bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative bone matrix density measurement by water‐ and fat‐suppressed proton projection MRI (WASPI) with polymer calibration phantoms
Authors: Cao Haihui , Ackerman Jerome L. , Hrovat Mirko I. , Graham Lila , Glimcher Melvin J. , Wu Yaotang 
Published: November 2008

AbstractThe density of the organic matrix of bone substance is a critical parameter necessary to clinically evaluate and distinguish structural and metabolic pathological conditions such as osteomalacia in adults and rickets in growing children. Water‐ and fat‐suppressed proton projection MRI (WASPI) was developed as a noninvasive means to obtain this information. In this study, a density calibration phantom was developed to convert WASPI intensity to true bone matrix density. The phantom contained a specifically designed poly(ethylene oxide)/poly(methyl methacrylate) (PEO/PMMA) blend, whose MRI properties (T1, T2, and resonance linewidth) were similar to those of solid bone matrix (collagen, tightly bound water, and other immobile molecules), minimizing the need to correct for differences in T1 and/or T2 relaxation between the phantom and the subject. Cortical and trabecular porcine bone specimens were imaged using WASPI with the calibration phantom in the field of view (FOV) as a stable intensity reference. Gravimetric and amino acid analyses were carried out on the same specimens after WASPI, and the chemical results were found to be highly correlated (r2 = 0.98 and 0.95, respectively) to the WASPI intensity. By this procedure the WASPI intensity can be used to obtain the true bone matrix mass density in g cm–3. Magn Reson Med 60:1433–1443, 2008. © 2008 Wiley‐Liss, Inc.
Tumor imaging using P866, a high‐relaxivity gadolinium chelate designed for folate receptor targeting
Authors: Corot Claire , Robert Philippe , Lancelot Eric , Prigent Philippe , Ballet Sébastien , Guilbert Irène , Raynaud Jean‐Sébastien , Raynal Isabelle , Port Marc 
Published: November 2008

AbstractThe objective of this study was to evaluate the potential of a high‐relaxivity macromolecular gadolinium (Gd) chelate to target folate receptors (FRs). P866 is a dimeric high‐relaxivity Gd chelate coupled to a folate moiety. Binding affinity, in vivo biodistribution studies in KB tumor‐bearing mice at 1, 4, and 24 h, and dynamic contrast‐enhanced (DCE)‐MRI (2.35 T) over 4 h were assessed. Binding and internalization of P866 through the FR was demonstrated. Due to the high molecular volume of P866, the binding affinity compared to free FA was decreased (KD = 59.3 ± 1.8 nM and 5.9 ± 0.2 nM, respectively). Tumor/muscle (T/M) uptake was 5.4 ± 1.0, 4 h after injection of 15 μmol/kg. Competition with free FA was less effective when the dose was increased due to a saturation of FR. At a dose of 5 μmol/kg, a 70% difference in signal enhancement was observed between P866 and the nonspecific reference compound, thus demonstrating the specificity of FR targeting. While this high‐relaxivity folate‐Gd chelate has demonstrated its potential capacity to target in vivo FR on tumors, the sensitivity is probably limited to a certain extent by the saturation of the FR and by the decrease in the apparent relaxivity of the internalized part of P866 in the tumor cells. Magn Reson Med 60:1337–1346, 2008. © 2008 Wiley‐Liss, Inc.
Kinetics of avidin‐induced clearance of biotinylated bimodal liposomes for improved MR molecular imaging
Authors: van Tilborg Geralda A.F. , Strijkers Gustav J. , Pouget Emilie M. , Reutelingsperger Chris P.M. , Sommerdijk Nico A.J.M. , Nicolay Klaas , Mulder Willem J.M. 
Published: November 2008

AbstractDual labeled liposomes, carrying both paramagnetic and fluorescent lipids, were recently proposed as potent contrast agents for MR molecular imaging. These nanoparticles are coated with poly(ethylene glycol) (PEG) to increase their blood circulation half‐life, which should allow extensive accumulation at the targeted site. To eliminate nonspecific blood pool signal from the MR images, the circulating liposomes should ideally be cleared from the circulation when sufficient target‐specific contrast enhancement is obtained. To that aim, we designed an avidin chase that allowed controlled and rapid clearance of paramagnetic biotinylated liposomes from the blood circulation in C57BL/6 mice. Avidin‐induced alterations in blood clearance kinetics and tissue distribution were studied quantitatively by determination of the Gd content in blood and tissue samples ex vivo. Intrinsic liposomal blood clearance showed bi‐exponential behavior with half‐lives t1/2α = 2.1 ± 1.1 and t1/2β = 15.1 ± 5.4 hours, respectively. In contrast, the contrast agent was cleared from the blood by the avidin infusion to <1% of the initial dose within 4 hours. Avidin‐induced liposomal blood clearance was also demonstrated in vivo by dynamic T1‐weighted MRI. The ability to rapidly clear circulating contrast agents opens up exciting possibilities to study targeting kinetics, to increase the specificity of molecular MRI and to optimize nanoparticulate contrast agent formulations. Magn Reson Med 60:1444–1456, 2008. © 2008 Wiley‐Liss, Inc.
Magnetic resonance noise measurements and signal‐quantization effects at very low noise levels
Authors: Dietrich Olaf , Raya José G. , Reiser Maximilian F. 
Published: November 2008

