bluuebunny/crossref_metadata_2025_split huggingface dataset:
System for prostate brachytherapy and biopsy in a standard 1.5 T MRI scanner
Authors: Susil Robert C. , Camphausen Kevin , Choyke Peter , McVeigh Elliot R. , Gustafson Gary S. , Ning Holly , Miller Robert W. , Atalar Ergin , Coleman C. Norman , Ménard Cynthia 
Published: August 2004

AbstractA technique for transperineal high‐dose‐rate (HDR) prostate brachytherapy and needle biopsy in a standard 1.5 T MRI scanner is demonstrated. In each of eight procedures (in four patients with intermediate to high risk localized prostate cancer), four MRI‐guided transperineal prostate biopsies were obtained followed by placement of 14–15 hollow transperineal catheters for HDR brachytherapy. Mean needle‐placement accuracy was 2.1 mm, 95% of needle‐placement errors were less than 4.0 mm, and the maximum needle‐placement error was 4.4 mm. In addition to guiding the placement of biopsy needles and brachytherapy catheters, MR images were also used for brachytherapy treatment planning and optimization. Because 1.5 T MR images are directly acquired during the interventional procedure, dependence on deformable registration is reduced and online image quality is maximized. Magn Reson Med 52:683–687, 2004. Published 2004 Wiley‐Liss, Inc.
Quantification of human atherosclerotic plaques using spatially enhanced cluster analysis of multicontrast‐weighted magnetic resonance images
Authors: Itskovich Vitalii V. , Samber Daniel D. , Mani Venkatesh , Aguinaldo Juan Gilberto S. , Fallon John T. , Tang Cheuk Y. , Fuster Valentin , Fayad Zahi A. 
Published: August 2004

AbstractOne of the current limitations of magnetic resonance imaging (MRI) is the lack of an objective method to classify plaque components. Here we present a cluster analysis technique that can objectively quantify and classify MR images of atherosclerotic plaques. We obtained three‐dimensional (3D) images from 12 human coronary artery specimens on a 9.4T imaging system using multicontrast‐weighted fast spin‐echo (T1‐, proton density‐, and T2‐weighted) imaging with an isotropic voxel size of 39 μ. Spatially enhanced cluster analysis (SECA) was performed on multicontrast MR images, and the resulting segmentation was evaluated against histological tracings. To visualize the overall structure of plaques, the MR images were rendered in 3D. The specimens exhibited lesions of American Heart Association (AHA) plaque classification types I‐VI. Both MR images and histological sections were independently reviewed, categorized, and compared. Overall, the classification obtained from the cluster‐analyzed MR and histopathology images showed very good agreement for all AHA types (92%, Cohen's κ = 0.89, P < 0.0001). All plaque types were identified and quantified by SECA with a high degree of correlation between cluster‐analyzed MR and manually traced histopathology data. MRI combined with SECA provides an objective method for atherosclerotic plaque component characterization and quantification. Magn Reson Med 52:515–523, 2004. © 2004 Wiley‐Liss, Inc.
Time course of 23Na signal intensity after myocardial infarction in humans
Authors: Sandstede Joern J.W. , Hillenbrand Hanns , Beer Meinrad , Pabst Thomas , Butter Felix , Machann Wolfram , Bauer Wolfgang , Hahn Dietbert , Neubauer Stefan 
Published: August 2004

