bluuebunny/crossref_metadata_2025_split huggingface dataset:
Balanced multipoint displacement encoding for DENSE MRI
Authors: Zhong Xiaodong , Helm Patrick A. , Epstein Frederick H. 
Published: February 2009

AbstractDisplacement encoding with stimulated echoes (DENSE) is a quantitative imaging technique that encodes tissue displacement in the phase of the acquired signal. Various DENSE sequences have encoded displacement using methods analogous to the simple multipoint methods of phase contrast (PC) MRI. We developed general n‐dimension balanced multipoint encoding for DENSE. Using these methods, phase noise variance decreased experimentally by 73.7%, 65.6%, and 61.9% compared with simple methods, which closely matched the theoretical decreases of 75%, 66.7%, and 62.5% for one‐dimensional (1D), 2D, and 3D encoding, respectively. Phase noise covariances decreased by 99.2% and 99.3% for balanced 2D and 3D encoding, consistent with the zero‐covariance prediction. The direction bias inherent to the simple methods was decreased to almost zero using balanced methods. Reduced phase noise and improved displacement and strain maps using balanced methods were visually observed in phantom and volunteer images. Balanced multipoint encoding can also be applied to PC MRI. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Novel reconstruction method for three‐dimensional axial continuously moving table whole‐body magnetic resonance imaging featuring autocalibrated parallel imaging GRAPPA
Authors: Zenge Michael O. , Ladd Mark E. , Quick Harald H. 
Published: February 2009

AbstractContinuously moving table MR imaging has been successfully evaluated for whole‐body tumor staging and metastasis screening. In previous studies it was demonstrated that three‐dimensional (3D) slab‐selective excitation with lateral readout can provide very efficient k‐space coverage when the longitudinal field of view (FOV) is limited. To reduce respiratory artifacts, data acquisition in the thoracoabdominal region of the patient typically must be performed during one single breath hold. This consequently restricts acquisition time and thus spatial resolution. In this work, a novel reconstruction method is introduced for axial 3D moving table data acquisition with lateral readout. The method features table position correction completely in k‐space and is compatible with autocalibrated parallel imaging (GRAPPA). Parallel imaging can be applied to increase spatial resolution while maintaining the breath‐holding time. A sophisticated protocol for whole‐body moving table MRI was developed. The impact of gradient nonlinearity on the featured imaging method was evaluated in phantom and volunteer experiments. Finally, the protocol was optimized toward minimizing residual artifacts. Moving table whole‐body MRI with lateral readout was performed in 5 healthy volunteers and was compared with lateral readout data acquired with a GRAPPA accelerated protocol providing increased spatial resolution. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Physiological origin of low‐frequency drift in blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI)
Authors: Yan Lirong , Zhuo Yan , Ye Yongquan , Xie Sharon X. , An Jing , Aguirre Geoffrey K. , Wang Jiongjiong 
Published: February 2009

AbstractWe investigated the biophysical mechanism of low‐frequency drift in blood‐oxygen‐level‐dependent (BOLD) functional magnetic resonance imaging (fMRI) (0.00–0.01 Hz), by exploring its spatial distribution, dependence on imaging parameters, and relationship with task‐induced brain activation. Cardiac and respiratory signals were concurrently recorded during MRI scanning and subsequently removed from MRI data. It was found that the spatial distribution of low‐frequency drifts in human brain followed a tissue‐specific pattern, with greater drift magnitude in the gray matter than in white matter. In gray matter, the dependence of drift magnitudes on TE was similar to that of task‐induced BOLD signal changes, i.e., the absolute drift magnitude reached the maximum when TE approached T whereas relative drift magnitude increased linearly with TE. By systematically varying the flip angle, it was found that drift magnitudes possessed a positive dependence on image intensity. In phantom experiments, the observed drift was not only much smaller than that of human brain, but also showed different dependence on TE and flip angle. In fMRI studies with visual stimulation, a strong positive correlation between drift effects at baseline and task‐induced BOLD signal changes was observed both across subjects and across activated pixels within individual participants. We further demonstrated that intrinsic, physiological drift effects are a major component of the spontaneous fluctuations of BOLD fMRI signal within the frequency range of 0.0–0.1 Hz. Our study supports brain physiology, as opposed to scanner instabilities or cardiac/respiratory pulsations, as the main source of low‐frequency drifts in BOLD fMRI. Magn Reson Med 61, 2009. © 2009 Wiley‐Liss, Inc.
MRI contrast using solid‐state, B1‐distorting, microelectromechanical systems (MEMS) microresonant devices (MRDs)
Authors: Ciocan Razvan , Lenkinski Robert E. , Bernstein Jonathan , Bancu Mirela , Marquis Robert , Ivanishev Alex , Kourtelidis Fotini , Matsui Aya , Borenstein Jeffrey , Frangioni John V. 
Published: February 2009

