bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vivo detection of GABA and glutamate with MEGA‐PRESS: Reproducibility and gender effects
Authors: O'Gorman Ruth L. , Michels Lars , Edden Richard A. , Murdoch James B. , Martin Ernst 
Published: April 2011

AbstractPurpose:To evaluate the reproducibility of γ‐amino‐butyric acid (GABA) and glutamate concentrations derived using three different spectral fitting methods, and to investigate gender‐related differences in neurotransmitter levels.Materials and Methods:Single voxel MEGA‐edited PRESS MR spectra were acquired from a 30‐mL voxel in the dorso‐lateral prefrontal cortex in 14 adult volunteers (7 female) at 3 Tesla (3T). For each participant, four consecutive resting spectra were acquired within the same scanning session. Metabolite concentrations were derived using LCModel, jMRUI, and locally written peak fitting software. The within‐session reproducibility for each analysis method was calculated as the average coefficient of variation (CV) of the GABA and Glx (glutamate+glutamine) concentrations. Gender differences in GABA and Glx were evaluated using a two‐tailed unpaired t‐test.Results:LCModel provided the best reproducibility for both GABA (CV 7%) and Glx (CV 6%). GABA, Glx, and glutamate concentrations were significantly higher in the male participants, (P = 0.02, P = 0.001, and P < 0.001, respectively).Conclusion:GABA and glutamate can be quantified in vivo with high reproducibility (CV 6–7%) using frequency‐domain spectral fitting methods like LCModel. However, the GABA and glutamate concentrations vary significantly between men and women, emphasizing the importance of gender‐matching for studies investigating differences in neurotransmitter concentrations between mixed‐cohort groups. J. Magn. Reson. Imaging 2011;33:1262–1267. © 2011 Wiley‐Liss, Inc.
Quantifying synovitis in rheumatoid arthritis using computer‐assisted manual segmentation with 3 tesla MRI scanning
Authors: Chand Arista S. , McHaffie Alexandra , Clarke Andrew W. , Reeves Quentin , Tan Yu Mwee , Dalbeth Nicola , Williams Megan , McQueen Fiona 
Published: April 2011

AbstractPurpose:To investigate the reliability, validity and feasibility of a computer‐assisted manual segmentation method for determining the synovial membrane volume as a surrogate measure for synovitis in patients with rheumatoid arthritis (RA).Materials and Methods:The 3 Tesla (T) MRI scans were acquired in 22 early RA and 16 established RA patients. Synovial membrane volumes in postcontrast T1w axial images at three wrist joint regions were determined by two nonradiologist observers using a computer‐assisted manual segmentation method.Results:Intraobserver reliability, measured by intraclass correlation coefficients (ICCs), was excellent in the early (ICC = 0.99) and established (ICC = 0.99) RA cohorts. Interobserver reliability (mean ICC [95% Confidence Interval]) was moderate to excellent in the early and established RA groups (ICCs = 0.87 [0.68,0.94] and 0.88 [0.66, 0.96], respectively). There was a strong correlation between the synovial membrane volumes derived by segmentation and the RA MRI scoring system (RAMRIS) scores for synovitis at all joints in the early (Spearman rho = 0.86–0.96) and established (Spearman rho = 0.85–0.93) RA cohorts. The entire segmentation technique took 19 to 21 min per patient.Conclusion:Measurement of MRI synovitis using a computer‐assisted manual segmentation method demonstrated excellent intraobserver and very good interobserver reliability, content validity (represented by its strong correlation with RAMRIS synovitis), and moderate feasibility. J. Magn. Reson. Imaging 2011;33:1106–1113. © 2011 Wiley‐Liss, Inc.
Sensitivity of USPIO‐enhanced R2 imaging to dynamic blood volume changes in the rat kidney
Authors: Storey Pippa , Ji Lin , Li Lu‐Ping , Prasad Pottumarthi V. 
Published: April 2011

