bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spontaneous nontraumatic intrasplenic pseudoaneurysm: Causes, sonographic diagnosis, and prognosis
Authors: Görg Christian , Cölle Julia , Wied Mathias , Schwerk Wolf B. , Zugmaier Gerhard 
Published: February 2003

AbstractPurposeThe aim of this study was to describe the incidence, causes, sonographic features, therapy, and prognosis of nontraumatic intrasplenic pseudoaneurysms (NTISPs), a rare complication of splenic infarction or infiltration by malignant systemic disorders or infectious diseases.MethodsWe retrospectively reviewed the medical and sonographic records of all patients seen at our clinic from July 1985 through December 2000 to identify patients with a sonographic diagnosis of spontaneous nontraumatic splenic rupture. We then examined the features of the resulting cases to identify patients in whom NTISPs were revealed by color Doppler sonography.ResultsIn total, 41 patients were identified. Among those patients, 5 (12%) had NTISPs. Three of those 5 patients had an underlying malignant disorder (1 case of non‐Hodgkin's lymphoma and 2 cases of chronic myelogenous leukemia), and the other 2 had an inflammatory disease (1 case of endocarditis and 1 case of pancreatitis). Three of the patients also had splenic infarctions. Three patients underwent splenectomy; in 2 of them, secondary delayed splenic rupture occurred before or during splenectomy. In 2 other patients, spontaneous thrombosis of the aneurysms occurred (after 16 hours in 1 and 15 days in the other).ConclusionsNTISPs may occur in about 12% of patients with sonographically detected nontraumatic spontaneous splenic rupture. NTISPs appear to be associated with an increased risk of secondary delayed splenic rupture, although spontaneous thrombosis may occur. Short‐term follow‐up sonographic examinations, particularly with color Doppler imaging, are recommended for early recognition of progression of NTISPs, which can guide treatment decisions. © 2003 Wiley Periodicals, Inc. J Clin Ultrasound 31:129–134, 2003
Sliding appendiceal inguinal hernia: Preoperative sonographic diagnosis
Authors: Çelik Ahmet , Ergün Orkan , Özbek S. Süreyya , Dökümcü Zafer , Balık Erol 
Published: February 2003

AbstractWe report the case of a 3‐month‐old boy with a right‐sided sliding appendiceal inguinal hernia that was diagnosed preoperatively with sonography. Surgery was performed, and intraoperative and histopathologic evaluations also revealed changes in the appendix that could have led to complications if left untreated. The infant's recovery was uneventful, and he was discharged on the second day after surgery. This condition is usually diagnosed intraoperatively, and to the best of our knowledge, this is only the second report in the English‐language medical literature in which such a case was correctly diagnosed preoperatively with sonography. In our case, the early sonographic diagnosis led to early intervention and the avoidance of potential complications. © 2003 Wiley Periodicals, Inc. J Clin Ultrasound 31:156–158, 2003
Accuracy and reproducibility of manual and semiautomated quantification of MS lesions by MRI
Authors: Ashton Edward A. , Takahashi Chihiro , Berg Michel J. , Goodman Andrew , Totterman Saara , Ekholm Sven 
Published: February 2003

AbstractPurposeTo evaluate the accuracy, reproducibility, and speed of two semiautomated methods for quantifying total white matter lesion burden in multiple sclerosis (MS) patients with respect to manual tracing and to other methods presented in recent literature.Materials and MethodsTwo methods involving the use of MRI for semiautomated quantification of total lesion burden in MS patients were examined. The first method, geometrically constrained region growth (GEORG), requires user specification of lesion location. The second technique, directed multispectral segmentation (DMSS), requires only the location of a single exemplar lesion. Test data sets included both clinical MS data and MS brain phantoms.ResultsThe mean processing times were 60 minutes for manual tracing, 10 minutes for region growth, and 3 minutes for directed segmentation. Intra‐ and interoperator coefficients of variation (CVs) were 5.1% and 16.5% for manual tracing, 1.4% and 2.3% for region growth, and 1.5% and 5.2% for directed segmentation. The average deviations from manual tracing were 9% for region growth and 5.7% for directed segmentation.ConclusionBoth semiautomated methods were shown to have a significant advantage over manual tracing in terms of speed and precision. The accuracy of both methods was acceptable, given the high variability of the manual results. J. Magn. Reson. Imaging 2003;17:300–308. © 2003 Wiley‐Liss, Inc.
Breast cancer detection in gadolinium‐enhanced MR images by static region descriptors and neural networks
Authors: Tzacheva Angelina A. , Najarian Kayvan , Brockway John P. 
Published: February 2003