AbstractPresently, signal generation in MRI depends on the concentration and relaxivity of protons or other MR‐active nuclei, and contrast depends on local differences in signal. In this proof‐of‐principle study, we explore the use of nonchemical, solid‐state devices for generating detectable signal and/or contrast in vitro and in vivo. We introduce the concept of microresonant devices (MRDs), which are micron‐sized resonators fabricated using microelectromechanical systems (MEMS) technology. Fifteen‐micrometer (15‐μm)‐thick, coil MRDs were designed to resonate at the 3T Larmor frequency of protons (127.7 MHz) and were fabricated using tantalum (Ta) oxide thin‐film capacitors and copper‐plated spiral inductors. The performance of MRDs having final diameters of 300, 500, and 1000 μm were characterized in saline using a radio frequency (RF) scanning microscope and a clinical 3T MR scanner. The measured B1 fields of 300 μm to 1000 μm MRDs ranged from 3.25 μT to 3.98 μT, and their quality factors (Q) ranged from 3.9 to 7.2. When implanted subcutaneously in the flank of a mouse, only MRDs tuned to the resonant frequency of protons generated a measurable in vivo B1 field. This study lays the foundation for a new class of solid‐state contrast agents for MRI. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Ultra‐low output impedance RF power amplifier for parallel excitation
Authors: Chu Xu , Yang Xing , Liu Yunfeng , Sabate Juan , Zhu Yudong 
Published: February 2009

AbstractInductive coupling between coil elements of a transmit array is one of the key challenges faced by parallel RF transmission. An ultra‐low output impedance RF power amplifier (PA) concept was introduced to address this challenge. In an example implementation, an output‐matching network was designed to transform the drain‐source impedance of the metallic oxide semiconductor field effect transistor (MOSFET) into a very low value for suppressing interelement coupling effect, and meanwhile, to match the input impedance of the coil to the optimum load of the MOSFET for maximizing the available output power. Two prototype amplifiers with 500‐W output rating were developed accordingly, and were further evaluated with a transmit array in phantom experiments. Compared to the conventional 50‐Ω sources, the new approach exhibited considerable effectiveness suppressing the effects of interelement coupling. The experiments further indicated that the isolation performance was comparable to that achieved by optimized overlap decoupling. The new approach, benefiting from a distinctive current‐source characteristic, also exhibited a superior robustness against load variation. Feasibility of the new approach in high‐field MR was demonstrated on a 3T clinical scanner. Magn Reson Med 61, 2009. © 2009 Wiley‐Liss, Inc.
Articular cartilage deformation determined in an intact tibiofemoral joint by displacement‐encoded imaging
Authors: Chan Deva D. , Neu Corey P. , Hull Maury L. 
Published: February 2009

AbstractThis study demonstrates the in vitro displacement and strain of articular cartilage in a cyclically‐compressed and intact joint using displacement‐encoded imaging with stimulated echoes (DENSE) and fast spin echo (FSE). Deformation and strain fields exhibited complex and heterogeneous patterns. The displacements in the loading direction ranged from −1688 to −1481 μm in the tibial cartilage and from −1601 to −764 μm in the femoral cartilage. Corresponding strains ranged from −9.8% to 0.7% and from −4.3% to 0.0%. The displacement and strain precision were determined to be 65 μm and less than 0.2%, respectively. Displacement‐encoded magnetic resonance imaging is capable of determining the nonuniform displacements and strains in the articular cartilage of an intact joint to a high precision. Knowledge of these nonuniform strains is critical for the in situ characterization of normal and diseased tissue, as well as the comprehensive evaluation of repair constructs designed using regenerative medicine. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Feasibility of concurrent dual contrast enhancement using CEST contrast agents and superparamagnetic iron oxide particles
Authors: Gilad Assaf A. , van Laarhoven Hanneke W.M. , McMahon Michael T. , Walczak Piotr , Heerschap Arend , Neeman Michal , van Zijl Peter C.M. , Bulte Jeff W.M. 
Published: February 2009

