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Magma

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https://www.readbyqxmd.com/read/28550650/single-breath-hold-3-d-cine-imaging-of-the-left-ventricle-using-cartesian-sampling
#1
Jens Wetzl, Michaela Schmidt, François Pontana, Benjamin Longère, Felix Lugauer, Andreas Maier, Joachim Hornegger, Christoph Forman
OBJECTIVES: Our objectives were to evaluate a single-breath-hold approach for Cartesian 3-D CINE imaging of the left ventricle with a nearly isotropic resolution of [Formula: see text] and a breath-hold duration of [Formula: see text]19 s against a standard stack of 2-D CINE slices acquired in multiple breath-holds. Validation is performed with data sets from ten healthy volunteers. MATERIALS AND METHODS: A Cartesian sampling pattern based on the spiral phyllotaxis and a compressed sensing reconstruction method are proposed to allow 3-D CINE imaging with high acceleration factors...
May 26, 2017: Magma
https://www.readbyqxmd.com/read/28550649/improved-formula-see-text-determination-in-23-na-35-cl-and-17-o-mri-using-iterative-partial-volume-correction-based-on-1-h-mri-segmentation
#2
Sebastian C Niesporek, Reiner Umathum, Thomas M Fiedler, Peter Bachert, Mark E Ladd, Armin M Nagel
OBJECTIVE: Functional parameters can be measured with the help of quantitative non-proton MRI where exact relaxometry parameters are needed. Investigation of [Formula: see text] is often biased by strong partial volume (PV) effects. Hence, in this work a PV correction algorithm approach was evaluated that uses iteratively adapted [Formula: see text]-values and high-resolution structural (1)H data to determine transverse relaxation in non-proton MRI more accurately. MATERIALS AND METHODS: Simulations, a phantom study and in vivo (23)Na, (17)O and (35)Cl MRI measurements of five healthy volunteers were performed to evaluate the algorithm...
May 26, 2017: Magma
https://www.readbyqxmd.com/read/28455630/relationship-between-carotid-plaque-surface-morphology-and-perfusion-a-3d-dce-mri-study
#3
Jianmin Yuan, Gregory Makris, Andrew Patterson, Ammara Usman, Tilak Das, Andrew Priest, Zhongzhao Teng, Sarah Hilborne, Dario Prudencio, Jonathan Gillard, Martin Graves
OBJECTIVE: This study aims to explore the relationship between plaque surface morphology and neovascularization using a high temporal and spatial resolution 4D contrast-enhanced MRI/MRA sequence. MATERIALS AND METHODS: Twenty one patients with either recent symptoms or a carotid artery stenosis ≥40% were recruited in this study. Plaque surface morphology and luminal stenosis were determined from the arterial phase MRA images. Carotid neovascularization was evaluated by a previously validated pharmacokinetic (PK) modeling approach...
April 28, 2017: Magma
https://www.readbyqxmd.com/read/28455629/validation-of-an-active-shape-model-based-semi-automated-segmentation-algorithm-for-the-analysis-of-thigh-muscle-and-adipose-tissue-cross-sectional-areas
#4
Jana Kemnitz, Felix Eckstein, Adam G Culvenor, Anja Ruhdorfer, Torben Dannhauer, Susanne Ring-Dimitriou, Alexandra M Sänger, Wolfgang Wirth
OBJECTIVE: To validate a semi-automated method for thigh muscle and adipose tissue cross-sectional area (CSA) segmentation from MRI. MATERIALS AND METHODS: An active shape model (ASM) was trained using 113 MRI CSAs from the Osteoarthritis Initiative (OAI) and combined with an active contour model and thresholding-based post-processing steps. This method was applied to 20 other MRIs from the OAI and to baseline and follow-up MRIs from a 12-week lower-limb strengthening or endurance training intervention (n = 35 females)...
April 28, 2017: Magma
https://www.readbyqxmd.com/read/28444504/correction-of-parallel-transmission-using-concurrent-rf-and-gradient-field-monitoring
#5
Mustafa Çavuşoğlu, Benjamin Emanuel Dietrich, David Otto Brunner, Markus Weiger, Klaas Paul Pruessmann
OBJECTIVES: The accuracy and precision of the parallel RF excitations are highly dependent on the spatial and temporal fidelity of the magnetic fields involved in spin excitation. The consistency between the nominal and effective fields is typically limited by the imperfections of the employed hardware existing both in the gradient system and the RF chain. In this work, we experimentally presented highly improved spatially tailored parallel excitations by turning the native hardware accuracy challenge into a measurement and control problem using an advanced field camera technology to fully correct parallel RF transmission experiment...
