bluuebunny/crossref_metadata_2025_split huggingface dataset:
Myelin water imaging: Implementation and development at 3.0T and comparison to 1.5T measurements
Authors: Kolind Shannon H. , Mädler Burkhard , Fischer Stefan , Li David K.B. , MacKay Alex L. 
Published: April 2009

AbstractMulticomponent T2 relaxation imaging can be used to measure signal from water trapped between myelin bilayers; the ratio of myelin water signal to total water is termed the myelin water fraction (MWF). The goal of this study was to implement and develop the single‐slice T2‐imaging technique proposed by Poon and Henkelman. For refinement, scan parameters (gradient crusher height and slew rate, bandwidth, echo spacing, matrix size, repetition time, and phase rewinding) were varied in water‐based phantoms and in fixed and in vivo brain. Changes in the standard deviation of the residuals of the multiexponential fit, MWF, T2, and peak width of the intra/extracellular water were monitored to determine which scan parameters minimized artifacts. Subsequently, we compared multicomponent T2 measurements at 1.5T and 3.0T for 10 healthy volunteers, and investigated the differences in SNR, fit residuals, MWF, and T2 and peak width of the intra/extracellular water, at higher magnetic field. MWF maps were found to be qualitatively similar between field strengths. MWFs were found to be significantly higher at 3.0T than at 1.5T, but with a strongly significant correlation between measurements (R2 > 0.92, P < 0.0005). The signal‐to‐noise ratio (SNR) was nearly double at 3.0T, but the standard deviation of residuals was increased in most cases. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Rapid single‐scan T‐mapping using exponential excitation pulses and image‐based correction for linear background gradients
Authors: Baudrexel Simon , Volz Steffen , Preibisch Christine , Klein Johannes C. , Steinmetz Helmuth , Hilker Rüdiger , Deichmann Ralf 
Published: April 2009

AbstractA method for fast quantitative T mapping based on multiple gradient‐echo (multi‐GE) imaging with correction for static magnetic field inhomogeneities is described, using an exponential excitation pulse. Field gradient maps are obtained from the phase information and modulus data are subsequently corrected, allowing for simple monoexponential T fitting. Echoes with long echo times suffering from major signal losses due to field inhomogeneities are excluded from the analysis. The acquisition time for a matrix size of 256 × 256, 1 mm in‐plane resolution, and 2 mm slice thickness amounts to 15 s per slice. An additional correction for in‐plane field gradients further improves accuracy. Phantom experiments show that the method provides accurate T values for field gradients up to 200 μT/m; for gradients up to 300 μT/m errors do not exceed 15%. In vivo T values acquired on healthy volunteers at 3T are in excellent agreement with results from the literature. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Aldehyde fixative solutions alter the water relaxation and diffusion properties of nervous tissue
Authors: Shepherd Timothy M. , Thelwall Peter E. , Stanisz Greg J. , Blackband Stephen J. 
Published: April 2009

AbstractChemically‐fixed nervous tissues are well‐suited for high‐resolution, time‐intensive MRI acquisitions without motion artifacts, such as those required for brain atlas projects, but the aldehyde fixatives used may significantly alter tissue MRI properties. To test this hypothesis, this study characterized the impact of common aldehyde fixatives on the MRI properties of a rat brain slice model. Rat cortical slices immersion‐fixed in 4% formaldehyde demonstrated 21% and 81% reductions in tissue T1 and T2, respectively (P < 0.001). The T2 reduction was reversed by washing slices with phosphate‐buffered saline (PBS) for 12 h to remove free formaldehyde solution. Diffusion MRI of cortical slices analyzed with a two‐compartment analytical model of water diffusion demonstrated 88% and 30% increases in extracellular apparent diffusion coefficient (ADCEX) and apparent restriction size, respectively, when slices were chemically‐fixed with 4% formaldehyde (P ≤ 0.021). Further, fixation with 4% formaldehyde increased the transmembrane water exchange rate 239% (P < 0.001), indicating increased membrane permeability. Karnovsky's and 4% glutaraldehyde fixative solutions also changed the MRI properties of cortical slices, but significant differences were noted between the different fixative treatments (P < 0.05). The observed water relaxation and diffusion changes help better define the validity and limitations of using chemically‐fixed nervous tissue for MRI investigations. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Quantitative analysis of peristaltic and segmental motion in vivo in the rat small intestine using dynamic MRI
Authors: Ailiani Amit C. , Neuberger Thomas , Brasseur James G. , Banco Gino , Wang Yanxing , Smith Nadine B. , Webb Andrew G. 
Published: April 2009

