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https://www.readbyqxmd.com/read/28547846/multiline-balanced-ssfp-for-rapid-functional-imaging-at-ultrahigh-field
#1
Philipp Ehses, Klaus Scheffler
PURPOSE: The goal of this study is to develop and evaluate a multiline balanced steady-state free-precession (bSSFP) sequence for passband functional MRI at ultrahigh field. METHODS: Passband bSSFP functional MRI experiments using a visual task were performed on a 9.4 T system with echo trains ranging from one up to seven echoes. We analyze the acquisition efficiency, temporal and thermal signal-to-noise ratio, as well as the observed blood oxygen-level-dependent (BOLD) signal changes...
May 25, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28543364/diffusion-weighted-mri-with-minimal-distortion-in-head-and-neck-radiotherapy-using-a-turbo-spin-echo-acquisition-method
#2
Tim Schakel, Johannes M Hoogduin, Chris H J Terhaard, Marielle E P Philippens
PURPOSE: Diffusion weighted (DW) MRI, showing high contrast between tumor and background tissue, is a promising technique in radiotherapy for tumor delineation. However, its use for head-and-neck patients is hampered by poor geometric accuracy in conventional echo planar imaging (EPI) DW-MRI. An alternative turbo spin echo sequence, DW-SPLICE, is implemented and demonstrated in patients. METHODS: The DW-SPLICE sequence was implemented on a 3.0T system and evaluated in 10 patients...
May 23, 2017: Medical Physics
https://www.readbyqxmd.com/read/28539914/functional-connectivity-mapping-in-the-animal-model-principles-and-applications-of-resting-state-fmri
#3
REVIEW
Martin Gorges, Francesco Roselli, Hans-Peter Müller, Albert C Ludolph, Volker Rasche, Jan Kassubek
"Resting-state" fMRI has substantially contributed to the understanding of human and non-human functional brain organization by the analysis of correlated patterns in spontaneous activity within dedicated brain systems. Spontaneous neural activity is indirectly measured from the blood oxygenation level-dependent signal as acquired by echo planar imaging, when subjects quietly "resting" in the scanner. Animal models including disease or knockout models allow a broad spectrum of experimental manipulations not applicable in humans...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28526430/combination-of-integrated-dynamic-shimming-and-readout-segmented-echo-planar-imaging-for-diffusion-weighted-mri-of-the-head-and-neck-region-at-3tesla
#4
Sven S Walter, Wei Liu, Alto Stemmer, Petros Martirosian, Konstantin Nikolaou, Mike Notohamiprodjo, Sergios Gatidis
PURPOSE: To evaluate the performance of combined integrated slice-by-slice shimming and readout-segmented EPI (irsEPI) for diffusion-weighted MR imaging (DWI) of the neck at 3Tesla. METHODS: This study was approved by the local ethics committee. An anthropometric phantom of the head/neck region incorporating compartments with different diffusivities was constructed. In vivo measurements were performed in 10 healthy volunteers. DWI of the phantom and volunteers was performed on a 3Tesla MR scanner using single shot EPI (sEPI), a prototype single shot EPI with integrated slice-by-slice shimming (iEPI), readout segmented EPI (rsEPI) and a prototype readout segmented EPI with integrated shimming irsEPI...
May 17, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28515412/utility-of-a-hybrid-ivim-dki-model-to-predict-the-development-of-distant-metastasis-in-head-and-neck-squamous-cell-carcinoma-patients
#5
Noriyuki Fujima, Tomohiro Sakashita, Akihiro Homma, Daisuke Yoshida, Kohsuke Kudo, Hiroki Shirato
PURPOSE: To evaluate the diagnostic power of hybrid intravoxel incoherent motion (IVIM)-diffusion kurtosis imaging (DKI) model parameters in pretreatment for the prediction of future distant metastasis in head and neck squamous cell carcinoma (HNSCC) patients. MATERIALS AND METHODS: We retrospectively evaluated 49 HNSCC patients who underwent curative chemoradiation therapy. Diffusion-weighted image (DWI) acquired by single-shot spin-echo echo-planar imaging with 12 b-values (0-2000) was performed in all patients before any treatment...
