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 potential of quantitative parameter images of the relaxation times T1 and T2, the proton density rho and the apparent diffusion coefficient (ADC) to characterize three different experimental rat brain tumors (F98 glioma, RN6 Schwannoma, and E376 neuroblastoma) was studied. All parameter values, as determined in hi...

journal_title：Magnetic resonance in medicine

authors： Eis M,Els T,Hoehn-Berlage M

更新日期：1995-12-01 00:00:00

abstract：:Phase contrast flow velocity measurements were performed in six healthy volunteers and 30 patients with arteriosclerotic disease. The iliac arteries were investigated in 8 cases and the femoral arteries in 28 cases. In the first 24 patients, 16 evenly distributed data sets were acquired during one cardiac cycle. In th...

journal_title：Magnetic resonance in medicine

authors： Krug B,Kugel H,Harnischmacher U,Heindel W,Schmidt R,Krings F

更新日期：1995-11-01 00:00:00

abstract：:A computer simulation program capable of demonstrating various artifacts, such as image distortion caused by metallic implants in MR imaging, is presented. The structure of the program allows for the implementation of various imaging situations as long as spins only experience weak interaction, i.e., the Bloch equatio...

journal_title：Magnetic resonance in medicine

authors： Olsson MB,Wirestam R,Persson BR

更新日期：1995-10-01 00:00:00

abstract：:A new contrast preparation based on modified driven equilibrium Fourier transfer is introduced and evaluated for generation of T1-weighted images for assessment of the myocardial perfusion with contrast agent first-pass kinetics. The new preparation scheme produces T1 contrast with insensitivity to arrhythmias in pros...

journal_title：Magnetic resonance in medicine

authors： Tsekos NV,Zhang Y,Merkle H,Wilke N,Jerosch-Herold M,Stillman A,Uğurbil K

更新日期：1995-10-01 00:00:00

abstract：:A number of techniques that recently have been used for fast NMR-imaging are based on a hybrid sequence of echo planar imaging (EPI) and FLASH imaging: after each NMR excitation several k-space lines are measured. The complete k-space is covered by performance of several excitations. It has been observed that there is...

journal_title：Magnetic resonance in medicine

authors： Deichmann R,Adolf H,Nöth U,Kuchenbrod E,Schwarzbauer C,Haase A

更新日期：1995-09-01 00:00:00

abstract：:Sequential albumin-Gd-DTPA and Gd-DTPA dynamic enhancement studies were performed in an animal tumor model for the comparison of regional vascularity and permeability parameters measured by these two different sizes of contrast agents. The early albumin-Gd-DTPA enhancement arises from the vascular compartment, and the...

journal_title：Magnetic resonance in medicine

authors： Su MY,Najafi AA,Nalcioglu O

更新日期：1995-09-01 00:00:00

abstract：:A kinetic analysis of water signal intensity changes measured in human visual cortex by PRESS localized 1H spectroscopy at 500 ms resolution with light-emitting diode (LED) goggle stimulation was used to determine vascular transit times for transitions between rest and activation. Monoexponential curve fitting was use...

journal_title：Magnetic resonance in medicine

authors： Detre JA,Wang Z,Stecker MM,Zimmerman RA

更新日期：1995-09-01 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 authors introduce several sets of time-efficient gradient waveforms for applying isotropic diffusion weighting in NMR experiments. This creates signal attenuation that depends on the trace of the diffusion tensor and is therefore rotationally invariant. Numerical methods for the calculation of such gradient sets a...

journal_title：Magnetic resonance in medicine

authors： Wong EC,Cox RW,Song AW

更新日期：1995-08-01 00:00:00

abstract：:A method is described for the correction of geometric distortions occurring in echo planar images. The geometric distortions are caused in large part by static magnetic field inhomogeneities, leading to pixel shifts, particularly in the phase encode direction. By characterizing the field inhomogeneities from a field m...

journal_title：Magnetic resonance in medicine

authors： Jezzard P,Balaban RS

更新日期：1995-07-01 00:00:00

abstract：:A double-echo two-excitation pulse sequence encoding fat and water signals for a phase-sensitive three-point Dixon-type analysis (DE-3PD) was developed and implemented on a 1.5 T MR imager. Data processing was performed using a previously developed two-dimensional (2D) region-growing algorithm, adapted to use double-e...