AbstractPurpose:To determine whether MRI in combination with an intravascular contrast agent is sensitive to pharmacologically induced vasodilation and vasoconstriction in the rat kidney.Materials and Methods:R2 imaging was performed in 25 Sprague Dawley rats at 3 Tesla in the presence of ferumoxytol, an ultrasmall superparamagnetic iron oxide (USPIO) agent with a long plasma half‐life. R2 changes were measured following manipulation of blood volume by intravenous administration of adenosine, a short‐acting vasodilator, or NG‐nitro‐L‐arginine methyl ester (L‐NAME), a long‐acting nitric oxide synthase inhibitor with known vasoconstrictive effects. As a control, R2 responses to adenosine and L‐NAME were also examined in the absence of ferumoxytol.Results:In the presence of ferumoxytol, adenosine induced a significant increase in R2, while L‐NAME produced a reduction, although the latter was not statistically significant. Control experiments revealed small R2 changes in the absence of ferumoxytol. An incidental finding was that the cross‐sectional area of the kidney also varied dynamically with adenosine and L‐NAME.Conclusion:Our results suggest that ferumoxytol‐enhanced R2 imaging is sensitive to adenosine‐induced vasodilation. The responses to L‐NAME, however, were not statistically significant. The variations in kidney size and the R2 changes in the absence of ferumoxytol may reflect alterations in the volume of the renal tubules. J. Magn. Reson. Imaging 2011;33:1091–1099. © 2011 Wiley‐Liss, Inc.
Assessment of small bowel motility function With cine‐MRI using balanced steady‐state free precession sequence
Authors: Wakamiya Makoto , Furukawa Akira , Kanasaki Shuzo , Murata Kiyoshi 
Published: April 2011

AbstractPurpose:To evaluate the use of cine‐magnetic resonance imaging (MRI) with a steady‐state free precession sequence to monitor and assess small bowel motility.Materials and Methods:Sequential MRI, using a balanced steady‐state free precession sequence, was performed in eight healthy male volunteers at 0, 15, 30, 45, and 60 minutes after oral administration of 1500 mL of nonabsorbable fluid to monitor small bowel contractions. Using the cine‐mode display, small bowel contractions were reviewed and the luminal diameter was measured on each image to obtain frequency and amplitude of bowel contractions.Results:The oral preparation was well tolerated without major complications. Cine‐MRI provided high temporal, spatial, and contrast resolution for monitoring bowel contractions. Mean values with standard deviations of frequency and amplitude of bowel contractions were 6.0 ± 2.98/min and 10.4 ± 4.53 mm, respectively, and were 5.1 ± 3.38/min and 9.59 ± 5.57 mm at the jejunal loops and 6.9 ± 2.22/min and 11.2 ± 3.06 mm at the ileal loops. With the passage of luminal fluid, frequency of bowel contractions decreased and the bowels tended to pause their contractions.Conclusion:Cine‐MRI provides sufficient dynamic images to observe small bowel contractions. Measurement of bowel caliber permits calculation of amplitude and frequency of the contractions for characterization and quantitative assessment of small bowel motility function. J. Magn. Reson. Imaging 2011;33:1235–1240. © 2011 Wiley‐Liss, Inc.
Quality assessment of high angular resolution diffusion imaging data using bootstrap on Q‐ball reconstruction
Authors: Cohen‐Adad Julien , Descoteaux Maxime , Wald Lawrence L. 
Published: April 2011

