bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of longitudinal metabolite relaxation times in different regions of the human brain at 1.5 and 3 Tesla
Authors: Ethofer Thomas , Mader Irina , Seeger Uwe , Helms Gunther , Erb Michael , Grodd Wolfgang , Ludolph Albert , Klose Uwe 
Published: December 2003

AbstractIn vivo longitudinal relaxation times of N‐acetyl compounds (NA), choline‐containing substances (Cho), creatine (Cr), myo‐inositol (mI), and tissue water were measured at 1.5 and 3 T using a point‐resolved spectroscopy (PRESS) sequence with short echo time (TE). T1 values were determined in six different brain regions: the occipital gray matter (GM), occipital white matter (WM), motor cortex, frontoparietal WM, thalamus, and cerebellum. The T1 relaxation times of water protons were 26–38% longer at 3 T than at 1.5 T. Significantly longer metabolite T1 values at 3 T (11–36%) were found for NA, Cho, and Cr in the motor cortex, frontoparietal WM, and thalamus. The amounts of GM, WM, and cerebrospinal fluid (CSF) within the voxel were determined by segmentation of a 3D image data set. No influence of tissue composition on metabolite T1 values was found, while the longitudinal relaxation times of water protons were strongly correlated with the relative GM content. Magn Reson Med 50:1296–1301, 2003. © 2003 Wiley‐Liss, Inc.
Catheter‐directed contrast‐enhanced coronary MR angiography in swine using magnetization‐prepared True‐FISP
Authors: Green Jordin D. , Omary Reed A. , Schirf Brian E. , Tang Richard , Li Debiao 
Published: December 2003

AbstractContrast‐enhanced (CE) coronary magnetic resonance angiography (MRA) following intraarterial (IA) injection of contrast agent was compared using two sequences in swine: magnetization‐prepared fast imaging with steady‐state precession (True‐FISP), and magnetization‐prepared fast low‐angle shot (FLASH). Thick‐slice projection images were acquired with submillimeter in‐plane spatial resolution (0.9 × 0.8 mm2). The magnetization‐preparation scheme provided a clear delineation of the major coronary arteries with excellent background suppression. The True‐FISP acquisition resulted in an increase in signal‐to‐noise ratio (SNR) and contrast‐to‐noise ratio (CNR) by approximately a factor of 2 over FLASH (P < 0.05). Magnetization‐prepared True‐FISP is a promising technique for catheter‐directed CE thick‐slice projection coronary MRA. Magn Reson Med 50:1317–1321, 2003. © 2003 Wiley‐Liss, Inc.
Sickle red blood cells accumulate in tumor
Authors: Brown S.L. , Ewing J.R. , Nagaraja T.N. , Swerdlow P.S. , Cao Y. , Fenstermacher J.D. , Kim J.H. 
Published: December 2003

AbstractThe preferential accumulation of sickle blood cells in tumor vasculature is demonstrated noninvasively using MRI and sickle red blood cells loaded with Gd‐DTPA and invasively by two other techniques. The distribution of red blood cells in rat brain tumors relative to normal brains were measured using three separate techniques: MRI of Gd‐DTPA loaded cells, fluorescent microscopy detection of Oregon Green 488 fluorescence conjugated to a streptavidin‐biotin complex that binds to red blood cell surface proteins, and autoradiography using a technetium 99mTc‐labeling kit. Labeled red cells were infused intravenously in rats with brain tumors. Sickle cells preferentially accumulated in tumor relative to normal brain, with highest concentrations near the tumor / normal tissue boundary, whereas control normal red cells did not preferentially aggregate at the tumor periphery. This demonstrates the potential of sickle red blood cells to accumulate in the abnormal tumor vessel network, and the ability to detect their aggregation noninvasively and at high spatial resolution using MRI. The application of the noninvasive measurement of sickle cells for imaging tumor neovasculature, or as a delivery tool for therapy, requires further study. Magn Reson Med 50:1209–1214, 2003. © 2003 Wiley‐Liss, Inc.
Efficient k‐space sampling by density‐weighted phase‐encoding
Authors: Greiser Andreas , von Kienlin Markus 
Published: December 2003