journal_title：Magnetic resonance in medicine

authors： Szumowski J,Coshow W,Li F,Coombs B,Quinn SF

更新日期：1995-07-01 00:00:00

abstract：:Longitudinal water proton relaxation rates of methemoglobin solutions show a strong dependence on temperature and pH. The increase of the relaxation rates with temperature is associated with shortened exchange lifetime of the coordinated water molecule. An accurate measurement of the relaxation rate of methemoglobin s...

journal_title：Magnetic resonance in medicine

authors： Aime S,Fasano M,Paoletti S,Arnelli A,Ascenzi P

更新日期：1995-06-01 00:00:00

abstract：:The relative distributions of N-acetylaspartate (NAA) + N-acetylaspartylglutamate (NAAG), creatine + phosphocreatine (Cr/PCr), and choline (Cho) in the gray and white matter of human brain were determined by utilizing proton magnetic resonance spectroscopic imaging (SI). The SI data was processed using an automated sp...

journal_title：Magnetic resonance in medicine

authors： Doyle TJ,Bedell BJ,Narayana PA

更新日期：1995-06-01 00:00:00

abstract：:The somatotopical organization of the human somatosensory cortex was analyzed with echo-planar imaging at 1.5 Tesla, utilizing deoxyhemoglobin as an endogenous contrast medium. Scrubbing stimulation at a frequency of 3 Hz was applied to one of three cutaneous areas: toes, fingertips, and tongue tip. Parasagittal echo-...

journal_title：Magnetic resonance in medicine

authors： Sakai K,Watanabe E,Onodera Y,Itagaki H,Yamamoto E,Koizumi H,Miyashita Y

更新日期：1995-05-01 00:00:00

abstract：:A common type of motion present in clinical magnetic resonance imaging examinations is rotational motion, such as that due to voluntary motion during head examinations. The correction scheme presented in this work offers a method for eliminating the effects of rotations within the imaging plane. Integral to the implem...

journal_title：Magnetic resonance in medicine

authors： Korin HW,Felmlee JP,Riederer SJ,Ehman RL

更新日期：1995-05-01 00:00:00

abstract：:We used deuterium magnetic resonance imaging (2H MRI) to visualize water movement in the rabbit eye. Dynamic 2H MRI was obtained every 3.5 min at 2 tesla by FLASH pulse sequence (TR, 300 ms; TE, 10 ms; alpha = 90 degrees) with a slice thickness of 10 mm using a surface coil (4 cm in diameter). After topical administra...

journal_title：Magnetic resonance in medicine

authors： Obata T,Ikehira H,Koga M,Yoshida K,Kimura F,Tateno Y

更新日期：1995-04-01 00:00:00

abstract：:In spin echo imaging, magnetization is assigned to a location defined by its frequency of rotation. In the presence of a static magnetic field inhomogeneity, however, this location does not correspond to the true location of the magnetization. This paper describes a magnetic resonance imaging technique called phase co...

journal_title：Magnetic resonance in medicine

authors： Kim JK,Plewes DB,Henkelman RM

更新日期：1995-04-01 00:00:00

abstract：:Nuclear Overhauser effect (NOE) enhancements and relaxation times of 31P metabolites in human calf were measured in 12 volunteers (4 men and 8 women) at 1.5 T using a dual tuned four-ring birdcage. The NOE enhancements of inorganic phosphate (Pi), phosphocreatine (PCr), gamma-, alpha-, and beta-nucleoside triphosphate...

journal_title：Magnetic resonance in medicine

authors： Brown TR,Stoyanova R,Greenberg T,Srinivasan R,Murphy-Boesch J

更新日期：1995-03-01 00:00:00

abstract：:Experiments were performed to determine whether changes in T2*-weighted MR images during and after hyperoxia differentiate tumors from normal tissue. Mammary adenocarcinomas implanted in the right hind limbs of rats were studied. Gradient echo images were obtained at 2 Tesla with an evolution time of 20 ms and a recyc...

journal_title：Magnetic resonance in medicine

authors： Kuperman VYu,River JN,Lewis MZ,Lubich LM,Karczmar GS

更新日期：1995-03-01 00:00:00

abstract：:Magnetic resonance images of the lungs of a guinea pig have been produced using hyperpolarized helium as the source of the MR signal. The resulting images are not yet sufficiently optimized to reveal fine structural detail within the lung, but the spectacular signal from this normally signal-deficient organ system off...