AbstractPurpose:To develop a bootstrap method to assess the quality of High Angular Resolution Diffusion Imaging (HARDI) data using Q‐Ball imaging (QBI) reconstruction.Materials and Methods:HARDI data were re‐shuffled using regular bootstrap with jackknife sampling. For each bootstrap dataset, the diffusion orientation distribution function (ODF) was estimated voxel‐wise using QBI reconstruction based on spherical harmonics functions. The reproducibility of the ODF was assessed using the Jensen‐Shannon divergence (JSD) and the angular confidence interval was derived for the first and the second ODF maxima. The sensitivity of the bootstrap method was evaluated on a human subject by adding synthetic noise to the data, by acquiring a map of image signal‐to‐noise ratio (SNR) and by varying the echo time and the b‐value.Results:The JSD was directly linked to the image SNR. The impact of echo times and b‐values was reflected by both the JSD and the angular confidence interval, proving the usefulness of the bootstrap method to evaluate specific features of HARDI data.Conclusion:The bootstrap method can effectively assess the quality of HARDI data and can be used to evaluate new hardware and pulse sequences, perform multifiber probabilistic tractography, and provide reliability metrics to support clinical studies. J. Magn. Reson. Imaging 2011;33:1194–1208. © 2011 Wiley‐Liss, Inc.
Measurement of temperature dependent changes in bone marrow using a rapid chemical shift imaging technique
Authors: Taylor Brian A. , Elliott Andrew M. , Hwang Ken‐Pin , Shetty Anil , Hazle John D. , Stafford R. Jason 
Published: April 2011

AbstractPurpose:To provide quantitative temperature monitoring for thermal therapies in bone marrow by measuring temperature‐dependent signal changes in the bone marrow of ex vivo canine femurs heated with a 980‐nm laser at 1.5T and 3.0T.Materials and Methods:Using a multi‐gradient echo (≤16) acquisition and signal modeling with the Stieglitz–McBride algorithm, the temperature sensitivity coefficients (TSC, ppm/°C) of water and multiple lipid components' proton resonance frequency (PRF) values are measured at high spatiotemporal resolutions (1.6 × 1.6 × 4 mm3, ≤5 seconds). Responses in R2* and amplitudes of each peak were also measured as a function of temperature simultaneously.Results:Calibrations demonstrate that lipid signal may be used to compensate for B0 errors to provide accurate temperature readings (<1.0°C). Over a temperature range of 17.2–57.2°C, the TSCs after correction to a bulk methylene reference are −0.87 × 10−2 ± 4.7 × 10−4 ppm/°C and −0.87 × 10−2 ± 4.0 × 10−4 ppm/°C for 1.5T and 3.0T, respectively.Conclusion:Overall, we demonstrate that accurate and precise temperature measurements can be made in bone marrow. In addition, the relationship of R2* and signal amplitudes with respect to temperature are shown to differ significantly where conformal changes are predicted by Arrhenius rate model analysis. J. Magn. Reson. Imaging 2011;33:1128–1135. © 2011 Wiley‐Liss, Inc.
Diffusion‐weighted MR imaging in pancreatic endocrine tumors correlated with histopathologic characteristics
Authors: Wang Yi , Chen Zongming E. , Yaghmai Vahid , Nikolaidis Paul , McCarthy Robert J. , Merrick Laura , Miller Frank H. 
Published: April 2011

AbstractPurpose:To retrospectively assess apparent diffusion coefficients (ADCs) of different subtypes of pancreatic endocrine tumors based on the World Health Organization (WHO) classification system and analyze the potentially responsible histopathologic characteristics.Materials and Methods:Following Institutional Review Board (IRB) approval, 18 patients with surgical pathology‐proven pancreatic endocrine tumors were evaluated. Tumors were subcategorized based on the WHO grading classification into well‐differentiated tumors with benign and uncertain behavior and endocrine carcinomas with well and poor differentiation. ADCs were measured on diffusion‐weighted (DW) images and compared using Student's t‐test and one‐way analysis of variance. The correlation between ADCs, tumor cellularity, Ki‐67 labeling index (an index of cell growth), and extracellular fibrosis were analyzed.Results:A difference was demonstrated in mean ADCs between well‐differentiated endocrine tumors (1.75 ± 0.53) and endocrine carcinomas (1.00 ± 0.19 × 10−3mm2/sec) (P < 0.01). After excluding the three well‐differentiated endocrine tumors with benign behavior and marked fibrosis, a significant inverse correlation between ADC values and cellularity of endocrine tumors was observed. An inverse correlation was seen between Ki‐67 labeling index and ADC values (r = −0.70; P < 0.01).Conclusion:Tumor cellularity and/or extracellular fibrosis may account for various ADCs in pancreatic endocrine tumors. ADC correlates well with the Ki‐67 labeling index and may help predict growth of endocrine tumors. J. Magn. Reson. Imaging 2011;33:1071–1079. © 2011 Wiley‐Liss, Inc.
Whole‐body MRI including diffusion‐weighted imaging (DWI) for patients with recurring prostate cancer: Technical feasibility and assessment of lesion conspicuity in DWI
Authors: Eiber Matthias , Holzapfel Konstantin , Ganter Carl , Epple Kathrin , Metz Stephan , Geinitz Hans , Kübler Hubert , Gaa Jochen , Rummeny Ernst J. , Beer Ambros J. 
Published: April 2011