AbstractThe well‐known noise distributions of magnetic resonance imaging (MRI) data (Rayleigh, Rician, or non‐central chi‐distribution) describe the probability density of real‐valued (i.e., floating‐point) signal intensities. MR image data, however, is typically quantized to integers before visualization or archiving. Depending on the scaling factors applied before the quantization and the signal‐to‐noise ratio (SNR), very low noise levels with substantial artifacts due to the quantization process can occur. The purpose of this study was to analyze the consequences of the signal quantization, to determine the theoretical absolute lower limit for noise measurements in discrete data, and to evaluate an improved method for noise and SNR measurements in the presence of very low noise levels. Image data were simulated with original noise levels of between 0.02 and 2.00. Noise measurements were performed based on the properties of background and foreground data using the conventional approach, which exploits the standard deviation or mean value of the signal, and a maximum‐likelihood approach based on the relative frequencies of the observed discrete signal intensities. Substantial deviations were found for the conventionally determined noise levels, while noise levels comparable to or lower than the quantization error can be accurately estimated with the proposed maximum‐likelihood approach. Magn Reson Med 60:1477–1487, 2008. © 2008 Wiley‐Liss, Inc.
FID sampling superior to spin‐echo sampling for T‐based quantification of holmium‐loaded microspheres: Theory and experiment
Authors: Seevinck Peter R. , Seppenwoolde Jan‐Henry , Zwanenburg Jaco J.M. , Nijsen Johannes F.W. , Bakker Chris J.G. 
Published: November 2008

AbstractThis work demonstrates both theoretically and experimentally that multiple gradient‐echo sampling of free induction decay (MGEFID) is superior to MGE sampling of spin echo (MGESE) for T‐based quantification of holmium‐loaded microspheres (HoMS). An interleaved sampling strategy was applied in great detail to characterize the MR signal behavior of FID and SE signals of gels and perfused rabbit livers containing HoMS in great detail. Diffusion sensitivity was demonstrated for MGESE sampling, resulting in non‐exponential signal decay on both sides of the SE peak and in an underestimation of the HoMS concentration. Other than MGESE sampling, MGEFID sampling was demonstrated to be insensitive to diffusion, to exhibit exponential signal decay, and to allow accurate T‐based quantification of HoMS. Furthermore, a fit procedure was proposed extending the upper limit of quantifiable R relaxation rates to at least 1500 sec–1. With this post‐processing step incorporated, MGEFID was shown to correctly estimate the integral amount of inhomogeneously distributed HoMS in liver tissue, up to a clinically relevant limit. All experimental findings could be explained with the theory of nuclear magnetic resonance (NMR) signal behavior in magnetically inhomogeneous tissues. HoMS were shown to satisfy the static dephasing regime when investigated with MGEFID and to violate the static dephasing conditions for MGESE at longer echo times typically used in SE. Magn Reson Med 60:1466–1476, 2008. © 2008 Wiley‐Liss, Inc.
An auto‐calibrated, angularly continuous, two‐dimensional GRAPPA kernel for propeller trajectories
Authors: Skare Stefan , Newbould Rexford D. , Nordell Anders , Holdsworth Samantha J. , Bammer Roland 
Published: November 2008

AbstractThe k‐space readout of propeller‐type sequences may be accelerated by the use of parallel imaging (PI). For PROPELLER, the main benefits are reduced blurring due to T2 decay and specific absorption ratio (SAR) reduction, whereas, for EPI‐based propeller acquisitions, such as Turbo‐PROP and short‐axis readout propeller EPI (SAP‐EPI), the faster k‐space traversal alleviates geometric distortions. In this work, the feasibility of calculating a two‐dimensional (2D) GRAPPA kernel on only the undersampled propeller blades themselves is explored, using the matching orthogonal undersampled blade. It is shown that the GRAPPA kernel varies slowly across blades; therefore, an angularly continuous 2D GRAPPA kernel is proposed, in which the angular variation of the weights is parameterized. This new angularly continuous kernel formulation greatly increases the numerical stability of the GRAPPA weight estimation, allowing for generation of fully sampled diagnostic quality images using only the undersampled propeller data. Magn Reson Med 60:1457–1465, 2008. © 2008 Wiley‐Liss, Inc.
New diffusion phantoms dedicated to the study and validation of high‐angular‐resolution diffusion imaging (HARDI) models
Authors: Poupon Cyril , Rieul Bernard , Kezele Irina , Perrin Muriel , Poupon Fabrice , Mangin Jean‐François 
Published: November 2008

