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https://www.readbyqxmd.com/read/28099808/dynamics-in-a-room-temperature-ionic-liquid-from-the-cation-perspective-2d-ir-vibrational-echo-spectroscopy
#1
Steven A Yamada, Heather E Bailey, Amr Tamimi, Chunya Li, Michael D Fayer
The dynamics of the room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BmimNTf2) were investigated with two dimensional infrared (2D IR) vibrational echo spectroscopy and polarization selective pump-probe (PSPP) experiments. The CN stretch frequency of a modified Bmim+ cation (referred to hereafter as 2-SeCN-Bmim+), in which a SeCN moiety was substituted onto the C-2 position of the imidazolium ring, was used as a vibrational probe. A major result of the 2D IR experiments is the observation of a long timescale structural spectral diffusion component of 600 ps in addition to short and intermediate timescales similar to those measured for selenocyanate anion (SeCN‒) dissolved in BmimNTf2...
January 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28096733/diagnosis-of-nerve-root-compromise-of-the-lumbar-spine-evaluation-of-the-performance-of-three-dimensional-isotropic-t2-weighted-turbo-spin-echo-space-sequence-at-3t
#2
Jinkyeong Sung, Won-Hee Jee, Joon-Yong Jung, Jinhee Jang, Jin-Sung Kim, Young-Hoon Kim, Kee-Yong Ha
OBJECTIVE: To explore the performance of three-dimensional (3D) isotropic T2-weighted turbo spin-echo (TSE) sampling perfection with application optimized contrasts using different flip angle evolution (SPACE) sequence on a 3T system, for the evaluation of nerve root compromise by disc herniation or stenosis from central to extraforaminal location of the lumbar spine, when used alone or in combination with conventional two-dimensional (2D) TSE sequence. MATERIALS AND METHODS: Thirty-seven patients who had undergone 3T spine MRI including 2D and 3D sequences, and had subsequent spine surgery for nerve root compromise at a total of 39 nerve levels, were analyzed...
January 2017: Korean Journal of Radiology: Official Journal of the Korean Radiological Society
https://www.readbyqxmd.com/read/28092785/integrated-ssfp-for-functional-brain-mapping-at-7t-with-reduced-susceptibility-artifact
#3
Kaibao Sun, Rong Xue, Peng Zhang, Zhentao Zuo, Zhongwei Chen, Bo Wang, Thomas Martin, Yi Wang, Lin Chen, Sheng He, Danny J J Wang
Balanced steady-state free precession (bSSFP) offers an alternative and potentially important tool to the standard gradient-echo echo-planar imaging (GE-EPI) for functional MRI (fMRI). Both passband and transition band based bSSFP have been proposed for fMRI. The applications of these methods, however, are limited by banding artifacts due to the sensitivity of bSSFP signal to off-resonance effects. In this article, a unique case of the SSFP-FID sequence, termed integrated-SSFP or iSSFP, was proposed to overcome the obstacle by compressing the SSFP profile into the width of a single voxel...
December 30, 2016: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28090666/quantitative-ultrashort-echo-time-imaging-for-assessment-of-massive-iron-overload-at-1-5-and-3-tesla
#4
Axel J Krafft, Ralf B Loeffler, Ruitian Song, Aaryani Tipirneni-Sajja, M Beth McCarville, Matthew D Robson, Jane S Hankins, Claudia M Hillenbrand
PURPOSE: Hepatic iron content (HIC) quantification via transverse relaxation rate (R2*)-MRI using multi-gradient echo (mGRE) imaging is compromised toward high HIC or at higher fields due to the rapid signal decay. Our study aims at presenting an optimized 2D ultrashort echo time (UTE) sequence for R2* quantification to overcome these limitations. METHODS: Two-dimensional UTE imaging was realized via half-pulse excitation and radial center-out sampling. The sequence includes chemically selective saturation pulses to reduce streaking artifacts from subcutaneous fat, and spatial saturation (sSAT) bands to suppress out-of-slice signals...
January 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28089491/satellite-and-central-transitions-selective-1-h-27-al-d-hmqc-experiments-at-very-fast-mas-for-quadrupolar-couplings-determination
#5
Nghia Tuan Duong, Yusuke Nishiyama
Recent study has demonstrated the application of the proton-detected heteronuclear multi-quantum coherence (HMQC) at ultrafast Magic Angle Spinning (MAS) to probe quadrupolar nuclei including (14)N and (35)Cl. In addition, for half-integer quadrupolar nucleus like (35)Cl, the quadrupolar product can be calculated based on the shift difference between the center band of satellite transition (ST) and the central transition (CT) peaks. The applicability of this technique is further investigated on spin I=5/2, namely (27)Al nucleus, and kaolin is chosen as the testing sample...