AbstractPurpose:To evaluate the principal methodological aspects of whole‐body magnetic resonance imaging (MRI) including diffusion‐weighted imaging (DWI) with background suppression using a time‐optimized protocol for restaging of prostate cancer patients in a technical feasibility study.Materials and Methods:Seventeen patients underwent MRI at 1.5T from the base of the skull to the proximal thigh using axial T1‐weighted (T1w), T2w short‐tau inversion recovery (STIR), and DWI (b‐values: 50 and 500 s/mm2) and sagittal T1w and T2w STIR of the spine. Apparent diffusion coefficient (ADC) values of liver, spleen, kidney, muscle, and bone were measured. Image quality in DWI was assessed by using a scale from 0–9. Contrast‐to‐noise ratios (CNRs) of lymph node and bone metastases were determined in T1w, T2w STIR, and DWI. Bone metastases were further subclassified according to their Hounsfield units (HU) in computed tomography (CT).Results:Mean acquisition and mean room times were 66:20 and 75:21 minutes, respectively. ADC values of normal organs showed good concordance with reported data. Good to excellent image quality was observed for DWI (mean scores 7.41–8.00) with the exception of the neck (mean score 4.76). CNR of DWI (b‐value 50 s/mm2) for lymph node metastases was clearly superior compared to all other sequences. For bone metastases T1w performed significantly better for sclerotic lesions (HU > 600), DWI (b‐value 50 s/mm2) for nonsclerotic lesion (HU < 300).Conclusion:In patients with recurrent prostate cancer a whole‐body MR protocol including DWI is technically robust. Due to the high CNR of DWI compared to T1w and T2w STIR, detection of malignant lesions should be facilitated by DWI, except for sclerotic bone metastases. J. Magn. Reson. Imaging 2011;33:1160–1170. © 2011 Wiley‐Liss, Inc.
Quantification of background enhancement in breast magnetic resonance imaging
Authors: Klifa C. , Suzuki S. , Aliu S. , Singer L. , Wilmes L. , Newitt D. , Joe B. , Hylton N. 
Published: April 2011

AbstractPurpose:To present a novel technique for measuring tissue enhancement in breast fibroglandular tissue regions on contrast‐enhanced breast magnetic resonance imaging (MRI) aimed at quantifying the enhancement of breast parenchyma, also known as “background enhancement.”Materials and Methods:Our quantitative method for measuring breast MRI background enhancement was evaluated in a population of 16 healthy volunteers. We also demonstrate the use of our new technique in the case study of one subject classified as high risk for developing breast cancer who underwent 3 months of tamoxifen therapy.Results:We obtained quantitative measures of background enhancement in all cases. The high‐risk patient exhibited a 37% mean reduction in background enhancement with treatment.Conclusion:Our quantitative method is a robust and promising tool that may allow investigators to quantify and document the potential adverse effect of background enhancement on diagnostic accuracy in larger populations. J. Magn. Reson. Imaging 2011;33:1229–1234. © 2011 Wiley‐Liss, Inc.
MRI for staging lymphoma: Whole‐body or less?
Authors: Kwee Thomas C. , Akkerman Erik M. , Fijnheer Rob , José Kersten Marie , Zsíros József , Ludwig Inge , Bierings Marc B. , Vermoolen Malou A. , van Leeuwen Maarten S. , Stoker Jaap , Nievelstein Rutger A.J. 
Published: April 2011

