bluuebunny/crossref_metadata_2025_split huggingface dataset:
Steering of aggregating magnetic microparticles using propulsion gradients coils in an MRI Scanner
Authors: Mathieu Jean‐Baptiste , Martel Sylvain 
Published: April 2010

AbstractUpgraded gradient coils can effectively enhance the MRI steering of magnetic microparticles in a branching channel. Applications of this method include MRI targeting of magnetic embolization agents for oncologic therapy. A magnetic suspension of Fe3O4 magnetic particles was injected inside a y‐shaped microfluidic channel. Magnetic gradients of 0, 50, 100, 200, and 400 mT/m were applied to the magnetic particles perpendicularly to the flow by a custom‐built gradient coil inside a 1.5‐T MRI scanner. Measurement of the steering ratio was performed both by video analyses and quantification of the mass of the particles collected at each outlet of the microfluidic channel, using atomic absorption spectroscopy. Magnetic particles steering ratios of 0.99 and 0.75 were reached with 400 mT/m gradient amplitude and measured by video analyses and atomic absorption spectroscopy, respectively. Experimental data shows that the steering ratio increases with higher magnetic gradients. Moreover, theory suggests that larger particles (or aggregates), higher magnetizations, and lower flows can also be used to improve the steering ratio. The technological limitation of the approach is that an MRI gradient amplitude increase to a few hundred milliteslas per meter is needed. A simple analytical method based on magnetophoretic velocity predictions and geometric considerations is proposed for steering ratio calculation. Magn Reson Med 63:1336–1345, 2010. © 2010 Wiley‐Liss, Inc.
Quantitative two‐dimensional HRMAS 1H‐NMR spectroscopy‐based metabolite profiling of human cancer cell lines and response to chemotherapy
Authors: Bayet‐Robert Mathilde , Loiseau Dominique , Rio Pascale , Demidem Aicha , Barthomeuf Chantal , Stepien Georges , Morvan Daniel 
Published: April 2010

AbstractNMR spectroscopy‐based metabolomics still needs development in quantification procedures. A method was designed for quantitative two‐dimensional high resolution magic angle spinning (HRMAS) proton‐NMR spectroscopy‐based metabolite profiling of intact cells. It uses referencing of metabolite‐related NMR signals to protein‐related NMR signals and yields straightforward and automatable metabolite profiling. The method enables exploitation of only two‐dimensionally visible metabolites and combination of one‐ and two‐dimensional spectra, thus providing an appreciable number of screened metabolites. With this procedure, 32 intracellular metabolites were attributed and quantified in human normal fibroblasts and tumor cells. The phenotype of several tumor cell lines (MCF7, PC3, 143B, and HepG2) was characterized by high levels of glutathione in cell lines with the higher proliferation rate, high levels of creatine, low levels of free amino acids, increased levels of phospholipid derivatives (mostly phosphocholine), and lower lactate content in cell lines with the higher proliferation rate. Other metabolites such as fatty acids differed widely among tumor cell lines. The response of tumor cell lines to chemotherapy also was evaluated by differential metabolite profiling, bringing insights into drug cytotoxicity and tumor cell adaptive mechanisms. The method may prove widely applicable to tumor cell phenotyping. Magn Reson Med 63:1172–1183, 2010. © 2010 Wiley‐Liss, Inc.
Quantitative evaluation of k‐space reordering schemes for compatible dual‐echo arteriovenography (CODEA)
Authors: Park Sung‐Hong , Shim Hackjoon , Moon Chan‐Hong , Kim Jung‐Hwan , Bae Kyongtae Ty 
Published: April 2010

