bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regional corpus callosum morphometry: Effect of field strength and pulse sequence
Authors: Abdul‐Kareem Ihssan A. , Stancak Andrej , Parkes Laura M. , Sluming Vanessa 
Published: October 2009

AbstractPurpose:To investigate whether scanning at different field strengths and pulse sequences would influence reproducibility of corpus callosum (CC) morphometric measurements as variations in scanning parameters may result in differences in contrast properties between resulting images that are independent of the underlying tissue but rather reflect the physics of the imaging process.Materials and Methods:Ten subjects were scanned twice at 3T using magnetization‐prepared rapid gradient‐echo imaging (MPRAGE) and modified driven equilibrium Fourier transform (MDEFT) sequences and once at 1.5T using MPRAGE. Cross‐sectional area measurements of four callosal regions were performed on midsagittal magnetic resonance imaging (MRI) sections.Results:Repeated measures analysis of variance with four regions as dependent variables and three scanning protocols (1.5T MPRAGE, 3T MPRAGE and 3T MDEFT) as independent variables revealed no significant region by protocol interaction: F(6,54) = 0.69, P = 0.52. Reliability measures for (3T MPRAGE/3T MDEFT) and (1.5T MPRAGE/3T MPRAGE; 1.5T MPRAGE/3T MDEFT) comparisons were high, ranging between 0.90 and 0.97.Conclusion:Based on our results, combining and comparing CC morphometric data obtained at different field strengths and/or with different pulse sequences appears possible. J. Magn. Reson. Imaging 2009;30:1184–1190. © 2009 Wiley‐Liss, Inc.
Optimized glutamate detection at 3T
Authors: Hancu Ileana 
Published: October 2009

AbstractPurpose:To identify the pulse sequence and acquisition parameters that result in the most accurate and repeatable measurements of glutamate (Glu) concentration in the brain at 3T.Materials and Methods:Simulations were performed to compare the accuracy and repeatability of 11 pulse sequences and acquisition parameters, within four general classes (PRESS, STEAM, Carr–Purcell PRESS [CPRESS] and TE averaged PRESS [JPRESS]), the majority of which were previously suggested as optimal for Glu detection. Three of the simulated acquisitions were implemented in a clinical scanner and measures of repeatability in vivo were compared to their simulated values.Results:Good agreement was demonstrated between simulated and experimentally determined measures of repeatability. Among the acquisitions considered, a CPRESS sequence with minimal echo time, together with, possibly, a short TE PRESS sequence, result in the most repeatable within session Glu measurements, while slightly overestimating the Glu concentration. Excellent accuracy is demonstrated by the simulations for a JPRESS sequence, at the expense of lower repeatability than optimal PRESS or CPRESS sequences.Conclusion:Further proof of concept is presented toward validation of a simulation approach to understand pulse sequence performance in measuring the concentration of a given metabolite. Improved within session Glu measurement repeatability is predicted for CPRESS and demonstrated in vivo. J. Magn. Reson. Imaging 2009;30:1155–1162. © 2009 Wiley‐Liss, Inc.
MR imaging in Duchenne muscular dystrophy: Quantification of T1‐weighted signal, contrast uptake, and the effects of exercise
Authors: Garrood Penelope , Hollingsworth Kieren G. , Eagle Michelle , Aribisala Benjamin S. , Birchall Daniel , Bushby Kate , Straub Volker 
Published: October 2009

AbstractPurpose:To quantify the differences between normal and corticosteroid‐treated Duchenne muscular dystrophy (DMD) lower limb muscle using signal intensity measurements on T1‐weighted and gadolinium contrast‐enhanced images and by measurement of muscle T2 values, and to investigate the effect of exercise.Materials and Methods:Eleven ambulant boys with DMD were imaged at 3 Tesla (T1‐weighted, gadolinium enhancement and T2 measurement) before stepping exercise and again (gadolinium, T2 measurement) 4 days later and were compared with five healthy controls imaged 4 days before and after stepping exercise. Muscle region‐of‐interest signal intensities were referenced to external oil and gadolinium phantoms.Results:DMD thigh muscle T2 values were significantly higher than normal values with the exception of the gracilis muscle. Eight of nine muscles studied showed a significant increase in T1‐w signal intensity in DMD as compared to normal muscle, suggestive of increased fat infiltration in DMD muscle. In the DMD boys, an exercise effect (increased contrast enhancement) was only seen for the tibialis anterior muscle.Conclusion:Referenced signal intensity measurements may be used to quantify differences between dystrophic and normal muscle without T1 mapping. Stepping exercise does not have a large impact on subsequent MR imaging of dystrophic muscle. J. Magn. Reson. Imaging 2009;30:1130–1138. © 2009 Wiley‐Liss, Inc.
Principal component analysis of breast DCE‐MRI adjusted with a model‐based method
Authors: Eyal Erez , Badikhi Daria , Furman‐Haran Edna , Kelcz Fredrick , Kirshenbaum Kevin J. , Degani Hadassa 
Published: October 2009