May 18, 2017: Magnetic Resonance in Medical Sciences: MRMS
https://www.readbyqxmd.com/read/28513892/assessment-of-nonarteritic-anterior-ischemic-optic-neuropathy-with-intravoxel-incoherent-motion-diffusion-weighted-imaging-using-readout-segmented-echo-planar-imaging-parallel-imaging-and-2d-navigator-based-reacquisition
#6
Ping Lu, Yan Sha, Hailin Wan, Feng Wang, Guohong Tan, Wenlin Tang
PURPOSE: To determine the feasibility of intravoxel incoherent motion (IVIM) for characterizing perfusion properties and its potential diagnostic utility for nonarteritic anterior ischemic optic neuropathy (NAION). IVIM diffusion-weighted imaging is a promising technique that can measure perfusion and diffusion characteristics simultaneously in a noninvasive manner. MATERIALS AND METHODS: Orbital IVIM in a 3.0T scanner was performed on 33 patients with NAION and 15 controls using readout-segmented echo-planar imaging, parallel imaging, and 2D navigator-based reacquisition (RESOLVE-IVIM)...
May 17, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28499849/a-geometrically-adjustable-receive-array-for-imaging-marmoset-cohorts
#7
Kyle M Gilbert, Joseph S Gati, L Martyn Klassen, Peter Zeman, David J Schaeffer, Stefan Everling, Ravi S Menon
The common marmoset (Callithrix jacchus) is an increasingly popular animal model for translational neuroscience studies, during which anatomical and functional MRI can be useful investigative tools. To attain the requisite SNR for high-resolution acquisitions, the radiofrequency coil must be optimized for the marmoset; however, relatively few custom coils have been developed that maximize SNR and are compatible with accelerated acquisitions. For the study of large populations of animals, the heterogeneity in animal size reduces the effectiveness of a "one size fits all" approach to coil sizing and makes coils tailored to individual animals cost and time prohibitive...
May 10, 2017: NeuroImage
https://www.readbyqxmd.com/read/28483719/multi-echo-epi-of-human-fear-conditioning-reveals-improved-bold-detection-in-ventromedial-prefrontal-cortex
#8
Brice Fernandez, Laura Leuchs, Philipp G Sämann, Michael Czisch, Victor I Spoormaker
Standard T2(*) weighted functional magnetic resonance imaging (fMRI) performed with echo-planar imaging (EPI) suffers from signal loss in the ventromedial prefrontal cortex (vmPFC) due to macroscopic field inhomogeneity. However, this region is of special interest to affective neuroscience and psychiatry. The Multi-echo EPI (MEPI) approach has several advantages over EPI but its performance against EPI in the vmPFC has not yet been examined in a study with sufficient statistical power using a task specifically eliciting activity in this region...
May 5, 2017: NeuroImage
https://www.readbyqxmd.com/read/28480603/a-single-shot-t2-mapping-protocol-based-on-echo-split-gradient-spin-echo-acquisition-and-parametric-multiplexed-sensitivity-encoding-based-on-projection-onto-convex-sets-reconstruction
#9
Mei-Lan Chu, Hing-Chiu Chang, Koichi Oshio, Nan-Kuei Chen
PURPOSE: To develop a high-speed T2 mapping protocol that is capable of accurately measuring T2 relaxation time constants from a single-shot acquisition. THEORY: A new echo-split single-shot gradient-spin-echo (GRASE) pulse sequence is developed to acquire multicontrast data while suppressing signals from most nonprimary echo pathways in Carr-Purcell-Meiboom-Gill (CPMG) echoes. Residual nonprimary pathway signals are taken into consideration when performing T2 mapping using a parametric multiplexed sensitivity encoding based on projection onto convex sets (parametric-POCSMUSE) reconstruction method that incorporates extended phase graph modeling of GRASE signals...
May 7, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28478960/use-of-reduced-field-of-view-acquisition-to-improve-prostate-cancer-visualization-on-diffusion-weighted-magnetic-resonance-imaging-in-the-presence-of-hip-implants-report-of-2-cases
#10
Andrew B Rosenkrantz, Samir S Taneja
In patients with metallic hip implants, distortions, and other artifacts relating to the echo-planar imaging acquisition may render prostate diffusion-weighted imaging (DWI) nondiagnostic. Reduced field-of-view (rFOV) acquisition, using parallel transmission and focused excitation, is a novel DWI approach that reduces distortions and improves images quality. This article presents images from both standard and rFOV DWI acquisitions in 2 prostate cancer patients with hip implants, showing the effect of rFOV DWI for improving tumor localization...