AbstractExperimental studies demonstrated persistently increased 23Na content in nonviable myocardium post‐myocardial infarction (MI). We hypothesized that nonviable myocardium in humans would show elevated 23Na content at all stages of infarct development, and therefore could be imaged with 23Na MRI. Ten patients were examined on days 4, 14, and 90 after infarction, and five of these patients participated in a 12‐month follow‐up. Double angulated short‐axis cardiac 23Na images were obtained with the use of a 23Na surface coil and an ECG‐triggered, 3D gradient‐echo sequence. 1H T2‐weighted imaging (N = 9) was performed on days 4, 14, and 90. Wall motion was assessed by cine MRI, and the infarct size was determined by late enhancement on day 90. The 23Na signal intensity (SI) of infarcted myocardium was expressed as the percentage increase over 23Na SI of noninfarcted myocardium. All of the patients showed an area of elevated SI on 23Na and 1H T2‐weighted images that correlated with wall motion abnormalities and late enhancement. 23Na SI was highest on day 4. It then decreased until day 90, but remained elevated (39% ± 18%, 31% ± 17%, 28% ± 13% on days 4, 14, and 90, respectively, P = 0.001). No further decrease was found 1 year after infarction (25% ± 7%, P = 0.89 vs. day 90). 1H T2‐weighted SI decreased between days 4 and 14, but on day 90 only six of nine patients had a residual elevated SI. Thus, 23Na SI is elevated in nonviable infarction at all time points following MI, and 23Na MRI may become a suitable technique for imaging nonviable myocardium in humans. Magn Reson Med 52:545–551, 2004. © 2004 Wiley‐Liss, Inc.
2D J‐resolved spiral spectroscopic imaging at 7 T: Application to mobile lipid mapping in a rat glioma
Authors: Hiba Bassem , Serduc Raphaël , Provent Peggy , Farion Régine , Rémy Chantal , Ziegler Anne 
Published: August 2004

AbstractLactate (Lac) and mobile lipids (Lip), which are present in rat gliomas, are difficult to map because their 1H resonances overlap in the 1.3 ppm region. 2D J‐resolved spectroscopy enables proper separation of the two resonance lines. To obtain high‐spatial‐resolution mapping of Lac and Lip resonances within a reasonable experiment time, we coupled 2D J‐resolved spectroscopy with a fast spectroscopic imaging (SI) method, based on an out‐and‐in spiral k‐space description. The method was applied to a rat glioma at 7 T, and Lac and Lip maps were reconstructed. The duration of SI (2D spatial, 2D spectral) was 64 min for a theoretical in‐plane resolution of 1 × 1 mm, and a slice thickness of 2 mm (voxel size 8.2 μl, taking into account the point‐spread function (PSF)). Magn Reson Med 52:658–662, 2004. © 2004 Wiley‐Liss, Inc.
Detection and volume determination of colonic tumors in Min mice by magnetic resonance micro‐imaging
Authors: Hensley Harvey H. , Chang Wen‐chi , Clapper Margie L. 
Published: August 2004

AbstractWe applied MRI to the in vivo detection of spontaneous colorectal tumors in a unique mouse model, the Fox Chase Cancer Center (FCCC) ApcMIN mouse. Unlike other Min (multiple intestinal neoplasia) strains, FCCC ApcMIN animals develop an appreciable number of tumors in the large intestine, which makes them an appropriate mouse model for colon cancer in humans. We describe a method for marking the colon on MRI data sets that involves a bowel‐cleansing procedure and the insertion of a polyurethane tube (filled with an MRI contrast agent) fully into the colon. We found that tumors as small as 1.5 mm in diameter can be consistently identified from MRI datasets with a voxel size of 0.1 mm × 0.133 mm × 0.133 mm. Tumor volumes were determined from the MRM data sets with the use of a novel approach to planimetry in 3D data sets. We observed a correlation between tumor volume (as measured from the MRI datasets) and tumor weight of 0.942, and a P‐value of 0.008, based on Spearman's test. These data show that MRI can be used to accurately monitor tumor growth in mouse models of colorectal carcinogenesis. Magn Reson Med 52:524–529, 2004. © 2004 Wiley‐Liss, Inc.
Determining the longitudinal relaxation time (T1) of blood at 3.0 Tesla
Authors: Lu Hanzhang , Clingman Chekesha , Golay Xavier , van Zijl Peter C.M. 
Published: August 2004