January 4, 2017: Solid State Nuclear Magnetic Resonance
https://www.readbyqxmd.com/read/28079395/diagnostic-performance-of-wrist-magnetic-resonance-mr-arthrography-comparison-of-three-dimensional-isotropic-t1-weighted-fast-spin-echo-mr-arthrography-and-two-dimensional-mr-arthrography
#6
Eunsun Oh, Young Cheol Yoon, Min Jong Park
OBJECTIVES: To compare the diagnostic performance of wrist direct magnetic resonance arthrography (D-MRA) with 2D T1-weighted fast spin-echo (FSE) and 3D isotropic T1-weighted FSE sequences for detecting triangular fibrocartilage (TFC) central perforations and scapholunate ligament (SLL) and lunotriquetral ligament (LTL) tears. METHODS: Twenty-six patients who had undergone preoperative wrist D-MRA with 2D and 3D isotropic T1-weighted FSE sequences and subsequent arthroscopic surgeries were included...
January 12, 2017: British Journal of Radiology
https://www.readbyqxmd.com/read/28073429/relation-of-the-myocardial-contraction-fraction-as-calculated-from-m-mode-echocardiography-with-incident-heart-failure-atherosclerotic-cardiovascular-disease-and-mortality-results-from-the-cardiovascular-health-study
#7
Mathew S Maurer, William J H Koh, Traci M Bartz, Sirish Vullaganti, Eddy Barasch, Julius M Gardin, John S Gottdiener, Bruce M Psaty, Jorge R Kizer
We evaluated the association between 2-dimensional (2D) echocardiography (echo)-determined myocardial contraction fraction (MCF) and adverse cardiovascular outcomes including incident heart failure (HF), atherosclerotic cardiovascular disease (ASCVD), and mortality. The MCF, the ratio of left ventricular (LV) stroke volume (SV) to myocardial volume (MV), is a volumetric measure of myocardial shortening that can distinguish pathologic from physiological hypertrophy. Using 2D echo-guided M-mode data from the Cardiovascular Health Study, we calculated MCF in subjects with LV ejection fraction (EF) ≥55% and used Cox models to evaluate its association with incident HF, ASCVD, and all-cause mortality after adjusting for clinical and echo parameters...
December 18, 2016: American Journal of Cardiology
https://www.readbyqxmd.com/read/28070903/myocardial-deformation-in-pediatric-patients-with-mucopolysaccharidoses-a-two-dimensional-speckle-tracking-echocardiography-study
#8
Francesco Borgia, Enrica Pezzullo, Vincenzo Schiano Lomoriello, Regina Sorrentino, Francesco Lo Iudice, Sara Cocozza, Roberto Della Casa, Giancarlo Parenti, Pietro Strisciuglio, Bruno Trimarco, Maurizio Galderisi
BACKGROUND: Mucopolysaccharidoses (MPS) are inherited lysosomal storage disorders caused by deficiency of required glycosaminoglycans breakdown enzymes, inducing cardiac involvement. Little is known about myocardial deformation involvement in MPS. Our aim was to assess biventricular structure and function in asymptomatic children with MPS using standard echo Doppler and 2D speckle tracking (STE). METHODS: Fifteen MPS children (one type I, six type II, three type III A, one III B, three IV A, one VI), asymptomatic for cardiac symptoms, and 15 age and sex-matched healthy controls underwent echo Doppler and STE...
January 10, 2017: Echocardiography
https://www.readbyqxmd.com/read/28067519/phase-resolved-heterodyne-detected-transient-grating-enhances-the-capabilities-of-2d-ir-echo-spectroscopy
#9
Geun Young Jin, Yung Sam Kim
2D IR echo spectroscopy, with high sensitivity and femtosecond time resolution, enables us to understand structure and ultrafast dynamics of molecular systems. Application of this experimental technique on weakly absorbing samples, however, had been limited by the precise and unambiguous phase determination of the echo signals. In this study, we propose a new experimental scheme that significantly increases the phase stability of the involved IR pulses. We have demonstrated that the incorporation of phase-resolved heterodyne-detected transient grating (PR-HDTG) spectroscopy greatly enhances the capabilities of 2D IR spectroscopy...