AbstractAcquisition‐weighting improves the localization of MRI experiments. An approach to acquisition‐weighting in a purely phase‐encoded experiment is presented that is based on a variation of the sampling density in k‐space. In contrast to conventional imaging or to accumulation‐weighting, where k‐space is sampled with uniform increments, density‐weighting varies the distance between neighboring sampling points Δk to approximate a given radial weighting function. A fast, noniterative algorithm has been developed to calculate the sampling matrix in one, two, and three dimensions from a radial weighting function w(k), the desired number of scans NAtot and the nominal spatial resolution Δxnom. Density‐weighted phase‐encoding combines the improved shape of the spatial response function and the high SNR of acquisition‐weighting with an extended field of view. The artifact energy that results from aliasing due to a small field of view is substantially reduced. The properties of density‐weighting are compared to uniform and to accumulation‐weighted phase‐encoding in simulations and experiments. Density‐weighted 31P 3D chemical shift imaging of the human heart is shown which demonstrates the superior performance of density‐weighted metabolic imaging. Magn Reson Med 50:1266–1275, 2003. © 2003 Wiley‐Liss, Inc.
Femoro‐tibial cartilage metrics from coronal MR image data: Technique, test–retest reproducibility, and findings in osteoarthritis
Authors: Glaser Christian , Burgkart Rainer , Kutschera Andrea , Englmeier Karl‐Hans , Reiser Maximilian , Eckstein Felix 
Published: December 2003

AbstractMRI‐based measures of cartilage morphology are being increasingly used as surrogate markers in osteoarthritis. In contrast to other knee joint surfaces, quantitative analysis of the femoral condyles from sagittal MRI suffers from limited precision. The objective, therefore, was to develop a technique for reproducible assessment of femoral cartilage morphology from coronal image data. Coronal MR images (3D T1‐w FLASHwe) of the knee were obtained in 16 healthy volunteers and in 7 patients with severe osteoarthritis (OA, prior to knee arthroplasty), with repositioning between repeated scans. After segmentation the cartilage volume, thickness, and joint surface areas were quantified in the tibia and in an anatomically defined region of the femoral condyle. Immediate test‐retest interscan precision errors (CV%) for femoral cartilage volume were 3.0% (SD = 26 μl) and 3.2% (29 μl) medially and laterally in volunteers, and 3.0% (34 μl) and 7.0% (37 μl) in OA patients. The estimated loss, from cross sectional data, in the patients in the medial femoral condyle (–61%/–4.4 SD) was higher than that in the medial tibia (–45%/–3.1 SD) and compared favorably with precision errors (ratio > 16:1). The technique proposed overcomes some of the problems associated with sagittal scans and thus shows high promise for reliable assessment of femoro‐tibial cartilage loss in OA. Magn Reson Med 50:1229–1236, 2003. © 2003 Wiley‐Liss, Inc.
High‐resolution 1H NMR spectroscopy in a live mouse subjected to 1.5 Hz magic angle spinning
Authors: Wind Robert A. , Hu Jian Zhi , Rommereim Donald N. 
Published: December 2003

AbstractIt is demonstrated that the resolution of the 1H NMR metabolite spectrum in a live mouse can be significantly enhanced by an ultraslow magic angle spinning of the animal combined with a modified phase‐corrected magic angle turning (PHORMAT) pulse sequence. Proton NMR spectra were measured of the torso and the top part of the belly of a female BALBc mouse in a 2 T field while spinning the animal at a speed of 1.5 Hz. It was found that even in this relatively low field, with PHORMAT an isotropic spectrum is obtained with line widths that are a factor of 4.6 smaller than those obtained in a stationary mouse. It is concluded that in vivo PHORMAT has the potential to significantly increase the utility of 1H NMR spectroscopy for biochemical and biomedical animal research. Magn Reson Med 50:1113–1119, 2003. © 2003 Wiley‐Liss, Inc.
Amide proton transfer (APT) contrast for imaging of brain tumors
Authors: Zhou Jinyuan , Lal Bachchu , Wilson David A. , Laterra John , van Zijl Peter C.M. 
Published: December 2003

AbstractIn this work we demonstrate that specific MR image contrast can be produced in the water signal that reflects endogenous cellular protein and peptide content in intracranial rat 9L gliosarcomas. Although the concentration of these mobile proteins and peptides is only in the millimolar range, a detection sensitivity of several percent on the water signal (molar concentration) was achieved. This was accomplished with detection sensitivity enhancement by selective radiofrequency (RF) labeling of the amide protons, and by utilizing the effective transfer of this label to water via hydrogen exchange. Brain tumors were also assessed by conventional T1‐weighted, T2‐weighted, and diffusion‐weighted imaging. Whereas these commonly‐used approaches yielded heterogeneous images, the new amide proton transfer (APT) technique showed a single well‐defined region of hyperintensity that was assigned to brain tumor tissue. Magn Reson Med 50:1120–1126, 2003. © 2003 Wiley‐Liss, Inc.
New hybrid technique for accurate and reproducible quantitation of dynamic contrast‐enhanced MRI data
Authors: Li Ka‐Loh , Jackson Alan 
Published: December 2003