April 25, 2017: Magma
https://www.readbyqxmd.com/read/28397150/quantitative-effects-of-acquisition-duration-and-temporal-resolution-on-the-measurement-accuracy-of-prostate-dynamic-contrast-enhanced-mri-data-a-phantom-study
#6
Silvin Paul Knight, Jacinta Elizabeth Browne, James Frances Mary Meaney, Andrew John Fagan
OBJECTIVES: The aim of this study was to investigate the effect of the temporal resolution (T res) and acquisition duration (AD) on the measurement accuracy of contrast concentration-time curves (CTCs), and derived phenomenological and pharmacokinetic parameter values, in a dynamic contrast-enhanced MRI experiment using a novel phantom test device. MATERIALS AND METHODS: 'Ground truth' CTCs were established using a highly precise optical imaging system. These precisely known CTCs were produced in an anthropomorphic environment, which mimicked the male pelvic region, and presented to the MRI scanner for measurement...
April 10, 2017: Magma
https://www.readbyqxmd.com/read/28382555/fitting-interrelated-datasets-metabolite-diffusion-and-general-lineshapes
#7
Victor Adalid, André Döring, Sreenath Pruthviraj Kyathanahally, Christine Sandra Bolliger, Chris Boesch, Roland Kreis
OBJECTIVE: Simultaneous modeling of true 2-D spectroscopy data, or more generally, interrelated spectral datasets has been described previously and is useful for quantitative magnetic resonance spectroscopy applications. In this study, a combined method of reference-lineshape enhanced model fitting and two-dimensional prior-knowledge fitting for the case of diffusion weighted MR spectroscopy is presented. MATERIALS AND METHODS: Time-dependent field distortions determined from a water reference are applied to the spectral bases used in linear-combination modeling of interrelated spectra...
April 5, 2017: Magma
https://www.readbyqxmd.com/read/28382554/measurement-of-vertebral-bone-marrow-proton-density-fat-fraction-in-children-using-quantitative-water-fat-mri
#8
Stefan Ruschke, Amber Pokorney, Thomas Baum, Holger Eggers, Jeffrey H Miller, Houchun H Hu, Dimitrios C Karampinos
OBJECTIVES: To investigate the feasibility of employing a 3D time-interleaved multi-echo gradient-echo (TIMGRE) sequence to measure the proton density fat fraction (PDFF) in the vertebral bone marrow (VBM) of children and to examine cross-sectional changes with age and intra-individual variations from the lumbar to the cervical region in the first two decades of life. MATERIALS AND METHODS: Quantitative water-fat imaging of the spine was performed in 93 patients (49 girls; 44 boys; age median 4...
April 5, 2017: Magma
https://www.readbyqxmd.com/read/28361185/assessment-of-pharmacokinetics-for-microvessel-proliferation-by-dce-mri-for-early-detection-of-physeal-bone-bridge-formation-in-an-animal-model
#9
Bernhard Neumayer, Eva Amerstorfer, Clemens Diwoky, Richard A Lindtner, Elisabeth Wadl, Eva Scheurer, Annelie-Martina Weinberg, Rudolf Stollberger
OBJECTIVES: Bone bridge formation occurs after physeal lesions and can lead to growth arrest if not reversed. Previous investigations on the underlying mechanisms of this formation used histological methods. Therefore, this study aimed to apply a minimally invasive method using dynamic contrast-enhanced MRI (DCE-MRI). MATERIALS AND METHODS: Changes in functional parameters related to the microvessel system were assessed in a longitudinal study of a cohort of an animal model applying a reference region model...
March 30, 2017: Magma
https://www.readbyqxmd.com/read/28332039/combined-quantification-of-fatty-infiltration-t-1-relaxation-times-and-t-2-relaxation-times-in-normal-appearing-skeletal-muscle-of-controls-and-dystrophic-patients
#10
Benjamin Leporq, Arnaud Le Troter, Yann Le Fur, Emmanuelle Salort-Campana, Maxime Guye, Olivier Beuf, Shahram Attarian, David Bendahan
OBJECTIVES: To evaluate the combination of a fat-water separation method with an automated segmentation algorithm to quantify the intermuscular fatty-infiltrated fraction, the relaxation times, and the microscopic fatty infiltration in the normal-appearing muscle. MATERIALS AND METHODS: MR acquisitions were performed at 1.5T in seven patients with facio-scapulo-humeral dystrophy and eight controls. Disease severity was assessed using commonly used scales for the upper and lower limbs...