AbstractConventional methods of quantifying segmental and peristaltic motion in animal models are highly invasive; involving, for example, the external isolation of segments of the gastrointestinal (GI) tract either from dead or anesthetized animals. The present study was undertaken to determine the utility of MRI to quantitatively analyze these motions in the jejunum region of anesthetized rats (N= 6) noninvasively. Dynamic images of the GI tract after oral gavage with a Gd contrast agent were acquired at a rate of six frames per second, followed by image segmentation based on a combination of three‐dimensional live wire (3D LW) and directional dynamic gradient vector flow snakes (DDGVFS). Quantitative analysis of the variation in diameter at a fixed constricting location showed clear indications of both segmental and peristaltic motions. Quantitative analysis of the frequency response gave results in good agreement with those acquired in previous studies using invasive measurement techniques. Principal component analysis (PCA) of the segmented data using active shape models resulted in three major modes. The individual modes revealed unique spatial patterns for peristaltic and segmental motility. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Ultrashort TE spectroscopic imaging (UTESI) using complex highly‐constrained backprojection with local reconstruction (HYPR LR)
Authors: Wang Kang , Du Jiang , O'Halloran Rafael , Fain Sean , Kecskemeti Steven , Wieben Oliver , Johnson Kevin M. , Mistretta Charles 
Published: April 2009

AbstractRecently, the highly‐constrained backprojection (HYPR) and HYPR with local reconstruction (HYPR LR) methods have been introduced to reconstruct magnitude images from a series of highly undersampled data while preserving high spatial and temporal resolution and high signal‐to‐noise ratio (SNR) in applications with spatiotemporal correlations. However, these conventional HYPR algorithms are limited to the generation of magnitude images and, therefore, have limitations in their potential applications. In this work, the HYPR LR algorithm has been modified to extend the use of algorithms in the HYPR family to applications that require processing of complex data, such as MR chemical shift imaging (CSI) or spectroscopic imaging. The proposed method processes the magnitude information the same way as in original HYPR LR processing. In addition, it improves the phase images by subtracting the phase map of a synthesized composite image. The feasibility and efficiency of this algorithm has been demonstrated on CSI of cortical bone, Achilles tendon, and a healthy volunteer on a clinical 3T scanner. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Radiofrequency current source (RFCS) drive and decoupling technique for parallel transmit arrays using a high‐power metal oxide semiconductor field‐effect transistor (MOSFET)
Authors: Lee WonJe , Boskamp Eddy , Grist Thomas , Kurpad Krishna 
Published: April 2009

AbstractA radiofrequency current source (RFCS) design using a high‐power metal oxide semiconductor field effect transistor (MOSFET) that enables independent current control for parallel transmit applications is presented. The design of an RFCS integrated with a series tuned transmitting loop and its associated control circuitry is described. The current source is operated in a gated class AB push‐pull configuration for linear operation at high efficiency. The pulsed RF current amplitude driven into the low impedance transmitting loop was found to be relatively insensitive to the various loaded loop impedances ranging from 0.4 to 10.3 ohms, confirming current mode operation. The suppression of current induced by a neighboring loop was quantified as a function of center‐to‐center loop distance, and was measured to be 17 dB for nonoverlapping, adjacent loops. Deterministic manipulation of the B1 field pattern was demonstrated by the independent control of RF phase and amplitude in a head‐sized two‐channel volume transmit array. It was found that a high‐voltage rated RF power MOSFET with a minimum load resistance, exhibits current source behavior, which aids in transmit array design. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Modified PROPELLER approach for T2‐mapping of the abdomen
Authors: Deng Jie , Larson Andrew C. 
Published: April 2009

