Quantification of the effect of water exchange in dynamic contrast MRI perfusion measurements in the brain and heart.

abstract：PURPOSE:Balanced steady state free precession (bSSFP) imaging suffers from off-resonance artifacts such as signal modulation and banding. Solutions for removal of bSSFP off-resonance dependence are described and compared, and an optimal solution is proposed. THEORY AND METHODS:An Algebraic Solution (AS) that complemen...

journal_title：Magnetic resonance in medicine

authors： Hoff MN,Andre JB,Xiang QS

更新日期：2017-02-01 00:00:00

abstract：:Noise in the composite magnitude signal from multiple-coil systems is usually assumed to follow a noncentral χ distribution when sum of squares is used to combine images sensed at different coils. However, this is true only if the variance of noise is the same for all coils, and no correlation exists between them. We ...

journal_title：Magnetic resonance in medicine

authors： Aja-Fernández S,Tristán-Vega A

更新日期：2012-02-01 00:00:00

abstract：:The image intensity in magnetic resonance magnitude images in the presence of noise is shown to be governed by a Rician distribution. Low signal intensities (SNR < 2) are therefore biased due to the noise. It is shown how the underlying noise can be estimated from the images and a simple correction scheme is provided ...

journal_title：Magnetic resonance in medicine

authors： Gudbjartsson H,Patz S

更新日期：1995-12-01 00:00:00

abstract：:The relaxation of (1)H nuclei due to their interaction with quadrupolar (14)N nuclei in gel structures is measured using fast field-cycling NMR. This phenomenon called quadrupolar dips has been reported in different (1)H-(14)N bond-rich species. In this study, we have studied quadrupolar dips in fibrin, an insoluble p...

journal_title：Magnetic resonance in medicine

authors： Broche LM,Ismail SR,Booth NA,Lurie DJ

更新日期：2012-05-01 00:00:00

abstract：PURPOSE:The aim of this study was to develop a technique for rapid collection of chemical exchange saturation transfer images with the saturation varied to modulate signal loss transfer and enhance contrast. METHODS:Multi-echo Length and Offset VARied Saturation (MeLOVARS) divides the saturation pulse of length Tsat i...

journal_title：Magnetic resonance in medicine

authors： Song X,Xu J,Xia S,Yadav NN,Lal B,Laterra J,Bulte JW,van Zijl PC,McMahon MT

更新日期：2015-02-01 00:00:00

abstract：PURPOSE:To evaluate convex gradient optimization (CVX) for increased spatiotemporal resolution and improved accuracy for phase-contrast MRI (PC-MRI). METHODS:A conventional flow-compensated and flow-encoded (FCFE) PC-MRI sequence was compared with a CVX PC-MRI sequence using numerical simulations, flow phantom experim...

journal_title：Magnetic resonance in medicine

authors： Middione MJ,Wu HH,Ennis DB

更新日期：2014-12-01 00:00:00

abstract：PURPOSE:To compare the performance of an 8-channel surface coil/clamshell transmitter and 32-channel head array coil/birdcage transmitter for hyperpolarized 13 C brain metabolic imaging. METHODS:To determine the field homogeneity of the radiofrequency transmitters, B1 + mapping was performed on an ethylene glycol head...

journal_title：Magnetic resonance in medicine

authors： Autry AW,Gordon JW,Carvajal L,Mareyam A,Chen HY,Park I,Mammoli D,Vareth M,Chang SM,Wald LL,Xu D,Vigneron DB,Nelson SJ,Li Y

更新日期：2019-08-01 00:00:00

abstract：:Some of the factors involved in the choice of field strength for NMR imaging are examined. The influences of relaxation times and chemical shift upon image quality and signal-to-noise ratio are highlighted, and power deposition is introduced as a significant factor which may limit the flexibility and information avail...

journal_title：Magnetic resonance in medicine

authors： Hoult DI,Chen CN,Sank VJ

更新日期：1986-10-01 00:00:00

abstract：:The purpose of the present study was to examine whether single human carcinoma cells labeled with iron oxide nanoparticles could be detected by magnetic resonance (MR) imaging on a clinical 3-T scanner using a surface coil only. WiDr human colon carcinoma cells were loaded with two kinds of iron oxide nanoparticles di...

journal_title：Magnetic resonance in medicine

authors： Pinkernelle J,Teichgräber U,Neumann F,Lehmkuhl L,Ricke J,Scholz R,Jordan A,Bruhn H

更新日期：2005-05-01 00:00:00

abstract：:Using NMR spectroscopy, we studied purified, human T lymphocytes in a serum-free medium. Purified cells were entrapped inside agarose beads and induced to proliferate by the mitogens phorbol-12-myristate-13-acetate and ionomycin. T lymphocytes in standard culture and inside agarose beads exhibit comparable viability, ...

