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https://www.readbyqxmd.com/read/28642625/testing-the-environmental-filtering-concept-in-global-drylands
#1
Yoann Le Bagousse-Pinguet, Nicolas Gross, Fernando T Maestre, Vincent Maire, Francesco de Bello, Carlos Roberto Fonseca, Jens Kattge, Enrique Valencia, Jan Leps, Pierre Liancourt
1. The environmental filtering hypothesis predicts that the abiotic environment selects species with similar trait values within communities. Testing this hypothesis along multiple - and interacting - gradients of climate and soil variables constitutes a great opportunity to better understand and predict the responses of plant communities to ongoing environmental changes. 2. Based on two key plant traits, maximum plant height and specific leaf area (SLA), we assessed the filtering effects of climate (mean annual temperature and precipitation, precipitation seasonality), soil characteristics (soil pH, sand content and total phosphorus) and all potential interactions on the functional structure and diversity of 124 dryland communities spread over the globe...
July 2017: Journal of Ecology
https://www.readbyqxmd.com/read/28640476/histogram-analyses-of-diffusion-kurtosis-indices-and-apparent-diffusion-coefficient-in-assessing-liver-regeneration-after-alpps-and-a-comparative-study-with-portal-vein-ligation
#2
Ruo-Fan Sheng, He-Qing Wang, Kai-Pu Jin, Li Yang, Hao Liu, Yuan Ji, Cai-Xia Fu, Meng-Su Zeng
PURPOSE: To investigate the value of diffusion kurtosis imaging (DKI) histogram analysis in assessing liver regeneration and the microstructure basis after associating liver partition and portal vein ligation for staged hepatectomy (ALPPS), in comparison with portal vein ligation (PVL). MATERIALS AND METHODS: Thirty rats were divided into the ALPPS, PVL, and control groups. Histograms of DKI using a 3T magnetic resonance imaging (MRI) scanner were performed for corrected apparent diffusion (D), kurtosis (K), and apparent diffusion coefficient (ADC)...
June 22, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28634366/quantifying-non-ergodicity-of-anomalous-diffusion-with-higher-order-moments
#3
Maria Schwarzl, Aljaž Godec, Ralf Metzler
Anomalous diffusion is being discovered in a fast growing number of systems. The exact nature of this anomalous diffusion provides important information on the physical laws governing the studied system. One of the central properties analysed for finite particle motion time series is the intrinsic variability of the apparent diffusivity, typically quantified by the ergodicity breaking parameter EB. Here we demonstrate that frequently EB is insufficient to provide a meaningful measure for the observed variability of the data...
June 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28634047/the-study-of-the-intervertebral-disc-microstructure-in-matured-rats-with-diffusion-kurtosis-imaging
#4
Li Li, Wenzhen Zhu, Weiwei Chen, Jicheng Fang, Jing Li
OBJECTIVES: The aim of this study was to use DKI to detect the microstructural change of the discs in matured normal rats. METHODS: Total 24 normal SD rats (12 males/12 females) underwent DWI/DKI and T2 sequences with a 3T MRI scanner to get the values of ADC, FA, MD, Da, Dr, MK, Ka and Kr. The discs were categorized using a five-grade degeneration grading system in the T2-images. The height of the discs and the parameters in DWI/DKI were measured to compare between the different grades and sexes...
June 17, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28629955/correlation-study-between-dki-and-conventional-dwi-in-brain-and-head-and-neck-tumors
#5
Silvia Minosse, Simona Marzi, Francesca Piludu, Antonello Vidiri
PURPOSE: To investigate the relationship between the Diffusion Kurtosis Imaging (DKI) parameters and conventional metrics provided by Diffusion-weighted imaging (DWI) in patients affected by Brain or Head and Neck (HN) cancer. METHODS: Ten patients affected by brain tumor and nine patients with HN tumor underwent a pre-treatment MR examination at 3 T. The largest tumor section was manually contoured by two expert neuroradiologists. The apparent diffusion coefficient (Dapp) and apparent diffusional kurtosis (Kapp) parameters were determined at the voxel level by using the DKI model, and compared to the apparent diffusion coefficient (ADC) and the tissue diffusion coefficient (Dmono) obtained from mono-exponential fitting methods...
