keyword
MENU ▼
Read by QxMD icon Read
search

iterative reconstruction

keyword
https://www.readbyqxmd.com/read/28333629/curl-constrained-gradient-estimation-for-image-recovery-from-highly-incomplete-spectral-data
#1
Chiara Ravazzi, Giulio Coluccia, Enrico Magli
In this paper, we introduce new gradient-based methods for image recovery from a small collection of spectral coefficients of the Fourier transform, which is of particular interest for several scanning technologies, such as magnetic resonance imaging. Since gradients of a medical image are much more sparse or compressible than the corresponding image, classical `1- minimization methods have been used to recover these relative differences. The image values can then be obtained by integration algorithms imposing boundary constraints...
March 21, 2017: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
https://www.readbyqxmd.com/read/28333040/rigid-motion-correction-of-dual-opposed-planar-projections-in-single-photon-imaging
#2
Georgios I Angelis, William Ryder, John Gillam, Frederic Boisson, Andre Kyme, Roger Fulton, Steven Meikle, Peter Kench
Awake and/or freely moving small animal single photon emission imaging allows the continuous study of molecules exhibiting slow kinetics without the need to restrain or anaesthetise the animals. Estimating motion free projections in freely moving small animal planar imaging can be considered as a limited angle tomography problem, except that we wish to estimate the 2D planar projections rather than the 3D volume, where the angular sampling in all three axes depends on the rotational motion of the animal. In this study, we hypothesise that the motion corrected planar projections estimated by reconstructing an estimate of the 3D volume using an iterative motion compensating reconstruction algorithm and integrating it along the projection path, will closely match the true, motion-less, planar distribution regardless of the object motion...
March 23, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28332026/interpolating-and-extrapolating-with-hmsist-%C3%A2-seeking-a-tmax-for-optimal-sensitivity-resolution-and-frequency-accuracy
#3
Sven G Hyberts, Scott A Robson, Gerhard Wagner
Non-Uniform Sampling has the potential to exploit the optimal resolution of high-field NMR instruments. This is not possible in 3D and 4D NMR experiments when using traditional uniform sampling due to the long overall measurement time. Nominally, uniformly sampled time domain data acquired to a maximum evolution time tmax can be extended to high resolution via a virtual maximum evolution time t*max while extrapolating with linear prediction or iterative soft thresholding (IST). At the high resolution obtainable with extrapolation of US data, however, the accuracy of peak positions is compromised as observed when comparing inter- and intra-residue peaks in a 3D HNCA experiment...
March 22, 2017: Journal of Biomolecular NMR
https://www.readbyqxmd.com/read/28328259/follow-up-study-on-fetal-ct-radiation-dose-in-japan-validating-the-decrease-in-radiation-dose
#4
Osamu Miyazaki, Hideaki Sawai, Takahiro Yamada, Jun Murotsuki, Gen Nishimura
OBJECTIVE: In 2011, we collected data on fetal CT radiation dose to determine the diagnostic reference level (DRL); however, continuous evaluation of the DRL is necessary. The hypothesis of this study is that the fetal CT radiation dose has decreased, and we predict a widespread use of iterative reconstruction (IR). We also predict that the national decrease in exposure is because of the DRL reported as a result of the previous national study. MATERIALS AND METHODS: Various testing protocols from each site were summarized as part of the study results...
April 2017: AJR. American Journal of Roentgenology
https://www.readbyqxmd.com/read/28327475/free-breathing-black-blood-cine-fast-spin-echo-imaging-for-measuring-abdominal-aortic-wall-distensibility-a-feasibility-study
#5
Jyh-Miin Lin, Andrew Patterson, Tzu-Cheng Chao, Chengcheng Zhu, Hing-Chiu Chang, Jason Mendes, Hsiao-Wen Chung, Jonathan Gillard, Martin Graves
The paper reports a free-breathing black-blood CINE fast-spin echo (FSE) technique for measuring abdominal aortic wall motion. The free-breathing CINE FSE includes the following MR techniques: 1) variable-density sampling with fast iterative reconstruction; 2) inner-volume imaging; and 3) a blood-suppression preparation pulse. The proposed technique was evaluated in eight healthy subjects. The inner-volume imaging significantly reduced the intraluminal artifacts of respiratory motion (p = 0.015). The quantitative measurements were a diameter of 16...