AbstractPurpose:To investigate a fast, objective, and standardized method for analyzing breast dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) applying principal component analysis (PCA) adjusted with a model‐based method.Materials and Methods:3D gradient‐echo DCE breast images of 31 malignant and 38 benign lesions, recorded on a 1.5T scanner, were retrospectively analyzed by PCA and by the model‐based three‐timepoints (3TP) method.Results:Intensity‐scaled (IS) and enhancement‐scaled (ES) datasets were reduced by PCA yielding a first IS‐eigenvector that captured the signal variation between fat and fibroglandular tissue; two IS‐eigenvectors and the two first ES‐eigenvectors captured contrast‐enhanced changes, whereas the remaining eigenvectors captured predominantly noise changes. Rotation of the two contrast‐related eigenvectors led to a high congruence between the projection coefficients and the 3TP parameters. The ES‐eigenvectors and the rotation angle were highly reproducible across malignant lesions, enabling calculation of a general rotated eigenvector base. Receiver operating characteristic (ROC) curve analysis of the projection coefficients of the two eigenvectors indicated high sensitivity of the first rotated eigenvector to detect lesions (area under the curve [AUC] > 0.97) and of the second rotated eigenvector to differentiate malignancy from benignancy (AUC = 0.87).Conclusion:PCA adjusted with a model‐based method provided a fast and objective computer‐aided diagnostic tool for breast DCE‐MRI. J. Magn. Reson. Imaging 2009;30:989–998. © 2009 Wiley‐Liss, Inc.
Personal exposure to static and time‐varying magnetic fields during MRI system test procedures
Authors: de Vocht Frank , Muller Floris , Engels Hans , Kromhout Hans 
Published: October 2009

AbstractPurpose:To assess personal time‐weighted average (TWA) static magnetic field and time‐varying magnetic field exposure for several system testing tasks routinely conducted by engineers at an MRI manufacturing plant.Materials and Methods:Personal exposure was measured using a personal dosimeter that measured B and dB/dt in all three orthogonal directions with a 1 Hz frequency. TWA exposure was calculated and random effects and linear mixed effects models were used to assess exposure levels and variability.Results:Whereas full‐body peak (2T) and TWA (200 mT/8 h) exposure limits for the static magnetic field originally proposed by ICNIRP were not exceeded, time‐varying magnetic field peaks (dB/dt) did exceed the proposed threshold value (767.9 mT/s) suggested by IEEE on several occasions at the 3.0 Tesla (T) whole‐body cylindrical system.Conclusion:TWA exposure levels are well below the proposed limit values, but peak exposure limits are exceeded during certain procedures performed on 1.0T to 3.0T systems. J. Magn. Reson. Imaging 2009;30:1223–1228. © 2009 Wiley‐Liss, Inc.
Shorter difference between myocardium and blood optimal inversion time suggests diffuse fibrosis in dilated cardiomyopathy
Authors: Han Yuchi , Peters Dana C. , Dokhan Basem , Manning Warren J. 
Published: October 2009

AbstractPurpose:To find evidence of diffuse fibrosis in dilated cardiomyopathy (DCM) patients by comparing measurements on clinical late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) studies between DCM and healthy subjects.Materials and Methods:LGE‐CMR and the Look–Locker images from 20 DCM patients and 17 healthy controls were analyzed. Blood signal‐to‐noise ratio (SNR), myocardium SNR, and blood‐to‐myocardium contrast‐to‐noise ratio (CNR) were measured on the LGE‐CMR images. The optimal inversion time (TI) to null blood and myocardium was determined on the Look–Locker images. The postcontrast T1 was estimated using a phantom study that correlated optimal TI and heart rate to T1.Results:The blood SNR was lower, myocardium SNR was higher, and the blood‐to‐myocardium CNR was lower (6.6 ± 0.7 vs. 10.3 ± 0.9, P = 0.004) on DCM LGE‐CMR images as compared to controls. The blood‐myocardium optimal TI difference (ΔTI) was lower (38 ± 2 msec vs. 55 ± 3 msec, P < 0.001) in DCM, and the estimated blood‐myocardium T1 difference (ΔT1) (116 ± 6 msec vs. 152 ± 8 msec, P = 0.001) was also lower.Conclusion:DCM patients have reduced blood‐myocardium ΔTI and ΔT1, and lower CNR as compared to controls, suggesting the presence of diffuse fibrosis. This may impact the interpretation of LGE data. J. Magn. Reson. Imaging 2009;30:967–972. © 2009 Wiley‐Liss, Inc.
MRI signal intensity based B‐Spline nonrigid registration for pre‐ and intraoperative imaging during prostate brachytherapy
Authors: Oguro Sota , Tokuda Junichi , Elhawary Haytham , Haker Steven , Kikinis Ron , Tempany Clare M.C. , Hata Nobuhiko 
Published: October 2009