AbstractQuantitative abdominal T2 measurements may be useful for lesion differentiation and functional tissue characterization. However, T2 mapping of the abdomen with conventional spin‐echo (SE) and turbo‐spin‐echo (TSE) approaches can be challenging due to physiologic motion artifacts. Multishot TSE‐based PROPELLER (Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction) can provide superior image quality due to reduced sensitivity to motion artifacts. With echo‐reordering to accurately estimate effective echo times and an extended slice thickness ratio to reduce stimulated echo effects, a modified PROPELLER approach may permit accurate, robust abdominal T2 measurements. We validated the accuracy of our modified PROPELLER T2‐mapping approach by comparison to conventional SE measurements in a phantom model and demonstrated the feasibility of acquiring accurate, high‐quality abdominal T2 maps in normal volunteers. Magn Reson Med 61:1269–1278, 2009. © 2009 Wiley‐Liss, Inc.
Relaxation effects of ferucarbotran‐labeled mesenchymal stem cells at 1.5T and 3T: Discrimination of viable from lysed cells
Authors: Henning Tobias D. , Wendland Michael F. , Golovko Daniel , Sutton Elizabeth J. , Sennino Barbara , Malek Farbod , Bauer Jan S. , McDonald Donald M. , Daldrup‐Link Heike 
Published: April 2009

AbstractHuman mesenchymal stem cells (hMSCs) were labeled with Ferucarbotran by simple incubation and cultured for up to 14 d. Iron content was determined by spectrometry and the intracellular localization of the contrast agent uptake was studied by electron and confocal microscopy. At various time points after labeling, ranging from 1 to 14 d, samples with viable or lysed labeled hMSCs, as well as nonlabeled controls, underwent MRI. Spin‐echo (SE) and gradient‐echo (GE) sequences with multiple TRs and TEs were used at 1.5T and 3T on a clinical scanner. Spectrometry showed an initial iron oxide uptake of 7.08 pg per cell. Microscopy studies revealed lysosomal compartmentalization. Contrast agent effects of hMSCs were persistent for up to 14 d after labeling. A marked difference in the T2 effect of compartmentalized iron oxides compared to free iron oxides was found on T2‐weighted sequences, but not on T‐weighted sequences. The observed differences may be explained by the loss of compartmentalization of iron oxide particles, the uniformity of distribution, and the subsequent increase in dephasing of protons on SE images. These results show that viable cells with compartmentalized iron oxides may—in principle—be distinguished from lysed cells or released iron oxides. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Robust estimation of the apparent diffusion coefficient (ADC) in heterogeneous solid tumors
Authors: Walker‐Samuel Simon , Orton Matthew , McPhail Lesley D. , Robinson Simon P. 
Published: April 2009

AbstractThe least‐squares algorithm is known to bias apparent diffusion coefficient (ADC) values estimated from magnitude MR data, although this effect is commonly assumed to be negligible. In this study the effect of this bias on tumor ADC estimates was evaluated in vivo and was shown to introduce a consistent and significant underestimation of ADC, relative to those given by a robust maximum likelihood approach (on average, a 23.4 ± 12% underestimation). Monte Carlo simulations revealed that the magnitude of the bias increased with ADC and decreasing signal‐to‐noise ratio (SNR). In vivo, this resulted in a much‐reduced ability to resolve necrotic regions from surrounding viable tumor tissue compared with a maximum likelihood approach. This has significant implications for the evaluation of diffusion MR data in vivo, in particular in heterogeneous tumor tissue, when evaluating bi‐ and multiexponential tumor diffusion models for the modeling of data acquired with larger b‐values (b > 1000 s/mm2) and for data with modest SNR. Use of a robust approach to modeling magnitude MR data from tumors is therefore recommended over the least‐squares approach when evaluating data from heterogeneous tumors. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Treatment of intestinal and hepatic mucormycosis in an immunocompromized child
Authors: Lüer Sonja , Berger Steffen , Diepold Miriam , Duppenthaler Andrea , von Gunten Michael , Mühlethaler Konrad , Wolf Rainer , Aebi Christoph 
Published: April 2009