AbstractA major challenge for cellular and molecular MRI is to study interactions between two different cell populations or biological processes. We studied the possibility to simultaneously image contrast agents based on two different MRI contrast mechanisms: chemical exchange saturation transfer (CEST) and enhancement of T2 relaxation. Various amounts of superparamagnetic iron oxide (SPIO) nanoparticles were mixed with a fixed concentration (250 μM) of the CEST agent poly‐L‐lysine. T2 maps, CEST maps, and frequency‐dependent saturation spectra were then measured. Color‐coded overlay maps demonstrated the feasibility of concurrent dual contrast enhancement. We found that at concentrations lower than 5 μg(Fe)/mL both contrast agents can be imaged simultaneously. At higher concentrations, the iron‐based agent can be used to “shut off” the signal arising from the CEST agent. These initial findings are a first step toward using dual CEST/T2 contrast imaging for studying multiple cellular or molecular targets simultaneously in vivo. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Nonparametric probabilistic approach of uncertainties for elliptic boundary value problem
Authors: Soize Christian 
Published: February 2009

AbstractThe paper is devoted to elliptic boundary value problems with uncertainties. Such a problem has already been analyzed in the context of the parametric probabilistic approach of system parameters uncertainties or for random media. Model uncertainties are induced by the mathematical–physical process, which allows the boundary value problem to be constructed from the design system. If experiments are not available, the Bayesian approach cannot be used to take into account model uncertainties. Recently, a nonparametric probabilistic approach of both the model uncertainties and system parameters uncertainties has been proposed by the author to analyze uncertain linear and non‐linear dynamical systems. Nevertheless, the use of this concept that has to be developed for dynamical systems cannot directly be applied for elliptic boundary value problem, for instance, for a linear elastostatic problem relative to an elastic bounded domain. We then propose an extension of the nonparametric probabilistic approach in order to take into account model uncertainties for strictly elliptic boundary value problems. The theory and its validation are presented. Copyright © 2009 John Wiley & Sons, Ltd.
Reduced human leukocyte antigen expression in advanced‐stage Ewing sarcoma: implications for immune recognition
Authors: Berghuis Dagmar , de Hooge Alfons SK , Santos Susy J , Horst Danielle , Wiertz Emmanuel J , van Eggermond Marja C , van den Elsen Peter J , Taminiau Antonie HM , Ottaviano Laura , Schaefer Karl‐Ludwig , Dirksen Uta , Hooijberg Erik , Mulder Arend , Melief Cornelis JM , Egeler R Maarten , Schilham Marco W , Jordanova Ekaterina S , Hogendoorn Pancras CW , Lankester Arjan C 
Published: February 2009