June 16, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28628946/structural-plasticity-of-the-ventral-stream-and-aphasia-recovery
#6
Emilie T McKinnon, Julius Fridriksson, G Russell Glenn, Jens H Jensen, Joseph A Helpern, Alexandra Basilakos, Christopher Rorden, Andy Y Shih, M Vittoria Spampinato, Leonardo Bonilha
Re-strengthening of the residual language network is likely crucial for speech recovery in post-stroke aphasia. Eight participants with chronic aphasia received intensive speech therapy for three weeks, with standardized naming tests and brain MRIs before and after therapy. Kurtosis-based diffusion tensor tractography was used to measure mean kurtosis (MK) along a segment of the inferior longitudinal fasciculus (ILF). Therapy related reduction in the number of semantic but not phonemic errors was associated with strengthening (renormalization) of ILF MK (r=-0...
June 19, 2017: Annals of Neurology
https://www.readbyqxmd.com/read/28624925/liver-fibrosis-in-vivo-evaluation-using-intravoxel-incoherent-motion-derived-histogram-metrics-with-histopathologic-findings-at-3-0-t
#7
Fubi Hu, Ru Yang, Zixing Huang, Min Wang, Hanmei Zhang, Xu Yan, Bin Song
PURPOSE: To retrospectively determine the feasibility of intravoxel incoherent motion (IVIM) imaging based on histogram analysis for the staging of liver fibrosis (LF) using histopathologic findings as the reference standard. METHODS: 56 consecutive patients (14 men, 42 women; age range, 15-76, years) with chronic liver diseases (CLDs) were studied using IVIM-DWI with 9 b-values (0, 25, 50, 75, 100, 150, 200, 500, 800 s/mm(2)) at 3.0 T. Fibrosis stage was evaluated using the METAVIR scoring system...
June 17, 2017: Abdominal Radiology
https://www.readbyqxmd.com/read/28616727/preliminary-study-of-diffusion-kurtosis-imaging-in-thyroid-nodules-and-its-histopathologic-correlation
#8
Ruo-Yang Shi, Qiu-Ying Yao, Qin-Yi Zhou, Qing Lu, Shi-Teng Suo, Jun Chen, Wen-Jie Zheng, Yong-Ming Dai, Lian-Ming Wu, Jian-Rong Xu
OBJECTIVES: To evaluate the utility of diffusion kurtosis imaging (DKI) of patients with thyroid nodules and to assess the probable correlation with histopathological factors. METHODS: The study included 58 consecutive patients with thyroid nodules who underwent magnetic resonance imaging (MRI) examination, including DKI and diffusion-weighted imaging (DWI). Histopathological analysis of paraffin sections included cell density and immunohistochemical analysis of Ki-67 and vascular endothelial growth factor (VEGF)...
June 14, 2017: European Radiology
https://www.readbyqxmd.com/read/28608327/diffusional-kurtosis-imaging-dki-incorporation-into-an-intravoxel-incoherent-motion-ivim-mr-model-to-measure-cerebral-hypoperfusion-induced-by-hyperventilation-challenge-in-healthy-subjects
#9
Aude Pavilla, Giulio Gambarota, Alessandro Arrigo, Mehdi Mejdoubi, Régis Duvauferrier, Hervé Saint-Jalmes
OBJECTIVES: The objectives were to investigate the diffusional kurtosis imaging (DKI) incorporation into the intravoxel incoherent motion (IVIM) model for measurements of cerebral hypoperfusion in healthy subjects. MATERIALS AND METHODS: Eight healthy subjects underwent a hyperventilation challenge with a 4-min diffusion weighted imaging protocol, using 8 b values chosen with the Cramer-Rao Lower Bound optimization approach. Four regions of interest in gray matter (GM) were analyzed with the DKI-IVIM model and the bi-exponential IVIM model, for normoventilation and hyperventilation conditions...
June 12, 2017: Magma
https://www.readbyqxmd.com/read/28604934/use-of-kurtosis-for-locating-deep-blood-vessels-in-raw-speckle-imaging-using-a-homogeneity-representation
#10
Hayde Peregrina-Barreto, Elizabeth Perez-Corona, Jose Rangel-Magdaleno, Ruben Ramos-Garcia, Roger Chiu, Julio C Ramirez-San-Juan
No abstract text is available yet for this article.