AbstractPurpose:To assess whether whole‐body MRI detects more clinically relevant lesions (i.e., leading to a change in Ann Arbor stage) than an MRI protocol that only includes the head/neck and trunk (i.e., from cranial vertex to groin, excluding the arms) in patients with lymphoma.Materials and Methods:One hundred consecutive patients with newly diagnosed lymphoma prospectively underwent T1‐weighted and T2‐weighted short inversion time inversion recovery whole‐body MRI. The number of lymphomatous sites at MRI with a field of view (FOV) limited to the head/neck and trunk, and the additional number of lymphomatous sites at whole‐body MRI and their influence on Ann Arbor stage were determined.Results:At MRI with a FOV limited to the head/neck and trunk, 507 sites were classified as lymphomatous. At whole‐body MRI, 7 additional sites outside the head/neck and trunk in 7 patients (7.0%; 95% confidence interval: 3.4–13.8%) were classified as lymphomatous, but Ann Arbor stage never changed.Conclusion:Whole‐body MRI did not detect any clinically relevant lesions outside the FOV of an MRI protocol that only includes the head/neck and trunk. Therefore, it may be sufficient to only include the head/neck and trunk when using MRI for staging lymphoma. J. Magn. Reson. Imaging 2011;33:1144–1150. © 2011 Wiley‐Liss, Inc.
Correlation of diffusion‐weighted imaging data with apoptotic and proliferation indexes in CT26 colorectal tumor homografts in balb/c mouse
Authors: Zhang Xiao‐Yan , Sun Ying‐Shi , Tang Lei , Xue Wei‐Cheng , Zhang Xiao‐Peng 
Published: April 2011

AbstractPurpose:To investigate whether the percentage of apparent diffusion coefficient (ADC) changes could be used as an imaging marker related to tumor cell apoptotic and Ki‐67 proliferation index of tumors.Materials and Methods:Mice bearing CT26 colorectal carcinoma tumors were scanned before radiotherapy, then divided into radiotherapy (n = 24) and control groups (n = 24). Diffusion‐weighted imaging (DWI) and anatomic T2WI were performed on six randomly chosen mice in total from two groups at different timepoints after radiotherapy (4, 8, 12 hours, 1, 2, 3, 5, 7 days). After imaging, six animals were sacrificed at each timepoint and histological analyses were undertaken. ADC maps were calculated on a pixel‐by‐pixel basis using built‐in software (Functool, GE). Regions of interest were manually circumscribed for all high‐signal areas on lesions observed during DWI. The percentage of ADC changes were calculated at predefined timepoints and compared with the apoptotic and proliferation index from the histological analyses by using the Pearson correlation test.Results:A significant positive correlation was found between the percentage of ADC changes of the viable tissue and apoptotic index. A significant negative correlation was found between the percentage of ADC changes of the viable tissue and Ki‐67 proliferation index.Conclusion:Our results suggest that the percentage of ADC changes can be used as a measurement of cell apoptotic and proliferation index in colorectal carcinoma. J. Magn. Reson. Imaging 2011;33:1171–1176. © 2011 Wiley‐Liss, Inc.
Optimizing the osteogenic potential of adult stem cells for skeletal regeneration
Authors: Lim Jung Yul , Loiselle Alayna E. , Lee Jeong Soon , Zhang Yue , Salvi Joshua D. , Donahue Henry J. 
Published: April 2011

AbstractAdult stem cells, including mesenchymal stem cells, display plasticity in that they can differentiate toward various lineages including bone cells, cartilage cells, fat cells, and other types of connective tissue cells. However, it is not clear what factors direct adult stem cell lineage commitment and terminal differentiation. Emerging evidence suggests that extracellular physical cues have the potential to control stem cell lineage specification. In this perspective article, we review recent findings on biomaterial surface and mechanical signal regulation of stem cell differentiation. Specifically, we focus on stem cell response to substrate nanoscale topography and fluid flow induced shear stress and how these physical factors may regulate stem cell osteoblastic differentiation in vitro. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29:1627–1633, 2011
Separation and determination of 11 marker pteridines in human urine by liquid chromatography and fluorimetric detection
Authors: de Llanos Alicia M. , Espinosa‐Mansilla Anunciación , Cañada‐Cañada Florentina , de la Peña Arsenio M. 
Published: April 2011