AbstractPurpose:To apply an intensity‐based nonrigid registration algorithm to MRI‐guided prostate brachytherapy clinical data and to assess its accuracy.Materials and Methods:A nonrigid registration of preoperative MRI to intraoperative MRI images was carried out in 16 cases using a Basis‐Spline algorithm in a retrospective manner. The registration was assessed qualitatively by experts' visual inspection and quantitatively by measuring the Dice similarity coefficient (DSC) for total gland (TG), central gland (CG), and peripheral zone (PZ), the mutual information (MI) metric, and the fiducial registration error (FRE) between corresponding anatomical landmarks for both the nonrigid and a rigid registration method.Results:All 16 cases were successfully registered in less than 5 min. After the nonrigid registration, DSC values for TG, CG, PZ were 0.91, 0.89, 0.79, respectively, the MI metric was −0.19 ± 0.07 and FRE presented a value of 2.3 ± 1.8 mm. All the metrics were significantly better than in the case of rigid registration, as determined by one‐sided t‐tests.Conclusion:The intensity‐based nonrigid registration method using clinical data was demonstrated to be feasible and showed statistically improved metrics when compare to only rigid registration. The method is a valuable tool to integrate pre‐ and intraoperative images for brachytherapy. J. Magn. Reson. Imaging 2009;30:1052–1058. © 2009 Wiley‐Liss, Inc.
T1 independent, T2* corrected MRI with accurate spectral modeling for quantification of fat: Validation in a fat‐water‐SPIO phantom
Authors: Hines Catherine D.G. , Yu Huanzhou , Shimakawa Ann , McKenzie Charles A. , Brittain Jean H. , Reeder Scott B. 
Published: October 2009

AbstractPurpose:To validate a T1‐independent, T2*‐corrected fat quantification technique that uses accurate spectral modeling of fat using a homogeneous fat‐water‐SPIO phantom over physiologically expected ranges of fat percentage and T2* decay in the presence of iron overload.Materials and Methods:A homogeneous gel phantom consisting of vials with known fat‐fractions and iron concentrations is described. Fat‐fraction imaging was performed using a multiecho chemical shift‐based fat‐water separation method (IDEAL), and various reconstructions were performed to determine the impact of T2* correction and accurate spectral modeling. Conventional two‐point Dixon (in‐phase/out‐of‐phase) imaging and MR spectroscopy were performed for comparison with known fat‐fractions.Results:The best agreement with known fat‐fractions over the full range of iron concentrations was found when T2* correction and accurate spectral modeling were used. Conventional two‐point Dixon imaging grossly underestimated fat‐fraction for all T2* values, but particularly at higher iron concentrations.Conclusion:This work demonstrates the necessity of T2* correction and accurate spectral modeling of fat to accurately quantify fat using MRI. J. Magn. Reson. Imaging 2009;30:1215–1222. © 2009 Wiley‐Liss, Inc.
Vessel size imaging using dual contrast agent injections
Authors: Hsu Yuan‐Yu , Yang Wei‐Shan , Lim Kun‐Eng , Liu Ho‐Ling 
Published: October 2009