AbstractWe present new diffusion phantoms dedicated to the study and validation of high‐angular‐resolution diffusion imaging (HARDI) models. The phantom design permits the application of imaging parameters that are typically employed in studies of the human brain. The phantoms were made of small‐diameter acrylic fibers, chosen for their high hydrophobicity and flexibility that ensured good control of the phantom geometry. The polyurethane medium was filled under vacuum with an aqueous solution that was previously degassed, doped with gadolinium‐tetraazacyclododecanetetraacetic acid (Gd‐DOTA), and treated by ultrasonic waves. Two versions of such phantoms were manufactured and tested. The phantom's applicability was demonstrated on an analytical Q‐ball model. Numerical simulations were performed to assess the accuracy of the phantom. The phantom data will be made accessible to the community with the objective of analyzing various HARDI models. Magn Reson Med 60:1276–1283, 2008. © 2008 Wiley‐Liss, Inc.
Field strength dependence of R1 and R relaxivities of human whole blood to prohance, vasovist, and deoxyhemoglobin
Authors: Blockley N.P. , Jiang L. , Gardener A.G. , Ludman C.N. , Francis S.T. , Gowland P.A. 
Published: November 2008

AbstractThis study has measured the longitudinal and transverse (T) relaxivity curves for ProHance (Gadoteridol), Vasovist (Gadofosveset) and deoxyhemoglobin at 1.5, 3.0, and 7.0 Tesla. The plots of R1 versus both contrast agent and deoxyhemoglobin concentration were linear. The plots of R versus deoxyhemoglobin concentration showed a quadratic dependence. R versus contrast agent concentration showed a parabolic dependence with a minimum occurring at contrast agent concentrations of approximately 1.5 mM, corresponding to an accessible concentration in vivo. Monte Carlo simulations were performed to support the hypothesis that the minimum results from the susceptibility of the red blood cells being matched to the susceptibility of the plasma. Relaxivity values (s−1mM−1) for R and R1 for all agents and all three field strengths are given. Magn Reson Med 60:1313–1320, 2008. © 2008 Wiley‐Liss, Inc.
In vivo single cell detection of tumor‐infiltrating lymphocytes with a clinical 1.5 Tesla MRI system
Authors: Smirnov Pierre , Poirier‐Quinot Marie , Wilhelm Claire , Lavergne Elise , Ginefri Jean‐Christophe , Combadière Béhazine , Clément Olivier , Darrasse Luc , Gazeau Florence 
Published: November 2008

AbstractWe demonstrate the feasibility of detecting individual tumor‐infiltrating cells in vivo, by means of cellular magnetic labeling and a 1.5 Tesla clinical MRI device equipped with a high‐resolution surface coil. Using a recently developed high‐temperature superconducting (HTS) surface coil, single cells were detected in vitro in voxels of (60 μm)3 at magnetic loads as low as 0.2 pg of iron per cell. The same imaging protocol was used in vivo to monitor infiltration of ovalbumin‐expressing tumors by transferred OVA antigen‐specific cytotoxic lymphocytes with low iron load. Magn Reson Med 60:1292–1297, 2008. © 2008 Wiley‐Liss, Inc.
In vivo serial evaluation of superparamagnetic iron‐oxide labeled stem cells by off‐resonance positive contrast
Authors: Suzuki Yoriyasu , Cunningham Charle H. , Noguchi Ken‐ichiro , Chen Ian Y. , Weissman Irving L. , Yeung Alan C. , Robbins Robert C. , Yang Phillip C. 
Published: November 2008