AbstractPurposeTo automate the diagnosis of malignancy by classifying breast tissues as negative or positive for malignancy in gadolinium‐enhanced dynamic magnetic resonance (MR) images, using static region descriptors and a neural network classifier.Materials and MethodsWe propose a novel approach whereby the classifier evaluates a number of parameters that identify important tumor characteristics, as obtained by digital image processing techniques. These parameters include static signal intensity (SI) after contrast enhancement, mass margin descriptors, evaluation of mass shape by calculation of eccentricity, mass size, and mass granularity by texture analysis. Datasets for 14 patients were obtained by use of the 1.5T PMRTOW Clinical Imager.ResultsStatistical performance evaluation of the neural networks indicated 90%–100% sensitivity, 91%–100% specificity, and 91%–100% accuracy.ConclusionAlthough this work is preliminary, it may reduce overall health‐care time and costs, and enable higher accuracy in automated breast cancer detection systems. J. Magn. Reson. Imaging 2003;17:337–342. © 2003 Wiley‐Liss, Inc.
T2 quantitation of articular cartilage at 1.5 T
Authors: Maier Cynthia F. , Tan Steve G. , Hariharan Hari , Potter Hollis G. 
Published: February 2003

AbstractPurposeTo evaluate sources of error when using a multiecho sequence for quantitative T2 mapping of articular cartilage at 1.5 T.Materials and MethodsPhantom measurements were used to assess the contribution of stimulated echoes to inaccuracy of T2 measurements in cartilage using a multiecho sequence. Five volunteer studies compared in vivo single‐echo spin echo results to multiecho, single‐slice and multiecho, multislice acquisitions for assessment of both the stimulated echo and magnetization transfer contrast (MTC) contributions to T2 measurement inaccuracy.ResultsPhantom experiments demonstrated that substantial inaccuracy (10%–13% longer T2 values) is introduced from stimulated echoes with a multiecho sequence with slice‐selective refocusing pulses. The in vivo volunteer studies also demonstrated increases in measured T2 by up to 48% with a multiecho sequence. Use of the multiecho sequence in the multislice mode resulted in T2 values closer to the single‐echo standards for the volunteer studies. However, this apparent increased accuracy should be regarded as circumstantial, as it only occurs because the error due to MTC has the opposite sign compared to the error due to the stimulated echo contribution.ConclusionUse of a multiecho, multislice sequence for cartilage T2 measurements should be undertaken with the caution that substantial inaccuracy is introduced from stimulated echoes and MTC. J. Magn. Reson. Imaging 2003;17:358–364. © 2003 Wiley‐Liss, Inc.
Comparison of MR and PET imaging for the evaluation of liver metastases
Authors: Yang Ming , Martin Diego R. , Karabulut Nevzat , Frick Mathis P. 
Published: February 2003

AbstractPurposeTo compare the accuracy of fluoro‐18‐deoxyglucose positron emission tomography (FDG‐PET) and dynamic‐enhanced magnetic resonance imaging (MRI) scans in the diagnosis of liver metastatic lesions from colon and other sources.Materials and MethodsThirty consecutive patients with known or suspected metastatic lesions were scanned by both MRI and PET. Histopathology and/or clinical outcome, including cross‐sectional imaging follow up, were used as a gold standard.ResultsOf 30 patients, 16 were positive by pathology and/or clinical outcome and 14 were negative for liver metastases. The sensitivity, specificity, and positive and negative predictive values on MRI were 85.7%, 100%, 100%, and 89%, respectively, compared to 71%, 93.7%, 90.9%, and 79% on FDG‐PET. The difference between the two methods was not significant (X2 = 0.2, P > 0.05).ConclusionOur study showed no significant difference in detection of liver metastases using MRI or FDG‐PET. However, MRI has advantages in spatial resolution and lesion characterization. J. Magn. Reson. Imaging 2003;17:343–349. © 2003 Wiley‐Liss, Inc.
Counternormative impression management, likeability, and performance ratings: the use of intimidation in an organizational setting
Authors: Bolino Mark C. , Turnley William H. 
Published: February 2003

