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Magma

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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
#1
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
#2
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
#3
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
#4
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
#5
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/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
#6
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
#7
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
https://www.readbyqxmd.com/read/28181027/track-weighted-imaging-methods-extracting-information-from-a-streamlines-tractogram
#8
REVIEW
Fernando Calamante
A whole-brain streamlines data-set (so-called tractogram) generated from diffusion MRI provides a wealth of information regarding structural connectivity in the brain. Besides visualisation strategies, a number of post-processing approaches have been proposed to extract more detailed information from the tractogram. One such approach is based on exploiting the information contained in the tractogram to generate track-weighted (TW) images. In the track-weighted imaging (TWI) approach, a very large number of streamlines are often generated throughout the brain, and an image is then computed based on properties of the streamlines themselves (e...
February 8, 2017: Magma
https://www.readbyqxmd.com/read/28120280/highly-accelerated-self-gated-free-breathing-3d-cardiac-cine-mri-validation-in-assessment-of-left-ventricular-function
#9
Jing Liu, Li Feng, Hsin-Wei Shen, Chengcheng Zhu, Yan Wang, Kanae Mukai, Gabriel C Brooks, Karen Ordovas, David Saloner
OBJECTIVE: This work presents a highly-accelerated, self-gated, free-breathing 3D cardiac cine MRI method for cardiac function assessment. MATERIALS AND METHODS: A golden-ratio profile based variable-density, pseudo-random, Cartesian undersampling scheme was implemented for continuous 3D data acquisition. Respiratory self-gating was achieved by deriving motion signal from the acquired MRI data. A multi-coil compressed sensing technique was employed to reconstruct 4D images (3D+time)...
January 24, 2017: Magma
https://www.readbyqxmd.com/read/28091836/assessment-of-edema-using-stir-via-3d-cardiovascular-magnetic-resonance-imaging-in-patients-with-suspected-myocarditis
#10
Michael Jeserich, Bela Merkely, Pascal Schlosser, Simone Kimmel, Gabor Pavlik, Stephan Achenbach
OBJECTIVE: To evaluate three-dimensional T2-weighted fast spin echo triple inversion recovery sequences (STIR+) for the diagnosis of myocardial edema in patients with suspected early myocarditis after respiratory or gastrointestinal tract viral infection and at follow-up. MATERIALS AND METHODS: We prospectively examined 28 patients with suspected myocarditis and 37 controls matched for gender and age. An ECG-triggered STIR+ was used to cover the entire left ventricle in short-axis images with 10-mm slice thickness and no interslice gap...
January 16, 2017: Magma
https://www.readbyqxmd.com/read/28070869/fast-t1-and-t2-mapping-methods-the-zoomed-u-flare-sequence-compared-with-epi-and-snapshot-flash-for-abdominal-imaging-at-11-7-tesla
#11
Géraldine Pastor, María Jiménez-González, Sandra Plaza-García, Marta Beraza, Torsten Reese
OBJECTIVE: A newly adapted zoomed ultrafast low-angle RARE (U-FLARE) sequence is described for abdominal imaging applications at 11.7 Tesla and compared with the standard echo-plannar imaging (EPI) and snapshot fast low angle shot (FLASH) methods. MATERIALS AND METHODS: Ultrafast EPI and snapshot-FLASH protocols were evaluated to determine relaxation times in phantoms and in the mouse kidney in vivo. Owing to their apparent shortcomings, imaging artefacts, signal-to-noise ratio (SNR), and variability in the determination of relaxation times, these methods are compared with the newly implemented zoomed U-FLARE sequence...
January 9, 2017: Magma
https://www.readbyqxmd.com/read/28063096/feasibility-of-in-vivo-three-dimensional-t-2-mapping-using-dicarboxy-proxyl-and-cw-epr-based-single-point-imaging
#12
Harue Kubota, Denis A Komarov, Hironobu Yasui, Shingo Matsumoto, Osamu Inanami, Igor A Kirilyuk, Valery V Khramtsov, Hiroshi Hirata
OBJECTIVES: The aim of this study was to demonstrate the feasibility of in vivo three-dimensional (3D) relaxation time T 2(*) mapping of a dicarboxy-PROXYL radical using continuous-wave electron paramagnetic resonance (CW-EPR) imaging. MATERIALS AND METHODS: Isotopically substituted dicarboxy-PROXYL radicals, 3,4-dicarboxy-2,2,5,5-tetra((2)H3)methylpyrrolidin-(3,4-(2)H2)-(1-(15)N)-1-oxyl ((2)H,(15)N-DCP) and 3,4-dicarboxy-2,2,5,5-tetra((2)H3)methylpyrrolidin-(3,4-(2)H2)-1-oxyl ((2)H-DCP), were used in the study...
January 6, 2017: Magma
https://www.readbyqxmd.com/read/28054143/a-low-cost-mr-compatible-ergometer-to-assess-post-exercise-phosphocreatine-recovery-kinetics
#13
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...
January 4, 2017: Magma
https://www.readbyqxmd.com/read/28000087/the-effect-of-diffusion-gradient-direction-number-on-corticospinal-tractography-in-the-human-brain-an-along-tract-analysis
#14
Claudia Testa, Stefania Evangelisti, Mariagrazia Popeo, Stefano Zanigni, Laura Ludovica Gramegna, Paola Fantazzini, Caterina Tonon, David Neil Manners, Raffaele Lodi
OBJECTIVES: We evaluated diffusion imaging measures of the corticospinal tract obtained with a probabilistic tractography algorithm applied to data of two acquisition protocols based on different numbers of diffusion gradient directions (NDGDs). MATERIALS AND METHODS: The corticospinal tracts (CST) of 18 healthy subjects were delineated using 22 and 66-NDGD data. An along-tract analysis of diffusion metrics was performed to detect possible local differences due to NDGD...
