bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fat and water magnetic resonance imaging
Authors: Bley Thorsten A. , Wieben Oliver , François Christopher J. , Brittain Jean H. , Reeder Scott B. 
Published: December 2009

AbstractA wide variety of fat suppression and water–fat separation methods are used to suppress fat signal and improve visualization of abnormalities. This article reviews the most commonly used techniques for fat suppression and fat–water imaging including 1) chemically selective fat suppression pulses “FAT‐SAT”; 2) spatial‐spectral pulses (water excitation); 3) short inversion time (TI) inversion recovery (STIR) imaging; 4) chemical shift based water–fat separation methods; and finally 5) fat suppression and balanced steady‐state free precession (SSFP) sequences. The basic physical background of these techniques including their specific advantages and disadvantages is given and related to clinical applications. This enables the reader to understand the reasons why some fat suppression methods work better than others in specific clinical settings. J. Magn. Reson. Imaging 2010;31:4–18. © 2009 Wiley‐Liss, Inc.
Short echo time MR spectroscopy of brain tumors: Grading of cerebral gliomas by correlation analysis of normalized spectral amplitudes
Authors: Weis Jan , Ring Patrik , Olofsson Tommie , Ortiz‐Nieto Francisco , Wikström Johan 
Published: December 2009

AbstractPurpose:To process single voxel spectra of low‐ and high‐grade gliomas. To propose correlation analysis of the scatter plots of normalized spectral amplitudes as a pattern recognition tool for the classification (grading) of brain tumors. To propose a spectrum processing approach that improves the differentiation of proton spectra with dominating macromolecule and lipid peaks.Materials and Methods:LCModel was used to process spectra. Mean metabolite concentrations and mean normalized spectra were obtained for normal white matter and for gliomas. The mean spectra of macromolecules and lipids (ML) in the range 1.4–0.9 ppm, and mean difference spectra (DS) without ML and lactate were computed. Correlation analysis of the scatter plot of the patient and mean normalized spectral amplitudes and dispersion of the scatter plot points were used for classification and grading of tumors.Results:It was found advantageous to perform the classifications using DS spectra. The shape of ML spectrum and concentration of tCr seem to be a good markers for glioma grade.Conclusion:Combining a qualitative comparison of the patient and mean DS spectra of the tumors using correlation analysis of normalized spectra amplitudes with a quantitative comparison of metabolite concentrations is a powerful tool in studying brain lesions. J. Magn. Reson. Imaging 2010;31:39–45. © 2009 Wiley‐Liss, Inc.
Objective and subjective evaluation of adaptive speech enhancement methods for functional MRI
Authors: Ramachandran Venkat R. , Panahi Issa M.S. , Milani Ali A. 
Published: December 2009

AbstractPurpose:To recover speech corrupted by functional magnetic resonance imaging (fMRI) acoustic noise using two‐channel adaptive speech enhancement techniques.Materials and Methods:Speech corrupted by noise generated from a 3 T MRI scanner was recorded using diffuse‐field microphones and a data acquisition board. Multiband and subband adaptive speech enhancement methods are used to recover the speech signal from the recordings. Normalized least mean squares (NLMS) algorithm was used for updating the filter coefficients in each band.Results:The methods are successful in enhancing the speech quality. They are successful in improving the convergence rate of the adaptive filter. Multiband and subband methods have a similar performance in terms of noise reduction and in the subjective tests. The subband method introduces less speech distortion compared to the multiband method. The subband method requires a lower number of computations per sample.Conclusion:Adaptive speech enhancement techniques are effective in reducing fMRI background noise in the recordings. Based on the analysis, we conclude that subband‐based methods are more suited for enhancing speech corrupted by fMRI noise. J. Magn. Reson. Imaging 2010;31:46–55. © 2009 Wiley‐Liss, Inc.
Diurnal stability of γ‐aminobutyric acid concentration in visual and sensorimotor cortex
Authors: Evans Christopher John , McGonigle David John , Edden Richard Anthony Edward 
Published: December 2009