journal_title：Magnetic resonance in medicine

authors： Middleton H,Black RD,Saam B,Cates GD,Cofer GP,Guenther R,Happer W,Hedlund LW,Johnson GA,Juvan K

更新日期：1995-02-01 00:00:00

abstract：:Dynamic MRI tracking of rat T-cells in vivo is performed in rat testicles after labeling isolated rat T-cells in vitro with superparamagnetic dextran-coated iron-oxide particles, BMS180549. Tissue inflammation induced by the local injection of the calcium ionophore, A23187, is used to attract labeled T-cells. Gradient...

journal_title：Magnetic resonance in medicine

authors： Yeh TC,Zhang W,Ildstad ST,Ho C

更新日期：1995-02-01 00:00:00

abstract：:To achieve optimal image quality and highest spatial resolution for inner ear imaging with a 3D gradient echo sequence, it is necessary to minimize susceptibility dephasing effects by using very short TE. Fractional RF pulses and echoes can yield short TE for moderate spatial resolution; however, for voxel size of les...

journal_title：Magnetic resonance in medicine

authors： Ying K,Schmalbrock P,Clymer B

更新日期：1995-01-01 00:00:00

abstract：:A novel ultra-rapid gradient echo (URGE) NMR imaging technique is introduced, which is capable of continuous high resolution 3D scanning while neither subject to fast gradient switching nor excessive RF power deposition. Sampling free induction decays instead of creating spin echoes enables maintaining a workable stea...

journal_title：Magnetic resonance in medicine

authors： Heid O,Deimling M,Huk WJ

更新日期：1995-01-01 00:00:00

abstract：:With the advent of breath-hold MR cardiac imaging techniques, the minimization of TR and TE for oblique planes has become a critical issue. The slew rates and maximum currents of gradient amplifiers limit the minimum possible TR and TE by adding dead-periods to the pulse sequences. We propose a method of designing gra...

journal_title：Magnetic resonance in medicine

authors： Atalar E,McVeigh ER

更新日期：1994-12-01 00:00:00

abstract：:In this high resolution magnetic resonance spectroscopic study of experimental allergic encephalomyelitis (EAE) and Semliki Forest virus (SFV) infection of the Biozzi AB/H mouse, marked increases in the initially low levels of N-trimethyl compounds in the spinal cord were observed during probable demyelinating episode...

journal_title：Magnetic resonance in medicine

authors： Preece NE,Amor S,Baker D,Gadian DG,O'Neill JK,Urenjak J

更新日期：1994-12-01 00:00:00

abstract：:Two single-shot volume imaging techniques are described. The first, single-echo echo-volume imaging, is essentially the echo-volume imaging (EVI) sequence suggested by Mansfield (J. Phys. C. 10, L55 (1977)). The second is a multi-spin-echo approach in which one plane of k-space is collected during each spin echo. In b...

journal_title：Magnetic resonance in medicine

authors： Song AW,Wong EC,Hyde JS

更新日期：1994-11-01 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 MMQ cell line is a unique prolactin-secreting rat pituitary cell line. MMQ cells entrapped in agarose gel threads are metabolically active, as determined by the uptake and phosphorylation of creatine and the maintenance of high energy phosphates for over 15 h. Forskolin activates the catalytic subunit of adenylyl ...

journal_title：Magnetic resonance in medicine

authors： Goger MJ,Login IS,Fernandez EJ,Grisham CM

更新日期：1994-11-01 00:00:00

abstract：:We have developed a method for measuring the electrocardiogram (ECG) continuously during MR examinations. In contrast to ECG acquisition by wires, our new method is to amplify and convert the ECG into an optical signal directly above the patient's heart. The optical signal is transmitted out of the magnet bore by opti...

journal_title：Magnetic resonance in medicine

authors： Felblinger J,Lehmann C,Boesch C

更新日期：1994-10-01 00:00:00

abstract：:Magnetization transfer experiments using an off-resonance irradiation technique were performed on bovine serum albumin solutions by varying the irradiation frequency and the concentration. A transition of the magnetization transfer spectrum from Lorentzian to Gaussian line shape was observed around the critical concen...