December 20, 2016: Magma
https://www.readbyqxmd.com/read/27981396/semi-automated-myocardial-segmentation-of-bright%C3%A2-blood-multi-gradient-echo-images-improves-reproducibility-of-myocardial-contours-and-t2-determination
#15
Pandji Triadyaksa, Niek H J Prakken, Jelle Overbosch, Robin B Peters, J Martijn van Swieten, Matthijs Oudkerk, Paul E Sijens
OBJECTIVES: Early detection of iron loading is affected by the reproducibility of myocardial contour assessment. A novel semi-automatic myocardial segmentation method is presented on contrast-optimized composite images and compared to the results of manual drawing. MATERIALS AND METHODS: Fifty-one short-axis slices at basal, mid-ventricular and apical locations from 17 patients were acquired by bright blood multi-gradient echo MRI. Four observers produced semi-automatic and manual myocardial contours on contrast-optimized composite images...
December 16, 2016: Magma
https://www.readbyqxmd.com/read/27981395/evaluation-of-exposure-to-ultra-high-static-magnetic-fields-during-activities-around-human-mri-scanners
#16
Mahsa Fatahi, Jolanta Karpowicz, Krzysztof Gryz, Amirmohammad Fattahi, Georg Rose, Oliver Speck
OBJECTIVE: To assess the individual exposure to the static magnetic field (SMF) and the motion-induced time-varying magnetic field (TVMF) generated by activities in an inhomogeneous SMF near high and ultra-high field magnetic resonance imaging (MRI) scanners. The study provides information on the level of exposure to high and ultra-high field MRI scanners during research activities. MATERIALS AND METHODS: A three-axis Hall magnetometer was used to determine the SMF and TVMF around human 3- and 7-Tesla (T) MRI systems...
December 16, 2016: Magma
https://www.readbyqxmd.com/read/27943055/reproducible-segmentation-of-white-matter-hyperintensities-using-a-new-statistical-definition
#17
Soheil Damangir, Eric Westman, Andrew Simmons, Hugo Vrenken, Lars-Olof Wahlund, Gabriela Spulber
OBJECTIVES: We present a method based on a proposed statistical definition of white matter hyperintensities (WMH), which can work with any combination of conventional magnetic resonance (MR) sequences without depending on manually delineated samples. MATERIALS AND METHODS: T1-weighted, T2-weighted, FLAIR, and PD sequences acquired at 1.5 Tesla from 119 subjects from the Kings Health Partners-Dementia Case Register (healthy controls, mild cognitive impairment, Alzheimer's disease) were used...
December 9, 2016: Magma
https://www.readbyqxmd.com/read/27394911/assessment-of-the-myelin-water-fraction-in-rodent-spinal-cord-using-t2-prepared-ultrashort-echo-time-mri
#18
Tim Klasen, Cornelius Faber
OBJECTIVE: Multi-component T2 relaxation allows for assessing the myelin water fraction in nervous tissue, providing a surrogate marker for demyelination. The assessment of the number and distribution of different T2 components for devising exact models of tissue relaxation has been limited by T2 sampling with conventional MR methods. MATERIALS AND METHODS: A T2-prepared UTE sequence was used to assess multicomponent T2 relaxation at 9.4 T of fixed mouse and rat spinal cord samples and of mouse spinal cord in vivo...
December 2016: Magma
https://www.readbyqxmd.com/read/27393351/reproducibility-of-macromolecule-suppressed-gaba-measurement-using-motion-and-shim-navigated-mega-special-with-lcmodel-jmrui-and-gannet
#19
Muhammad G Saleh, Jamie Near, Alqadafi Alhamud, Frances Robertson, André J W van der Kouwe, Ernesta M Meintjes
OBJECTIVE: Measuring the pure form of GABA has become increasingly important because of its association with behaviour and certain pathologies. The aim of this study was to assess the reproducibility of GABA measurements using a shim and motion navigated MEGA-SPECIAL sequence with LCModel, jMRUI and GANNET software. MATERIALS AND METHODS: Motion and shim navigated MEGA-SPECIAL scans were acquired in 20 healthy subjects. Two acquisitions were performed for each of two regions: the anterior cingulate (ACC) and medial-parietal (PAR) cortices...
December 2016: Magma
https://www.readbyqxmd.com/read/27384463/magnetization-transfer-imaging-of-cortical-bone-in-vivo-using-a-zero-echo-time-sequence-in-mice-at-4-7%C3%A2-t-a-feasibility-study
#20
Magda Marcon, Markus Weiger, Daniel Keller, Moritz C Wurnig, Christian Eberhardt, Daniel Eberli, Andreas Boss
OBJECTIVE: To investigate the feasibility of magnetization transfer (MT) imaging in mice in vivo for the assessment of cortical bone. MATERIALS AND METHODS: MT-zero echo time data were acquired at 4.7 T in six mice using MT preparation pulses with two different flip angles (FAs) and a series of ten different off-resonance frequencies (500-15000 Hz). Regions of interest were drawn at multiple levels of the femoral cortical bone. The MT ratio (MTR) was computed for each combination of FAs and off-resonance frequencies...
December 2016: Magma
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