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Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine

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https://www.readbyqxmd.com/read/28432747/whole-body-adipose-tissue-and-lean-muscle-volumes-and-their-distribution-across-gender-and-age-mr-derived-normative-values-in-a-normal-weight-swiss-population
#1
Erika J Ulbrich, Daniel Nanz, Olof Dahlqvist Leinhard, Magda Marcon, Michael A Fischer
PURPOSE: To determine age- and gender-dependent whole-body adipose tissue and muscle volumes in healthy Swiss volunteers in Dixon MRI in comparison with anthropometric and bioelectrical impedance (BIA) measurements. METHODS: Fat-water-separated whole-body 3 Tesla MRI of 80 healthy volunteers (ages 20 to 62 years) with a body mass index (BMI) of 17.5 to 26.2 kg/m(2) (10 men, 10 women per decade). Age and gender-dependent volumes of total adipose tissue (TAT), visceral adipose tissue (VAT), total abdominal subcutaneous adipose tissue (ASAT) and total abdominal adipose tissue (TAAT), and the total lean muscle tissue (TLMT) normalized for body height were determined by semi-automatic segmentation, and correlated with anthropometric and BIA measurements as well as lifestyle parameters...
April 22, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28426162/motion-corrected-simultaneous-cardiac-positron-emission-tomography-and-coronary-mr-angiography-with-high-acquisition-efficiency
#2
Camila Munoz, Radhouene Neji, Gastão Cruz, Andrew Mallia, Sami Jeljeli, Andrew J Reader, Rene M Botnar, Claudia Prieto
PURPOSE: Develop a framework for efficient free-breathing simultaneous whole-heart coronary magnetic resonance angiography (CMRA) and cardiac positron emission tomography (PET) on a 3 Tesla PET-MR system. METHODS: An acquisition that enables nonrigid motion correction of both CMRA and PET has been developed. The proposed method estimates translational motion from low-resolution 2D MR image navigators acquired at each heartbeat and 3D nonrigid respiratory motion between different respiratory bins from the CMRA data itself...
April 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28426147/propagation-of-error-from-parameter-constraints-in-quantitative-mri-example-application-of-multiple-spin-echo-t2-mapping
#3
Christopher L Lankford, Mark D Does
PURPOSE: Quantitative MRI may require correcting for nuisance parameters which can or must be constrained to independently measured or assumed values. The noise and/or bias in these constraints propagate to fitted parameters. For example, the case of refocusing pulse flip angle constraint in multiple spin echo T2 mapping is explored. METHODS: An analytical expression for the mean-squared error of a parameter of interest was derived as a function of the accuracy and precision of an independent estimate of a nuisance parameter...
April 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28421683/a-numerical-investigation-on-the-effect-of-rf-coil-feed-variability-on-global-and-local-electromagnetic-field-exposure-in-human-body-models-at-64-mhz
#4
Elena Lucano, Micaela Liberti, Tom Lloyd, Francesca Apollonio, Steve Wedan, Wolfgang Kainz, Leonardo M Angelone
PURPOSE: This study aims to investigate how the positions of the feeding sources of the transmit radiofrequency (RF) coil, field orientation direction with respect to the patient, and patient dimensions affect the global and local electromagnetic exposure in human body models. METHODS: Three RF coil models were implemented, namely a specific two-source (S2) feed and two multisource feed configurations: generic 32-source (G32) and hybrid 16-source (H16). Thirty-two feeding conditions were studied for the S2, whereas two were studied for the G32 and H16...
April 18, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28419591/application-of-spin-echoes-in-the-regime-of-weak-dephasing-to-t1-mapping-of-the-lung
#5
Jakob Assländer, Steffen J Glaser, Jürgen Hennig
PURPOSE: This work presents an approach to mapping the entire lung's proton density and T1 within a single breath-hold and analyzes the apparent T1 when exciting with a spin echo generating pulse in comparison to a standard gradient echo acquisition. METHODS: An inversion-recovery SNAPSHOT-FLASH sequence with a stack-of-stars k-space readout with a golden angle increment was modified to use a spin echo generating radiofrequency-pulse for excitation. Data of five volunteers were acquired on a 3T scanner and image reconstruction was performed by an iterative algorithm adopted from MR-Fingerprinting...