AbstractIt is important to determine the longitudinal relaxation time of blood for black blood imaging, as well as for quantifying blood flow by arterial spin labeling (ASL). In this study a circulation system was used to measure blood T1 under physiological conditions at the new clinical field strength of 3.0T. It was found that 1/T1 in s−1 was linearly dependent (P < 0.05) on hematocrit (Hct) within a normal range of 0.38–0.46. The relationships were 1/T1 = (0.52 ± 0.15) · Hct + (0.38 ± 0.06) and 1/T1 = (0.83 ± 0.07) · Hct + (0.28 ± 0.03) for arterial (oxygenation = 92% ± 7%) and venous blood (69% ± 8%), respectively, which led to estimated T1 values of 1664 ± 14 ms (arterial) and 1584 ± 5 ms (venous) at a typical human Hct of 0.42. The temperature dependencies of blood T1 were 22.3 ± 0.6 ms/°C and 19.8 ± 0.8 ms/°C for Hct values of 0.42 and 0.38, respectively. When a head coil transmit/receive setup was used, radiation damping caused a slight reduction (19 ms) of the measured T1 values. Magn Reson Med 52:679–682, 2004. © 2004 Wiley‐Liss, Inc.
In vivo study of microbubbles as an MR susceptibility contrast agent
Authors: Wong Kelvin K. , Huang Ingjye , Kim Young R. , Tang Haiying , Yang Edward S. , Kwong Kenneth K. , Wu Ed X. 
Published: August 2004

AbstractThe potential application of gas microbubbles as a unique intravascular susceptibility contrast agent for MRI has not been fully explored. In this study, the MR susceptibility effect of an ultrasound microbubble contrast agent, Optison®, was studied with rat liver imaging at 7 T. Optison® suspension in two different doses (0.15 mL/kg and 0.4 mL/kg) was injected into rats, and induced transverse relaxation rate increases (ΔR2*) of 29.1 ± 1.6 s−1(N= 2) and 61.5 ± 12.9 s−1(N= 6), respectively, in liver tissue. Liver uptake of intact albumin microbubbles was observed 10 min after injection. Eight of the 16 rats studied showed no susceptibility enhancement. This is probably attributable to the intravascular microbubble growth due to transmural CO2supersaturation in the cecum and colon in small animals that causes microbubble aggregation and trapping in the inferior vena cava (IVC). In vitro ΔR2* measurements of Optison® suspension at different concentrations are also reported. Magn Reson Med 52:445–452, 2004. © 2004 Wiley‐Liss, Inc.
Measurement of tumor interstitial volume fraction: Method and implication for drug delivery
Authors: Kim Y.R. , Savellano M.D. , Savellano D.H. , Weissleder R. , Bogdanov A. 
Published: August 2004

AbstractIt is important to evaluate the tumor interstitial volume fraction that is accessible for drug accumulation during the distribution phase in order to determine the potential efficacy of cancer chemotherapy. In this study, we performed simulations of magnetic resonance imaging (MRI) signal intensity using a two‐compartment tissue model for quantitative analyses of absolute interstitial volume measurements while we experimentally characterized a mouse tumor model with a dual MR contrast‐agent method. Previously, consecutive intravenous injections of a strictly intravascular T1 contrast agent followed by an extravasating agent were used as a strategy for the quantification of both relative blood volume (Rel_BV) and relative interstitial volume (Rel_ITST) (Weissleder et al. Eur J Cancer 1998;34:1448–1454; Bogdanov et al. Neoplasia 1991;1:438–435). In the current study, we demonstrate that this approach can be further improved, and that it enables one to accurately evaluate both relative and absolute interstitial volumes. The animal data indicated that a significant difference exists between the absolute interstitial volume fractions of subcutaneously implanted MDA PCa 2b tumor and skeletal muscle tissue (27.5 ± 9.1% and 15.9 ± 0.7%, respectively (P < 0.05)), while only a minor difference was found for the absolute blood volumes (Abs_BV) (Kim et al. Magn Reson Med 2002;47:1110–1120) of these tissues. Magn Reson Med 52:485–494, 2004. © 2004 Wiley‐Liss, Inc.
Highly resolved in vivo 1H NMR spectroscopy of the mouse brain at 9.4 T
Authors: Tkáč Ivan , Henry Pierre‐Gilles , Andersen Peter , Keene C. Dirk , Low Walter C. , Gruetter Rolf 
Published: August 2004

