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Jonathan M Scott, Stephen E Robinson, Tom Holroyd, Richard Coppola, Susumu Sato, Sara K Inati
PURPOSE: To describe and optimize an automated beamforming technique followed by identification of locations with excess kurtosis (g2) for efficient detection and localization of interictal spikes in patients with medically refractory epilepsy. METHODS: Synthetic aperture magnetometry with g2 averaged over a sliding time window (SAMepi) was performed in seven patients with focal epilepsy and five healthy volunteers. The effect of varied window lengths on detection of spiking activity was evaluated...
October 2016: Journal of Clinical Neurophysiology: Official Publication of the American Electroencephalographic Society
Jing Xuan Jiang, Zuo Hua Tang, Yu Feng Zhong, Jin Wei Qiang
PURPOSE: The study aimed to evaluate diffusion kurtosis imaging (DKI) in the differentiation between benign and malignant sinonasal lesions, and to compare the diagnostic performance of DKI with diffusion weighted imaging (DWI). MATERIALS AND METHODS: Eight-one patients with solid sinonasal lesions confirmed by surgery and pathology (46 malignant and 35 benign) underwent conventional MRI, DWI, and DKI. DKI was performed employing a 13 extended b-value ranging from 0 to 2500 s/mm(2) ...
October 19, 2016: Journal of Magnetic Resonance Imaging: JMRI
Meghan K Cain, Zhiyong Zhang, Ke-Hai Yuan
Nonnormality of univariate data has been extensively examined previously (Blanca et al., Methodology: European Journal of Research Methods for the Behavioral and Social Sciences, 9(2), 78-84, 2013; Miceeri, Psychological Bulletin, 105(1), 156, 1989). However, less is known of the potential nonnormality of multivariate data although multivariate analysis is commonly used in psychological and educational research. Using univariate and multivariate skewness and kurtosis as measures of nonnormality, this study examined 1,567 univariate distriubtions and 254 multivariate distributions collected from authors of articles published in Psychological Science and the American Education Research Journal...
October 17, 2016: Behavior Research Methods
Johann-Martin Hempel, Sotirios Bisdas, Jens Schittenhelm, Cornelia Brendle, Benjamin Bender, Henk Wassmann, Marco Skardelly, Ghazaleh Tabatabai, Salvador Castaneda Vega, Ulrike Ernemann, Uwe Klose
No abstract text is available yet for this article.
September 22, 2016: Journal of Neuro-oncology
B F Kjølby, A R Khan, A Chuhutin, L Pedersen, J B Jensen, S Jakobsen, D Zeidler, R Sangill, J R Nyengaard, S N Jespersen, B Hansen
Diffusion kurtosis imaging (DKI) is sensitive to tissue microstructure and may therefore be useful in the diagnosis and monitoring of disease in brain and body organs. Generally, diffusion magnetic resonance imaging (dMRI) in the body is challenging because of the heterogeneous body composition, which can cause image artefacts as a result of chemical shifts and susceptibility differences. In addition, the abdomen possesses physiological factors (e.g. breathing, heartbeat, blood flow) which may severely reduce image quality, especially when echo planar imaging is employed, as is typical in dMRI...
October 12, 2016: NMR in Biomedicine
Tim Vanbellingen, Beatrice Ottiger, Tobias Pflugshaupt, Jan Mehrholz, Stephan Bohlhalter, Tobias Nef, Thomas Nyffeler
BACKGROUND: Good responsive functional outcome measures are important to measure change in stroke patients. The aim of study was to compare the internal and external responsiveness, floor and ceiling effects of the motor, cognition, and communication subscales of the Lucerne ICF-based Multidisciplinary Observation Scale (LIMOS) with the motor and cognition subscales of the Functional Independence Measure (FIM), and the Barthel Index (BI), in a large cohort of stroke patients. METHODS: One hundred eighteen stroke patients participated in this study...
2016: Frontiers in Neurology
Qin Hu, Jonathan D Victor
Natural image statistics play a crucial role in shaping biological visual systems, understanding their function and design principles, and designing effective computer-vision algorithms. High-order statistics are critical for conveying local features, but they are challenging to study - largely because their number and variety is large. Here, via the use of two-dimensional Hermite (TDH) functions, we identify a covert symmetry in high-order statistics of natural images that simplifies this task. This emerges from the structure of TDH functions, which are an orthogonal set of functions that are organized into a hierarchy of ranks...