AbstractCompatible dual‐echo arteriovenography (CODEA) is a recently developed technique for simultaneous acquisition of time‐of‐flight MR angiogram (MRA) and blood oxygenation level–dependent MR venogram (MRV) using an echo‐specific k‐space reordering scheme. In this study, we evaluated and compared the image quality of CODEA MRA/MRV implemented with two different schemes of echo‐specific k‐space reordering: one along the 1st phase‐encode direction (one‐dimensional) only and the other along both phase‐encode directions (two‐dimensional). Our results showed that use of the two‐dimensional reordering scheme improved contrast‐to‐noise ratio of small arteries by ∼8%, although not statistically significant (P > 0.1). Contrast‐to‐noise ratio of the CODEA MRAs was better than that for the non‐CODEA dual‐echo MRA without k‐space reordering (contrast‐to‐noise ratio increased in large arteries by ∼10% and small arteries by ∼45%; P < 0.1). Contrast‐to‐noise ratio of the CODEA MRAs was comparable with that of the conventional single‐echo MRA for large arteries but reduced by ∼20% for small arteries. Contrast‐to‐noise ratio of veins on the CODEA MRVs was equivalent to that of the conventional single‐echo and the non‐CODEA dual‐echo MRVs. However, some veins in the CODEA MRVs showed stronger contrast than those in the single‐echo MRV in relation to the contrast of neighboring arterial signals. Magn Reson Med 63:1404–1410, 2010. © 2010 Wiley‐Liss, Inc.
Model‐based reconstruction for cardiac cine MRI without ECG or breath holding
Authors: Odille Freddy , Uribe Sergio , Batchelor Philip G. , Prieto Claudia , Schaeffter Tobias , Atkinson David 
Published: April 2010

AbstractThis paper describes an acquisition and reconstruction strategy for cardiac cine MRI that does not require the use of electrocardiogram or breath holding. The method has similarities with self‐gated techniques as information about cardiac and respiratory motion is derived from the imaging sequence itself; here, by acquiring the center k‐space line at the beginning of each segment of a balanced steady‐state free precession sequence. However, the reconstruction step is fundamentally different: a generalized reconstruction by inversion of coupled systems is used instead of conventional gating. By correcting for nonrigid cardiac and respiratory motion, generalized reconstruction by inversion of coupled systems (GRICS) uses all acquired data, whereas gating rejects data acquired in certain motion states. The method relies on the processing and analysis of the k‐space central line data: local information from a 32‐channel cardiac coil is used in order to automatically extract eigenmodes of both cardiac and respiratory motion. In the GRICS framework, these eigenmodes are used as driving signals of a motion model. The motion model is defined piecewise, so that each cardiac phase is reconstructed independently. Results from six healthy volunteers, with various slice orientations, show improved image quality compared to combined respiratory and cardiac gating. Magn Reson Med 63:1247–1257, 2010. © 2010 Wiley‐Liss, Inc.
Postprocessing correction for distortions in T2* decay caused by quadratic cross‐slice B0 inhomogeneity
Authors: Yang Xiangyu , Sammet Steffen , Schmalbrock Petra , Knopp Michael V. 
Published: April 2010

AbstractRelaxometric measurement of the effective transverse relaxation rate R plays an important role in the quantitative evaluation of brain function, perfusion, and tissue iron content. However, accurate measurement of R is prone to macroscopic background field inhomogeneity. In clinical applications and systems, postprocessing correction techniques are more flexible in implementation than unsupported protocol or hardware modifications. The current postprocessing correction approach assumes the cross‐slice background field inhomogeneity can be approximated by a linear gradient and corrects for a sinc modulation function. The importance of the high‐order terms in background field inhomogeneity has increased with the fast development of high‐ and ultrahigh‐field scanners in recent years. In this study, we derived an analytical expression of the free induction decay signal modulation in the presence of a quadratic cross‐slice background field inhomogeneity. The proposed quadratic correction method was applied to phantom and volunteer studies and demonstrated to be superior to the classic monoexponential model, monoexponential‐plus‐constant model, and the linear sinc correction method in recovering background field inhomogeneity‐induced. R overestimations with visual inspection of R parametric maps and a statistical model selection technique. We also tabulated 7‐T T/R measurements of several human brain structures and MnCl2 solutions with various concentrations for fellow researchers' reference. Magn Reson Med 63:1258–1268, 2010. © 2010 Wiley‐Liss, Inc.
Phase‐sensitive, dual‐acquisition, single‐slab, 3D, turbo‐spin‐echo pulse sequence for simultaneous T2‐weighted and fluid‐attenuated whole‐brain imaging
Authors: Park Jaeseok , Park Suhyung , Yeop Kim Eung , Suh Jin‐Suck 
Published: April 2010