AbstractPurpose:To investigate the feasibility of a vessel size imaging (VSI) technique with separate contrast agent injections for evaluation of the vessel caliber in normal tissues and in brain tumors.Materials and Methods:Computer simulation was first performed to assess the potential errors in the estimation of vessel caliber that could result from time shifts between the dual contrast agent injections. Eight patients (four female, four male, 37–77 years old) with brain tumors (three high‐grade gliomas, two low‐grade gliomas, and three meningiomas) were recruited for clinical study. Dynamic susceptibility contrast magnetic resonance imaging (MRI) using gradient echo (GE) and spin echo (SE) echo‐planar imaging sequences were performed separately with a 10‐minute interval on a 3.0T scanner. Vessel caliber maps were calculated and analyzed in regions of interest at cortical gray matter (GM), thalamus, white matter (WM), and tumors.Results:From the computer simulation, the error of vessel caliber measurement was less than 8% when the difference between the time‐to‐peak of the GE and the SE studies was 1.5 seconds, and reduced to within 5% when the difference was 1 second. From the patient datasets of a 64 × 64 matrix, the estimated vessel calibers were 37.4 ± 12.9 μm for cortical gray matter, 20.7 ± 8.8 μm for thalamus, and 15.0 ± 5.1 μm for white matter, comparable to results in the literature. Two patients had a VSI with 128 × 128 matrix and showed similar results in vessel calibers of normal tissues. All the tumors had larger mean vessel diameter than normal‐appearing tissues. The difference in vascular size between normal tissue and tumor was demonstrated clearly in both the VSIs of regular and high spatial resolution.Conclusion:This study suggests that VSI with a dual injection method is a feasible technique for estimating microvascular calibers of normal tissues and brain tumors in clinical scanners. J. Magn. Reson. Imaging 2009;30:1078–1084. © 2009 Wiley‐Liss, Inc.
Characterization of sodium alginate and its block fractions by surface‐enhanced Raman spectroscopy
Authors: Campos‐Vallette Marcelo M. , Chandía Nancy P. , Clavijo Ernesto , Leal David , Matsuhiro Betty , Osorio‐Román Igor O. , Torres Simonet 
Published: October 2009

AbstractThe surface‐enhanced Raman scattering (SERS) of sodium alginates and their hetero‐ and homopolymeric fractions obtained from four seaweeds of the Chilean coast was studied. Alginic acid is a copolymer of β‐D‐mannuronic acid (M) and α‐L guluronic acid (G), linked 1 → 4, forming two homopolymeric fractions (MM and GG) and a heteropolymeric fraction (MG). The SERS spectra were registered on silver colloid with the 632.8 nm line of a HeNe laser. The SERS spectra of sodium alginate and the polyguluronate fraction present various carboxylate bands which are probably due to the coexistence of different molecular conformations. SERS allows to differentiate the hetero‐ and homopolymeric fractions of alginic acid by characteristic bands. In the fingerprint region, all the poly‐D‐mannuronate samples present a band around 946 cm−1 assigned to CO stretching, and CCH and COH deformation vibrations, a band at 863 cm−1 assigned to deformation vibration of β‐C1H group, and one at 799–788 cm−1 due to the contributions of various vibration modes. Poly‐L‐guluronate spectra show three characteristic bands, at 928–913 cm−1 assigned to symmetric stretching vibration of COC group, at 890–889 cm−1 due to CCH, skeletal CC, and CO vibrations, and at 797 cm−1 assigned to α C1H deformation vibration. The heteropolymeric fractions present two characteristic bands in the region with the more important one being an intense band at 730 cm−1 due to ring breathing vibration mode. Copyright © 2009 John Wiley & Sons, Ltd.
Survival of molecular information under surfaced‐enhanced resonance Raman (SERRS) conditions
Authors: Jernshøj K. D. , Hassing S. 
Published: October 2009

AbstractIn the present paper, we discuss the molecular information that can be derived from surface‐enhanced resonance Raman Scattering (SERRS) experiments performed with different excitation wavenumbers, which are close to resonance with an excited electronic state of the molecule [surface‐enhanced Raman dispersion spectroscopy (SERADIS)]. We specifically consider the situation, where a molecule is physisorbed to a site characterized by a local electric field with a direction independent of the direction of the external, exciting field. The molecular information available in this experimental situation is compared with the information available in a corresponding Raman dispersion spectroscopy (RADIS) experiment performed on a free molecule or a molecule physisorbed to a site, where the local field is isotropic. The consequences for resonance Raman scattering (RRS) and RADIS, when the molecule is adsorbed in the highly anisotropic hot spot (HS), are discussed; here it is shown that only the molecular information originating from the symmetric part of the scattering tensor can survive in SERRS and in SERADIS. Besides, it is shown that the depolarization ratio can no longer be used to discriminate between totally and non‐totally symmetric modes in the polarized surface‐enhanced Raman scattering (SERS) spectra. These results have implications for the resonance Raman spectra, but even more important for the application of the resonance Raman effect in the investigation of excited vibronic molecular states, in general, and in the investigation of electronic states in larger bio‐molecules, such as the various metallo‐porphyrins. Copyright © 2009 John Wiley & Sons, Ltd.
The use of alternative lipid resources for bioenergy
Authors: Zyaykina Nadezhda Zyaykina, Vera Van Hoed, Wim De Greyt and Roland Ve , Van Hoed Vera , De Greyt Wim , Verhé Roland 
Published: October 2009