March 18, 2017: Current Problems in Diagnostic Radiology
https://www.readbyqxmd.com/read/28474393/dynamic-1-h-imaging-of-hyperpolarized-1-13-c-lactate-in-vivo-using-a-reverse-inept-experiment
#11
Jiazheng Wang, Felix Kreis, Alan J Wright, Richard L Hesketh, Malcolm H Levitt, Kevin M Brindle
PURPOSE: Dynamic magnetic resonance spectroscopic imaging of hyperpolarized (13) C-labeled cell substrates has enabled the investigation of tissue metabolism in vivo. Currently observation of these hyperpolarized substrates is limited mainly to (13) C detection. We describe here an imaging pulse sequence that enables proton observation by using polarization transfer from the hyperpolarized (13) C nucleus to spin-coupled protons. METHODS: The pulse sequence transfers (13) C hyperpolarization to (1) H using a modified reverse insensitive nuclei enhanced by polarization transfer (INEPT) sequence that acquires a fully refocused echo...
May 5, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28471524/non-gaussian-diffusion-evaluation-of-the-human-kidney-by-pad%C3%A3-exponent-model
#12
Alexandra Ljimani, Rotem S Lanzman, Anja Müller-Lutz, Gerald Antoch, Hans-Jörg Wittsack
PURPOSE: To evaluate the feasibility of renal diffusion quantification using the Padé exponent model (PEM) in healthy subjects. MATERIALS AND METHODS: Diffusion measurements were completed in 10 healthy subjects (mean age, 32.4 ± 8.9 years) on a 3T MRI scanner (Magnetom Trio, Siemens AG, Germany). A respiratory-triggered echo planar imaging sequence (15 slices with 6 mm thickness; 16 b-values [0-750 s/mm(2) ]; three diffusion directions; field of view: 400 × 375 mm; Matrix 192 × 192; repetition time/echo time: 3000/74 ms) was acquired in the coronal direction...
May 4, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28470915/comparison-of-fast-acquisition-strategies-in-whole-heart-four-dimensional-flow-cardiac-mr-two-center-1-5-tesla-phantom-and-in-vivo-validation-study
#13
Pankaj Garg, Jos J M Westenberg, Pieter J van den Boogaard, Peter P Swoboda, Rahoz Aziz, James R J Foley, Graham J Fent, F G J Tyl, L Coratella, Mohammed S M ElBaz, R J van der Geest, David M Higgins, John P Greenwood, Sven Plein
PURPOSE: To validate three widely-used acceleration methods in four-dimensional (4D) flow cardiac MR; segmented 4D-spoiled-gradient-echo (4D-SPGR), 4D-echo-planar-imaging (4D-EPI), and 4D-k-t Broad-use Linear Acquisition Speed-up Technique (4D-k-t BLAST). MATERIALS AND METHODS: Acceleration methods were investigated in static/pulsatile phantoms and 25 volunteers on 1.5 Tesla MR systems. In phantoms, flow was quantified by 2D phase-contrast (PC), the three 4D flow methods and the time-beaker flow measurements...
May 4, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28458603/assessment-of-cervical-cancer-with-a-parameter-free-intravoxel-incoherent-motion-imaging-algorithm
#14
Anton S Becker, Jose A Perucho, Moritz C Wurnig, Andreas Boss, Soleen Ghafoor, Pek-Lan Khong, Elaine Y P Lee
OBJECTIVE: To evaluate the feasibility of a parameter-free intravoxel incoherent motion (IVIM) approach in cervical cancer, to assess the optimal b-value threshold, and to preliminarily examine differences in the derived perfusion and diffusion parameters for different histological cancer types. MATERIALS AND METHODS: After Institutional Review Board approval, 19 female patients (mean age, 54 years; age range, 37-78 years) gave consent and were enrolled in this prospective magnetic resonance imaging study...
May 2017: Korean Journal of Radiology: Official Journal of the Korean Radiological Society
https://www.readbyqxmd.com/read/28446645/hypothalamus-as-a-mediator-of-chronic-migraine-evidence-from-high-resolution-fmri
#15
Laura H Schulte, Angie Allers, Arne May
OBJECTIVE: To identify pathophysiologic mechanisms of migraine chronification using a recently standardized protocol for high-resolution brainstem imaging of trigeminal nociceptive stimulation. METHODS: Eighteen episodic migraineurs (EMs), 17 chronic migraineurs (CMs), and 19 healthy controls (HCs) underwent painful ammonia stimulation of the left nostril in a 3T MRI scanner. Functional images were acquired with a brainstem-optimized protocol for high-resolution echo-planar imaging...