AbstractConventional T2‐weighted turbo/fast spin echo imaging is clinically accepted as the most sensitive method to detect brain lesions but generates a high signal intensity of cerebrospinal fluid (CSF), yielding diagnostic ambiguity for lesions close to CSF. Fluid‐attenuated inversion recovery can be an alternative, selectively eliminating CSF signals. However, a long time of inversion, which is required for CSF suppression, increases imaging time substantially and thereby limits spatial resolution. The purpose of this work is to develop a phase‐sensitive, dual‐acquisition, single‐slab, three‐dimensional, turbo/fast spin echo imaging, simultaneously achieving both conventional T2‐weighted and fluid‐attenuated inversion recovery–like high‐resolution whole‐brain images in a single pulse sequence, without an apparent increase of imaging time. Dual acquisition in each time of repetition is performed, wherein an in phase between CSF and brain tissues is achieved in the first acquisition, while an opposed phase, which is established by a sequence of a long refocusing pulse train with variable flip angles, a composite flip‐down restore pulse train, and a short time of delay, is attained in the second acquisition. A CSF‐suppressed image is then reconstructed by weighted averaging the in‐ and opposed‐phase images. Numerical simulations and in vivo experiments are performed, demonstrating that this single pulse sequence may replace both conventional T2‐weighted imaging and fluid‐attenuated inversion recovery. Magn Reson Med 63:1422–1430, 2010. © 2010 Wiley‐Liss, Inc.
An automated method for nonparametric kinetic analysis of clinical DCE‐MRI data: Application to glioblastoma treated with bevacizumab
Authors: Ferl Gregory Z. , Xu Lu , Friesenhahn Michel , Bernstein Lisa J. , Barboriak Daniel P. , Port Ruediger E. 
Published: April 2010

AbstractHere, we describe an automated nonparametric method for evaluating gadolinium‐diethylene triamine pentaacetic acid (Gd‐DTPA) kinetics, based on dynamic contrast‐enhanced–MRI scans of glioblastoma patients taken before and after treatment with bevacizumab; no specific model or equation structure is assumed or used. Tumor and venous blood concentration‐time profiles are smoothed, using a robust algorithm that removes artifacts due to patient motion, and then deconvolved, yielding an impulse response function. In addition to smoothing, robustness of the deconvolution operation is assured by excluding data that occur prior to the plasma peak; an exhaustive analysis was performed to demonstrate that exclusion of the prepeak plasma data does not significantly affect results. All analysis steps are executed by a single R script that requires blood and tumor curves as the sole input. Statistical moment analysis of the Impulse response function yields the area under the curve (AUC) and mean residence time (MRT). Comparison of deconvolution results to fitted Tofts model parameters suggests that
${{AUC} \over {{\rm MRT}}}$
and AUC of the Impulse response function closely approximate fractional clearance from plasma to tissue (Ktrans) and fractional interstitial volume (ve) . Intervisit variability is shown to be comparable when using the deconvolution method (11% [${{AUC} \over {{\rm MRT}}}$] and 13%[AUC]) compared to the Tofts model (14%[Ktrans] and 24%[ve]). AUC and ${{AUC} \over {{\rm MRT}}}$
both exhibit a statistically significant decrease (P < 0.005) 1 day after administration of bevacizumab. Magn Reson Med 63:1366–1375, 2010. © 2010 Wiley‐Liss, Inc.
Pixel‐based comparison of spinal cord MR diffusion anisotropy with axon packing parameters
Authors: Golabchi Fatemeh N. , Brooks Dana H. , Hoge W. Scott , De Girolami Umberto , Maier Stephan E. 
Published: April 2010

AbstractWater diffusion in nerve fibers is strongly influenced by axon architecture. In this study, fractional diffusion anisotropy and transverse and longitudinal diffusion coefficients were measured in excised human cervical spinal cord with MR line‐scan diffusion imaging, at 625 μm in‐plane resolution and 3 mm slice thickness. A pixel‐based comparison of fractional diffusion anisotropy, transverse diffusion coefficient, and longitudinal diffusion coefficient data with axon packing parameters derived from corresponding stained histological sections was performed for four slices. The axon packing parameters, axon density, axon area‐fraction, and average axon size for entire specimen cross‐sections were calculated by computerized segmentation of optical microscopy data obtained at 0.53 μm resolution. Salient features could be recognized on fractional diffusion anisotropy, transverse diffusion coefficient, axon density, axon area fraction, and average axon size maps. For white matter regions only, the average correlation coefficients for fractional diffusion anisotropy compared to histology‐based parameters axon density and axon area fraction were 0.37 and 0.21, respectively. For transverse diffusion coefficient compared to axon density and axon area fraction, they were −0.40 and −0.36, and for longitudinal diffusion coefficient compared to axon density and axon area fraction, −0.14 and −0.30. All average correlation coefficients for average axon size were low. Correlation coefficients for collectively analyzed white and gray matter regions were significantly higher than correlation coefficients derived from analysis of white matter regions only. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Phase‐contrast velocimetry with simultaneous fat/water separation
Authors: Johnson Kevin M. , Wieben Oliver , Samsonov Alexey A. 
Published: April 2010