AbstractThe accuracy and precision of two major approaches for analyzing dynamic MRI data from the first passage of a Gd‐DTPA contrast bolus are examined, using a Monte Carlo simulation. Method 1 fits the contrast concentration curve of the first pass to a two‐compartment kinetic model to determine the tissue pharmacokinetic parameters. Method 2 decomposes intravascular and interstitial components of the first‐pass curve based on a leakage profile (LP) model. Based on the results of these Monte Carlo simulations, a new “hybrid” method is proposed that combines both analytical approaches to optimize accuracy and precision of estimates of Ktrans, ve, and vp. The new method was evaluated by computer simulation and used on experimental results from a patient with primary brain tumors. The new method has the potential to provide more accurate quantification of tissue plasma volume and vessel permeability. Magn Reson Med 50:1286–1295, 2003. © 2003 Wiley‐Liss, Inc.
In vivo quantification of choline compounds in the breast with 1H MR spectroscopy
Authors: Bolan Patrick J. , Meisamy Sina , Baker Eva H. , Lin Joseph , Emory Timothy , Nelson Michael , Everson Lenore I. , Yee Douglas , Garwood Michael 
Published: December 2003

AbstractThis work describes a methodology for quantifying levels of total choline‐containing compounds (tCho) in the breast using in vivo 1H MR spectroscopy (MRS) at high field (4 Tesla). Water is used as an internal reference compound to account for the partial volume of adipose tissue. Peak amplitudes are estimated by fitting one peak at a time over a narrow frequency band to allow measurement of small metabolite resonances in spectra with large lipid peaks. This quantitative method significantly improves previously reported analysis methods by accounting for the variable sensitivity of breast 1H MRS measurements. Using this technique, we detected and quantified a tCho peak in 214 of 500 in vivo spectra. tCho levels were found to be significantly higher in malignancies than in benign abnormalities and normal breast tissues, which suggests that this technique could be used to diagnose suspicious lesions and monitor response to cancer treatments. Magn Reson Med 50:1134–1143, 2003. © 2003 Wiley‐Liss, Inc.
Evaluation of two‐dimensional L‐COSY and JPRESS using a 3 T MRI scanner: from phantoms to human brain in vivo
Authors: Thomas M. Albert , Hattori Noriaki , Umeda Masahiro , Sawada Tohru , Naruse Shoji 
Published: December 2003

AbstractLocalized versions of two‐dimensional (2D) magnetic resonance spectroscopic (MRS) sequences, namely JPRESS and L‐COSY, have been implemented on a whole‐body 3T MRI/MRS scanner. Volume selection was achieved using three slice‐selective radio‐frequency (RF) pulses: 90°–180°–180° in JPRESS and 90°–180°–90° in L‐COSY with a CHESS sequence prior to voxel localization for global water suppression. The last 180° RF pulse was used for resolving the J‐coupled cross peaks in JPRESS, whereas the last 90° RF pulse was used for coherence transfer between J‐coupled metabolites in L‐COSY. A head MRI coil for ‘transmission’ and a 4 inch receive surface coil for ‘reception’ or a head coil transmit/receive were used. A total of 16 healthy volunteers were investigated using these 2D MRS sequences. Voxel sizes of 18 and 27 ml were localized in the occipito‐parietal gray and white matter regions and the total duration for each 2D signal acquisition was typically 35 min. Compared with 2D L‐COSY, reduced spectral width along the second spectral dimension and shorter 2D spectral acquisition were the major advantages of 2D JPRESS. In contrast, increased spectral width along the new spectral dimension in L‐COSY resulted in an improved spectral dispersion enabling the detection of several brain metabolites at low concentrations that have not been resolved using the conventional one‐dimensional (1D) MRS techniques. Due to increased sampling rate, severe loss of metabolite signals due to T2 during t1 was a major drawback of 2D JPRESS in vivo. Copyright © 2003 John Wiley & Sons, Ltd.
REST‐PEEP: reduced scan time phase‐encoded echo planar imaging
Authors: Guilfoyle David N. , Hrabe Jan 
Published: December 2003

