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diffusion kurtosis

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https://www.readbyqxmd.com/read/27893768/macromolecular-crowding-regulates-the-gene-expression-profile-by-limiting-diffusion
#1
Mahdi Golkaram, Stefan Hellander, Brian Drawert, Linda R Petzold
We seek to elucidate the role of macromolecular crowding in transcription and translation. It is well known that stochasticity in gene expression can lead to differential gene expression and heterogeneity in a cell population. Recent experimental observations by Tan et al. have improved our understanding of the functional role of macromolecular crowding. It can be inferred from their observations that macromolecular crowding can lead to robustness in gene expression, resulting in a more homogeneous cell population...
November 2016: PLoS Computational Biology
https://www.readbyqxmd.com/read/27866239/diffusion-kurtosis-imaging-and-diffusion-weighted-imaging-in-assessment-of-liver-fibrosis-stage-and-necroinflammatory-activity
#2
Ruo Fan Sheng, He Qing Wang, Li Yang, Kai Pu Jin, Yan Hong Xie, Cai Zhong Chen, Meng Su Zeng
PURPOSE: To investigate and compare the diagnostic value of diffusion kurtosis imaging (DKI) with diffusion-weighted imaging (DWI) in assessing and quantifying hepatic fibrosis. METHODS: Thirty rats were divided into the control group (n = 6) and the fibrosis experimental groups (n = 6 per group) with CCl4 administration for 2, 4, 6, and 8 weeks. Liver fibrosis stage (S) and necroinflammatory activity grade (G) were histopathologically determined. DKI and DWI were performed; mean apparent diffusion (MD), mean kurtosis (MK), and apparent diffusion coefficient (ADC) values were calculated...
November 19, 2016: Abdominal Radiology
https://www.readbyqxmd.com/read/27862582/whole-tumor-mri-histogram-analyses-of-hepatocellular-carcinoma-correlations-with-ki-67-labeling-index
#3
Xin-Xing Hu, Zhao-Xia Yang, He-Yue Liang, Ying Ding, Robert Grimm, Cai-Xia Fu, Hui Liu, Xu Yan, Yuan Ji, Meng-Su Zeng, Sheng-Xiang Rao
PURPOSE: To evaluate whether whole-tumor histogram-derived parameters for an apparent diffusion coefficient (ADC) map and contrast-enhanced magnetic resonance imaging (MRI) could aid in assessing Ki-67 labeling index (LI) of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: In all, 57 patients with HCC who underwent pretreatment MRI with a 3T MR scanner were included retrospectively. Histogram parameters including mean, median, standard deviation, skewness, kurtosis, and percentiles (5(th) , 25(th) , 75(th) , 95(th) ) were derived from the ADC map and MR enhancement...
November 10, 2016: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/27834215/diffusion-weighted-imaging-uncovers-likely-sources-of-processing-speed-deficits-in-schizophrenia
#4
Peter Kochunov, Laura M Rowland, Els Fieremans, Jelle Veraart, Neda Jahanshad, George Eskandar, Xiaoming Du, Florian Muellerklein, Anya Savransky, Dinesh Shukla, Hemalatha Sampath, Paul M Thompson, L Elliot Hong
Schizophrenia, a devastating psychiatric illness with onset in the late teens to early 20s, is thought to involve disrupted brain connectivity. Functional and structural disconnections of cortical networks may underlie various cognitive deficits, including a substantial reduction in the speed of information processing in schizophrenia patients compared with controls. Myelinated white matter supports the speed of electrical signal transmission in the brain. To examine possible neuroanatomical sources of cognitive deficits, we used a comprehensive diffusion-weighted imaging (DWI) protocol and characterized the white matter diffusion signals using diffusion kurtosis imaging (DKI) and permeability-diffusivity imaging (PDI) in patients (n = 74), their nonill siblings (n = 41), and healthy controls (n = 113)...
November 22, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27825037/evaluation-of-histopathological-changes-in-the-microstructure-at-the-center-and-periphery-of-glioma-tumors-using-diffusional-kurtosis-imaging
#5
Fuyan Li, Wenqi Shi, Dawei Wang, Yanjie Xu, Hongxia Li, Jingzhen He, Qingshi Zeng
OBJECTIVE: To explore the relationship between alterations in gliomas revealed by diffusional kurtosis imaging (DKI) and the histopathological microstructural changes. METHODS: Thirty-seven patients with cerebral gliomas underwent conventional MRI and DKI at 3.0T. Normalized fractional anisotropy (FA), mean diffusivity (MD) and mean kurtosis (MK) were compared in different regions of glioma tumors. Parameters with a high sensitivity and specificity regarding the discrimination of glioma grade were evaluated using receiver operating characteristic (ROC) curve analysis...
