper and preferably implemented through a reweighted fast iterative shrinkage-thresholding algorithm...
March 1, 2018: Applied Optics
Anna K Trull, Jelle van der Horst, Lucas J van Vliet, Jeroen Kalkman
We present a comparison of image reconstruction techniques for optical projection tomography. We compare conventional filtered back projection, sinogram filtering using the frequency-distance relationship (FDR), image deconvolution, and 2D point-spread-function-based iterative reconstruction. The latter three methods aim to remove the spatial blurring in the reconstructed image originating from the limited depth of field caused by the point spread function of the imaging system. The methods are compared based on simulated data, experimental optical projection tomography data of single fluorescent beads, and high-resolution optical projection tomography imaging of an entire zebrafish larva...
March 10, 2018: Applied Optics
Adrien Besson, Dimitris Perdios, Florian Martinez, Zhouye Chen, Rafael E Carrillo, Marcel Arditi, Yves Wiaux, Jean-Philippe Thiran
Conventional ultrasound (US) image reconstruction methods rely on delay-and-sum (DAS) beamforming, which is a relatively poor solution to the image reconstruction problem. An alternative to DAS consists in using iterative techniques, which require both an accurate measurement model and a strong prior on the image under scrutiny. Toward this goal, much effort has been deployed in formulating models for US imaging, which usually require a large amount of memory to store the matrix coefficients. We present two different techniques, which take advantage of fast and matrix-free formulations derived for the measurement model and its adjoint, and rely on sparsity of US images in well-chosen models...
March 2018: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Adem Polat, Isa Yildirim
BACKGROUND: Iterative image reconstruction in Digital Breast Tomosynthesis (DBT) is a developing modality that produces three-dimensional (3D) reconstructed images of a breast to detect suspicious lesions. Algebraic reconstruction technique (ART), one of the iterative image reconstruction methods, was applied to reconstruct 3D data of breast and is becoming as one alternative method for the conventional image reconstruction techniques such as filtered back projection (FBP) in DBT imaging...
February 27, 2018: Journal of X-ray Science and Technology
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