AbstractPurpose:To establish the diurnal stability of edited magnetic resonance spectroscopy measurements of gamma‐aminobutyric acid (GABA) in visual and sensorimotor regions of the brain.Materials and Methods:GABA measurements were made in two regions of the brain (an occipital, “visual” region and a “sensorimotor” region centered on the precentral gyrus) using the MEGA‐PRESS editing method, scanning eight healthy adults at five timepoints during a single day. GABA concentration was quantified from the ratio of the GABA integral to the unsuppressed water signal.Results:No significant effect of time on GABA concentration was seen (P = 0.35). GABA was shown to be significantly more concentrated in visual regions than in sensorimotor regions (1.10 i.u. and 1.03 i.u., respectively; P = 0.050). Coefficients of variability (CVs) across all subjects of 9.1% and 12% (visual and sensorimotor) were significantly higher than mean within‐subjects CVs of 6.5% and 8.8.Conclusion:This study demonstrates the excellent reproducibility of MEGA‐PRESS detection of GABA, demonstrating that the method is sufficiently sensitive to detect inter‐subject variability, and suggests that (within the sensitivity limits of current measurements) time of day can be ignored in the design of MRS studies of visual and sensorimotor regions. J. Magn. Reson. Imaging 2010;31:204–209. © 2009 Wiley‐Liss, Inc.
Improved correction of spatial inhomogeneities of surface coils in quantitative analysis of first‐pass myocardial perfusion imaging
Authors: Kremers Frans P.P.J. , Hofman Mark B.M. , Groothuis Jan G.J. , Jerosch‐Herold Michael , Beek Aernout M. , Zuehlsdorff Sven , Nielles‐Vallespin Sonia , van Rossum Albert C. , Heethaar Robert M. 
Published: December 2009

AbstractPurpose:To test whether image normalization using either a separate 3D proton‐density (PD)‐weighted prescan, or 2D PD‐weighted images prior to the perfusion series, improves correction of differences in spatial sensitivity induced by radiofrequency (RF) surface receiver coils. Originally, this correction was applied using the baseline signal in the myocardium before arrival of the contrast agent. This is of importance, as quantitative analysis of magnetic resonance (MR) myocardial perfusion using deconvolution with the arterial input assumes equal signal sensitivity over the heart.Materials and Methods:First‐pass myocardial perfusion measurements were obtained in 13 patients without known coronary artery disease. Absolute perfusion values were assessed for 18 myocardial segments without any normalization and using the three different normalization methods.Results:Using 2D or 3D PD‐weighted normalization, similar mean perfusion values were found, but with reduced spatial variance over the 18 segments. The relative dispersion of perfusion at rest was 23% and 35% for the 3D prescan normalization and the baseline normalization, respectively. With 2D and 3D PD‐weighted prescan normalization the relative dispersion was closer to the expected physiological heterogeneity.Conclusion:PD‐weighted prescan normalization proved to be a valuable addition to quantitative analysis of myocardial perfusion, and better than baseline‐based normalization. J. Magn. Reson. Imaging 2010;31:227–233. © 2009 Wiley‐Liss, Inc.
Diffusion‐weighted images differentiate benign from malignant thyroid nodules
Authors: Erdem Gulnur , Erdem Tamer , Muammer Hakki , Mutlu Deniz Yakar , Fırat Ahmet Kemal , Sahin Ibrahim , Alkan Alpay 
Published: December 2009