March 22, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28320657/regularized-dual-averaging-image-reconstruction-for-full-wave-ultrasound-computed-tomography
#6
Thomas Matthews, Kun Wang, Cuiping Li, Neb Duric, Mark Anastasio
Ultrasound computed tomography (USCT) holds great promise for breast cancer screening. Waveform inversionbased image reconstruction methods account for higher-order diffraction effects and can produce high-resolution USCT images, but are computationally demanding. Recently, a source encoding technique was combined with stochastic gradient descent to greatly reduce image reconstruction times. However, this method bundles the stochastic data fidelity term with the deterministic regularization term. This limitation can be overcome by replacing stochastic gradient descent (SGD) with a structured optimization method, such as the regularized dual averaging (RDA) method, that exploits knowledge of the composition of the cost function...
March 14, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28314613/improved-image-quality-with-simultaneously-reduced-radiation-exposure-knowledge-based-iterative-model-reconstruction-algorithms-for-coronary-ct-angiography-in-a-clinical-setting
#7
Florian André, Philipp Fortner, Mani Vembar, Dirk Mueller, Wolfram Stiller, Sebastian J Buss, Hans-Ulrich Kauczor, Hugo A Katus, Grigorios Korosoglou
BACKGROUND: The aim of this study was to assess the potential for radiation dose reduction using knowledge-based iterative model reconstruction (K-IMR) algorithms in combination with ultra-low dose body mass index (BMI)-adapted protocols in coronary CT angiography (coronary CTA). METHODS: Forty patients undergoing clinically indicated coronary CTA were randomly assigned to two groups with BMI-adapted (I: <25.0 kg/m(2), II: <28.0 kg/m(2), III: <30.0 kg/m(2), IV: ≥30...
February 23, 2017: Journal of Cardiovascular Computed Tomography
https://www.readbyqxmd.com/read/28303644/applications-of-nonlocal-means-algorithm-in-low-dose-x-ray-ct-image-processing-and-reconstruction-a-review
#8
REVIEW
Hao Zhang, Dong Zeng, Hua Zhang, Jing Wang, Zhengrong Liang, Jianhua Ma
Low-dose X-ray computed tomography (LDCT) imaging is highly recommended for use in the clinic because of growing concerns over excessive radiation exposure. However, the CT images reconstructed by the conventional filtered back-projection (FBP) method from low-dose acquisitions may be severely degraded with noise and streak artifacts due to excessive X-ray quantum noise, or with view-aliasing artifacts due to insufficient angular sampling. In 2005, the nonlocal means (NLM) algorithm was introduced as a non-iterative edge-preserving filter to denoise natural images corrupted by additive Gaussian noise, and showed superior performance...
March 2017: Medical Physics
https://www.readbyqxmd.com/read/28302073/image-quality-improvement-using-model-based-iterative-reconstruction-in-low-dose-chest-ct-for-children-with-necrotizing-pneumonia
#9
Jihang Sun, Tong Yu, Jinrong Liu, Xiaomin Duan, Di Hu, Yong Liu, Yun Peng
BACKGROUND: Model-based iterative reconstruction (MBIR) is a promising reconstruction method which could improve CT image quality with low radiation dose. The purpose of this study was to demonstrate the advantage of using MBIR for noise reduction and image quality improvement in low dose chest CT for children with necrotizing pneumonia, over the adaptive statistical iterative reconstruction (ASIR) and conventional filtered back-projection (FBP) technique. METHODS: Twenty-six children with necrotizing pneumonia (aged 2 months to 11 years) who underwent standard of care low dose CT scans were included...