June 1, 2017: Journal of Biomedical Optics
https://www.readbyqxmd.com/read/28592331/thyroid-nodule-recognition-in-computed-tomography-using-first-order-statistics
#11
Wenxian Peng, Chenbin Liu, Shunren Xia, Dangdang Shao, Yihong Chen, Rui Liu, Zhiping Zhang
BACKGROUND: Computed tomography (CT) is one of the popular tools for early detection of thyroid nodule. The pixel intensity of thyroid in CT image is very important information to distinguish nodule from normal thyroid tissue. The pixel intensity in normal thyroid tissues is homogeneous and smooth. In the benign or malignant nodules, the pixel intensity is heterogeneous. Several studies have shown that the first order features in ultrasound image can be used as imaging biomarkers in nodule recognition...
June 2, 2017: Biomedical Engineering Online
https://www.readbyqxmd.com/read/28587542/evaluation-of-cerebral-glioma-using-3t-diffusion-kurtosis-tensor-imaging-and-the-relationship-between-diffusion-kurtosis-metrics-and-tumor-cellularity
#12
Chong Qi, Song Yang, Lanxi Meng, Huiyuan Chen, Zhenlan Li, Sijia Wang, Tao Jiang, Shaowu Li
Purpose To evaluate the clinical utility of diffusion kurtosis tensor imaging in the characterization of cerebral glioma and investigate correlations between diffusion and kurtosis metrics with tumor cellularity. Materials and Methods A group of 163 patients (age: 40.5 ± 11.5 years) diagnosed with cerebral glioma underwent diffusion kurtosis tensor imaging with a 3 T scanner. Diffusion and kurtosis metrics were measured in the solid part of tumors, and their abilities to distinguish between tumor grades was evaluated...
January 1, 2017: Journal of International Medical Research
https://www.readbyqxmd.com/read/28583627/resectable-pancreatic-adenocarcinoma-role-of-ct-quantitative-imaging-biomarkers-for-predicting-pathology-and-patient-outcomes
#13
Christophe Cassinotto, Jaron Chong, George Zogopoulos, Caroline Reinhold, Laurence Chiche, Jean-Pierre Lafourcade, Adeline Cuggia, Eric Terrebonne, Anthony Dohan, Benoît Gallix
BACKGROUNDS: Patients with a pancreatic cancer amenable to surgery still have a poor prognosis and high risk of post-operative recurrence. We aimed to assess the value of quantitative imaging biomarkers using computed-tomography (CT) texture analysis to evaluate the pathologic tumor aggressiveness and predict disease-free survival (DFS) in patients with resectable pancreatic adenocarcinoma. METHODS: We retrospectively performed attenuation measurements and texture analysis on the portal-venous phase of the pre-operative CT scan of 99 patients that underwent resection of a pancreatic ductal adenocarcinoma in two university hospitals...
May 2017: European Journal of Radiology
https://www.readbyqxmd.com/read/28583625/residual-tumour-detection-in-post-treatment-granulation-tissue-by-using-advanced-diffusion-models-in-head-and-neck-squamous-cell-carcinoma-patients
#14
Noriyuki Fujima, Daisuke Yoshida, Tomohiro Sakashita, Akihiro Homma, Kohsuke Kudo, Hiroki Shirato
PURPOSE: To evaluate the detectability of the residual tumour in post-treatment granulation tissue using parameters obtained with an advanced diffusion model in patients with head and neck squamous cell carcinoma (HNSCC) treated by chemoradiation therapy. MATERIALS AND METHODS: We retrospectively evaluated 23 patients with HNSCC after the full course of chemoradiation therapy. The diffusion-weighted image (DWI) acquisition used single-shot spin-echo echo-planar imaging with 11 b-values (0-1000)...
May 2017: European Journal of Radiology
https://www.readbyqxmd.com/read/28577335/application-of-whole-lesion-histogram-analysis-of-pharmacokinetic-parameters-in-dynamic-contrast-enhanced-mri-of-breast-lesions-with-the-caipirinha-dixon-twist-vibe-technique
#15
Zhiwei Li, Tao Ai, Yiqi Hu, Xu Yan, Marcel Dominik Nickel, Xiao Xu, Liming Xia
PURPOSE: To investigate the application of whole-lesion histogram analysis of pharmacokinetic parameters for differentiating malignant from benign breast lesions on dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). MATERIALS AND METHODS: In all, 92 women with 97 breast lesions (26 benign and 71 malignant lesions) were enrolled in this study. Patients underwent dynamic breast MRI at 3T using a prototypical CAIPIRINHA-Dixon-TWIST-VIBE (CDT-VIBE) sequence and a subsequent surgery or biopsy...