October 27, 2016: Clinical Neurology and Neurosurgery
https://www.readbyqxmd.com/read/27818577/parameter-estimation-error-dependency-on-the-acquisition-protocol-in-diffusion-kurtosis-imaging
#6
Nima Gilani, Paul N Malcolm, Glyn Johnson
Mono-exponential kurtosis model is routinely fitted on diffusion weighted, magnetic resonance imaging data to describe non-Gaussian diffusion. Here, the purpose was to optimize acquisitions for this model to minimize the errors in estimating diffusion coefficient and kurtosis. Similar to a previous study, covariance matrix calculations were used, and coefficients of variation in estimating each parameter of this model were calculated. The acquisition parameter, b values, varied in discrete grids to find the optimum ones that minimize the coefficient of variation in estimating the two non-Gaussian parameters...
2016: Applied Magnetic Resonance
https://www.readbyqxmd.com/read/27807795/can-we-shorten-the-q-space-imaging-to-make-it-clinically-feasible
#7
Koji Sakai, Kei Yamada, Kentaro Akazawa, Jun Tazoe, Masashi Yasuike, Hitomi Nagano, Hiroyasu Ikeno, Toshiaki Nakagawa
PURPOSE: Q-space imaging (QSI) is a novel magnetic resonance imaging (MRI) technique that enables assessment of micro-structural changes of white matter. The acquisition time, however, is comparatively long to use for routine clinical assessment. Therefore, the present study investigated the clinically feasible b value combinations to measure the water molecular displacement probability density function (PDF) in healthy subjects. METHODS: The subjects consisted of five healthy volunteers (1 female and 4 male; 40...
November 2, 2016: Japanese Journal of Radiology
https://www.readbyqxmd.com/read/27801694/non-gaussian-diffusion-imaging-shows-brain-myelin-and-axonal-changes-in-obstructive-sleep-apnea
#8
Sudhakar Tummala, Bhaswati Roy, Ruchi Vig, Bumhee Park, Daniel W Kang, Mary A Woo, Ravi Aysola, Ronald M Harper, Rajesh Kumar
OBJECTIVE: Obstructive sleep apnea (OSA) is accompanied by brain changes in areas that regulate autonomic, cognitive, and mood functions, which were initially examined by Gaussian-based diffusion tensor imaging measures, but can be better assessed with non-Gaussian measures. We aimed to evaluate axonal and myelin changes in OSA using axial (AK) and radial kurtosis (RK) measures. MATERIALS AND METHODS: We acquired diffusion kurtosis imaging data from 22 OSA and 26 controls; AK and RK maps were calculated, normalized, smoothed, and compared between groups using analysis of covariance...
October 31, 2016: Journal of Computer Assisted Tomography
https://www.readbyqxmd.com/read/27796448/assessment-of-tissue-heterogeneity-using-diffusion-tensor-and-diffusion-kurtosis-imaging-for-grading-gliomas
#9
Rajikha Raja, Neelam Sinha, Jitender Saini, Anita Mahadevan, Kvl Narasinga Rao, Aarthi Swaminathan
INTRODUCTION: In this work, we aim to assess the significance of diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) parameters in grading gliomas. METHODS: Retrospective studies were performed on 53 subjects with gliomas belonging to WHO grade II (n = 19), grade III (n = 20) and grade IV (n = 14). Expert marked regions of interest (ROIs) covering the tumour on T2-weighted images. Statistical texture measures such as entropy and busyness calculated over ROIs on diffusion parametric maps were used to assess the tumour heterogeneity...
October 29, 2016: Neuroradiology
https://www.readbyqxmd.com/read/27796081/intravoxel-incoherent-motion-ivim-derived-parameters-in-diffusion-weighted-mri-associations-with-prognostic-factors-in-invasive-ductal-carcinoma
#10
Youn Joo Lee, Sung Hun Kim, Bong Joo Kang, Young Jee Kang, Heesoo Yoo, Jaewan Yoo, Jaeun Lee, Yo Han Son, Robert Grimm
PURPOSE: To investigate relationships between intravoxel incoherent motion (IVIM) metrics of invasive ductal carcinoma of the breast and prognostic factors. MATERIALS AND METHODS: This retrospective study included a total of 82 masses from 72 patients who underwent 3T breast magnetic resonance imaging (MRI) and diffusion-weighted imaging. IVIM metrics of tissue diffusivity (Dslow ), pseudodiffusivity (Dfast ), and perfusion fraction (Dpf ) were measured using histogram analysis for whole lesion volumes...