journal_title：Magnetic resonance in medicine

authors： Bental M,Deutsch C

更新日期：1993-03-01 00:00:00

abstract：:Three-dimensional spatial-spectral radiofrequency pulses using a stack-of-spirals trajectory can achieve two-dimensional spatial localization and one-dimensional spectral selection simultaneously. These pulses are useful, for example, in reduced field-of-view applications that also require frequency specificity such a...

journal_title：Magnetic resonance in medicine

authors： Deng W,Stenger VA

更新日期：2010-03-01 00:00:00

abstract：:In vivo effective relaxation rates in normal rat liver were evaluated for four dextran coated iron oxide agents: monocrystalline iron oxide nanocolloid (MION) with a mean particle diameter of 3.9 nm, a polycrystalline agent (PION) with a larger mean diameter of 12 nm, and these two agents labeled with the asialofetuin...

journal_title：Magnetic resonance in medicine

authors： Mandeville JB,Moore J,Chesler DA,Garrido L,Weissleder R,Weisskoff RM

更新日期：1997-06-01 00:00:00

abstract：:A method is presented that improves the effectiveness of RF-spoiling whenever an image consists of the averaging of several identical single acquisitions. Using this method, it becomes possible to reduce the necessary moment of the spoiler gradient by a factor equal to the number of averages. The idea is to perform th...

journal_title：Magnetic resonance in medicine

authors： Leupold J,Hennig J

更新日期：2011-10-01 00:00:00

abstract：PURPOSE:To improve signal-to-noise ratio (SNR) for high-resolution spectroscopic imaging using a subspace-based technique known as SPectroscopic Imaging by exploiting spatiospectral CorrElation (SPICE). METHODS:The proposed method is based on a union-of-subspaces model of MRSI signals, which exploits the partial separ...

journal_title：Magnetic resonance in medicine

authors： Ma C,Lam F,Ning Q,Johnson CL,Liang ZP

更新日期：2017-02-01 00:00:00

abstract：:Double wave vector diffusion weighting uses gradients along two different directions between excitation and acquisition. It has been shown theoretically that for restricted diffusion the signal amplitude in such an experiment can depend on the angle between the two gradient vectors. The highest amplitude is obtained w...

journal_title：Magnetic resonance in medicine

authors： Koch MA,Finsterbusch J

更新日期：2008-07-01 00:00:00

abstract：PURPOSE:Establishing a high-resolution non-ECG-gated first-pass perfusion (FPP) cardiac MRI technique may improve accessibility and diagnostic capability of FPP imaging. We propose a non-ECG-gated FPP imaging technique using continuous magnetization-driven golden-angle radial acquisition. The main purpose of this preli...

journal_title：Magnetic resonance in medicine

authors： Sharif B,Dharmakumar R,Arsanjani R,Thomson L,Bairey Merz CN,Berman DS,Li D

更新日期：2014-12-01 00:00:00

abstract：:The prebolus technique allows one to quantify perfusion in the human heart with a low variability by means of MRI. In this study the prebolus technique was used to determine quantitative perfusion values in the human heart under adenosine stress and to measure the myocardial perfusion reserve (MPR). Twelve healthy vol...

journal_title：Magnetic resonance in medicine

authors： Ritter C,Brackertz A,Sandstede J,Beer M,Hahn D,Köstler H

更新日期：2006-10-01 00:00:00

abstract：:A technique for noninvasively quantifying the concentration of sodium ((23) Na) ions was applied to the study of ischemic stroke. (23) Na-magnetic resonance imaging techniques have shown considerable potential for measuring subtle changes in ischemic tissue, although studies to date have suffered primarily from poor s...

journal_title：Magnetic resonance in medicine

authors： Wetterling F,Gallagher L,Macrae IM,Junge S,Fagan AJ

更新日期：2012-03-01 00:00:00

abstract：:Unusually high image contrast in vivo magnetic resonance imaging of the brain becomes observable at high magnetic fields when the blood oxygenation level is lowered. The cause of the contrast has been attributed to a magnetic susceptibility effect induced by paramagnetic deoxyhemoglobin in red cells. When the cylinder...

journal_title：Magnetic resonance in medicine

authors： Ogawa S,Lee TM

更新日期：1990-10-01 00:00:00

abstract：PURPOSE:Measurement of venous oxygenation (Yv) is a critical step toward quantitative assessment of brain oxygen metabolism, a key index in many brain disorders. The present study aims to develop a noninvasive, rapid, and reproducible method to measure Yv in a vessel-specific manner. THEORY:The method, T2-Relaxation-U...