AbstractEcho planar methodology can be used for rapid acquisition in three dimensions of k‐space. There are two groups of sequences which have thus far been implemented. The first group is characterized by three‐dimensional acquisition from a single RF excitation. Echo planar shift mapping and echo volumar imaging are single‐shot chemical shift imaging and three‐dimensional spatial imaging techniques, respectively. Even though these methods are extremely fast, their spatial and spectral resolutions are poor. In the second group of sequences, echo planar imaging acquisition is repeated for every phase‐encode gradient step to improve upon the spatial resolution and signal‐to‐noise ratio at the expense of acquisition time. Here we report a novel combination of these two groups of sequences aimed at providing additional flexibility in trade‐offs between the spectral bandwidth, signal‐to‐noise ratio, spatial resolution and imaging time. Preliminary results for both chemical shift imaging and three‐dimensional spatial imaging are presented. The chemical shift imaging was optimized for excitation of the N‐acetyl aspartate (NAA). An interesting consequence of our approach is that the Nyquist ghost is transferred from the spectrum to the metabolite image. Copyright © 2001 John Wiley & Sons, Ltd.
Three‐dimensional MRI of cerebral projections in rat brain in vivo after intracortical injection of MnCl2
Authors: Allegrini Peter R. , Wiessner Christoph 
Published: December 2003

AbstractIn this study we investigated the potential of in vivo MRI detection of axonal Mn2+ transport for tracing neuronal projections originating in the sensorimotor cortex in healthy and lesioned rat brains. Special attention was given to the potential of visualizing neuronal sprouting of central nervous system across the midline. After injecting unchelated MnCl2 into the forelimb area of sensorimotor cortex of 18 healthy and 10 lesioned rats corticofugal projections could be traced through the internal capsule to the cerebral peduncle and the pyramidal decussation. Although the neuronal tract was visible as early as 6 h after MnCl2 injection, best contrast was achieved after 24–48 h. Beside the cortico‐spinal tract, the cortico‐thalamic fibres were also visualized by anterograde Mn2+ transport. Cortico‐striatal fibres were partially masked by the very high signal near the MnCl2 injection site but could be discerned as well. Slight, diffuse signal enhancement of cortical tissue contralateral to the MnCl2 injection site in healthy rat brains suggests interhemispheric connections or passive diffusion of Mn2+. However, enhanced fibre tract contrast connecting both hemispheres was visible 16 weeks after onset of focal photothrombotic cortical injury. In conclusion our study has shown that we were able to visualize reproducibly the main descending corticofugal projections and interhemispheric connections by non‐invasive MRI after localized injection of MnCl2. The appearence of interhemispheric Mn2+‐enhanced fibres after photothrombotic focal injury indicates that the method may bear potential to follow non‐invasively gross plastic changes of connectivity in the brain after injury. Copyright © 2001 John Wiley & Sons, Ltd.
An adaptive survivability admission control algorithm using backup path for high‐speed networks
Authors: Lo Chi‐Chun , Chuang Bin‐Wen 
Published: December 2003

AbstractIn this paper, we propose an adaptive survivability admission control algorithm using a backup path for high‐speed networks. For each call request, the proposed algorithm selects a combination of working path and backup path. Two BP selection methods, min‐cost and min‐expectation, are suggested. Computational experiments indicate that the proposed algorithm significantly reduces the consumption of backup capacity while still maintaining 100% survivability upon a single link failure and near 80% survivability upon double link failures. Copyright © 2003 John Wiley & Sons, Ltd.
Network capacity allocation for traffic with time priorities
Authors: Liu Xian 
Published: December 2003

AbstractThe packet switching techniques are undergoing evolution. The conventional ‘best effort’ approach will no longer be the dominant service. The next generation of IP networks must provide QoS to customers. Inadequacy is obvious when the conventional capacity allocation (CA) models are applied to the new IP architecture. In this paper, we propose several CA models that characterize: (1) the service priority scheme; (2) the service preemption scheme; and (3) the non‐Poisson traffic in which the packets follow heavy tailed distributions. Copyright © 2003 John Wiley & Sons, Ltd.
A scalable key‐management scheme with minimizing key storage for secure group communications
Authors: Tseng Yuh‐Min 
Published: December 2003