AbstractPurpose:To reveal the possible role of diffusion‐weighted images (DWI) in the differential diagnosis of benign and malignant thyroid nodules by comparing the results of fine‐needle aspiration cytology (FNAC).Materials and Methods:In an 18‐month period (December 2005 to May 2007), 27 cases with benign thyroid nodules with a total of 52 benign nodules, nine cases with thyroid gland malignancy, and 24 healthy control cases were included in the study. Cases that were indicated to undergo to FNAC examination and sent by a clinician for biopsy to the radiology unit were included in the study to assess the cytopathologic confirmation of the clinic, ultrasonographic, and magnetic resonance imaging (MRI) findings.Results:The mean apparent diffusion coefficient (ADC) values of thyroid nodules were 2745.3 ± 601.1 × 10−6 mm2/s (1605–3899 × 10−6mm2/s) in the benign group and 695.2 ± 312.5 × 10−6mm2/s (165–1330 × 10−6mm2/s) in the malignant group. Normal thyroid tissues had mean ADC values of 1344.1 ± 276.4 × 10−6 mm2/s (1015–1764 × 10−6mm2/s). The ADC values of three subgroups were significantly different (P = 0.0001). A reduced ADC was observed in most types of malignant tumors due to the consequent decrease of the extracellular extravascular space.Conclusion:Our preliminary results showed that ADC values of nodules may provide useful data about the nature of a thyroid nodule. J. Magn. Reson. Imaging 2010;31:94–100. © 2009 Wiley‐Liss, Inc.
Neural specificity of acupuncture stimulation at pericardium 6: Evidence from an FMRI study
Authors: Bai Lijun , Yan Hao , Li Linling , Qin Wei , Chen Peng , Liu Peng , Gong Qiyong , Liu Yijun , Tian Jie 
Published: December 2009

AbstractPurpose:To investigate the neural specificity of pericardium PC6, with the same meridian acupoint PC7 and a treatment‐irrelevant acupoint GB37 as separate controls.Materials and Methods:Functional magnetic resonance imaging (MRI) of the whole brain was performed in 36 healthy subjects receiving acupuncture at three acupoints, respectively: the study acupoint (PC6), and control acupoints (PC7 and GB37). A novel nonrepeated event‐related (NRER) design paradigm was applied to separately detect neural activities related to different stages of acupuncture (needling manipulation and post‐acupuncture rest epoch). Psychophysical responses (Deqi sensations) were also assessed.Results:Neuroimaging studies of PC6 presented extensive signal attenuations in the cerebrocerebellar and subcortical areas, whereas acupuncture at GB37 induced widespread signal potentiations. In addition, acupuncture at PC6, in comparison with stimulations at PC7 and GB37, selectively evoked neural responses of the insula, hypothalamus, and flocculonodular lobe of cerebellum (nodulus and uvula).Conclusion:These findings may provide preliminary evidence for specific involvements of the cerebellar‐hypothalamus and insula following acupuncture at PC6, which underlies the autonomic regulation of vestibular functions. The predominantly time‐prolonged deactivations in these areas may also serve the clinical efficacy of PC6 in producing a sedative or tranquilizing effect in antiemetic treatment. J. Magn. Reson. Imaging 2010;31:71–77. © 2009 Wiley‐Liss, Inc.
Early identification of aortic valve sclerosis using iron oxide enhanced MRI
Authors: Hamilton Amanda M. , Rogers Kem A. , Belisle Andre J.L. , Ronald John A. , Rutt Brian K. , Weissleder Ralph , Boughner Derek R. 
Published: December 2009

