Passive radiofrequency shimming in the thighs at 3 Tesla using high permittivity materials and body coil receive uniformity correction.

abstract：:In vivo or ex vivo electron paramagnetic resonance imaging (EPRI) is a powerful technique for determining the spatial distribution of free radicals and other paramagnetic species in living organs and tissues. However, applications of EPRI have been limited by long projection acquisition times and the consequent fact t...

journal_title：Magnetic resonance in medicine

authors： Chen Z,Reyes LA,Johnson DH,Velayutham M,Yang C,Samouilov A,Zweier JL

更新日期：2013-02-01 00:00:00

abstract：PURPOSE:To exploit the improved comparability and hardware independency of quantitative MRI, databases of MR physical parameters in healthy tissue are required, to which tissue properties of patients can be compared. In this work, normative values for longitudinal and transverse relaxation times in the brain were estab...

journal_title：Magnetic resonance in medicine

authors： Piredda GF,Hilbert T,Granziera C,Bonnier G,Meuli R,Molinari F,Thiran JP,Kober T

更新日期：2020-01-01 00:00:00

abstract：:Uncertainty regarding the intracellular/extracellular distribution of inorganic phosphate (P(i)) in tumors has raised concerns that pH calculated from the tumor P(i) chemical shift may not accurately represent the intracellular pH (pHin). This issue was addressed in subcutaneously transplanted murine radiation induced...

journal_title：Magnetic resonance in medicine

authors： Soto GE,Zhu Z,Evelhoch JL,Ackerman JJ

更新日期：1996-11-01 00:00:00

abstract：:Kinetic analysis with mathematical models has become increasingly important to quantify physiological parameters in computed tomography (CT), positron emission tomography (PET), and dynamic contrast-enhanced MRI (DCE-MRI). The modified Kety/Tofts model and the graphical (Patlak) model have been widely applied to DCE-M...

journal_title：Magnetic resonance in medicine

authors： Chen H,Li F,Zhao X,Yuan C,Rutt B,Kerwin WS

更新日期：2011-09-01 00:00:00

abstract：PURPOSE:Quantitative mapping of the native T1 of the heart using the modified look-locker inversion recovery (MOLLI) technique provides high quality diagnostic information without requiring contrast agents. Previous work has considered the effects of T2 relaxation on MOLLI T1 measurements, finding that the T1 measured ...

journal_title：Magnetic resonance in medicine

authors： Robson MD,Piechnik SK,Tunnicliffe EM,Neubauer S

更新日期：2013-09-01 00:00:00

abstract：:Advances in modern magnetic resonance imaging (MRI) pulse sequences have enabled clinically practical cortical bone imaging. Human cortical bone is known to contain a distribution of T(1) and T(2) components attributed to bound and pore water, although clinical imaging approaches have yet to discriminate bound from po...

journal_title：Magnetic resonance in medicine

authors： Horch RA,Gochberg DF,Nyman JS,Does MD

更新日期：2012-12-01 00:00:00

abstract：:In the pulsed arterial spin labeling (ASL) techniques EPISTAR, PICORE, and FAIR, subtraction of two images in which inflowing blood is first tagged and then not tagged yields a qualitative map of perfusion. An important reason this map is not quantitative is that there is a spatially varying delay in the transit of bl...

journal_title：Magnetic resonance in medicine

authors： Wong EC,Buxton RB,Frank LR

更新日期：1998-05-01 00:00:00

abstract：PURPOSE:Within multiple sclerosis (MS) lesions iron is present in chronically activated microglia. Thus, iron detection with MRI might provide a biomarker for chronic inflammation within lesions. Here, we examine contributions of iron and myelin to magnetic susceptibility of lesions on quantitative susceptibility mappi...

journal_title：Magnetic resonance in medicine

authors： Wisnieff C,Ramanan S,Olesik J,Gauthier S,Wang Y,Pitt D

更新日期：2015-08-01 00:00:00

abstract：:The preovulatory rat follicle reaches a diameter of 1 mm with no internal blood vessels. Nutrient supply to the enclosed oocyte depends solely on passive diffusion across the follicular wall and the follicular fluid. Spin-echo and stimulated-echo NMR microscopy experiments were applied here for studying modulations in...

journal_title：Magnetic resonance in medicine

authors： Tempel C,Schiffenbauer YS,Meir G,Neeman M

更新日期：1995-08-01 00:00:00

abstract：:The purpose of this study was the simulation and measurement of balanced steady-state free precession (bSSFP) slice profiles for a detailed analysis of the influence of off-resonance effects on slice profile shape and bSSFP signal intensity. Due to the frequency response function of the bSSFP sequence, measurements th...