AbstractA simple liquid chromatographic method has been developed to achieve the complete separation and determination of a wide range of pteridinic compounds and creatinine (CREA) in urine samples, in just one run. The influences of mobile phase composition and buffer pH have been studied. The optimized mobile phase was composed of a Tris‐HCl buffer (15 mmol/L) at pH 6.10 solution (eluent A) and a Tris‐HCl buffer (15 mmol/L) at pH 6.40 solution (eluent B), in gradient mode. Analytes were determined by fluorimetric detection, exciting at 272 nm, and measuring the fluorescence emission at three wavelengths, 410, 445 and 465 nm. CREA, as a reference of metabolites excretion in urine, was determined by photometric detection at 230 nm. Pteridines detection limits varied from 0.2 to 6.1 ng/mL, and 0.2 g/mL for CREA. Calculated precision values expressed as RSD (%) varied from 1.1 to 5.9. Two different oxidation procedures for urine samples were optimized. The neopterin/biopterin ratios found were 0.98 and 0.86 for adults and children, respectively, by means of the alkaline iodide/iodine oxidation and 0.45 and 0.57 using neutral KMnO4 oxidation.
Is the Reduction in Tracer Diffusivity under Nanoscopic Confinement Related to a Frustrated Segmental Mobility?
Authors: Napolitano Simone , Rotella Cinzia , Wübbenhorst Michael 
Published: April 2011

AbstractWe developed an experimental method for the determination of the tracer diffusivity Dtr in ultrathin polymer films, and the changes in the segmental mobility of tracer molecules while they diffuse through matrices of different thickness and get adsorbed onto a target substrate. Dtr starts decreasing already at 120–150 nm and drops to 1% of its bulk value in films as thin as 7.5 nm. We discuss the results highlighting a strong decoupling between the reduction in mass transport at the nanoscale and the increase in the glass transition temperature determined via capacitive dilatometry together with a breakdown of the Stokes–Einstein relation between orientational and translational degrees of freedom. magnified image
Precision Synthesis of Poly(3‐hexylthiophene) from Catalyst‐Transfer Suzuki−Miyaura Coupling Polymerization
Authors: Yokozawa Tsutomu , Suzuki Ryosuke , Nojima Masataka , Ohta Yoshihiro , Yokoyama Akihiro 
Published: April 2011

AbstracttBu3 PPd(Ph)Br (1)‐catalyzed Suzuki‐Miyaura coupling polymerization of 2‐(4‐hexyl‐5‐iodo‐2‐thienyl)‐4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolane (2) was investigated. Monomer 2 was polymerized with 1 at 0 °C in the presence of CsF and 18‐crown‐6 in THF containing a small amount of water to yield P3HT with a narrow molecular weight distribution and almost perfect head‐to‐tail regioregularity. The $\overline {M} _{{\rm n}} $ values increased up to 11 400 g · mol−1 in proportion to the feed ratio of 2 to 1. The MALDI‐TOF mass spectra showed that P3HT with moderate molecular weight uniformly had a phenyl group at one end and a hydrogen atom at the other, indicating involvement of a catalyst‐transfer mechanism. Successive 1‐catalyzed polymerization of fluorene monomer 3 and then 2 yielded a well‐defined block copolymer of polyfluorene and P3HT. magnified image
Combining RAFT Radical Polymerization and Click/Highly Efficient Coupling Chemistries: A Powerful Strategy for the Preparation of Novel Materials
Authors: Harvison M. Alyse , Lowe Andrew B. 
Published: April 2011

AbstractThis paper highlights the powerful combination of reversible addition–fragmentation chain transfer (RAFT) radical polymerization and various click/coupling chemistries. This is not an exhaustive review but rather an overview demonstrating the impressive possibilities that the “marriage” of these two synthetic approaches offers in modern macromolecular design and synthesis. magnified image