September 2016: Symmetry
Yanfei Jia, Xiaodong Yang
Fetal electrocardiogram (FECG) extraction is very important procedure for fetal health assessment. In this article, we propose a fast one-unit independent component analysis with reference (ICA-R) that is suitable to extract the FECG. Most previous ICA-R algorithms only focused on how to optimize the cost function of the ICA-R and payed little attention to the improvement of cost function. They did not fully take advantage of the prior information about the desired signal to improve the ICA-R. In this paper, we first use the kurtosis information of the desired FECG signal to simplify the non-Gaussian measurement function and then construct a new cost function by directly using a nonquadratic function of the extracted signal to measure its non-Gaussianity...
2016: Computational and Mathematical Methods in Medicine
Jian Xiong, Shulin Tian, Chenglin Yang
This paper presents a novel fault diagnosis method for analog circuits using ensemble empirical mode decomposition (EEMD), relative entropy, and extreme learning machine (ELM). First, nominal and faulty response waveforms of a circuit are measured, respectively, and then are decomposed into intrinsic mode functions (IMFs) with the EEMD method. Second, through comparing the nominal IMFs with the faulty IMFs, kurtosis and relative entropy are calculated for each IMF. Next, a feature vector is obtained for each faulty circuit...
2016: Computational Intelligence and Neuroscience
Jeong Hee Yoon, Jeong Min Lee, Eunju Kim, Tomoyuki Okuaki, Joon Koo Han
Purpose To determine whether B1 inhomogeneity-corrected volumetric T1 maps of gadoxetic acid-enhanced liver magnetic resonance (MR) imaging are able to demonstrate global liver function and functional heterogeneity in patients with cirrhosis and to investigate their relationship with the development of hepatic insufficiency and decompensation. Materials and Methods This institutional review board-approved retrospective study with waiver of informed consent included 234 consecutive patients who underwent gadoxetic acid-enhanced liver MR imaging, including B1 inhomogeneity-corrected volumetric T1 mapping...
October 3, 2016: Radiology
Iris Yuwen Zhou, Yingkun Guo, Takahiro Igarashi, Yu Wang, Emiri Mandeville, Suk-Tak Chan, Lingyi Wen, Mark Vangel, Eng H Lo, Xunming Ji, Phillip Zhe Sun
Diffusion kurtosis imaging (DKI) has been shown to augment diffusion-weighted imaging (DWI) for the definition of irreversible ischemic injury. However, the complexity of cerebral structure/composition makes the kurtosis map heterogeneous, limiting the specificity of kurtosis hyperintensity to acute ischemia. We propose an Inherent COrrelation-based Normalization (ICON) analysis to suppress the intrinsic kurtosis heterogeneity for improved characterization of heterogeneous ischemic tissue injury. Fast DKI and relaxation measurements were performed on normal (n = 10) and stroke rats following middle cerebral artery occlusion (MCAO) (n = 20)...
October 3, 2016: NMR in Biomedicine
Xiao-Xue Zhang, Le-Kang Yin, Xiao-Zhu Hao, Jia-Qi Tian, Chan-Chan Li, Xiao-Yuan Feng, Yan-Mei Yang
BACKGROUND: The purpose of our study is to explore the relationship between recovery of neural function and transformation of the internal capsule (IC) after transient middle cerebral artery occlusion (MCAO) by using diffusion kurtosis imaging (DKI). METHODS: Six male adult Sprague-Dawley rats implemented with transient MCAO were used in this study. Sensorimotor function was assessed according to repetitive behavioral testing on day 1, 3, 7, 14, and 28 after cerebral ischemia...
September 29, 2016: Journal of Stroke and Cerebrovascular Diseases: the Official Journal of National Stroke Association
Katsuya Mitamura, Yuka Yamamoto, Nobuyuki Kudomi, Yukito Maeda, Takashi Norikane, Keisuke Miyake, Yoshihiro Nishiyama
BACKGROUND: The nucleoside analog 3'-deoxy-3'-(18)F-fluorothymidine (FLT) has been investigated for evaluating tumor proliferating activity in brain tumors. We evaluated FLT uptake heterogeneity using textural features from the histogram analysis in patients with newly diagnosed gliomas and examined correlation of the results with proliferative activity and patient prognosis, in comparison with the conventional PET parameters. METHODS: FLT PET was investigated in 37 patients with newly diagnosed gliomas...