AbstractPhase‐contrast MRI can provide high‐resolution angiographic velocity images, especially in conjunction with non‐Cartesiank‐space sampling. However, acquisitions can be sensitive to errors from artifacts from main magnetic field inhomogeneities and chemical shift from fat. Particularly in body imaging, fat content can cause degraded image quality, create errors in the velocity measurements, and prevent the use of self‐calibrated amplitude of static field heterogeneity corrections. To reduce the influence of fat and facilitate self‐calibrated amplitude of static field heterogeneity corrections, a combination of chemical shift imaging with phase‐contrast velocimetry with nonlinear least‐squares estimation of velocity, fat, and water signals is proposed. A chemical shift and first‐moment symmetric dual‐echo sequence is proposed to minimize the scan time penalty, and initial investigations are performed in phantoms and volunteers that show reduced influence from fat in velocity images. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Multiband multislice GE‐EPI at 7 tesla, with 16‐fold acceleration using partial parallel imaging with application to high spatial and temporal whole‐brain fMRI
Authors: Moeller Steen , Yacoub Essa , Olman Cheryl A. , Auerbach Edward , Strupp John , Harel Noam , Uğurbil Kâmil 
Published: April 2010

AbstractParallel imaging in the form of multiband radiofrequency excitation, together with reduced k‐space coverage in the phase‐encode direction, was applied to human gradient echo functional MRI at 7 T for increased volumetric coverage and concurrent high spatial and temporal resolution. Echo planar imaging with simultaneous acquisition of four coronal slices separated by 44mm and simultaneous 4‐fold phase‐encoding undersampling, resulting in 16‐fold acceleration and up to 16‐fold maximal aliasing, was investigated. Task/stimulus‐induced signal changes and temporal signal behavior under basal conditions were comparable for multiband and standard single‐band excitation and longer pulse repetition times. Robust, whole‐brain functional mapping at 7 T, with 2 × 2 × 2mm3 (pulse repetition time 1.25 sec) and 1 × 1 × 2mm3 (pulse repetition time 1.5 sec) resolutions, covering fields of view of 256 × 256 × 176mm3 and 192 × 172 × 176mm3, respectively, was demonstrated with current gradient performance. Magn Reson Med 63:1144–1153, 2010. © 2010 Wiley‐Liss, Inc.
Super‐resolved spatially encoded single‐scan 2D MRI
Authors: Ben‐Eliezer Noam , Irani Michal , Frydman Lucio 
Published: April 2010

AbstractSingle‐scan MRI underlies a wide variety of clinical and research activities, including functional and diffusion studies. Most common among these “ultrafast” MRI approaches is echo‐planar imaging. Notwithstanding its proven success, echo‐planar imaging still faces a number of limitations, particularly as a result of susceptibility heterogeneities and of chemical shift effects that can become acute at high fields. The present study explores a new approach for acquiring multidimensional MR images in a single scan, which possesses a higher built‐in immunity to this kind of heterogeneity while retaining echo‐planar imaging's temporal and spatial performances. This new protocol combines a novel approach to multidimensional spectroscopy, based on the spatial encoding of the spin interactions, with image reconstruction algorithms based on super‐resolution principles. Single‐scan two‐dimensional MRI examples of the performance improvements provided by the resulting imaging protocol are illustrated using phantom‐based and in vivo experiments. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
In vivo assessment of wall shear stress in the atherosclerotic aorta using flow‐sensitive 4D MRI
Authors: Harloff Andreas , Nußbaumer Andrea , Bauer Simon , Stalder Aurélien F. , Frydrychowicz Alex , Weiller Cornelius , Hennig Jürgen , Markl Michael 
Published: April 2010