October 31, 2016: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/27784203/repetitive-model-of-mild-traumatic-brain-injury-produces-cortical-abnormalities-detectable-by-magnetic-resonance-diffusion-imaging-dti-dki-histopathology-and-behavior
#11
Fengshan Yu, Dinesh Shukla, Regina C Armstrong, Christina Marie Marion, Kryslaine L Radomski, Reed G Selwyn, Bernard Dardzinski
Non-invasive detection of mild traumatic brain injury (mTBI) is important for evaluating acute through chronic effects of head injuries, particularly after repetitive impacts. To better detect abnormalities from mTBI, we performed longitudinal studies (baseline, 3, 6, 42 days) using magnetic resonance diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) in adult mice after repetitive mTBI (r-mTBI; daily x 5), or sham procedure. This r-mTBI produced righting reflex delay and was first characterized in the corpus callosum to demonstrate low levels of axon damage, astrogliosis, and microglial activation, without microhemorrhages...
October 26, 2016: Journal of Neurotrauma
https://www.readbyqxmd.com/read/27779254/brain-white-matter-plasticity-and-functional-reorganization-underlying-the-central-pathogenesis-of-trigeminal-neuralgia
#12
Tian Tian, Linying Guo, Jing Xu, Shun Zhang, Jingjing Shi, Chengxia Liu, Yuanyuan Qin, Wenzhen Zhu
Peripheral nerve damage does not fully explain the pathogenesis of trigeminal neuralgia (TN). Central nervous system changes can follow trigeminal nerve dysfunction. We hypothesized that brain white matter and functional connectivity changes in TN patients were involved in pain perception, modulation, the cognitive-affective system, and motor function; moreover, changes in functional reorganization were correlated with white matter alterations. Twenty left TN patients and twenty-two healthy controls were studied...
October 25, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27772768/cognitive-impairment-after-traumatic-brain-injury-the-role-of-mri-and-possible-pathological-basis
#13
Ming-Liang Wang, Wen-Bin Li
Traumatic brain injury (TBI) is closely related to increased incidence of cognitive impairment from the acute phase to chronic phase. At present, the pathological mechanism leading to cognitive impairment after TBI is still not fully understood. We hypothesize that neuron loss, diffuse axonal injury, microbleed, and blood-brain barrier (BBB) disruption altogether contribute to the development of cognitive impairment. Furthermore, the disruption of structural and functional neural network related to the cognitive function might bring about the final step in the occurrence of cognitive impairment after TBI...
November 15, 2016: Journal of the Neurological Sciences
https://www.readbyqxmd.com/read/27770816/apparent-diffusion-coefficient-histogram-shape-analysis-for-monitoring-early-response-in-patients-with-advanced-cervical-cancers-undergoing-concurrent-chemo-radiotherapy
#14
Jie Meng, Lijing Zhu, Li Zhu, Huanhuan Wang, Song Liu, Jing Yan, Baorui Liu, Yue Guan, Yun Ge, Jian He, Zhengyang Zhou, Xiaofeng Yang
BACKGROUND: To explore the role of apparent diffusion coefficient (ADC) histogram shape related parameters in early assessment of treatment response during the concurrent chemo-radiotherapy (CCRT) course of advanced cervical cancers. METHODS: This prospective study was approved by the local ethics committee and informed consent was obtained from all patients. Thirty-two patients with advanced cervical squamous cell carcinomas underwent diffusion weighted magnetic resonance imaging (b values, 0 and 800 s/mm(2)) before CCRT, at the end of 2nd and 4th week during CCRT and immediately after CCRT completion...
October 22, 2016: Radiation Oncology
https://www.readbyqxmd.com/read/27758016/diffusion-kurtosis-imaging-for-differentiating-between-the-benign-and-malignant-sinonasal-lesions
#15
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
https://www.readbyqxmd.com/read/27752885/erratum-to-in-vivo-molecular-profiling-of-human-glioma-using-diffusion-kurtosis-imaging
#16
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
https://www.readbyqxmd.com/read/27731906/fast-diffusion-kurtosis-imaging-of-fibrotic-mouse-kidneys
#17
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...
December 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27696558/fast-diffusion-kurtosis-imaging-dki-with-inherent-correlation-based-normalization-icon-enhances-automatic-segmentation-of-heterogeneous-diffusion-mri-lesion-in-acute-stroke
#18
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)...
December 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27693403/imaging-the-transformation-of-ipsilateral-internal-capsule-following-focal-cerebral-ischemia-in-rat-by-diffusion-kurtosis-imaging
#19
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
https://www.readbyqxmd.com/read/27670633/evaluation-of-non-gaussian-diffusion-in-cardiac-mri
#20
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
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