AbstractSocial‐role theory suggests that women are likely to be penalized for acting assertively (or in other ways that are counter to stereotypical expectations). Using a sample of 76 supervisor–subordinate dyads, this research investigates the reactions of supervisors to the use of intimidation strategies by men and women working in a law enforcement agency. The findings suggest that, among female employees, the use of intimidation tactics of impression management is negatively related to supervisor ratings of likeability. In contrast, among males, the use of intimidation is unrelated to supervisor ratings of likeability. In addition, for females, the use of intimidation is unrelated to performance ratings; among male employees, though, the relationship between intimidation and performance evaluations is positive. The implications of this study for management practice and future research are also discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Proton transverse relaxation rate (R2) images of iron‐loaded liver tissuepping local tissue iron concentrations with MRI
Authors: Clark Paul R. , Chua‐anusorn Wanida , St. Pierre Timothy G. 
Published: February 2003

AbstractProton transverse relaxation rate (R2) imaging measurements were made on post mortem iron‐loaded human liver tissue samples (both intact and dissected into approximately 1‐cm cubes) from a single subject. Iron concentrations for the dissected samples as measured by atomic absorption spectrometry varied from 10.8 to 23.3 mg Fe.g−1 dry tissue. A significant linear correlation between the mean R2 and iron concentration of each sample was found (r = 0.95). In addition, regions of liver tissue with micronodular cirrhosis exhibited lower R2 values, corresponding to the displacement of iron by fibrotic septa. The cirrhotic tissue was clearly identified as a separate peak in the R2 distribution of the tissue. The relaxivity of the iron did not appear to depend on the microarchitecture of the tissue. Magn Reson Med 49:572–575, 2003. © 2003 Wiley‐Liss, Inc.
Multiecho sequences with variable refocusing flip angles: Optimization of signal behavior using smooth transitions between pseudo steady states (TRAPS)
Authors: Hennig Juergen , Weigel Matthias , Scheffler Klaus 
Published: February 2003

AbstractA variation of the rapid acquisition with relaxation enhancement (RARE) sequence (also called turbo spin‐echo (TSE) or fast spin‐echo (FSE)) is presented. This technique uses variable flip angles along the echo train such that magnetization is initially prepared into the static pseudo steady state (PSS) for a low refocusing flip angle (α < 180°). It is shown that after such a preparation, magnetization will always stay very close to the static PSS even after significant variation of the subsequent refocusing flip angles. This allows the design of TSE sequences in which high refocusing flip angles yielding 100% of the attainable signal are applied only for the important echoes encoding for the center of k‐space. It is demonstrated that a reduction of the RF power (RFP) by a factor of 2.5–6 can be achieved without any loss in signal intensity. The contribution of stimulated‐echo pathways leads to a reduction of the effective TE by a factor ft, which for typical implementations is on the order of 0.5–0.8. This allows the use of longer echo readout times, and thus longer echo trains, for acquiring images with a given T2 contrast. Magn Reson Med 49:527–535, 2003. © 2003 Wiley‐Liss, Inc.
Mapping fiber orientation in human muscle by proton MR spectroscopic imaging
Authors: Vermathen Peter , Boesch Chris , Kreis Roland 
Published: February 2003

AbstractProton magnetic resonance spectroscopic imaging (1H‐MRSI) was used to determine muscle fiber orientations in human calf muscles. The method is based on the fact that some resonances show orientation‐dependent dipolar splitting, caused by incomplete motional averaging. This leads to proton spectra that depend strongly on the angle between muscle fibers and the magnetic field B0. The orientation‐dependent dipolar splittings were mapped using a fit with a basis set of predefined coupling patterns reflecting the fiber orientation. The fitted coupling patterns were displayed as images and assigned to different muscles based on segmented MR images. They showed gross differences in fiber orientation between some muscles, including m. soleus and m. tibialis anterior, for all subjects. In addition, smaller but significant differences between subjects were detected, which could be due to localization differences or real interindividual differences. Since dipolar splitting affects metabolite intensities, it is important to take this effect into account when calculating metabolite concentrations from MR spectra in muscle tissue. Spatial maps of the MR signals of trimethyl‐ammonium groups and creatine/ phosphocreatine revealed significant differences in intensity between muscles. Magn Reson Med 49:424–432, 2003. © 2003 Wiley‐Liss, Inc.
In vivo multiple‐mouse imaging at 1.5 T
Authors: Xu S. , Gade T.P.F. , Matei C. , Zakian K. , Alfieri A.A. , Hu X. , Holland E.C. , Soghomonian S. , Tjuvajev J. , Ballon D. , Koutcher J.A. 
Published: February 2003