AbstractMRI is emerging as a diagnostic modality to track iron‐oxide‐labeled stem cells. This study investigates whether an off‐resonance (OR) pulse sequence designed to generate positive contrast at 1.5T can assess the location, quantity, and viability of delivered stem cells in vivo. Using mouse embryonic stem cell transfected with luciferase reporter gene (luc‐mESC), multimodality validation of OR signal was conducted to determine whether engraftment parameters of superparamagnetic iron‐oxide labeled luc‐mESC (SPIO‐luc‐mESC) could be determined after cell transplantation into the mouse hindlimb. A significant increase in signal‐ and contrast‐to‐noise of the SPIO‐luc‐mESC was achieved with the OR technique when compared to a gradient recalled echo (GRE) sequence. A significant correlation between the quantity of SPIO‐luc‐mESC and OR signal was observed immediately after transplantation (R2 = 0.74, P < 0.05). The assessment of transplanted cell viability by bioluminescence imaging (BLI) showed a significant increase of luciferase activities by day 16, while the MRI signal showed no difference. No significant correlation between BLI and MRI signals of cell viability was observed. In conclusion, using an OR sequence the precise localization and quantitation of SPIO‐labeled stem cells in both space and time were possible. However, the OR sequence did not allow evaluation of cell viability. Magn Reson Med 60:1269–1275, 2008. © 2008 Wiley‐Liss, Inc.
Challenges of conducting multi‐center, multi‐disciplinary urinary incontinence clinical trials: Experience of the urinary incontinence Treatment Network
Authors: Steers William , Richter Holly , Nyberg Leroy , Kusek John , Kraus Stephen , Dandreo Kimberly , Chai Toby , Brubaker Linda 
Published: November 2008

AbstractAimsThe Urinary Incontinence Treatment Network (UITN) was established in 2000 as a multi‐disciplinary, multi‐institutional network by the National Institute for Diabetes, Digestive, and Kidney Diseases (NIDDK) to investigate treatments for urinary incontinence in women.MethodsOver 8 years this network composed of urologists, urogynecologists, geriatricians, behavioral psychologists, physical therapists, nurses, epidemiologists, social scientists and statisticians from nine academic sites and a Data Coordinating Center has been effective in designing and completing prospective randomized clinical trials for treatments of urinary incontinence in women.ResultsTwo major clinical trials have been completed and a third has completed recruitment. The focus of the completed trials was a comparison of surgical methods to treat stress urinary incontinence whereas the third examined the potential benefit of combined behavioral intervention and antimuscarinic drug therapy to eliminate the need for long‐term use of drug therapy alone to manage urge urinary incontinence. The scientific output of the network measured by abstracts, original papers and presentations demonstrates the productivity of the network.ConclusionsMany unique challenges are posed by a multi‐disciplinary team located at sites across the United States undertaking several clinical trials. This review presents some of the logistics, barriers, tactics, and strategies used to create this successful clinical trials network focused on urinary incontinence. Neurourol. Urodynam. 28:170–176, 2009. © 2008 Wiley‐Liss, Inc.
Psychometric validation of the overactive bladder satisfaction with treatment questionnaire (OAB‐SAT‐q)
Authors: Margolis Mary Kay , Fox Kathleen M. , Cerulli Annamaria , Ariely Rinat , Kahler Kristijan H. , Coyne Karin S. 
Published: November 2008

AbstractAimsValid and reliable questionnaires must be used to accurately assess patients' satisfaction with overactive bladder (OAB) treatment. This study evaluated the reliability and validity of the OAB Satisfaction with Treatment Questionnaire (OAB‐SAT‐q).MethodsThis was a secondary analysis of clinical study data of patients randomized to darifenacin or darifenacin plus Behavioral Modification Program. Patients completed the Overactive Bladder Questionnaire (OAB‐q) and a 3‐day bladder diary at Baseline and Week 12 and the OAB‐SAT‐q at Week 12. Internal consistency reliability was assessed by Cronbach's alpha. Concurrent validity was assessed through correlations with OAB‐q change scores and adverse events (AEs). Discriminant validity was assessed among subgroups using general linear models.ResultsAnalyses utilized a per‐protocol population (completion of OAB‐q at Baseline and OAB‐q and OAB‐SAT‐q at Week 12) (n = 375). Exploratory factor analysis of the OAB‐SAT‐q revealed three 3‐item subscales (Satisfaction, Side Effects, Endorsement) and two single items (Convenience, Preference). Cronbach's alphas = 0.84–0.95. Subscale‐to‐subscale correlations = 0.10–0.67 (all P < 0.01 except Side Effects and Convenience). The Side Effects subscale significantly correlated with number of treatment‐related AEs (r = 0.27; P < 0.01) and discriminated between patients with/without dry mouth and patients with/without constipation. The Satisfaction and Endorsement subscales discriminated between patients who worsened or had no change in micturition frequency and urinary urgency and patients who had a reduction of >3 episodes (all P < 0.001). The OAB‐SAT‐q does not appear to discriminate by incontinence episodes.ConclusionThe OAB‐SAT‐q demonstrated good psychometric properties in this initial evaluation—including internal consistency reliability and concurrent and discriminant validity—and appears to be a useful assessment of OAB treatment satisfaction. Neurourol. Urodynam. 28:416–422, 2009. © 2008 Wiley‐Liss, Inc.
A finite element formulation for thermoelastic damping analysis
Authors: Serra Enrico , Bonaldi Michele 
Published: November 2008