April 26, 2017: Neurology
https://www.readbyqxmd.com/read/28438709/characterization-of-high-resolution-gradient-echo-and-spin-echo-epi-for-fmri-in-the-human-visual-cortex-at-7t
#16
Catarina Rua, Mauro Costagli, Mark R Symms, Laura Biagi, Graziella Donatelli, Mirco Cosottini, Alberto Del Guerra, Michela Tosetti
The increased signal-to-noise ratio (SNR) offered by functional Magnetic Resonance Imaging (fMRI) at 7T allows the acquisition of functional data at sub-millimetric spatial resolutions. However, simply reducing partial volume effects is not sufficient to precisely localize task-induced activation due to the indirect mechanisms that relate brain function and the changes in the measured signal. In this work T2* and T2 weighted Echo Planar Imaging (EPI) schemes based on Gradient Recalled Echo (GRE) and Spin Echo (SE) were evaluated in terms of temporal SNR, percent signal change, contrast to noise ratio (CNR), activation volume, and sensitivity and specificity to gray matter...
April 22, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28438298/intravoxel-incoherent-motion-magnetic-resonance-imaging-in-head-and-neck-cancer-a-systematic-review-of-the-diagnostic-and-prognostic-value
#17
REVIEW
Daniel P Noij, Roland M Martens, J Tim Marcus, Remco de Bree, C René Leemans, Jonas A Castelijns, Marcus C de Jong, Pim de Graaf
Intravoxel incoherent motion (IVIM) imaging is increasingly applied in the assessment of head and neck cancer (HNC). Our purpose was to determine the diagnostic and prognostic performance of IVIM in HNC by performing a critical review of the literature. Pubmed and EMBASE were searched until May 2016. Study and patients characteristics, imaging protocol and diagnostic or prognostic outcomes were extracted by 2 independent reviewers. The studied IVIM parameters were diffusion coefficient (D), pseudodiffusion coefficient (D∗), and perfusion fraction (f)...
May 2017: Oral Oncology
https://www.readbyqxmd.com/read/28432796/an-acetone-based-phantom-for-quantitative-diffusion-mri
#18
Xiaoke Wang, Scott B Reeder, Diego Hernando
PURPOSE: To propose and evaluate an acetone-D2 O phantom that has an extended range of apparent diffusion coefficient (ADC) for quantitative diffusion magnetic resonance imaging (MRI), as well as to compare its properties to previously described water-based phantoms. MATERIALS AND METHODS: The proposed acetone-D2 O, and previously described sucrose water solution and polyvinylpyrrolidone (PVP) water solution phantoms, were constructed in a number of concentrations between 0% and 50%...
April 22, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28430583/non-invasive-prediction-of-the-tumor-growth-rate-using-advanced-diffusion-models-in-head-and-neck-squamous-cell-carcinoma-patients
#19
Noriyuki Fujima, Tomohiro Sakashita, Akihiro Homma, Taisuke Harada, Yukie Shimizu, Khin Khin Tha, Kohsuke Kudo, Hiroki Shirato
We assessed parameters of advanced diffusion weighted imaging (DWI) models for the prediction of the tumor growth rate in 55 head and neck squamous cell carcinoma (HNSCC) patients. The DWI acquisition used single-shot spin-echo echo-planar imaging with 12 b-values (0-2000). We calculated 14 DWI parameters using mono-exponential, bi-exponential, tri-exponential, stretched exponential and diffusion kurtosis imaging models. We directly measured the tumor growth rate from two sets of different-date imaging data...
May 16, 2017: Oncotarget
https://www.readbyqxmd.com/read/28424572/functional-sensitivity-of-2d-simultaneous-multi-slice-echo-planar-imaging-effects-of-acceleration-on-g-factor-and-physiological-noise
#20
Nick Todd, Oliver Josephs, Peter Zeidman, Guillaume Flandin, Steen Moeller, Nikolaus Weiskopf
Accelerated data acquisition with simultaneous multi-slice (SMS) imaging for functional MRI studies leads to interacting and opposing effects that influence the sensitivity to blood oxygen level-dependent (BOLD) signal changes. Image signal to noise ratio (SNR) is decreased with higher SMS acceleration factors and shorter repetition times (TR) due to g-factor noise penalties and saturation of longitudinal magnetization. However, the lower image SNR is counteracted by greater statistical power from more samples per unit time and a higher temporal Nyquist frequency that allows for better removal of spurious non-BOLD high frequency signal content...
2017: Frontiers in Neuroscience
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