AbstractPurpose:To test the ability of MION‐47 enhanced MRI to identify tissue macrophage infiltration in a rabbit model of aortic valve sclerosis (AVS).Materials and Methods:The aortic valves of control and cholesterol‐fed New Zealand White rabbits were imaged in vivo pre‐ and 48 h post‐intravenous administration of MION‐47 using a 1.5 Tesla (T) MR clinical scanner and a CINE fSPGR sequence. MION‐47 aortic valve cusps were imaged ex vivo on a 3.0T whole‐body MR system with a custom gradient insert coil and a three‐dimensional (3D) FIESTA sequence and compared with aortic valve cusps from control and cholesterol‐fed contrast‐free rabbits. Histopathological analysis was performed to determine the site of iron oxide uptake.Results:MION‐47 enhanced the visibility of both control and cholesterol‐fed rabbit valves in in vivo images. Ex vivo image analysis confirmed the presence of significant signal voids in contrast‐administered aortic valves. Signal voids were not observed in contrast‐free valve cusps. In MION‐47 administered rabbits, histopathological analysis revealed iron staining not only in fibrosal macrophages of cholesterol‐fed valves but also in myofibroblasts from control and cholesterol‐fed valves.Conclusion:Although iron oxide labeling of macrophage infiltration in AVS has the potential to detect the disease process early, a macrophage‐specific iron compound rather than passive targeting may be required. J. Magn. Reson. Imaging 2010;31:110–116. © 2009 Wiley‐Liss, Inc.
Scan‐rescan reproducibility of carotid atherosclerotic plaque morphology and tissue composition measurements using multicontrast MRI at 3T
Authors: Li Feiyu , Yarnykh Vasily L. , Hatsukami Thomas S. , Chu Baocheng , Balu Niranjan , Wang Jinnan , Underhill Hunter R. , Zhao Xihai , Smith Robin , Yuan Chun 
Published: December 2009

AbstractPurpose:To evaluate interscan reproducibility of both vessel morphology and tissue composition measurements of carotid atherosclerosis using a fast, optimized, 3T multicontrast protocol.Materials and Methods:A total of 20 patients with carotid stenosis >15% identified by duplex ultrasound were recruited for two independent 3T MRI (Philips) scans within one month. A multicontrast protocol including five MR sequences was applied: TOF, T1‐/T2‐/PD‐weighted and magnetization‐prepared rapid acquisition gradient‐echo (MP‐RAGE). Carotid artery morphology (wall volume, lumen volume, total vessel volume, normalized wall index, and mean/maximum wall thickness) and plaque component size (lipid rich/necrotic core, calcification, and hemorrhage) were measured over two time points.Results:After exclusion of images with poor image quality, 257 matched locations from 18 subjects were available for analysis. For the quantitative carotid morphology measurements, coefficient of variation (CV) ranged from 2% to 15% and intraclass correlation coefficient (ICC) ranged from 0.87 to 0.99. Except for maximum wall thickness (ICC = 0.87), all ICC were larger than 0.90. For the quantitative plaque composition measurements, the ICC of the volume and relative content of lipid rich/necrotic core and calcification were larger than 0.90 with CV ranging from 22% to 32%.Conclusion:The results from the multicontrast high‐resolution 3T MR study show high reliability for carotid morphology and plaque component measurements. 3T MRI is a reliable tool for longitudinal clinical trials, with shorter scan time compared to 1.5T. J. Magn. Reson. Imaging 2010;31:168–176. © 2009 Wiley‐Liss, Inc.
Measuring aortic diameter with different MR techniques: Comparison of three‐dimensional (3D) navigated steady‐state free‐precession (SSFP), 3D contrast‐enhanced magnetic resonance angiography (CE‐MRA), 2D T2 black blood, and 2D cine SSFP
Authors: Potthast Silke , Mitsumori Lee , Stanescu Luana A. , Richardson Michael L. , Branch Kelley , Dubinsky Theodore J. , Maki Jeffrey H. 
Published: December 2009