AbstractDuring ALL chemotherapy, a 4‐year‐old patient presented with febrile neutropenia and abdominal pain. Ultrasound examinations were repeatedly normal. Computerized tomography on day 7 demonstrated appendicitis and multiple hepatic foci identified as mucormycosis (Absidia corymbifera). Successful outcome was achieved by aggressive re‐surgery, long‐term antifungal therapy with serum level‐monitored posaconazole, and recovery of neutrophil counts. Considering the interference of posaconazole with CYP3A4, vincristine was administered during 72 hr posaconazole windows. Pediatric intestinal mucormycosis, still associated with a >70% case‐fatality rate, calls for early imaging and surgery to establish the diagnosis, reduce the fungal mass, and provide a rationale for using posaconazole. Pediatr Blood Cancer 2009;52:872–874. © 2009 Wiley‐Liss, Inc.
Cushing syndrome as a presenting symptom of renal tumors in children
Authors: Segers H. , van der Heyden J.C. , van den Akker E.L.T. , de Krijger R.R. , Zwaan C.M. , van den Heuvel‐Eibrink M.M. 
Published: April 2009

AbstractCushing syndrome as the presenting symptom of a malignant renal tumor in children is rare. We report the first case of paraneoplastic Cushing syndrome due to a Wilms tumor, in which clinical and biological signs of hypercortisolism regressed during preoperative chemotherapy. Additionally, we reviewed the literature on paraneoplastic Cushing syndrome secondary to pediatric renal tumors. Pediatr Blood Cancer 2009;53:211–213. © 2009 Wiley‐Liss, Inc.
Renal function after hematopoietic stem cell transplantation in children
Authors: Hazar Volkan , Gungor Ozgul , Guven Ayfer Gur , Aydin Funda , Akbas Halide , Gungor Fırat , Tezcan Gulsun , Akman Sema , Yesilipek Akif 
Published: April 2009

AbstractObjectivesThe aim of this study was to assess glomerular and tubular renal function after HSCT in children in a prospective trial.MethodsRenal function was assessed prospectively before HSCT (on day −10), on days +30, +100, and at least 6 months after transplantation in 34 patients (21 females/13 males) with a mean age of 8.2 years. The following parameters were investigated: glomerular filtration rate (GFR) by creatinine clearance (CrCl), cystatin C (CysC)‐based formula and plasma clearance of radiolabeled diethylenetriaminepentaacetic acid (99mTc‐DTPA), urinary excretion of β2‐microglobulin (β2M), β‐N‐acetylglucosaminidase (β‐NAG), fractional excretion of sodium (FENa) and fractional tubular phosphate reabsorption (TP/CrCl).ResultsNine patients (26.4%) suffered from acute renal insufficiency within the first 100 days after transplantation. All patients who developed acute renal insufficiency were treated successfully without renal replacement therapy. Age, sex, primary diagnosis, sepsis, veno‐occlusive disease, acute graft versus host disease, and use of vancomycin were not significant risk factors for the development of acute renal insufficiency. The medians 99mTc‐DTPA‐based GFR of patients after HSCT showed a statistically significant decrease when compared with pre‐transplant values. β‐NAG excretion was significantly elevated in the first 30 days after HSCT.ConclusionAcute and chronic renal impairment can be developed in patients who undergo HSCT even though the pre‐transplant renal function is in normal limits and the conditioning regimen does not include TBI. Both glomerular and tubular renal function evaluation should be part of a long‐term follow‐up in children following HSCT. Pediatr Blood Cancer 2009;53:197–202. © 2009 Wiley‐Liss, Inc.
Infection of T lymphocytes in Epstein‐Barr virus‐associated hemophagocytic lymphohistiocytosis in children of non‐Asian origin
Authors: Beutel Karin , Gross‐Wieltsch Ute , Wiesel Thomas , Stadt Udo Zur , Janka Gritta , Wagner Hans‐Joachim 
Published: April 2009