journal_title：Magnetic resonance in medicine

authors： Staehle F,Leupold J,Hennig J,Markl M

更新日期：2008-05-01 00:00:00

abstract：:A novel radio-frequency (RF) pulse design algorithm is presented that generates fast slice-selective excitation pulses that mitigate B+1 inhomogeneity present in the human brain at high field. The method is provided an estimate of the B+1 field in an axial slice of the brain and then optimizes the placement of sinc-li...

journal_title：Magnetic resonance in medicine

authors： Zelinski AC,Wald LL,Setsompop K,Alagappan V,Gagoski BA,Goyal VK,Adalsteinsson E

更新日期：2008-06-01 00:00:00

abstract：:In the present work, diffusion-weighted (DW)-NMR spectroscopy of glutamate was performed during a (13)C-labeled glucose infusion in monkey brain (six experiments). It is shown that glutamate (13)C labeling occurs significantly faster at higher diffusion weightings-slightly for glutamate in position C4, and more marked...

journal_title：Magnetic resonance in medicine

authors： Valette J,Chaumeil M,Guillermier M,Bloch G,Hantraye P,Lebon V

更新日期：2008-08-01 00:00:00

abstract：PURPOSE:To introduce a multiplatform, Python language-based, development environment called graphical programming interface for prototyping MRI techniques. METHODS:The interface allows developers to interact with their scientific algorithm prototypes visually in an event-driven environment making tasks such as paramet...

journal_title：Magnetic resonance in medicine

authors： Zwart NR,Pipe JG

更新日期：2015-11-01 00:00:00

abstract：:Orientational anisotropy of T2 and T1 relaxation times, diffusion, and magnetization transfer has been investigated for six different tissues: tendon, cartilage, kidney, muscle, white matter, and optic nerve. Relaxation anisotropy was observed for tendon and cartilage, and diffusional anisotropy was measured in kidney...

journal_title：Magnetic resonance in medicine

authors： Henkelman RM,Stanisz GJ,Kim JK,Bronskill MJ

更新日期：1994-11-01 00:00:00

abstract：:The changes in the response of skeletal muscle to maximal dynamic exercise were investigated in going from a fasted state to a refed state by means of 31P NMR spectroscopy. It was found that in the fasted state, exercise-induced changes in Pi/PCr and in pH were both inhibited, in comparison with those in the refed sta...

journal_title：Magnetic resonance in medicine

authors： Lunt JA,Allen PS,Brauer M,Swinamer D,Treiber EO,Belcastro A,Eccles R,King EG

更新日期：1986-12-01 00:00:00

abstract：:Some of the important features of how pulsatile flow generates artifacts in three-dimensional magnetic resonance imaging are analyzed and demonstrated. Time variations in the magnetic resonance signal during the heart cycle lead to more complex patterns of artifacts in 3D imaging than in 2D imaging. The appearance and...

journal_title：Magnetic resonance in medicine

authors： Frank LR,Buxton RB,Kerber CW

更新日期：1993-09-01 00:00:00

abstract：:Of the various techniques employed to quantify temperature changes by MR, proton resonance frequency (PRF) shift-based phase-difference imaging (PDI) is the most accurate and widely used. However, PDI is associated with various artifacts. Motivated by these limitations, we developed a new method to monitor temperature...

journal_title：Magnetic resonance in medicine

authors： Paliwal V,El-Sharkawy AM,Du X,Yang X,Atalar E

更新日期：2004-10-01 00:00:00

abstract：:Consideration of spatially variable noise fields is becoming increasingly necessary in MRI given recent innovations in artifact identification and statistically driven image processing. Fast imaging methods enable study of difficult anatomical targets and improve image quality but also increase the spatial variability...

journal_title：Magnetic resonance in medicine

authors： Landman BA,Bazin PL,Smith SA,Prince JL

更新日期：2009-08-01 00:00:00

abstract：:A MultiEcho Segmented EPI with z-shimmed BAckground gradient Compensation (MESBAC) pulse sequence is proposed and validated for functional MRI (fMRI) study in regions suffering from severe susceptibility artifacts. This sequence provides an effective tradeoff between spatial and temporal resolution and reduces image d...

journal_title：Magnetic resonance in medicine

authors： Li Z,Wu G,Zhao X,Luo F,Li SJ

更新日期：2002-08-01 00:00:00

abstract：PURPOSE:The aim of the study was to investigate whether incorrectly compensated eddy currents are the source of persistent X-nuclear spectroscopy and imaging artifacts, as well as methods to correct this. METHODS:Pulse-acquire spectra were collected for 1 H and X-nuclei (23 Na or 31 P) using the minimum TR permitted o...

journal_title：Magnetic resonance in medicine

authors： McLean MA,Hinks RS,Kaggie JD,Woitek R,Riemer F,Graves MJ,McIntyre DJO,Gallagher FA,Schulte RF