AbstractOur purpose was to correlate atherogenic low wall shear stress (WSS) and high oscillatory shear index (OSI) with the localization of aortic plaques. Flow‐sensitive four‐dimensional MRI was used to acquire three‐dimensional blood flow in the aorta of 62 patients with proven aortic atherosclerosis and 31 healthy volunteers. Multiplanar data analysis of WSS magnitude and OSI in 12 wall segments was performed in analysis planes distributed along the aorta. Disturbed WSS and OSI were defined as areas exposed to low WSS magnitude and high OSI beyond individual 15% thresholds. Planewise analysis revealed a good correlation (r = 0.85) of individual low WSS magnitude but not of high OSI with plaque distribution. Although plaques occurred only rarely in the ascending aorta, the incidence of low WSS magnitude and high OSI was similar to findings in other aortic segments where plaques occurred more frequently. Case‐by‐case comparisons of plaque location and critical wall parameters revealed a shift of atherogenic WSS magnitude (78% of all cases) and OSI (91%) to wall segments adjacent to the atheroma. Our results indicate that the predictive value of WSS for plaque existence depends on the aortic segment and that locations of critical wall parameters move to neighboring segments of regions affected by atherosclerosis. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Mixed incontinence: Current evidence and future perspectives
Authors: Khullar Vik , Cardozo Linda , Dmochowski Roger 
Published: April 2010

AbstractThe epidemiology and treatment of mixed incontinence has received relatively little attention. However, mixed incontinence—defined as the combination of stress and urge incontinence accounts for ∼33% of all cases of incontinence in women. The condition often responds poorly to treatment, either pharmacologic or surgical. Potential pharmacologic approaches for mixed incontinence include antimuscarinic agents, estrogen replacement therapy (for postmenopausal women), and dopamine, serotonin, or norepinephrine reuptake inhibitors. In a large‐scale, multinational, placebo‐controlled, clinical trial, the antimuscarinic agent tolterodine significantly reduced incontinence episodes in women with mixed symptoms. The benefits of tolterodine continued to increase during the 8 weeks of the trial and extended to additional end points, including frequency, urgency, and urge incontinence. A limited number of studies have examined the use of estrogen for mixed incontinence and have produced conflicting results. Duloxetine oxalate, a combined serotonin/norepinephrine reuptake inhibitor, has shown great promise in animal studies, as well as in phase 2 and 3 clinical trials. This agent is the first to demonstrate efficacy as a sole therapy for stress incontinence and has exhibited favorable effects on bladder capacity, suggesting possible benefits in mixed incontinence. Only five studies (two of which were conducted during the 1980s) have specifically examined the use of surgery for the treatment of mixed incontinence; the cure rates reported have varied. The current body of information supports use of an antimuscarinic agent as initial therapy for mixed incontinence, although long‐term trials are needed to shed more light on the duration of benefit. Neurourol. Urodynam. 29:618–622, 2010. Copyright © 2010 Wiley‐Liss, Inc.
Potential insights into lower urinary function derived from CNS imaging
Authors: Drake Marcus J. , Tannenbaum Cara , Kanai Anthony J. 
Published: April 2010

AbstractPowerful advances in central nervous system (CNS) imaging technology offer an unprecedented opportunity to identify which CNS structures coordinate lower urinary tract (LUT) function in health and disease. Positron emission tomography and functional magnetic resonance imaging studies have already yielded preliminary insights into the neural control of continence mechanisms and their dysfunction. Such technologies have also enabled researchers to begin investigating the changes in CNS activity that occur with age, or after implementation of incontinence therapies, such as sacral neuromodulation. Nonetheless, the use of CNS imaging for understanding LUT function remains in a state of infancy. Several challenges, such as the relative spatial and temporal resolutions of the different technologies, and valid and reliable interpretation of the findings under non‐physiological conditions, limit the ability to constructively understand LUT control. This paper reviews state‐of‐the‐art CNS knowledge, discusses issues related to the use of CNS technology in LUT research, and raises key questions that need to be addressed. Neurourol. Urodynam. 29:629–633, 2010. © 2010 Wiley‐Liss, Inc.