June 3, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28577319/diffusion-kurtosis-mri-versus-conventional-diffusion-weighted-imaging-for-evaluating-inflammatory-activity-in-crohn-s-disease
#16
Li Huang, Xue-Hua Li, Si-Yun Huang, Zhong-Wei Zhang, Xu-Feng Yang, Jin-Jiang Lin, Meng-Jie Jiang, Shi-Ting Feng, Can-Hui Sun, Zi-Ping Li
PURPOSE: To assess the efficacy of diffusion kurtosis imaging (DKI) and to compare DKI-derived parameters with that of conventional diffusion-weighted imaging (DWI) for grading the inflammatory activity of Crohn's disease (CD). MATERIALS AND METHODS: In all, 38 patients with CD underwent 3T magnetic resonance enterography (MRE) with DKI (b values of 0-2000 s/mm(2) ). The inflammatory activity of the bowel segments was graded by magnetic resonance index of activity (MaRIA) as inactive (<7), mild (≥7 and <11), or moderate-severe (≥11)...
June 3, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28575105/assessment-of-treatment-response-during-chemoradiation-therapy-for-pancreatic-cancer-based-on-quantitative-radiomic-analysis-of-daily-cts-an-exploratory-study
#17
Xiaojian Chen, Kiyoko Oshima, Diane Schott, Hui Wu, William Hall, Yingqiu Song, Yalan Tao, Dingjie Li, Cheng Zheng, Paul Knechtges, Beth Erickson, X Allen Li
PURPOSE: In an effort for early assessment of treatment response, we investigate radiation induced changes in quantitative CT features of tumor during the delivery of chemoradiation therapy (CRT) for pancreatic cancer. METHODS: Diagnostic-quality CT data acquired daily during routine CT-guided CRT using a CT-on-rails for 20 pancreatic head cancer patients were analyzed. On each daily CT, the pancreatic head, the spinal cord and the aorta were delineated and the histograms of CT number (CTN) in these contours were extracted...
2017: PloS One
https://www.readbyqxmd.com/read/28572153/diffusional-kurtosis-imaging-of-the-corticospinal-tract-in-multiple-sclerosis-association-with-neurologic-disability
#18
M V Spampinato, M R Kocher, J H Jensen, J A Helpern, H R Collins, N U Hatch
BACKGROUND AND PURPOSE: Multiple sclerosis is an autoimmune disorder resulting in progressive neurologic disability. Our aim was to evaluate the associations between diffusional kurtosis imaging-derived metrics for the corticospinal tract and disability in multiple sclerosis. MATERIALS AND METHODS: Forty patients with MS underwent brain MR imaging including diffusional kurtosis imaging. After we masked out T2 hyperintense lesions, the fractional anisotropy, mean diffusivity, radial diffusivity, axial diffusivity, mean kurtosis, radial kurtosis, and axial kurtosis were estimated for the corticospinal tract...
June 1, 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/28560158/application-and-evaluation-of-noddi-in-the-cervical-spinal-cord-of-multiple-sclerosis-patients
#19
Samantha By, Junzhong Xu, Bailey A Box, Francesca R Bagnato, Seth A Smith
INTRODUCTION: There is a need to develop imaging methods sensitive to axonal injury in multiple sclerosis (MS), given the prominent impact of axonal pathology on disability and outcome. Advanced multi-compartmental diffusion models offer novel indices sensitive to white matter microstructure. One such model, neurite orientation dispersion and density imaging (NODDI), is sensitive to neurite morphology, providing indices of apparent volume fractions of axons (vin), isotropic water (viso) and the dispersion of fibers about a central axis (orientation dispersion index, ODI)...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28558395/the-perception-of-hazy-gloss
#20
Peter Vangorp, Pascal Barla, Roland W Fleming
Most previous work on gloss perception has examined the strength and sharpness of specular reflections in simple bidirectional reflectance distribution functions (BRDFs) having a single specular component. However, BRDFs can be substantially more complex and it is interesting to ask how many additional perceptual dimensions there could be in the visual representation of surface reflectance qualities. To address this, we tested materials with two specular components that elicit an impression of hazy gloss. Stimuli were renderings of irregularly shaped objects under environment illumination, with either a single Ward specular BRDF component (Ward, 1992), or two such components, with the same total specular reflectance but different sharpness parameters, yielding both sharp and blurry highlights simultaneously...
May 1, 2017: Journal of Vision
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