January 9, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28065851/high-resolution-distortion-free-diffusion-imaging-using-hybrid-spin-warp-and-echo-planar-psf-encoding-approach
#10
Myung-Ho In, Oleg Posnansky, Oliver Speck
High-resolution diffusion-weighted imaging (DWI) has great potential to provide unique information about tissue microstructure in-vivo. Although single-shot echo-planar imaging (EPI) is a most popular tool for DWI, its application for high-resolution DWI is limited due to T2⁎ blurring and susceptibility- and eddy-current-induced geometric distortions, especially at ultra-high field (UHF) such as 7T. In this study, we adapt a hybrid spin-warp and echo-planar encoding strategy inspired by point spread function (PSF) mapping and optimize it for high-resolution and distortion-free diffusion imaging applications...
January 5, 2017: NeuroImage
https://www.readbyqxmd.com/read/28063447/accelerating-two-dimensional-nuclear-magnetic-resonance-correlation-spectroscopy-via-selective-coherence-transfer
#11
Qimiao Ye, Lin Chen, Wenqi Qiu, Liangjie Lin, Huijun Sun, Shuhui Cai, Zhiliang Wei, Zhong Chen
Nuclear magnetic resonance (NMR) spectroscopy serves as an important tool for both qualitative and quantitative analyses of various systems in chemistry, biology, and medicine. However, applications of one-dimensional (1)H NMR are often restrained by the presence of severe overlap among different resonances. The advent of two-dimensional (2D) (1)H NMR constitutes a promising alternative by extending the crowded resonances into a plane and thereby alleviating the spectral congestions. However, the enhanced ability in discriminating resonances is achieved at the cost of extended experimental duration due to necessity of various scans with progressive delays to construct the indirect dimension...
January 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28061002/closed-form-expressions-for-flip-angle-variation-that-maximize-total-signal-in-t1-weighted-rapid-gradient-echo-mri
#12
Matthias Drobnitzky, Uwe Klose
PURPOSE: Magnetization-prepared rapid gradient-echo (MPRAGE) sequences are commonly employed for T1-weighted structural brain imaging. Following a contrast preparation radiofrequency (RF) pulse the data acquisition proceeds under non-equilibrium conditions of the relaxing longitudinal magnetization. Variation of the flip angle can be used to maximize total available signal. Simulated annealing or greedy algorithms have so far been published to numerically solve this problem, with signal to noise ratios optimized for clinical imaging scenarios by adhering to a predefined shape of the signal evolution...
January 6, 2017: Medical Physics
https://www.readbyqxmd.com/read/28054208/is-2d-speckle-tracking-echocardiography-useful-for-detecting-and-monitoring-myocardial-dysfunction-in-adult-m-3243a-g-carriers-a-retrospective-pilot-study
#13
S Koene, J Timmermans, G Weijers, P de Laat, C L de Korte, J A M Smeitink, M C H Janssen, L Kapusta
OBJECTIVES: Cardiomyopathy is a common complication of mitochondrial disorders, associated with increased mortality. Two dimensional speckle tracking echocardiography (2DSTE) can be used to quantify myocardial deformation. Here, we aimed to determine the usefulness of 2DSTE in detecting and monitoring subtle changes in myocardial dysfunction in carriers of the 3243A>G mutation in mitochondrial DNA. METHODS: In this retrospective pilot study, 30 symptomatic and asymptomatic carriers of the mitochondrial 3243A>G mutation of whom two subsequent echocardiograms were available were included...