AbstractA multiple‐mouse solenoidal MR coil was developed for in vivo imaging of up to 13 mice simultaneously to screen for tumors on a 1.5 T clinical scanner. For the coil to be effective as a screening tool, it should permit acquisition of MRIs in which orthotopic tumors with diameters >2 mm are detectable in a reasonable period of time (<1 hr magnet time) and their sizes accurately measured. Using a spin echo sequence, we demonstrated that this coil provides sufficient sensitivity for moderately high resolution images (156–176 μm in plane‐resolution, 1.5 mm slice thickness). This spatial resolution permitted detection of primary brain tumors in transgenic/knockout mice and orthotopic xenografts. Brain tumor size as measured by MRI was correlated with size measured by histopathology (P < 0.001). Metastatic tumors in the mouse lung were also successfully imaged in a screening setting. The multiple mouse coil is simple in construction and may be implemented without any significant modification to the hardware or software on a clinical scanner. Magn Reson Med 49:551–557, 2003. © 2003 Wiley‐Liss, Inc.
Indirect 17O‐magnetic resonance imaging of cerebral blood flow in the rat
Authors: Tailor Dharmesh R. , Roy Arijit , Regatte Ravinder R. , Charagundla Sridhar R. , McLaughlin Alan C. , Leigh John S. , Reddy Ravinder 
Published: February 2003

AbstractProton T1ρ‐dispersion MRI is demonstrated for indirect, in vivo detection of 17O in the brain. This technique, which may be readily implemented on any clinical MRI scanner, is applied towards high‐resolution, quantitative mapping of cerebral blood flow (CBF) in the rat by monitoring the clearance of 17O‐enriched water. Strategies are derived and employed for 1) quantitation of absolute H217O tracer concentration from a ratio of high‐ and low‐frequency spin‐locked T1ρ images, and 2) mapping CBF without having to transform the T1ρ signal to H217O tracer concentration. Absolute regional blood flow was mapped in a single 3‐mm brain slice at an in‐plane resolution of 0.4 × 0.8 mm within a 5‐min tracer washout time; these data are consistent with the less localized CBF measurements reported in the literature. T1ρ‐weighted imaging yields excellent signal‐to‐noise ratios, spatiotemporal resolution, and anatomical contrast for mapping CBF. Magn Reson Med 49:479–487, 2003. © 2003 Wiley‐Liss, Inc.
Dynamic shim updating (DSU) for multislice signal acquisition
Authors: de Graaf Robin A. , Brown Peter B. , McIntyre Scott , Rothman Douglas L. , Nixon Terence W. 
Published: February 2003

AbstractDynamic shim updating (DSU) is a technique for achieving optimal magnetic field homogeneity over extended volumes by dynamically updating an optimal shim setting for each individual slice in a multislice acquisition protocol. Here the practical implementation of DSU using all first‐ and second‐order shims is described. In particular, the hardware modifications and software requirements are demonstrated. Furthermore, the temporal effects of dynamically switching shim currents are investigated and a Z2‐to‐Z0 compensation unit is described and implemented to counteract the temporal Z0 variations following a change in the Z2 shim current. The optimal shim settings for all slices are determined with a quantitative and user‐independent, multislice phase‐mapping sequence. The performance of DSU is evaluated from multislice phase maps and spectroscopic images acquired on rat brain in vivo. DSU improved the magnetic field homogeneity over all spatial slices, with a more pronounced effect on the slices positioned away from the magnet isocenter, thereby making the magnetic field homogeneity highly uniform over an extended volume. Magn Reson Med 49:409–416, 2003. © 2003 Wiley‐Liss, Inc.
MR molecular imaging of the Her‐2/neu receptor in breast cancer cells using targeted iron oxide nanoparticles
Authors: Artemov Dmitri , Mori Noriko , Okollie Baasil , Bhujwalla Zaver M. 
Published: February 2003

AbstractMR molecular imaging is an exciting new frontier in the biomedical applications of MR. One of the clinically relevant targets is the tyrosine kinase Her‐2/neu receptor, which has a significant role in staging and treating breast cancer. In this study Her‐2/neu receptors were imaged in a panel of breast cancer cells expressing different numbers of the receptors on the cell membrane. Commercially available streptavidin‐conjugated superparamagnetic nanoparticles were used as targeted MR contrast agent. The nanoparticles were directed to receptors prelabeled with a biotinylated monoclonal antibody and generated strong T2 MR contrast in Her‐2/neu‐expressing cells. The contrast observed in MR images was proportional to the expression level of Her‐2/neu receptors determined independently with FACS analysis. In these experiments, iron oxide nanoparticles were attached to the cell surface and were not internalized into the cells, which is a major advantage for in vivo applications of the method. Magn Reson Med 49:403–408, 2003. © 2003 Wiley‐Liss, Inc.
Analysis of nets with hexagonal mesh using triangular elements
Authors: Priour Daniel 
Published: February 2003