journal_title：Magnetic resonance in medicine

authors： Krishnamurthy LC,Liu P,Ge Y,Lu H

更新日期：2014-03-01 00:00:00

abstract：PURPOSE:Develop and test an analytic correction method to correct the signal intensity variation caused by the inhomogeneous reception profile of an eight-channel phased array for hyperpolarized (13) C imaging. THEORY AND METHODS:Fiducial markers visible in anatomical images were attached to the individual coils to pr...

journal_title：Magnetic resonance in medicine

authors： Dominguez-Viqueira W,Geraghty BJ,Lau JY,Robb FJ,Chen AP,Cunningham CH

更新日期：2016-02-01 00:00:00

abstract：PURPOSE:To demonstrate the feasibility of a novel, ellipse fitting approach, named PLANET, for simultaneous estimation of relaxation times T1 and T2 from a single 3D phase-cycled balanced steady-state free precession (bSSFP) sequence. METHODS:A method is presented in which the elliptical signal model is used to descri...

journal_title：Magnetic resonance in medicine

authors： Shcherbakova Y,van den Berg CAT,Moonen CTW,Bartels LW

更新日期：2018-02-01 00:00:00

abstract：:A proton NMR relaxation and pulsed field gradient self-diffusion study of water in fibrin gels, plasma, and blood clots has been performed with special emphasis on the effect of the sol-gel and shrinkage transitions. Deuteron NMR in fibrin gels was also studied to supplement the proton data. It is shown that a measure...

journal_title：Magnetic resonance in medicine

authors： Blinc A,Lahajnar G,Blinc R,Zidansek A,Sepe A

更新日期：1990-04-01 00:00:00

abstract：PURPOSE:Diffusion-weighted imaging (DWI) and 18 F-fluorodeoxyglucose-positron emission tomography (18 F-FDG-PET) independently correlate with malignancy in breast cancer, but the relationship between their structural and metabolic metrics is not completely understood. This study spatially correlates diffusion, perfusio...

journal_title：Magnetic resonance in medicine

authors： Ostenson J,Pujara AC,Mikheev A,Moy L,Kim SG,Melsaether AN,Jhaveri K,Adams S,Faul D,Glielmi C,Geppert C,Feiweier T,Jackson K,Cho GY,Boada FE,Sigmund EE

更新日期：2017-09-01 00:00:00

abstract：PURPOSE:To test octafluorocyclobutane (OFCB) as an inhalation contrast agent for fluorine-19 MRI of the lung, and to compare the image quality of OFCB scans with perfluoropropane (PFP) scans THEORY AND METHODS: After normalizing for the number of signal averages, a theoretical comparison between the OFCB signal-to-nois...

journal_title：Magnetic resonance in medicine

authors： Shepelytskyi Y,Li T,Grynko V,Newman C,Hane FT,Albert MS

更新日期：2021-02-01 00:00:00

abstract：:Cell death by apoptosis is critical in myocardial diseases, and noninvasive detection of early, reversible apoptosis might be useful clinically. Exogenous Annexin-V (ANX) protein binds membrane phosphatidylserine, which is externalized in early apoptosis. A molecular MRI probe was constructed with superparamagnetic ir...

journal_title：Magnetic resonance in medicine

authors： Dash R,Chung J,Chan T,Yamada M,Barral J,Nishimura D,Yang PC,Simpson PC

更新日期：2011-10-01 00:00:00

abstract：PURPOSE:Atherosclerotic carotid plaques can be quantified in vivo by MRI. However, the accuracy in segmentation and quantification of components such as the thin fibrous cap (FC) and lipid-rich necrotic core (LRNC) remains unknown due to the lack of a submillimeter scale ground truth. METHODS:A novel approach was take...

journal_title：Magnetic resonance in medicine

authors： Nieuwstadt HA,Geraedts TR,Truijman MT,Kooi ME,van der Lugt A,van der Steen AF,Wentzel JJ,Breeuwer M,Gijsen FJ

更新日期：2014-07-01 00:00:00

abstract：:A comparison between contrast and signal-to-noise ratio (SNR), as obtained by both maximum entropy (ME) and 2DFT reconstruction, is reported for NMR images. Our results show that in the ME elaboration the contrast and SNR are generally increased with respect to the 2DFT elaboration. The magnitude of such an increase d...

journal_title：Magnetic resonance in medicine

authors： De Simone BC,De Luca F,Maraviglia B

更新日期：1988-11-01 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：:Three-dimensional (3D) coronary imaging has the potential to overcome problems resulting from vessel tortuosity and to reduce partial volume effects. With these techniques, however, acquisition times are long and respiratory motion artifacts problematical. This work describes the development of a method that applies p...

journal_title：Magnetic resonance in medicine

authors： Jhooti P,Keegan J,Gatehouse PD,Collins S,Rowe A,Taylor AM,Firmin DN

更新日期：1999-03-01 00:00:00