AbstractPurpose:To compare nongated three‐dimensional (3D) contrast‐enhanced magnetic resonance angiography (CE‐MRA) with 3D‐navigated cardiac‐gated steady‐state free‐precession bright blood (3D‐nav SSFP) and noncontrast 2D techniques for ascending aorta dimension measurements.Materials and Methods:Twenty‐five clinical exams were reviewed to evaluate the ascending aorta at 1.5T using: breathhold cine bright blood (SSFP), cardiac‐triggered T2 black blood (T2 BB), axial 3D‐nav SSFP, and nongated 3D CE‐MRA. Three radiologists independently measured aortic size at three specified locations for each sequence. Means, SDs, interobserver correlation, and vessel edge sharpness were statistically evaluated.Results:Measurements were greatest for 3D‐nav SSFP and 3D CE‐MRA and smallest for T2 BB. There was no significant difference between 3D‐nav SSFP and 3D CE‐MRA (P = 0.43–0.86), but significance was observed comparing T2 BB to all sequences. Interobserver agreement was uniformly >0.9, with T2 BB best, followed closely by 3D‐nav SSFP and 2D cine SSFP, and 3D CE‐MRA being the worst. Edge sharpness was significantly poorer for 3D CE‐MRA compared to the other sequences (P < 0.001).Conclusion:If diameter measurements are the main clinical concern, 3D‐nav SSFP appears to be the best choice, as it has a sharp edge profile, is easy to acquire and postprocess, and shows very good interobserver correlation. J. Magn. Reson. Imaging 2010;31:177–184. © 2009 Wiley‐Liss, Inc.
Cerebral asymmetry in patients with schizophrenia: A voxel‐based morphometry (VBM) and diffusion tensor imaging (DTI) study
Authors: Takao Hidemasa , Abe Osamu , Yamasue Hidenori , Aoki Shigeki , Kasai Kiyoto , Ohtomo Kuni 
Published: December 2009

AbstractPurpose:To evaluate the differences in gray‐ and white‐matter asymmetry between schizophrenia patients and normal subjects.Materials and Methods:Forty‐eight right‐handed patients with chronic schizophrenia (24 males and 24 females) and 48 right‐handed age‐ and sex‐matched healthy controls (24 males and 24 females) were included in this study. The effects of diagnosis on gray‐matter volume asymmetry and white‐matter fractional anisotropy (FA) asymmetry were evaluated with use of voxel‐based morphometry (VBM) and voxel‐based analysis of FA maps derived from diffusion tensor imaging (DTI), respectively.Results:The mean gray‐ and white‐matter volumes were significantly smaller in the schizophrenia group than in the control group. The voxel‐based morphometry (VBM) showed no significant effect of diagnosis on gray‐matter volume asymmetry. The voxel‐based analysis of DTI also showed no significant effect of diagnosis on white‐matter FA asymmetry.Conclusion:Our results of voxel‐based analyses showed no significant differences in either gray‐matter volume asymmetry or white‐matter FA asymmetry between schizophrenia patients and normal subjects. J. Magn. Reson. Imaging 2010;31:221–226. © 2009 Wiley‐Liss, Inc.
B1 transmission‐field inhomogeneity and enhancement ratio errors in dynamic contrast‐enhanced MRI (DCE‐MRI) of the breast at 3T
Authors: Azlan Che A. , Di Giovanni Pierluigi , Ahearn Trevor S. , Semple Scott I.K. , Gilbert Fiona J. , Redpath Thomas W. 
Published: December 2009

AbstractPurpose:To quantify B1 transmission‐field inhomogeneity in breast imaging of normal volunteers at 3T using 3D T1‐weighted spoiled gradient echo and to assess the resulting errors in enhancement ratio (ER) measured in dynamic contrast‐enhanced MRI (DCE‐MRI) studies of the breast.Materials and Methods:A total of 25 volunteers underwent breast imaging at 3T and the B1 transmission‐fields were mapped. Gel phantoms that simulate pre‐ and postcontrast breast tissue T1 were developed. The effects of B1‐field inhomogeneity on ER, as measured using a 3D spoiled gradient echo sequence, were investigated by computer simulation and experiments on gel phantoms.Results:It was observed that by using the patient orientation and MR scanner employed in this study, the B1 transmission‐field field is always reduced toward the volunteer's right side. The median B1‐field in the right breast is reduced around 40% of the expected B1‐field. For some volunteers the amplitude was reduced by more than 50%. Computer simulation and experiment showed that a reduction in B1‐field decreases ER. This reduction increases with both B1‐field error and contrast agent uptake.Conclusion:B1 transmission‐field inhomogeneity is a critical issue in breast imaging at 3T and causes errors in quantifying ER. These errors would be sufficient to reduce the conspicuity of a malignant lesion and could result in reduced sensitivity for cancer detection. J. Magn. Reson. Imaging 2010;31:234–239. © 2009 Wiley‐Liss, Inc.
Modern lipid‐, carbohydrate‐, and peptide‐based delivery systems for peptide, vaccine, and gene products
Authors: Simerska Pavla , Moyle Peter M. , Toth Istvan 
Published: December 2009