AbstractThe calculation of net shapes is achieved using the finite element method. A triangular element is developed for the modelling of the net. The main hypotheses are that the strain in each triangular element is constant, that the hexagonal meshes have three directions of twine, and that the twines are elastic.The forces due to the tension in twines are described and calculated by a direct method. The results of the model based on such triangular elements are provided. The comparison with a model where each twine is described as an elastic bar, is quite good. Copyright © 2003 John Wiley & Sons, Ltd.
Comparison of static response of structures using convex models and interval analysis method
Authors: Qiu Zhiping 
Published: February 2003

AbstractIn this paper, by combining the finite element analysis and non‐probabilistic convex models, we present the numerical algorithm of non‐probabilistic convex models and interval analysis method for the static displacement of structures with uncertain‐but‐bounded parameters. Under the condition of the box or interval vector determined from the ellipsoid of the uncertain‐but‐bounded structural parameter vector, by comparing the numerical algorithm of non‐probabilistic convex models and the interval analysis method in the mathematical proof and the numerical example, we can see that the width of the maximum or upper and minimum or lower bounds on the static displacement yielded by the numerical algorithm of non‐probabilistic convex models is tighter than those produced by the interval analysis method. Copyright © 2003 John Wiley & Sons, Ltd.
Recursive second order convergence method for natural frequencies and modes when using dynamic stiffness matrices
Authors: Yuan Si , Ye Kangsheng , Williams Fred W. , Kennedy David 
Published: February 2003

AbstractWhen exact dynamic stiffness matrices are used to compute natural frequencies and vibration modes for skeletal and certain other structures, a challenging transcendental eigenvalue problem results. The present paper presents a newly developed, mathematically elegant and computationally efficient method for accurate and reliable computation of both natural frequencies and vibration modes. The method can also be applied to buckling problems. The transcendental eigenvalue problem is first reduced to a generalized linear eigenvalue problem by using Newton's method in the vicinity of an exact natural frequency identified by the Wittrick–Williams algorithm. Then the generalized linear eigenvalue problem is effectively solved by using a standard inverse iteration or subspace iteration method. The recursive use of the Newton method employing the Wittrick–Williams algorithm to guide and guard each Newton correction gives secure second order convergence on both natural frequencies and mode vectors. The second order mode accuracy is a major advantage over earlier transcendental eigenvalue solution methods, which typically give modes of much lower accuracy than that of the natural frequencies. The excellent performance of the method is demonstrated by numerical examples, including some demanding problems, e.g. with coincident natural frequencies, with rigid body motions and large‐scale structures. Copyright © 2003 John Wiley & Sons, Ltd.
Tumour necrosis factor‐α, interleukin‐2 soluble receptor and different inflammatory parameters in patients with rheumatoid arthritis
Authors: Fröde Tânia Silvia , Tenconi Patrícia , Debiasi Marilei Reynaud , Medeiros Yara Santos 
Published: February 2003

Background and aims: Although the participation of cytokines in the pathogenesis of rheumatoid arthritis (RA) seems to be unequivocal, their relationship with current serum markers of this disease is not clear. The present study analyses whether there is any correlation between the levels of tumour necrosis factor‐α (TNF‐α), interlukin‐2 soluble receptor (sIL‐2R) and the concentrations of C‐reactive protein (CRP), erythrocyte sedimentation rate (ESR) and β2‐microglobulin in a group of 21 patients with RA, all rheumatoid factor positive.Methods: The levels of TNF‐α and sIL‐2R were analysed in association with other parameters of inflammation (ESR, CRP and β2‐microglobulin).Results: In comparison with the control group, RA patients presented high median levels of both cytokines, TNF‐α (6.4 pg/ml) and sIL‐2R (56 pmol/L), as well as of ESR (34 mm/h), CRP (0.9 mg/dl) and β2‐microglobulin (1.6 mg/dl)
(p < 0.01).
However, only ESR levels in the RA group significantly differ from the control group
(p < 0.01).
No correlation was found between the inflammatory parameters.Conclusions: These results suggested that TNF‐α and slL‐2R levels are up‐regulated in RA patients but did not significantly differ from the control group. Due to the chronic course of this disease, other inflammatory markers must be identified in order to provide early therapeutic strategies to these patients.