AbstractRecently, many group communication services have become the focus for future developments in the Internet and wireless network applications, such as video‐conferencing, collaborative work, networking games or online videos. In particular, these applications require data delivery from one sender to a large number of authorized receivers. Therefore, secure multicast communication will become an important networking issue in the future. Using a common encryption key only known by authorized members to encrypt transmitted data is a practical approach. But, whenever a group member joins or leaves the group, the common encryption key must be updated to ensure both past and future secrecy. As a result, minimizing key update communication cost and the key storage requirement of a group controller is a critical issue in a scalable and dynamically changing large group. A new key‐management scheme is proposed to reduce the key storage requirement of a group controller to a constant size, which is far better than that of the previously proposed schemes, while retaining the same key update communication cost. In addition, the correlation between the key storage requirement of each group member and key update communication cost are also presented. Copyright © 2003 John Wiley & Sons, Ltd.
Consistency adjustments for pairwise comparison matrices
Authors: Farkas András , Lancaster Peter , Rózsa Pál 
Published: December 2003

AbstractThis paper is concerned with the development of a ‘best’ rank one transitive approximation to a general paired comparison matrix in a least‐squares sense. A direct attack on the non‐linear problem is frequently replaced by a sub‐optimal linear problem and, here, the best procedure of this kind is obtained. The Newton–Kantorovich method for the solution of the non‐linear problem is also studied, including the role of the best linear approximation as a starting point for this method. Numerical examples are included. Copyright © 2002 John Wiley & Sons, Ltd.
A centrosymmetric matrix based technique for the interpolation of a Hermitian signal
Authors: Hanna Magdy Tawfik , Mansoori Sana Ahmed 
Published: December 2003

AbstractThis work is concerned with the signal interpolation problem, i.e. given only samples of a signal, a method is derived for evaluating its samples on finer grids. The derivation is based on a discrete‐time decimation formula. In the special case where the known samples have the Hermitian property, two schemes are presented and mathematically proved to result in interpolated points having the same property. The first scheme does not utilize the known sample at the origin and results in a square system of equations to be solved for the unknown interpolated points of the signal. The second scheme has the merit of utilizing all the known samples, but it results in an overdetermined system of equations to be solved by the least squares method. The exploitation of the elegant properties of the involved centrosymmetric matrices is central to the treatment presented here. Copyright © 2002 John Wiley & Sons, Ltd.
The impact of state governance structures on management and performance of public organizations: A study of higher education institutions
Authors: Knott Jack H. , Payne A. Abigail 
Published: December 2003

AbstractLegislative statutes are passed by political majorities which support structures that insulate the implementing
agency from its political opponents over time. Political actors also respond to different constituencies.
Depending on the broad or narrow base of these constituencies, actors favor different kinds of governance
structures. We apply this theoretical framework to the question of whether the state governance structures of
boards of higher education affect the way university managers allocate resources, develop sources of revenue, and
promote research and undergraduate education. Over the past two decades state governments have given considerable
attention to state governance issues, resulting in many universities operating in a more regulated setting today.
This paper develops a classification of higher education structures and shows the effects of differences in these
structures on university management and performance using a data set that covers the period from 1987 to 1998. The
analysis suggests that, for most of the measures, productivity and resources are higher at universities with a
statewide board that is more decentralized and has fewer regulatory powers. © 2004 by the Association for
Public Policy Analysis and Management.
Will empowering developers to challenge exclusionary zoning increase suburban housing choice?
Authors: Mitchell James L. 
Published: December 2003

AbstractThe municipal zoning process in the United States has come under increasing attack as a tool to create and maintain suburban socioeconomic homogeneity by mandating sprawl‐producing single‐family detached houses at the expense of less costly townhouses, apartments, and mobile homes. Beginning in the 1970s, the Supreme Courts of the neighboring states of Pennsylvania and New Jersey addressed municipal exclusionary zoning in different ways: Pennsylvania empowered residential developers to compel municipalities practicing exclusionary zoning to authorize market‐rate development of all types of housing, while developer empowerment in New Jersey was conditioned upon inclusion of low‐ and moderate‐income units. Using aerial survey and housing census data over a 20‐year period, this article finds that outcomes by housing type over a 20‐year period in Pennsylvania municipalities around Philadelphia were more diverse than those in adjacent New Jersey municipalities. © 2004 by the Association for Public Policy Analysis and Management.