AbstractAn efficient shim system and an optimized localization sequence were used to measure in vivo 1H NMR spectra from cerebral cortex, hippocampus, striatum, and cerebellum of C57BL/6 mice at 9.4 T. The combination of automatic first‐ and second‐order shimming (FASTMAP) with strong custom‐designed second‐order shim coils (shim strength up to 0.04 mT/cm2) was crucial to achieve high spectral resolution (water line width of 11–14 Hz). Requirements for second‐order shim strengths to compensate field inhomogeneities in the mouse brain at 9.4 T were assessed. The achieved spectral quality (resolution, S/N, water suppression, localization performance) allowed reliable quantification of 16 brain metabolites (LCModel analysis) from 5–10‐μL brain volumes. Significant regional differences (up to 2‐fold, P < 0.05) were found for all quantified metabolites but Asp, Glc, and Gln. In contrast, 1H NMR spectra measured from the striatum of C57BL/6, CBA, and CBA/BL6 mice revealed only small (<13%, P < 0.05) interstrain differences in Gln, Glu, Ins, Lac, NAAG, and PE. It is concluded that 1H NMR spectroscopy at 9.4 T can provide precise biochemical information from distinct regions of the mouse brain noninvasively that can be used for monitoring of disease progression and treatment as well as phenotyping in transgenic mice models. Magn Reson Med 52:478–484, 2004. © 2004 Wiley‐Liss, Inc.
In vivo diffusion tensor imaging of the human prostate
Authors: Sinha Shantanu , Sinha Usha 
Published: August 2004

AbstractThis study demonstrates the feasibility of in vivo prostate diffusion tensor imaging (DTI) in human subjects. We implemented an EPI‐based diffusion‐weighted (DW) sequence with seven‐direction diffusion gradient sensitization, and acquired DT images from six subjects using cardiac gating with a phased‐array prostate surface coil operating in a linear mode. We calculated two indices to quantify diffusion anisotropy. The direction of the eigenvector corresponding to the leading eigenvalue was displayed by means of a color‐coding scheme. The average diffusion values of the prostate peripheral zone (PZ) and central gland (CG) were 1.95 ± 0.08 × 10–3 mm2 s and 1.53 ± 0.34 × 10–3 mm2 s, respectively. The average fractional anisotropy (FA) values for the PZ and CG were 0.46 ± 0.04 and 0.40 ± 0.08, respectively. The diffusion ellipsoid in prostate tissue was anisotropic and approximated a prolate model, as shown in the color maps of the anisotropy. Consistent with the tissue architecture, the prostate fiber orientations were predominantly in the superior–inferior (SI) direction for both the PZ and CG. This study shows the feasibility of in vivo DTI and establishes normative DT values for six subjects. Magn Reson Med 52:530–537, 2004. © 2004 Wiley‐Liss, Inc.
View ordering for magnetization prepared steady state free precession acquisition: Application in contrast‐enhanced MR angiography
Authors: Spincemaille Pascal , Nguyen Thanh D. , Wang Yi 
Published: August 2004

AbstractMagnetization prepared segmented acquisition requires a view order that maximizes signal contrast during the acquisition of the central portion of k‐space. Steady state free precession (SSFP) acquisition further requires a view order that minimizes changes in phase‐encoding gradients from one repetition to the next in order to minimize eddy current artifacts. In this article, optimal view ordering schemes satisfying these two requirements are formulated and applied to inversion prepared 3D SSFP contrast‐enhanced MR angiography (MRA). Experiments on phantoms and pigs demonstrated improved background suppression and reduced image artifacts. Magn Reson Med 52:461–466, 2004. © 2004 Wiley‐Liss, Inc.
Self‐calibrated spiral SENSE
Authors: Qian Yongxian , Zhang Zhenghui , Stenger V. Andrew , Wang Yi 
Published: August 2004