March 22, 2017: Magma
https://www.readbyqxmd.com/read/28321524/what-are-the-true-volumes-of-sega-tumors-reliability-of-planimetric-and-popular-semi-automated-image-segmentation-methods
#11
Konrad Stawiski, Joanna Trelińska, Dobromiła Baranska, Iwona Dachowska, Katarzyna Kotulska, Sergiusz Jóźwiak, Wojciech Fendler, Wojciech Młynarski
OBJECTIVE: To evaluate the reliability of the standard planimetric methodology of volumetric analysis and three different open-source semi-automated approaches of brain tumor segmentation. MATERIALS AND METHODS: The volumes of subependymal giant cell astrocytomas (SEGA) examined by 30 MRI studies of 10 patients from a previous everolimus-related trial (EMINENTS study) were estimated using four methods: planimetric method (modified MacDonald ellipsoid method), ITK-Snap (pixel clustering, geodesic active contours, region competition methods), 3D Slicer (level-set thresholding), and NIRFast (k-means clustering, Markov random fields)...
March 20, 2017: Magma
https://www.readbyqxmd.com/read/28283853/long-t2-suppression-in-native-lung-3-d-imaging-using-k-space-reordered-inversion-recovery-dual-echo-ultrashort-echo-time-mri
#12
Neville D Gai, Ashkan A Malayeri, David A Bluemke
OBJECTIVE: Long T2 species can interfere with visualization of short T2 tissue imaging. For example, visualization of lung parenchyma can be hindered by breathing artifacts primarily from fat in the chest wall. The purpose of this work was to design and evaluate a scheme for long T2 species suppression in lung parenchyma imaging using 3-D inversion recovery double-echo ultrashort echo time imaging with a k-space reordering scheme for artifact suppression. MATERIALS AND METHODS: A hyperbolic secant (HS) pulse was evaluated for different tissues (T1/T2)...
March 10, 2017: Magma
https://www.readbyqxmd.com/read/28281146/influence-of-the-cardiac-cycle-on-pcasl-cardiac-triggering-of-the-end-of-labeling
#13
Jasper Verbree, Matthias J P van Osch
OBJECTIVE: In arterial spin labeling (ASL), the cardiac cycle might adversely influence signal-stability by varying the amount of label created, labeling efficiency and/or transport times. Due to the long labeling duration in pseudo-Continuous ASL (pCASL), the blood labeled last contributes most to the ASLsignal. The present study investigated, using numerical simulations and in vivo experiments, the effect of the cardiac cycle on pCASL, thereby focusing on the end-of-labeling. MATERIALS AND METHODS: In the in vivo experiments the end-of-labeling was timed to a specific cardiac phase while a long labeling duration of >7 s was used to isolate the influence of the lastly labeled spins on ASL-signal stability...
March 9, 2017: Magma
https://www.readbyqxmd.com/read/28265814/a-comparative-study-of-the-sensitivity-of-diffusion-related-parameters-obtained-from-diffusion-tensor-imaging-diffusional-kurtosis-imaging-q-space-analysis-and-bi-exponential-modelling-in-the-early-disease-course-24%C3%A2-h-of-hyperacute-6%C3%A2-h-ischemic-stroke-patients
#14
Gaëtan Duchêne, Frank Peeters, André Peeters, Thierry Duprez
OBJECTIVES: To compare the sensitivity and early temporal changes of diffusion parameters obtained from diffusion tensor imaging (DTI), diffusional kurtosis imaging (DKI), q-space analysis (QSA) and bi-exponential modelling in hyperacute stroke patients. MATERIALS AND METHODS: A single investigational acquisition allowing the four diffusion analyses was performed on seven hyperacute stroke patients with a 3T system. The percentage change between ipsi- and contralateral regions were compared at admission and 24 h later...
March 6, 2017: Magma
https://www.readbyqxmd.com/read/28054143/a-low-cost-mr-compatible-ergometer-to-assess-post-exercise-phosphocreatine-recovery-kinetics
#15
Niels D Naimon, Jerzy Walczyk, James S Babb, Oleksandr Khegai, Xuejiao Che, Leeor Alon, Ravinder R Regatte, Ryan Brown, Prodromos Parasoglou
OBJECTIVE: To develop a low-cost pedal ergometer compatible with ultrahigh (7 T) field MR systems to reliably quantify metabolic parameters in human lower leg muscle using phosphorus magnetic resonance spectroscopy. MATERIALS AND METHODS: We constructed an MR compatible ergometer using commercially available materials and elastic bands that provide resistance to movement. We recruited ten healthy subjects (eight men and two women, mean age ± standard deviation: 32...