更新日期：2020-12-04 00:00:00

abstract：:High-signal artifacts produced by cerebrospinal fluid (CSF) flow can adversely affect fluid-attenuated inversion recovery (FLAIR) imaging of the brain and spinal cord. This study explores the use of a nonslice-selective inversion pulse to eliminate CSF flow artifacts together with a technique called "K-space Reordered...

journal_title：Magnetic resonance in medicine

authors： Herlihy AH,Oatridge A,Curati WL,Puri BK,Bydder GM,Hajnal JV

更新日期：2001-08-01 00:00:00

abstract：:A 3D sequence for dynamic susceptibility imaging is proposed which combines echo-shifting principles (such as PRESTO), sensitivity encoding (SENSE), and partial-Fourier acquisition. The method uses a moderate SENSE factor of 2 and takes advantage of an alternating partial k-space acquisition in the "slow" phase encode...

journal_title：Magnetic resonance in medicine

authors： Klarhöfer M,Dilharreguy B,van Gelderen P,Moonen CT

更新日期：2003-10-01 00:00:00

abstract：:Optimal control theory has been applied in the past for the design of RF pulses for selective excitation. This was the outcome of having established the controllability of the MR spin system for the selective excitation problem. "Minimum distance" was the main formulation used for the solution. Because of their robust...

journal_title：Magnetic resonance in medicine

authors： Rosenfeld D,Zur Y

更新日期：1996-09-01 00:00:00

abstract：:A method for evaluating the sensitivity of MRI protocols to changes in an arbitrary number of tissue parameters over a broad range of parameter values is presented. This analysis is useful for choosing an optimal basis set of images for either a "survey" protocol or tissue segmentation algorithms. A survey protocol is...

journal_title：Magnetic resonance in medicine

authors： McVeigh ER,Henkelman RM,Bronskill MJ

更新日期：1990-02-01 00:00:00

abstract：PURPOSE:Anesthesia is necessary for most animal studies requiring invasive procedures. It is well documented that various types of anesthesia modulate a wide variety of important metabolic and functional processes in the body, and as such, represent a potential limitation in the study design. In the present study, we a...

journal_title：Magnetic resonance in medicine

authors： Qi H,Mariager CØ,Lindhardt J,Nielsen PM,Stødkilde-Jørgensen H,Laustsen C

更新日期：2018-11-01 00:00:00

abstract：PURPOSE:Fluorescence lifetime imaging microscopy (FLIM) of endogenous fluorescent metabolites permits the measurement of cellular metabolism in cell, tissue and animal models. In parallel, magnetic resonance spectroscopy (MRS) of dynamic nuclear (hyper)polarized (DNP) 13 C-pyruvate enables measurement of metabolism at ...

journal_title：Magnetic resonance in medicine

authors： Cox BL,Erickson-Bhatt S,Szulczewski JM,Squirrell JM,Ludwig KD,Macdonald EB,Swader R,Ponik SM,Eliceiri KW,Fain SB

更新日期：2019-05-01 00:00:00

abstract：PURPOSE:A purely experimental method for MRI-based transfer function (TF) determination is presented. A TF characterizes the potential for radiofrequency heating of a linear implant by relating the incident tangential electric field to a scattered electric field at its tip. We utilize the previously introduced transfer...

journal_title：Magnetic resonance in medicine

authors： Tokaya JP,Raaijmakers AJE,Luijten PR,Sbrizzi A,van den Berg CAT

更新日期：2020-03-01 00:00:00

abstract：PURPOSE:MR-based quantification of liver magnetic susceptibility may enable field strength-independent measurement of liver iron concentration (LIC). However, susceptibility quantification is challenging, due to nonlocal effects of susceptibility on the B0 field. The purpose of this work is to demonstrate feasibility o...

journal_title：Magnetic resonance in medicine

authors： Hernando D,Cook RJ,Diamond C,Reeder SB

更新日期：2013-09-01 00:00:00

abstract：PURPOSE:To develop a fully automated trajectory and gradient waveform design for the non-Cartesian shells acquisition, and to develop a magnetization-prepared (MP) shells acquisition to achieve an efficient three-dimensional acquisition with improved gray-to-white brain matter contrast. METHODS:After reviewing the she...

journal_title：Magnetic resonance in medicine

authors： Shu Y,Tao S,Trzasko JD,Huston J 3rd,Weavers PT,Bernstein MA

更新日期：2018-04-01 00:00:00

abstract：:Certain kinds of artifacts have been reported when projection reconstruction (PR) techniques are used in magnetic resonance imaging (MRI). These will occur if the spacing between samples in k-space is too large. It has been suggested that PR requires finer k-space sampling than does two-dimensional Fourier reconstruct...

journal_title：Magnetic resonance in medicine

authors： Joseph PM

更新日期：1998-09-01 00:00:00