April 17, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28419582/free-breathing-liver-fat-quantification-using-a-multiecho-3d-stack-of-radial-technique
#6
Tess Armstrong, Isabel Dregely, Alto Stemmer, Fei Han, Yutaka Natsuaki, Kyunghyun Sung, Holden H Wu
PURPOSE: The diagnostic gold standard for nonalcoholic fatty liver disease is an invasive biopsy. Noninvasive Cartesian MRI fat quantification remains limited to a breath-hold (BH). In this work, a novel free-breathing 3D stack-of-radial (FB radial) liver fat quantification technique is developed and evaluated in a preliminary study. METHODS: Phantoms and healthy subjects (n = 11) were imaged at 3 Tesla. The proton-density fat fraction (PDFF) determined using FB radial (with and without scan acceleration) was compared to BH single-voxel MR spectroscopy (SVS) and BH 3D Cartesian MRI using linear regression (correlation coefficient ρ and concordance coefficient ρc ) and Bland-Altman analysis...
April 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28411394/improved-magnetic-resonance-fingerprinting-reconstruction-with-low-rank-and-subspace-modeling
#7
Bo Zhao, Kawin Setsompop, Elfar Adalsteinsson, Borjan Gagoski, Huihui Ye, Dan Ma, Yun Jiang, P Ellen Grant, Mark A Griswold, Lawrence L Wald
PURPOSE: This article introduces a constrained imaging method based on low-rank and subspace modeling to improve the accuracy and speed of MR fingerprinting (MRF). THEORY AND METHODS: A new model-based imaging method is developed for MRF to reconstruct high-quality time-series images and accurate tissue parameter maps (e.g., T1 , T2 , and spin density maps). Specifically, the proposed method exploits low-rank approximations of MRF time-series images, and further enforces temporal subspace constraints to capture magnetization dynamics...
April 15, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28401643/ultrafast-compartmentalized-relaxation-time-mapping-with-linear-algebraic-modeling
#8
Yi Zhang, Xiaoyang Liu, Jinyuan Zhou, Paul A Bottomley
PURPOSE: To dramatically accelerate compartmental-average longitudinal (T1 ) and transverse (T2 ) relaxation measurements using the minimal-acquisition linear algebraic modeling (SLAM) method, and to validate it in phantoms and humans. METHODS: Relaxation times were imaged at 3 Tesla in phantoms, in the abdomens of six volunteers, and in six brain tumor patients using standard inversion recovery and multi-spin-echo sequences. k-space was fully sampled to provide reference T1 and T2 measurements, and SLAM was performed using a limited set of phase encodes from central k-space...
April 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28394085/dual-echo-epi-sequence-for-integrated-distortion-correction-in-3d-time-resolved-hyperpolarized-13-c-mri
#9
Benjamin J Geraghty, Justin Y C Lau, Albert P Chen, Charles H Cunningham
PURPOSE: To provide built-in off-resonance correction in time-resolved, volumetric hyperpolarized (13) C metabolic imaging by implementing a novel dual-echo 3D echo-planar imaging (EPI) sequence and reconstruction. METHODS: A spectral-spatial pulse for single-resonance excitation followed by a dual-echo 3D EPI readout was implemented to provide 64 × 8 × 6 cm(3) coverage at 5 × 5 × 5 mm(3) nominal resolution. Multiple sources of EPI distortions were encoded using a multi-echo (1) H EPI reference scan...
April 10, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28394083/bone-volume-to-total-volume-ratio-measured-in-trabecular-bone-by-single-sided-nmr-devices
#10
Leonardo Brizi, Marco Barbieri, Fabio Baruffaldi, Villiam Bortolotti, Chiara Fersini, Huabing Liu, Marcel Nogueira d'Eurydice, Sergei Obruchkov, Fangrong Zong, Petrik Galvosas, Paola Fantazzini
PURPOSE: Reduced bone strength is associated with a loss of bone mass, usually evaluated by dual-energy X-ray absorptiometry, although it is known that the bone microstructure also affects the bone strength. Here, a method is proposed to measure (in laboratory) the bone volume-to-total volume ratio by single-sided NMR scanners, which is related to the microstructure of the trabecular bone. METHODS: Three single-sided scanners were used on animal bone samples. These low-field, mobile, low-cost devices are able to detect the NMR signal, regardless of the sample sizes, without the use of ionizing radiations, with the further advantage of signal localization offered by their intrinsic magnetic field gradients...