March 16, 2017: BMC Medical Imaging
https://www.readbyqxmd.com/read/28301535/quantitative-assessment-of-pulmonary-alveolar-proteinosis-pap-with-ultra-dose-ct-and-correlation-with-pulmonary-function-tests-pfts
#10
Xin Sui, Qianni Du, Kai-Feng Xu, Xinlun Tian, Lan Song, Xiao Wang, Xiaoli Xu, Zixing Wang, Yuyan Wang, Jun Gu, Wei Song, Zhengyu Jin
BACKGROUND: The purpose of this study was to investigate whether ultra-low-dose chest computed tomography (CT) can be used for visual assessment of CT features in patients with pulmonary alveolar proteinosis (PAP) and to evaluate the relationship between the quantitative analysis of the ultra-low-dose CT scans and the pulmonary function tests (PFTs). METHODS: Thirty-eight patients (mean [SD] age, 44.47 [12.28] years; 29 males, 9 females) with PAP were enrolled and subjected to two scans each with low-dose CT (reference parameters: 120 kV and 50 mAs) and ultra-low-dose CT (reference parameters, 80 kV, 25 mAs)...
2017: PloS One
https://www.readbyqxmd.com/read/28297460/a-noise-power-spectrum-study-of-a-new-model-based-iterative-reconstruction-system-veo-3-0
#11
Guang Li, Xinming Liu, Cristina T Dodge, Corey T Jensen, X John Rong
The purpose of this study was to evaluate performance of the third generation of model-based iterative reconstruction (MBIR) system, Veo 3.0, based on noise power spectrum (NPS) analysis with various clinical presets over a wide range of clinically applicable dose levels. A CatPhan 600 surrounded by an oval, fat-equivalent ring to mimic patient size/shape was scanned 10 times at each of six dose levels on a GE HD 750 scanner. NPS analysis was performed on images reconstructed with various Veo 3.0 preset combinations for comparisons of those images reconstructed using Veo 2...
September 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297318/a-qualitative-and-quantitative-analysis-of-radiation-dose-and-image-quality-of-computed-tomography-images-using-adaptive-statistical-iterative-reconstruction
#12
Fahad Ahmed Hussain, Noor Mail, Abdulrahman M Shamy, Suliman Alghamdi, Abdelhamid Saoudi
Image quality is a key issue in radiology, particularly in a clinical setting where it is important to achieve accurate diagnoses while minimizing radiation dose. Some computed tomography (CT) manufacturers have introduced algorithms that claim significant dose reduction. In this study, we assessed CT image quality produced by two reconstruction algorithms provided with GE Healthcare's Discovery 690 Elite positron emission tomography (PET) CT scanner. Image quality was measured for images obtained at various doses with both conventional filtered back-projection (FBP) and adaptive statistical iterative reconstruction (ASIR) algorithms...
May 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297315/practical-considerations-for-noise-power-spectra-estimation-for-clinical-ct-scanners
#13
Steven Dolly, Hsin-Chen Chen, Mark Anastasio, Sasa Mutic, Hua Li
Local noise power spectra (NPS) have been commonly calculated to represent the noise properties of CT imaging systems, but their properties are significantly affected by the utilized calculation schemes. In this study, the effects of varied calculation parameters on the local NPS were analyzed, and practical suggestions were provided regarding the estimation of local NPS for clinical CT scanners. The uniformity module of a Catphan phantom was scanned with a Philips Brilliance 64 slice CT simulator with varied scanning protocols...
May 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28297293/dose-reduction-in-ct-urography-and-vasculature-phantom-studies-using-model-based-iterative-reconstruction
#14
Leland Page, Wei Wei, Vikas Kundra, X John Rong
To evaluate the feasibility of radiation dose reduction using model-based iterative reconstruction (MBIR) for evaluating the ureters and vasculature in a phantom, a tissue-equivalent CT dose phantom was scanned using a 64-channel CT scanner. Tubes of varying diameters filled with different dilutions of a contrast agent, simulating ureters or vessels, were inserted into the center of the phantom. Each combination was scanned using an existing renal protocol at 140 kVp or 120 kVp, yielding a display volumetric CT dose index (CTDIvol) of 24 mGy...