AbstractCurrent standard sensitivity‐encoded parallel imaging (SENSE) utilizes a fully sampled low‐resolution reference scan to estimate the coil sensitivities. This reference scan adds scan time and may introduce misregistration artifacts. The purpose of this study was to investigate the feasibility of estimating the coil sensitivities for spiral SENSE directly from an undersampled k‐space center. The limited spatial frequencies of the coil sensitivities, and the undersampling beyond the Nyquist radius cause image artifacts. A point spread function (PSF) analysis and experiments on both phantoms and humans identified an optimal radius for the k‐space center by minimizing these image artifacts. The preliminary data indicate that self‐calibrated SENSE is as accurate as standard SENSE, which uses a fully sampled reference scan. Magn Reson Med 52:688–692, 2004. © 2004 Wiley‐Liss, Inc.
Improvement of the asymptotic behaviour of the Euler–Maclaurin formula for Cauchy principal value and Hadamard finite‐part integrals
Authors: Choi U. Jin , Kim Shin Wook , Yun Beong In 
Published: August 2004

AbstractIn the recent works (Commun. Numer. Meth. Engng 2001; 17: 881; to appear), the superiority of the non‐linear transformations containing a real parameter b ≠ 0 has been demonstrated in numerical evaluation of weakly singular integrals. Based on these transformations, we define a so‐called parametric sigmoidal transformation and employ it to evaluate the Cauchy principal value and Hadamard finite‐part integrals by using the Euler–Maclaurin formula. Better approximation is expected due to the prominent properties of the parametric sigmoidal transformation of whose local behaviour near x = 0 is governed by parameter b.Through the asymptotic error analysis of the Euler–Maclaurin formula using the parametric sigmoidal transformation, we can observe that it provides a distinct improvement on its predecessors using traditional sigmoidal transformations. Numerical results of some examples show the availability of the present method. Copyright © 2004 John Wiley & Sons, Ltd.
A three‐dimensional model describing stress‐temperature induced solid phase transformations: solution algorithm and boundary value problems
Authors: Auricchio Ferdinando , Petrini Lorenza 
Published: August 2004

AbstractAn always increasing knowledge on material properties as well as a progressively more sophisticated production technology make shape memory alloys (SMA) extremely interesting for the industrial world. At the same time, SMA devices are typically characterized by complex multi‐axial stress states as well as non‐homogeneous and non‐isothermal conditions both in space and time.This aspect suggests the finite element method as a useful tool to help and improve application design and realization. With this aim, we focus on a three‐dimensional macroscopic thermo‐mechanical model able to reproduce the most significant SMA features (Int. J. Numer. Methods Eng. 2002; 55: 1255–1264), proposing a simple modification of such a model. However, the suggested modification allows the development of a time‐discrete solution algorithm, which is more effective and robust than the one previously discussed in the literature.We verify the computational tool ability to simulate realistic mechanical boundary value problems with prescribed temperature dependence, studying three SMA applications: a spring actuator, a self‐expanding stent, a coupling device for vacuum tightness. The effectiveness of the model to solve thermo‐mechanical coupled problems will be discussed in a forthcoming work. Copyright © 2004 John Wiley & Sons, Ltd.
A three‐dimensional model describing stress‐temperature induced solid phase transformations: thermomechanical coupling and hybrid composite applications
Authors: Auricchio Ferdinando , Petrini Lorenza 
Published: August 2004