AbstractWe present a finite element formulation based on a weak form of the boundary value problem for fully coupled thermoelasticity. The thermoelastic damping is calculated from the irreversible flow of entropy due to the thermal fluxes that have originated from the volumetric strain variations. Within our weak formulation we define a dissipation function that can be integrated over an oscillation period to evaluate the thermoelastic damping. We show the physical meaning of this dissipation function in the framework of the well‐known Biot's variational principle of thermoelasticity. The coupled finite element equations are derived by considering harmonic small variations of displacement and temperature with respect to the thermodynamic equilibrium state. In the finite element formulation two elements are considered: the first is a new 8‐node thermoelastic element based on the Reissner–Mindlin plate theory, which can be used for modeling thin or moderately thick structures, while the second is a standard three‐dimensional 20‐node iso‐parametric thermoelastic element, which is suitable to model massive structures. For the 8‐node element the dissipation along the plate thickness has been taken into account by introducing a through‐the‐thickness dependence of the temperature shape function. With this assumption the unknowns and the computational effort are minimized. Comparisons with analytical results for thin beams are shown to illustrate the performances of those coupled‐field elements. Copyright © 2008 John Wiley & Sons, Ltd.
Preparation of porous ultrafine polyacrylonitrile (PAN) fibers by electrospinning
Authors: Ma Guiping , Yang Dongzhi , Nie Jun 
Published: November 2008

AbstractA facile method for the preparation of porous ultrafine nanofibers was demonstrated. The PAN/NaHCO3 composite nanofibers were electrospun, and then NaHCO3 was removed by a selective dissolution and reaction with the solution of hydrochloric acid (10 wt%). The obtained PAN fibers showed highly porous surfaces after the extraction of NaHCO3. The structure and properties of ultrafine PAN nanofibers were characterized by Fourier transform infrared (FT‐IR), X‐ray diffraction (XRD), and thermogravimetry (TG). The results indicated that NaHCO3 could be introduced into the PAN solution and successfully electrospun. CO2 is released and pores are formed on the fibers. The morphology image of the fibers was detected by scanning electron microscope (SEM) and showed that many pores aligned the nanofibers. Copyright © 2008 John Wiley & Sons, Ltd.
Clinical practice guideline improves the treatment of sickle cell disease vasoocclusive pain
Authors: Morrissey Lisa K. , Shea Joan O'Brien , Kalish Leslie A. , Weiner Debra L. , Branowicki Patricia , Heeney Matthew M. 
Published: November 2008

AbstractBackgroundPain is the most common complication of sickle cell disease requiring emergency department (ED) visits and hospitalization. A Clinical Practice Guideline (CPG) to manage acute sickle cell pain offers clinicians a standardized approach for the provision of evidence‐based, cost‐effective care. After CPG implementation, monitoring of pre‐established indicators is a strategy to evaluate progress toward meeting the goal of providing rapid, effective pain relief for patients with acute sickle cell pain.MethodsA retrospective chart review of patients with sickle cell disease admitted through the ED at Children's Hospital Boston with the primary diagnosis of vaso‐occlusive pain was performed for a period before and after implementation of the CPG. Endpoints measured were: use of a validated pain scale, time from ED triage to first dose of analgesic, use of adequate weight‐based analgesic dosing, frequency and location of PCA initiation, and time from ED triage to patient controlled analgesia (PCA) initiation.ResultsTwo hundred sixty three sickle cell pain admissions in 93 unique subjects were analyzed, 51 pre‐CPG and 212 post‐CPG. Statistically significant improvements in use of pain scale, appropriate weight‐based analgesic dosing, utilization of PCA, and time to initiation of PCA were observed. There was not a statistically significant improvement in the percentage of subjects who received their 1st dose of analgesic within 1 hr; however the median time to first analgesic was reduced significantly from 80 to 65 min (P = 0.003).ConclusionsImplementation of a CPG to manage acute sickle cell pain in the ED improves the ability to deliver timely, effective analgesia to this patient population. Establishing and monitoring internal benchmarks provides a means for ongoing evaluation of the pre‐established goals for patient care. Pediatr Blood Cancer 2009;52:369–372. © 2008 Wiley‐Liss, Inc.