April 10, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28394080/parallel-transmit-capability-of-various-rf-transmit-elements-and-arrays-at-7t-mri
#11
Stefan H G Rietsch, Stephan Orzada, Andreas K Bitz, Marcel Gratz, Mark E Ladd, Harald H Quick
PURPOSE: In this work, 22 configurations for remote radiofrequency (RF) coil arrays consisting of different transmit element designs for 7 Tesla (T) ultrahigh-field MRI are compared by numerical simulations. METHODS: Investigated transmit RF element types are rectangular loops, micro striplines, micro striplines with meanders, 250-mm shielded dipoles with meanders, and lambda over two dipoles with and without shield. These elements are combined in four different configurations of circumferential RF body arrays with four or eight transmit elements each...
April 10, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28394030/the-effect-of-realistic-geometries-on-the-susceptibility-weighted-mr-signal-in-white-matter
#12
Tianyou Xu, Sean Foxley, Michiel Kleinnijenhuis, Way Cherng Chen, Karla L Miller
PURPOSE: To investigate the effect of realistic microstructural geometry on the susceptibility-weighted MR signal in white matter (WM), with application to demyelination. METHODS: Previous work has modeled susceptibility-weighted signals under the assumption that axons are cylindrical. In this study, we explored the implications of this assumption by considering the effect of more realistic geometries. A three-compartment WM model incorporating relevant properties based on the literature was used to predict the MR signal...
April 10, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28382726/improved-dark-blood-late-gadolinium-enhancement-db-lge-imaging-using-an-optimized-joint-inversion-preparation-and-t2-magnetization-preparation
#13
Tamer A Basha, Maxine C Tang, Connie Tsao, Cory M Tschabrunn, Elad Anter, Warren J Manning, Reza Nezafat
PURPOSE: To develop a dark blood-late gadolinium enhancement (DB-LGE) sequence that improves scar-blood contrast and delineation of scar region. METHODS: The DB-LGE sequence uses an inversion pulse followed by T2 magnetization preparation to suppress blood and normal myocardium. Time delays inserted after preparation pulses and T2 -magnetization-prep duration are used to adjust tissue contrast. Selection of these parameters was optimized using numerical simulations and phantom experiments...
April 5, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28382658/regional-assessment-of-in-vivo-myocardial-stiffness-using-3d-magnetic-resonance-elastography-in-a-porcine-model-of-myocardial-infarction
#14
Shivaram P Arunachalam, Arvin Arani, Francis Baffour, Joseph A Rysavy, Phillip J Rossman, Kevin J Glaser, David S Lake, Joshua D Trzasko, Armando Manduca, Kiaran P McGee, Richard L Ehman, Philip A Araoz
PURPOSE: The stiffness of a myocardial infarct affects the left ventricular pump function and remodeling. Magnetic resonance elastography (MRE) is a noninvasive imaging technique for measuring soft-tissue stiffness in vivo. The purpose of this study was to investigate the feasibility of assessing in vivo regional myocardial stiffness with high-frequency 3D cardiac MRE in a porcine model of myocardial infarction, and compare the results with ex vivo uniaxial tensile testing. METHODS: Myocardial infarct was induced in a porcine model by embolizing the left circumflex artery...
April 5, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28382642/effects-of-concentration-and-vendor-specific-composition-of-formalin-on-postmortem-mri-of-the-human-brain
#15
Christoph Birkl, Martin Soellradl, Anna Maria Toeglhofer, Stefanie Krassnig, Marlene Leoni, Lukas Pirpamer, Thomas Vorauer, Heinz Krenn, Johannes Haybaeck, Franz Fazekas, Stefan Ropele, Christian Langkammer
PURPOSE: Formalin fixation prevents tissue autolysis by crosslinking proteins and changes tissue microstructure and MRI signal characteristics. Previous studies showed high variations in MR relaxation time constants of formalin fixed brain tissue, which has been attributed to the use of different formalin concentrations. Our investigations confirmed the influence of formalin concentration on relaxation times and unexpectedly revealed an influence of vendor specific formalin composition, which has not been investigated so far...