AbstractEwing sarcoma (EWS) is a tumour most commonly arising in bone, although on occasion in soft tissue, with a poor prognosis in patients with refractory or relapsed disease, despite multimodal therapy. Immunotherapeutic strategies based on tumour‐reactive T and/or natural killer cells may improve the treatment of advanced‐stage EWS. Since cellular immune recognition critically depends on human leukocyte antigen (HLA) expression, knowledge about HLA expression in EWS is crucial in the design of cellular immunotherapeutic strategies. Constitutive and IFNγ‐induced HLA class I expression was analysed in EWS cell lines (n = 6) by flow cytometry, using antibodies against both monomorphic and allele‐specific antigens. Expression of antigen processing pathway components and beta‐2 microglobulin (β2m) was assessed by western blot. Expression of class II transactivator (CIITA), and its contribution to HLA class II expression, was evaluated by qRT‐PCR, transduction assays, and flow cytometry. β2m/HLA class I and class II expression was validated in EWS tumours (n = 67) by immunofluorescence. Complete or partial absence of HLA class I expression was observed in 79% of EWS tumours. Lung metastases consistently lacked HLA class I and sequential tumours demonstrated a tendency towards decreased expression upon disease progression. Together with absent or low constitutive expression levels of specific HLA class I loci and alleles, and differential induction of identical alleles by IFNγ in different cell lines, these results may reflect the existence of an immune escape mechanism. Inducible expression of TAP‐1/‐2, tapasin, LMP‐2/‐7, and the β2m/HLA class I complex by IFNγ suggests that regulatory mechanisms are mainly responsible for heterogeneity in constitutive class I expression. EWSs lack IFNγ‐inducible HLA class II, due to lack of functional CIITA. The majority of EWS tumours, particularly if advanced‐stage, exhibit complete or partial absence of both classes of HLA. This knowledge will be instrumental in the design of cellular immunotherapeutic strategies for advanced‐stage EWS. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Massage therapy reduces physical discomfort and improves mood disturbances in women with breast cancer
Authors: Listing Miriam , Reißhauer Anett , Krohn Michaela , Voigt Barbara , Tjahono Gracia , Becker Janine , Klapp Burghard F. , Rauchfuß Martina 
Published: February 2009

AbstractBackground. A randomized controlled trial was conducted to investigate the efficacy of classical massage treatment in reducing breast cancer‐related symptoms and in improving mood disturbances.Methods. Women diagnosed with primary breast cancer were randomized into an intervention group and a control group. For a period of 5 weeks, the intervention group received bi‐weekly 30‐min classical massages in the back and head–neck areas. The control group received no additional treatment to their routine healthcare. To evaluate treatment efficacy, the following validated questionnaires were administrated at baseline (T1), at the end of the intervention (T2), and at a followup at 11 weeks (T3): the Short Form‐8 Health Survey™, the European Organization of Research and Treatment of Cancer quality of life questionnaire breast module (EORTC QLQ‐BR23), the Giessen Complaints Inventory (GBB), and the Berlin Mood Questionnaire (BSF).Results. Eighty‐six eligible women (mean age: 59 years) were enrolled in the study. A significantly higher reduction of physical discomfort was found in the intervention group compared with the control group at T2 (p=0.001) and at T3 (p=0.038). A decrease in fatigue was also observed. Women in the intervention group reported significantly lower mood disturbances at T2 (p<0.01) but not at T3. The effect of treatment on mood disturbances was significantly higher if a patient was treated continuously by the same masseur.Conclusion. Classical massage seems to be an effective adjuvant treatment for reducing physical discomfort and fatigue, and improving mood disturbances in women with early stage breast cancer. Copyright © 2009 John Wiley & Sons, Ltd.
Illness perceptions in Greek patients with cancer: a validation of the Revised‐Illness Perception Questionnaire
Authors: Giannousi Zoe , Manaras Irene , Georgoulias Vassilis , Samonis George 
Published: February 2009

AbstractObjective: The Revised‐Illness Perception Questionnaire (IPQ‐R) assesses illness perceptions according to Leventhal's self‐regulatory model. The aim of this paper is to present findings on the reliability and validity of the IPQ‐R in a population of Greek cancer patients.Methods: A total of 206 patients completed a Greek translation of the IPQ‐R and the Greek version of the Beck Depression Inventory (BDI). The scale's reliability was investigated by examining its internal consistency (Cronbach's alpha) and its test–retest reliability. Structural validity was examined through factor analyses. Predictive validity was tested by regressing BDI scores on IPQ subscale scores. Inter‐relationships between IPQ‐R dimensions were also examined by computing Pearson's Correlation Coefficients.Results: Cronbach's alpha showed satisfactory internal consistency for the IPQ‐R subscales. Paired samples' t‐test showed good test–retest reliability. Factor analysis of the IPQ‐R items revealed that the Greek version reflects the structure of the original with the only difference being that the ‘Consequences’ and ‘Emotional Representations’ subscales loaded on one factor. Factor analysis of the causal dimension items revealed a different structure of Causal Representations than that of the original questionnaire yielding three main factors: Psychological Attributions, Behavioral, and External Factors. Multiple regression analyses showed that Consequences, Emotional Representations, Illness Identity, and Psychological Attributions were the best predictors for depression.Conclusions: Translation of the IPQ‐R has good reliability and similar structure to that of the original. Difficulties to confirm the structure of Causal Representations may represent cultural differences in understanding illness causation. Copyright © 2009 John Wiley & Sons, Ltd.
Prostatic chondroitin sulfate is increased in patients with metastatic disease but does not predict survival outcome
Authors: Ricciardelli Carmela , Sakko Andrew J. , Stahl Jürgen , Tilley Wayne D. , Marshall Villis R. , Horsfall David J. 
Published: February 2009