AbstractAlternative resources such as animal fats, used cooking oils and side streams from oil refining can be used for the production of biodiesel. The quality of the biodiesel is largely dependent upon the quality and properties of the feedstock. A number of technologies involving pretreatment of the feedstock, post treatment of the biodiesel and new production processes have been developed in order to meet the biodiesel standards.
Stearic acid or palmitic acid as a substitute for trans fatty acids?
Authors: Stanley John C. 
Published: October 2009

AbstractThe evidence for unfavourable effects of trans fatty acids on risk of developing coronary heart disease is overwhelming. The food industry must now search for substitutes for trans fatty acids with acceptable nutritional properties which at the same time retain the functionality of fats for baking and margarine manufacture. Comparisons of fats rich in stearic acid with fats rich in mixtures of palmitic, myristic and lauric acids show that fasting total and LDL‐cholesterol levels, postprandial lipaemia and factor VII activation are lower in response to stearic rich fats. All of these effects of stearic acid would be expected to lower the risk of developing coronary heart disease by comparison with palmitic acid. While fasting HDL‐cholesterol levels are higher in response to the saturated fatty acid mixture than in response to stearic acid this is probably due to the lauric acid content of the mixture rather than its palmitic acid content. To date there is no evidence that randomization of stearic acid or palmitic acid caused by interesterification has any effect on risk factors for coronary heart disease although more research is needed. It can be concluded that stearic acid is a better substitute for trans fatty acids than palmitic acid in fats for baking and margarine manufacture.
Lipid analysis via HPLC with a charged aerosol detector
Authors: Moreau Robert A. 
Published: October 2009

AbstractMost lipid extracts are a mixture of saturated and unsaturated molecules. Therefore, the most successful high performance liquid chromatography (HPLC) detectors for the quantitative analysis of lipids have involved the use of “universal” or “mass” detectors such as flame ionization detectors and evaporative light scattering detectors. Recently a new type of HPLC “universal” detector, a charged aerosol detector (CAD), was developed and is now commercially available. This detection method involves nebulizing the HPLC column effluent, evaporating the solvents, charging the aerosol particles and measuring the current from the charged aerosol flux. During the approximately four years that the charged aerosol detector has been commercially available, several publications have described HPLC‐CAD methods for lipid analysis. The most common lipids can be quantitatively analyzed via HPLC‐CAD except for some volatile lipids such as common fatty acid methyl esters and short chain free fatty acids (<C16). The major results of these publications will be summarized in this report.
Simultaneous measurement of NH and CαHα coupling constants in proteins
Authors: Pantoja‐Uceda David , Santoro Jorge 
Published: October 2009

AbstractWe present a pulse sequence for the simultaneous measurement of NH and CαHα couplings in double‐labeled proteins from 2D spectra. The proposed sequence, a modification of the HN(CO)CA experiment, combines the J‐modulation method and the IPAP scheme. The couplings can be readily retrieved from a series of 2D 15N1H correlation spectra, differing in the time point at which a 1H 180° pulse is applied. This induces an intensity modulation of the 15N1H correlation peaks with the CαHα coupling. The CαHα coupling is then obtained by fitting the observed intensities to the modulation equation. The NH coupling is measured in each member of the set from peak‐to‐peak separations in the IPAP subspectra. The pulse sequence is experimentally verified with a sample of 15N/13C‐enriched ubiquitin. Copyright © 2009 John Wiley & Sons, Ltd.
The development of the birdcage resonator: a historical perspective
Authors: Hayes Cecil E. 
Published: October 2009

AbstractThe author gives a personal account of the development of the birdcage resonator while he worked at GE Medical Systems. The emphasis is on promoting an intuitive understanding of the underlying principles of RF coil design by recounting the assumptions, misconceptions, and reasoning involved in addressing the challenging problems in a new field of technology. Topics covered include the historic context of early MRI development, the critical role of RF coil technology in high field imaging, the need for an RF shield, the importance of distributed capacitance, the scientific controversies over magnetic field strength for imaging, a comparison of the birdcage design to an earlier Technicare phased coil, the distribution of electric fields in birdcage resonators, and the limitations of birdcages at very high fields. The author often cites less well‐known patent literature on RF coil technology. Copyright © 2009 John Wiley & Sons, Ltd.