journal_title：Magnetic resonance in medicine

authors： Iino M

更新日期：1994-10-01 00:00:00

abstract：:For diffusion-weighted magnetic resonance imaging and under circumstances where patient movement can be modeled as rigid body motion, it is shown both theoretically and experimentally that translations and rotations produce phase errors which are zero- and first-order, respectively, in position. While a navigator echo...

journal_title：Magnetic resonance in medicine

authors： Anderson AW,Gore JC

更新日期：1994-09-01 00:00:00

abstract：:Magnetization transfer imaging (MT) and localized proton spectroscopy (1H-MRS) were utilized in the evaluation of lesions (high signal abnormalities on T2-weighted images) and normal-appearing white matter (NAWM) in multiple sclerosis (MS). Eleven patients with a clinical diagnosis of MS were independently evaluated w...

journal_title：Magnetic resonance in medicine

authors： Hiehle JF Jr,Lenkinski RE,Grossman RI,Dousset V,Ramer KN,Schnall MD,Cohen JA,Gonzalez-Scarano F

更新日期：1994-09-01 00:00:00

abstract：:A method for the acquisition of localized 2D shift-correlated spectra, based on the combination of the stimulated-echo volume-selection and gradient-enhanced COSY experiments, is described. The sequence can be modified to perform a number of localized experiments including HOHAHA and DQF-COSY. The method is demonstrat...

journal_title：Magnetic resonance in medicine

authors： Brereton IM,Galloway GJ,Rose SE,Doddrell DM

更新日期：1994-08-01 00:00:00

abstract：:To quantify metabolite and cation concentrations using NMR spectroscopy, the volumes of intracellular and extracellular spaces must be known. We describe a simple 31P NMR spectroscopic method that employs dimethyl methylphosphonate (DMMP) as a marker of total water space and phenylphosphonate (PPA) as a marker of extr...

journal_title：Magnetic resonance in medicine

authors： Clarke K,Anderson RE,Nédélec JF,Foster DO,Ally A

更新日期：1994-08-01 00:00:00

abstract：:Previous theoretical reports described the dependence of interpretation of the observed phase of the NMR signal on the time origin(s) of moment calculations and position's Taylor series expansion. This work provides experimental confirmation of predictions derived from that theory. For accelerative motion, experimenta...

journal_title：Magnetic resonance in medicine

authors： Duerk JL,Simonetti OP,Hurst GC,Finelli DA

更新日期：1994-07-01 00:00:00

abstract：:T1 is often ill-determined. This means that an Ernst angle excitation often cannot be precisely defined for the simple pulse and acquire experiment. Here, published 31P T1 values of metabolites in human muscle, liver, heart, and brain are archived, some new data on heart and brain added, and overall confidence interva...

journal_title：Magnetic resonance in medicine

authors： Bottomley PA,Ouwerkerk R

更新日期：1994-07-01 00:00:00

abstract：:We exploit the intrinsic difference in magnetic resonance spin-spin relaxation time, T2, between water associated with myelin sheaths and water in other central nervous system tissue in order to measure myelin water content within any region of an image or to generate indirectly a myelin map of the brain. In normal vo...

journal_title：Magnetic resonance in medicine

authors： MacKay A,Whittall K,Adler J,Li D,Paty D,Graeb D

更新日期：1994-06-01 00:00:00

abstract：:The natural abundance 13C NMR intensity of the glycogen C1 resonance was measured in the surgically exposed liver of rabbits in vivo (n = 17) by integration from 98 to 104 ppm and compared double blindedly to the subsequent biochemical measurement. Coil loading was measured each time from a reference sphere at the coi...

journal_title：Magnetic resonance in medicine

authors： Gruetter R,Magnusson I,Rothman DL,Avison MJ,Shulman RG,Shulman GI

更新日期：1994-06-01 00:00:00

abstract：:The utility of MRI using magnetization transfer (MT) enhanced pulse sequences to diagnose hepatic cirrhosis in a rat model was investigated. Hepatic T1 was measured with and without MT off-resonance RF pulses in 17 treated and six control rats. The livers were evaluated histologically, and the hydroxyproline content q...

journal_title：Magnetic resonance in medicine

authors： Aisen AM,Doi K,Swanson SD

更新日期：1994-05-01 00:00:00