April 5, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28370289/estimating-breast-tumor-blood-flow-during-neoadjuvant-chemotherapy-using-interleaved-high-temporal-and-high-spatial-resolution-mri
#16
Leonidas Georgiou, Nisha Sharma, David A Broadbent, Daniel J Wilson, Barbara J Dall, Anmol Gangi, David L Buckley
PURPOSE: To evaluate an interleaved MRI sampling strategy that acquires both high temporal resolution (HTR) dynamic contrast-enhanced (DCE) data for quantifying breast tumor blood flow (TBF) and high spatial resolution (HSR) DCE data for clinical reporting, following a single standard injection of contrast agent. METHODS: A simulation study was used to evaluate the performance of the interleaved technique under different conditions. In a prospective clinical study, 18 patients with primary breast cancer, who were due to undergo neoadjuvant chemotherapy (NACT), were examined using interleaved HTR and HSR DCE-MRI at 1...
April 3, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28370252/fetal-cardiac-cine-imaging-using-highly-accelerated-dynamic-mri-with-retrospective-motion-correction-and-outlier-rejection
#17
Joshua F P van Amerom, David F A Lloyd, Anthony N Price, Maria Kuklisova Murgasova, Paul Aljabar, Shaihan J Malik, Maelene Lohezic, Mary A Rutherford, Kuberan Pushparajah, Reza Razavi, Joseph V Hajnal
PURPOSE: Development of a MRI acquisition and reconstruction strategy to depict fetal cardiac anatomy in the presence of maternal and fetal motion. METHODS: The proposed strategy involves i) acquisition and reconstruction of highly accelerated dynamic MRI, followed by image-based ii) cardiac synchronization, iii) motion correction, iv) outlier rejection, and finally v) cardiac cine reconstruction. Postprocessing entirely was automated, aside from a user-defined region of interest delineating the fetal heart...
April 3, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28370494/tailored-spiral-in-out-spectral-spatial-water-suppression-pulses-for-magnetic-resonance-spectroscopic-imaging
#18
Jun Ma, Carrie Wismans, Zhipeng Cao, Dennis W J Klomp, Jannie P Wijnen, William A Grissom
PURPOSE: To develop short water suppression sequences for 7 T magnetic resonance spectroscopic imaging, with mitigation of subject-specific transmit RF field ( B1+) inhomogeneity. METHODS: Patient-tailored spiral in-out spectral-spatial saturation pulses were designed for a three-pulse WET water suppression sequence. The pulses' identical spatial subpulses were designed using patient-specific B1+ maps and a spiral in-out excitation k-space trajectory. The subpulse train was weighted by a spectral envelope that was root-flipped to minimize peak RF demand...
March 31, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28370458/gaba-editing-with-macromolecule-suppression-using-an-improved-mega-special-sequence
#19
Meng Gu, Ralph Hurd, Ralph Noeske, Laima Baltusis, Roeland Hancock, Matthew D Sacchet, Ian H Gotlib, Frederick T Chin, Daniel M Spielman
PURPOSE: The most common γ-aminobutyric-acid (GABA) editing approach, MEGA-PRESS, uses J-editing to measure GABA distinct from larger overlapping metabolites, but suffers contamination from coedited macromolecules (MMs) comprising 40 to 60% of the observed signal. MEGA-SPECIAL is an alternative method with better MM suppression, but is not widely used primarily because of its relatively poor spatial localization. Our goal was to develop an improved MM-suppressed GABA editing sequence at 3 Tesla...
March 31, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28370409/slice-profile-effects-on-ncpmg-ss-fse
#20
Eric K Gibbons, Patrick Le Roux, John M Pauly, Adam B Kerr
PURPOSE: To determine the effects of the RF refocusing pulse profile on the magnitude of the transverse signal smoothness throughout the echo train in non-Carr-Purcell-Meiboom-Gill (nCPMG) single-shot fast spin echo (SS-FSE) imaging and to design an RF refocusing pulse that provides improved signal stability. THEORY AND METHODS: nCPMG SS-FSE quadratic phase modulation requires sufficiently high and uniform refocusing flip angle to achieve a stable signal. Typically, refocusing pulses used in SS-FSE sequences are designed for minimum duration to minimize echo spacing and as a consequence have poor selectivity...
March 31, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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