AbstractBetween composite materials, shape memory alloy (SMA) composites are having a more and more relevant role. Typically, SMA wires are embedded in a metallic or a polymeric matrix to obtain materials with native multi‐functionality and adaptive properties. This work approaches the computational study of the mechanical response of a composite in which SMA wires, previously deformed, are activated by electrical current heating, and accordingly try to recover the original shape inducing a shape change or a prestress in the structure.In particular, since the SMA behaviour is strongly affected by the thermo‐mechanical coupling, in the first part of this work we present a 3D phenomenological model able to take into account this aspect. The model time‐discrete counterpart is used to develop a 3D solid finite element able to describe the thermo‐electro‐mechanical coupled problem due to shape memory alloy response and to Joule effect. Finally, in the second part of the paper, we employ the developed computational tool to simulate different feasible SMA composite applications. Copyright © 2004 John Wiley & Sons, Ltd.
Numerical comparison of some explicit time integration schemes used in DEM, FEM/DEM and molecular dynamics
Authors: Rougier E. , Munjiza A. , John N. W. M. 
Published: August 2004

AbstractDiscontinua simulations are becoming an important part of Computational Mechanics to the extent that Computational Mechanics of Discontinua is becoming a separate subdiscipline of Computational Mechanics. Among the most widely used methods of Computational Mechanics of Discontinua are Discrete Element Methods, Molecular Dynamics Methods, Combined Finite‐Discrete Element Methods, DDA, Manifold Methods, etc. The common feature of all these methods is time discretization of the governing equations and the resulting mostly explicit time integration schemes. A wide range of time integration schemes is available in the literature. In this paper a comparative study of some of the most commonly used explicit time integration schemes is made in terms of accuracy, stability and CPU efficiency. The study has been performed using numerical experiments based on a one degree of freedom mass‐spring system. The results are presented as charts that can be used when deciding which scheme to use for a particular discontinua problem. Copyright © 2004 John Wiley & Sons, Ltd.
On general isotropic tensor functions of one tensor
Authors: de Souza Neto E. A. 
Published: August 2004

AbstractThis paper discusses general isotropic real symmetric tensor‐valued functions of one real symmetric tensor. By exploiting the eigenprojection‐based spectral representation of such functions, eigenprojection‐based closed formulae for the function derivatives are derived. The derived formulae provide an alternative to the eigenvector‐based derivative expressions proposed by Chadwick and Ogden (Arch. Rat. Mech. Anal. 1971; 44:54–68) for the same class of functions and are an extension of the eigenprojection‐based derivative expressions obtained by Carlson and Hoger (Quart. Appl. Math. 1986; 44(3):409–423) for a subset of the present class of functions. The material presented here is restricted to two‐ and three‐dimensional spaces, which are of particular relevance to continuum mechanics. For completeness, algorithms for closed form computation of the isotropic tensor functions as well as their derivatives, based on the eigenprojection representation, are also presented. These should be of interest to computational mechanics researchers dealing with functions of the present type. Copyright © 2004 John Wiley & Sons, Ltd.
Was sind Phytoestrogene und Phyto‐SERMs?: Pflanzeninhaltsstoffe mit Wirkung auf das Hormonsystem
Authors: Vollmer Günter , Zierau Oliver 
Published: August 2004

AbstractPhytoestrogene sind Inhaltsstoffe von Pflanzen, die mit estrogenabhängigen Signalkaskaden interagieren und ihre Wirkung bevorzugt über die Rezeptoren ER‐α und ER‐β ausüben. Werden nicht alle Wirkungen hervorgerufen, die auch durch Estradiol auszulösen sind, sondern organspezifische, mehr oder weniger selektive Wirkprofile stimuliert, so spricht man von einem “Selectiven Estrogen Receptor Modulator” (SERM). Dieser SERM‐Begriff, angewandt auf Phytoestrogene, führt zur Klassifizierung einiger Phytoestrogene als Phyto‐SERMs. Pflanzliche Inhaltsstoffe mit estrogener Aktivität weisen mehr oder weniger stark ausgeprägte SERM‐Eigenschaften auf. Prinzipiell handelt es sich bei diesen “Phyto‐SERMS” um pharmakologisch interessante Substanzen, die zwar schon z.T. klinisch genutzt werden, für die aber aus der Sicht Molekularer Endokrinologen durchaus noch ein mehr oder weniger stark ausgeprägter Bedarf zur weiteren Charakterisierung besteht.