September 29, 2016: Annals of Nuclear Medicine
Darryl McClymont, Irvin Teh, Eric Carruth, Jeffrey Omens, Andrew McCulloch, Hannah J Whittington, Peter Kohl, Vicente Grau, Jürgen E Schneider
PURPOSE: The diffusion tensor model assumes Gaussian diffusion and is widely applied in cardiac diffusion MRI. However, diffusion in biological tissue deviates from a Gaussian profile as a result of hindrance and restriction from cell and tissue microstructure, and may be quantified better by non-Gaussian modeling. The aim of this study was to investigate non-Gaussian diffusion in healthy and hypertrophic hearts. METHODS: Thirteen rat hearts (five healthy, four sham, four hypertrophic) were imaged ex vivo...
September 26, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Guillermo Robles, José Manuel Fresno, Romano Giannetti
The design and optimization of protective equipment and devices such as exoskeletons and prosthetics have the potential to be enhanced by the ability of accurately measure the positions of the bones during movement. Existing technologies allow a quite precise measurement of motion-mainly by using coordinate video-cameras and skin-mounted markers-but fail in directly measuring the bone position. Alternative approaches, as fluoroscopy, are too invasive and not usable during extended lapses of time, either for cost or radiation exposure...
September 22, 2016: ISA Transactions
Shaobo Jin, Fan Yang-Wallentin
Asymptotic robustness against misspecification of the underlying distribution for the polychoric correlation estimation is studied. The asymptotic normality of the pseudo-maximum likelihood estimator is derived using the two-step estimation procedure. The t distribution assumption and the skew-normal distribution assumption are used as alternatives to the normal distribution assumption in a numerical study. The numerical results show that the underlying normal distribution can be substantially biased, even though skewness and kurtosis are not large...
September 22, 2016: Psychometrika
Xianglong Chen, Fuzhou Feng, Bingzhi Zhang
Kurtograms have been verified to be an efficient tool in bearing fault detection and diagnosis because of their superiority in extracting transient features. However, the short-time Fourier Transform is insufficient in time-frequency analysis and kurtosis is deficient in detecting cyclic transients. Those factors weaken the performance of the original kurtogram in extracting weak fault features. Correlated Kurtosis (CK) is then designed, as a more effective solution, in detecting cyclic transients. Redundant Second Generation Wavelet Packet Transform (RSGWPT) is deemed to be effective in capturing more detailed local time-frequency description of the signal, and restricting the frequency aliasing components of the analysis results...
2016: Sensors
Farida Grinberg, Ivan I Maximov, Ezequiel Farrher, Irene Neuner, Laura Amort, Heike Thönneßen, Eileen Oberwelland, Kerstin Konrad, N Jon Shah
The most common modality of diffusion MRI used in the ageing and development studies is diffusion tensor imaging (DTI) providing two key measures, fractional anisotropy and mean diffusivity. Here, we investigated diffusional changes occurring between childhood (average age 10.3 years) and mitddle adult age (average age 54.3 years) with the help of diffusion kurtosis imaging (DKI), a recent novel extension of DTI that provides additional metrics quantifying non-Gaussianity of water diffusion in brain tissue...
September 14, 2016: NeuroImage
Caitlin O'Connell, Leon C Ho, Matthew C Murphy, Ian P Conner, Gadi Wollstein, Rakie Cham, Kevin C Chan
Human visual performance has been observed to show superiority in localized regions of the visual field across many classes of stimuli. However, the underlying neural mechanisms remain unclear. This study aims to determine whether the visual information processing in the human brain is dependent on the location of stimuli in the visual field and the corresponding neuroarchitecture using blood-oxygenation-level-dependent functional MRI (fMRI) and diffusion kurtosis MRI, respectively, in 15 healthy individuals at 3 T...
November 9, 2016: Neuroreport
Jing Yu, Qing Xu, Jia-Cheng Song, Yan Li, Xin Dai, Dong-Ya Huang, Ling Zhang, Yang Li, Hai-Bin Shi
OBJECTIVES: To evaluate the feasibility and value of diffusion kurtosis (DK) imaging in assessing treatment response to neoadjuvant chemoradiotherapy (CRT) in patients with locally advanced rectal cancer (LARC). METHODS: Forty-one patients were included. All patients underwent pre- and post-CRT DCE-MRI on a 3.0-Tesla MRI scanner. Imaging indices (D app , K app and ADC values) were measured. Change value (∆X) and change ratio (r∆X) were calculated. Pathological tumour regression grade scores (Mandard) were the standard reference (good responders: pTRG 1-2; poor responders: pTRG 3-5)...
September 8, 2016: European Radiology
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