January 4, 2017: Journal of Inherited Metabolic Disease
https://www.readbyqxmd.com/read/28048467/su-g-jep2-08-image-guided-radiation-therapy-using-synthetic-cts-in-brain-cancer
#14
R G Price, J Kim, W Zheng, I J Chetty, C Glide-Hurst
PURPOSE: Synthetic-CTs(synCTs) are essential for MR-only treatment planning. However, the performance of synCT for IGRT must be carefully assessed. This work evaluated the accuracy of synCT and synCT-generated DRRs and determined their performance for IGRT in brain cancer radiation therapy. METHODS: MR-SIM and CT-SIM images were acquired of a novel anthropomorphic phantom and a cohort of 12 patients. SynCTs were generated by combining an ultra-short echo time (UTE) sequence with other MRI datasets using voxel-based weighted summation...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048261/su-g-jep2-11-polymer-gels-as-3d-qa-devices-in-magnetic-resonance-guided-radiation-therapy
#15
Y Roed, M Kadbi, J Wang, L Pinsky, G Ibbott
PURPOSE: To demonstrate the potential of polymer gels to serve as 3D QA devices in MR-guided radiotherapy. METHODS: Custom-designed polymer gel dosimeters (MGS Research, Madison, CT) were centered on the penumbras of a radiation field, parallel to the magnetic field lines inside a 1.5 T MR scanner integrated with a 7 MV linac (MR-Linac). 15 Gy were delivered perpendicular to the magnetic field. Coronal MR images were acquired with a 2D balanced-Fast Field Echo (b-FFE) sequence in real-time during irradiation and with a 2D spin echo sequence at different times after irradiation...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048129/su-f-i-15-evaluation-of-a-new-mr-compatible-respiratory-motion-device-at-3t
#16
A Soliman, B Chugh, B Keller, A Sahgal, W Song
PURPOSE: Recent advances in MRI-guided radiotherapy has inspired the development of MRI-compatible motion devices that simulate patient periodic motion in the scanner, particularly respiratory motion. Most commercial devices rely on non MR-safe ferromagnetic stepper motors which are not practical for regular QA testing. This work evaluates the motion performance of a new fully MRI compatible respiratory motion device at 3T. METHODS: The QUASAR™ MRI-compatible respiratory motion phantom has been recently developed by Modus QA Inc...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047962/tu-h-206-03-characterizing-b1-inhomogeneities-in-dce-mri
#17
H Gach, N Mason
PURPOSE: Dynamic Contrast Enhanced (DCE) MRI is a valuable technique for measuring perfusion and permeability characteristics of tumors. Exogenous contrast concentrations are calculated based on changes in T1 measured using fast 3D gradient echo (FLASH) sequences. However, the slab selective pulses used in 3D MRI may result in B1 inhomogeneities across the volume of interest that can lead to errors in T1 and thus the estimated gadolinium concentration. We compared three FLASH DCE sequences (GRE, TWIST, and VIBE) to determine their signal homogeneity across slices and the accuracy in calculating T1 using acquisitions with variable flip angles...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047502/su-g-iep1-04-comparison-of-cerebral-blood-volume-estimated-by-dsc-and-dcemri
#18
M Aryal, Y Cao
PURPOSE: The cerebral blood volume (CBV) is commonly estimated from T2*/T2-weighted dynamic susceptibility contrast (DSC) MRI acquired by an EPI sequence. There are several challenges with DSC imaging, including geometric distortion, limited brain spatial coverage, and unreliable arterial input function (AIF) due to the partial volume effect. However, CBV can be estimated from T1-weighted dynamic contrast enhanced (DCE) MRI. This study aimed to examine whether CBV estimated from DCE-MRI is comparable to one from DSC-MRI...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047055/su-g-jep2-06-dosimetric-and-workflow-evaluation-of-first-commercial-synthetic-ct-software-for-clinical-use-in-pelvis
#19
N Tyagi, J Zhang, L Happersett, M Kadbi, J Mechalakos, J Deasy, M Hunt
PURPOSE: evaluate a commercial synthetic CT (syn-CT) software for use in prostate radiotherapy METHODS: Twenty prostate patients underwent CT and MR simulation scans in treatment position on a 3T Philips scanner. The MR protocol consisted of a T2w turbo spin-echo for soft tissue contrast, a 2D balanced-fast field echo (b-FFE) for fiducial identification, a dual-echo 3D FFE B0 map for distortion analysis and a 3D mDIXON FFE sequence to generate syn-CT. Two echoes are acquired during mDIXON scan, allowing water, fat, and in-phase images to be derived using the frequency shift of the fat and water protons...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28046948/su-f-j-159-influence-of-the-elevated-posterior-position-by-using-the-customized-vacuum-bag-on-the-abdominal-mr-image-quality-a-quantitative-phantom-study
#20
O Wong, J Yuan, M Law, A Ding, S Yu, K Cheung
PURPOSE: Signal-to-noise ratio(SNR) of MR abdominal imaging in diagnostic radiology is maximized by minimizing the coil-to-patient distance. However, for radiotherapy applications, customized vacuum-bag is needed for abdominal immobilization at the cost of the increasing distance to the posterior spine coil. This sub-optimized coil setting for RT applications may compromise image quality, such as SNR and homogeneity, thus potentially affect tissue delineation. In this study, we quantitatively evaluate the effect of the vertical position change on SNR and image quality change using an ACR MR phantom...
June 2016: Medical Physics
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