AbstractBACKGROUNDPrevious studies from our laboratory demonstrated a strong association between an elevated level of chondroitin sulfate (CS) in peritumoral stroma and PSA‐relapse in patients with early stage disease. In this study we determined whether CS levels could predict overall survival in men diagnosed with advanced prostate cancer subsequently treated by orchiectomy alone.METHODSCS was localized in archived prostatic tissues by immunohistochemistry, and the level of CS expression as measured by video image analysis was compared in cohorts of 157 and 60 men with early stage or advanced disease, respectively.RESULTSThe CS levels in the peritumoral stroma of patients without relapse after treatment for early stage disease was significantly reduced compared to levels in prostate tissue from patients who either relapsed (P = 0.003) or were diagnosed with advanced prostate cancer (P < 0.00001). There was no difference between the median CS level in the peritumoral prostatic stroma of early stage patients that relapsed after treatment and patients diagnosed with advanced prostate cancer. Increased CS levels (P < 0.0001) and high Gleason score (P < 0.0001) were associated with an increased rate of PSA‐relapse in the cohort of patients with early stage disease. However, neither CS level nor Gleason score alone or in combination could predict survival outcome in patients with advanced prostate cancer following androgen deprivation therapy.CONCLUSIONSAlthough peritumoral CS levels and Gleason score are strong predictors of relapse‐free survival in early stage prostate cancer patients, neither peritumoral CS levels nor Gleason score can predict survival outcome in patients with advanced disease. Prostate 69: 761–769, 2009. © 2009 Wiley‐Liss, Inc.
Selective expression of CD44, a putative prostate cancer stem cell marker, in neuroendocrine tumor cells of human prostate cancer
Authors: Palapattu Ganesh S. , Wu Chengyu , Silvers Christopher R. , Martin Heather B. , Williams Karin , Salamone Linda , Bushnell Timothy , Huang Li‐Shan , Yang Qi , Huang Jiaoti 
Published: February 2009

AbstractBACKGROUNDHormonal therapy is effective for advanced prostate cancer (PC) but the disease often recurs and becomes hormone‐refractory. It is hypothesized that a subpopulation of cancer cells, that is, cancer stem cells (CSCs), survives hormonal therapy and leads to tumor recurrence. CD44 expression was shown to identify tumor cells with CSC features. PC contains secretory type epithelial cells and a minor population of neuroendocrine cells. Neuroendocrine cells do not express androgen receptor and are quiescent, features associated with CSCs. The purpose of the study was to determine the expression of CD44 in human PC and its relationship to neuroendocrine tumor cells.METHODSImmunohistochemistry and immunofluorescence were performed to study CD44 expression in PC cell lines, single cells from fresh PC tissue and archival tissue sections of PC. We then determined if CD44+ cells represent neuroendocrine tumor cells.RESULTSIn human PC cell lines, expression of CD44 is associated with cells of NE phenotype. In human PC tissues, NE tumor cells are virtually all positive for CD44 and CD44+ cells, excluding lymphocytes, are all NE tumor cells.CONCLUSIONSSelective expression of the stem cell‐associated marker CD44 in NE tumor cells of PC, in combination with their other known features, further supports the significance of such cells in therapy resistance and tumor recurrence. Prostate 69: 787–798, 2009. © 2009 Wiley‐Liss, Inc.