June 2017: Magma
https://www.readbyqxmd.com/read/27815649/magnetic-resonance-imaging-detection-of-multiple-ischemic-injury-produced-in-an-adult-rat-model-of-minor-stroke-followed-by-mild-transient-cerebral-ischemia
#16
Ursula I Tuor, Min Qiao
OBJECTIVES: To determine whether cumulative brain damage produced adjacent to a minor stroke that is followed by a mild transient ischemia is detectable with MRI and histology, and whether acute or chronic recovery between insults influences this damage. MATERIALS AND METHODS: A minor photothrombotic (PT) stroke was followed acutely (1-2 days) or chronically (7 days) by a mild transient middle cerebral artery occlusion (tMCAO). MRI was performed after each insult, followed by final histology...
April 2017: Magma
https://www.readbyqxmd.com/read/27787676/insight-into-the-labeling-mechanism-of-acceleration-selective-arterial-spin-labeling
#17
Sophie Schmid, Esben T Petersen, Matthias J P Van Osch
OBJECTIVES: Acceleration selective arterial spin labeling (AccASL) is a spatially non-selective labeling technique, used in traditional ASL methods, which labels spins based on their flow acceleration rather than spatial localization. The exact origin of the AccASL signal within the vasculature is not completely understood. To obtain more insight into this, the acceleration selective module was performed followed by a velocity selective module, which is used in velocity selective arterial spin labeling (VS-ASL)...
April 2017: Magma
https://www.readbyqxmd.com/read/27785640/can-mri-t1-be-used-to-detect-early-changes-in-5xfad-alzheimer-s-mouse-brain
#18
Nicholas G Spencer, David P Lovell, Kay Elderfield, Brian Austen, Franklyn A Howe
OBJECTIVES: In the present study, we have tested whether MRI T1 relaxation time is a sensitive marker to detect early stages of amyloidosis and gliosis in the young 5xFAD transgenic mouse, a well-established animal model for Alzheimer's disease. MATERIALS AND METHODS: 5xFAD and wild-type mice were imaged in a 4.7 T Varian horizontal bore MRI system to generate T1 quantitative maps using the spin-echo multi-slice sequence. Following immunostaining for glial fibrillary acidic protein, Iba-1, and amyloid-β, T1 and area fraction of staining were quantified in the posterior parietal and primary somatosensory cortex and corpus callosum...
April 2017: Magma
https://www.readbyqxmd.com/read/28246950/biomarkers-from-in-vivo-molecular-imaging-of-breast-cancer-pretreatment-18-f-fdg-pet-predicts-patient-prognosis-and-pretreatment-dwi-mr-predicts-response-to-neoadjuvant-chemotherapy
#19
Francesca Gallivanone, Marta Maria Panzeri, Carla Canevari, Claudio Losio, Luigi Gianolli, Francesco De Cobelli, Isabella Castiglioni
OBJECTIVE: Human cancers display intra-tumor phenotypic heterogeneity and recent research has focused on developing image processing methods extracting imaging descriptors to characterize this heterogeneity. This work assesses the role of pretreatment (18)F-FDG PET and DWI-MR with respect to the prognosis and prediction of neoadjuvant chemotherapy (NAC) outcomes when image features are used to characterize primitive lesions from breast cancer (BC). MATERIALS AND METHODS: A retrospective protocol included 38 adult women with biopsy-proven BC...
February 28, 2017: Magma
https://www.readbyqxmd.com/read/28220266/interpretation-of-cardiac-wall-motion-from-cine-mri-combined-with-parametric-imaging-based-on-the-hilbert-transform
#20
Narjes Benameur, Enrico Gianluca Caiani, Younes Arous, Nejmeddine Ben Abdallah, Tarek Kraiem
OBJECT: The aim of this study was to test and validate the clinical impact of parametric amplitude images obtained using the Hilbert transform on the regional interpretation of cardiac wall motion abnormalities from cine-MR images by non-expert radiologists compared with expert consensus. MATERIALS AND METHODS: Cine-MRI short-axis images obtained in 20 patients (10 with myocardial infarction, 5 with myocarditis and 5 with normal function) were processed to compute a parametric amplitude image for each using the Hilbert transform...
February 20, 2017: Magma
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