November 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28296730/image-quality-evaluation-for-care-kv-technique-combined-with-iterative-reconstruction-for-chest-computed-tomography-scanning
#15
Bin Yang, Zheng-Liang Li, Yi Gao, Ya-Ying Yang, Wei Zhao
BACKGROUND: To investigate the radiation dose and image quality for iterative reconstruction combined with the CARE kV technique in chest computed tomography (CT) scanning for physical examination. METHODS: A total of 130 patients who underwent chest CT scanning were randomly chosen and the quality reference value was set as 80 mAs. The scanning scheme was set and the patients were randomly divided into groups according to the scanning scheme. Sixty patients underwent a chest scan with 100 kV using the CARE kV technique and SAFIRE reconstruction (value=3) (experimental group) and the other 70 patients underwent chest scanning with 120 kV (control group)...
March 2017: Medicine (Baltimore)
https://www.readbyqxmd.com/read/28296330/an-energy-minimization-method-for-the-correction-of-cupping-artifacts-in-cone-beam-ct
#16
Shipeng Xie, Wenqin Zhuang, Haibo Li
The purpose of this study was to reduce cupping artifacts and improve quantitative accuracy of the images in cone-beam CT (CBCT). An energy minimization method (EMM) is proposed to reduce cupping artifacts in reconstructed image of the CBCT. The cupping artifacts are iteratively optimized by using efficient matrix computations, which are verified to be numerically stable by matrix analysis. Moreover, the energy in our formulation is convex in each of its variables, which brings the robustness of the proposed energy minimization algorithm...
July 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28295418/technical-note-on-the-accuracy-of-parametric-two-parameter-cross-section-models-in-dual-energy-ct-applications
#17
Dong Han, Mariela A Porras-Chaverri, Joseph A O'Sullivan, David G Politte, Jeffrey F Williamson
PURPOSE: To evaluate and compare the theoretically achievable accuracy of two families of two-parameter photon cross-section models: basis vector model (BVM) and modified parametric fit model (mPFM). METHOD: The modified PFM assumes that photoelectric absorption and scattering cross sections can be accurately represented by power functions in effective atomic number and / or energy plus the Klein-Nishina cross section, along with empirical corrections that enforce exact prediction of elemental cross sections...
March 15, 2017: Medical Physics
https://www.readbyqxmd.com/read/28295405/optimal-reconstruction-and-quantitative-image-features-for-computer-aided-diagnosis-tools-for-breast-ct
#18
Juhun Lee, Robert M Nishikawa, Ingrid Reiser, John M Boone
PURPOSE: The purpose of this study is to determine the optimal representative reconstruction and quantitative image feature set for a computer-aided diagnosis (CADx) scheme for dedicated breast computer tomography (bCT). METHOD: We used 93 bCT scans that contain 102 breast lesions (62 malignant, 40 benign). Using an iterative image reconstruction (IIR) algorithm, we created 37 reconstructions with different image appearances for each case. In addition, we added a clinical reconstruction for comparison purposes...
March 15, 2017: Medical Physics
https://www.readbyqxmd.com/read/28295066/contrast-transfer-function-phase-retrieval-based-on-compressed-sensing
#19
Pablo Villanueva-Perez, Filippo Arcadu, Peter Cloetens, Marco Stampanoni
We report on a new contrast-transfer-function (CTF) phase-retrieval method based on the alternating direction method of multipliers (ADMMs), which allows us to exploit any compressed sensing regularization scheme reflecting the sparsity of the investigated object. The proposed iterative algorithm retrieves accurate phase maps from highly noisy single-distance projection microscopy data and is characterized by a stable convergence, not bounded to the prior knowledge of the object support or to the initialization strategy...
March 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28290345/first-experiences-with-model-based-iterative-reconstructions-influence-on-quantitative-plaque-volume-and-intensity-measurements-in-coronary-computed-tomography-angiography
#20
H Precht, P H Kitslaar, A Broersen, O Gerke, J Dijkstra, J Thygesen, K Egstrup, J Lambrechtsen
PURPOSE: Investigate the influence of adaptive statistical iterative reconstruction (ASIR) and the model-based IR (Veo) reconstruction algorithm in coronary computed tomography angiography (CCTA) images on quantitative measurements in coronary arteries for plaque volumes and intensities. METHODS: Three patients had three independent dose reduced CCTA performed and reconstructed with 30% ASIR (CTDIvol at 6.7 mGy), 60% ASIR (CTDIvol 4.3 mGy) and Veo (CTDIvol at 1...
February 2017: Radiography
keyword
keyword
83320
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"