AbstractResearch related to peptide, vaccine, and gene delivery has grown exponentially over the last decade. In this review, we discuss the development of delivery systems for peptides, gene and vaccine products. Special focus is given to different lipidation and glycosylation strategies to improve the metabolic stability and membrane permeability of therapeutics, and their targeting to specific sites. The synthetic methods for preparation of the systems are also described. © 2009 Wiley Periodicals, Inc. Med Res Rev, 31, No. 4, 520–547, 2011
The design of orally bioavailable 2, 5‐diketopiperazine oxytocin antagonists: from concept to clinical candidate for premature labor
Authors: Borthwick Alan D. , Liddle John 
Published: December 2009

AbstractA short, efficient and highly stereoselective synthesis has been developed for a series of 6‐indanyl‐3‐alkyl‐7‐aryl/heterocyclic‐(3R, 6R, 7R)‐2, 5‐diketopiperazine amides that are potent and selective oxytocin (OT) antagonists. Property‐based design using an estimate of human oral absorption enabled focus to be directed to those templates with the greatest chance of delivering high bioavailability in humans. This led to the 2′, 4′‐difluorophenyl dimethylamide 40, a highly potent (pKi=9.2) and selective OT antagonist (>1,000‐fold selectivity vs. the human vasopressin receptors V1a, V2, and V1b) with good oral bioavailability (>50%) in the rat and dog. Increased solubility and an improved Cyp450 profile was achieved with a range of 2′‐substituted 7‐(1′,3′‐oxazol‐4′‐yl)‐(3R,6R,7R)‐2,5‐diketopiperazine amides and branching at the α‐carbon of the 3‐butyl group led to a superior rat pharmacokinetic profile that resulted in the discovery of the 2′‐methyl‐1′,3′‐oxazol‐4′‐yl morpholine amide derivative 74 GSK221149A (Retosiban), which had the best oral exposure and bioavailability in the rat. Retosiban has sub‐nanomolar affinity (Ki=0.65 nM) for the oxytocin receptor with >1400‐fold selectivity over the closely related vasopressin receptors. It has good solubility, low protein binding and has a good Cyp450 profile with no significant inhibition IC50>100 µM. Retosiban is >15‐fold more potent at the human oxytocin receptor than atosiban (a marketed i.v, peptide OT antagonist) and it has been shown to be an effective tocolytic by i.v. and by oral administration in rats, and was selected for progression as a potential clinical candidate for preterm labor.  © 2009 Wiley Periodicals, Inc. Med Res Rev 31:576‐604, 2011
When does two‐grid optimality carry over to the V‐cycle?
Authors: Napov Artem , Notay Yvan 
Published: December 2009

AbstractWe investigate additional condition(s) that confirm that a V‐cycle multigrid method is satisfactory (say, optimal) when it is based on a two‐grid cycle with satisfactory (say, level‐independent) convergence properties. The main tool is McCormick's bound on the convergence factor (SIAM J. Numer. Anal. 1985; 22:634–643), which we showed in previous work to be the best bound for V‐cycle multigrid among those that are characterized by a constant that is the maximum (or minimum) over all levels of an expression involving only two consecutive levels; that is, that can be assessed considering only two levels at a time. We show that, given a satisfactorily converging two‐grid method, McCormick's bound allows us to prove satisfactory convergence for the V‐cycle if and only if the norm of a given projector is bounded at each level. Moreover, this projector norm is simple to estimate within the framework of Fourier analysis, making it easy to supplement a standard two‐grid analysis with an assessment of the V‐cycle potentialities. The theory is illustrated with a few examples that also show that the provided bounds may give a satisfactory sharp prediction of the actual multigrid convergence. Copyright © 2009 John Wiley & Sons, Ltd.