AbstractBackgroundEpstein‐Barr virus (EBV) is one of the most frequent triggers of hemophagocytic lymphohistiocytosis (HLH). EBV‐associated HLH (EBV‐HLH) and ectopic infection of T cells has been particularly described in patients from Far East Asia.ProcedureIn a cohort of 12 children with EBV‐HLH treated in Germany, the EB viral load was detected by real‐time polymerase chain reaction in plasma and peripheral blood mononuclear cells (PBMC). Virological and clinical data were analyzed retrospectively.ResultsAmong the 12 mainly German patients, children with underlying immunodeficiencies as well as otherwise healthy individuals were affected. The clinical course ranged from a steroid‐responding to a fatal disease despite intensive treatment. Increased EBV copy numbers in plasma and/or PBMC were found in all patients. Serial measurements reflected the course of the disease. Cell‐type specific viral load was determined in seven patients and revealed EBV‐infection of T cells in all of them. In contrast to the reported Asian patients a significant viral load was also found in B cells.ConclusionsT cell infection appears to be a typical feature of EBV‐associated HLH irrespective of patients ethnic background and the clinical course. Evaluation of cell‐type specific infection should be considered when targeted therapy is applied. Pediatr Blood Cancer 2009;53:184–190. © 2009 Wiley‐Liss, Inc.
Atypical varicella zoster infection associated with hemophagocytic lymphohistiocytosis
Authors: van der Werff ten Bosch Jutte E. , Kollen Wouter J.W. , Ball Lynne M. , Brinkman Danielle M.C. , Vossen Anne C.T.M. , Lankester Arjan C. , Egeler R. Maarten , Bredius Robbert G.M. 
Published: April 2009

AbstractTwo adolescents, on immunosuppressive therapy for graft‐versus‐host disease, developed hemophagocytic lymphohistiocytosis (HLH) after varicella zoster virus (VZV) reactivation. In the absence of dermatome restricted characteristic skin lesions, VZV reactivation was not immediately recognized and treatment with acyclovir was delayed. The first patient developed optical neuritis and died 2 months after the VZV episode due to massive intracranial hemorrhage. The second patient presented with severe abdominal pain and pancreatitis, followed by atypical skin eruptions, which prompted a faster diagnosis. Both patients recovered from their HLH, the first patient being successfully treated with immunosuppressive agents and the second with VZV treatment only. These two cases demonstrate the difficulties in recognizing VZV reactivation, and in order to start adequate and timely treatment, the need to consider VZV as a possible cause of HLH in severely immunocompromised patients. Pediatr Blood Cancer 2009;53:226–228. © 2009 Wiley‐Liss, Inc.
Evaluating access to pediatric cancer care centers of children and adolescents with rare tumors in Italy: The TREP project
Authors: Pastore Guido , De Salvo Gian Luca , Bisogno Gianni , Dama Elisa , Inserra Alessandro , Cecchetto Giovanni , Ferrari Andrea 
Published: April 2009

AbstractBackgroundA national project focusing on rare malignant pediatric tumors (the TREP project) was launched in Italy in 2000. The present study compared the number of these tumors expected to be diagnosed in Italy with the number of cases actually enrolled in the TREP database in 2000–2006.MethodsThe predicted number of cases was calculated from incidence data from the Italian network of cancer registries (AIRTum).ResultsThe TREP database included 336 patients under 18 years, that is, 261 children and 75 adolescents, as compared to 305 and 400 expected cases, respectively. For the 0–14 years old age‐group, the ratio of observed to expected cases was 1:1 for nasopharyngeal carcinoma, adrenocortical tumors, renal cell carcinoma, and gonadal non‐germ‐cell tumors, while for the 15–17‐year old individuals there was a statistically significant under‐reporting for all tumor types.ConclusionsOur study showed that the TREP project succeeded in registering and treating the vast majority of the patients under 15 years of age with rare pediatric tumors, demonstrating the feasibility of cooperative protocols even for rare diseases. Conversely, there was a large gap between those registered compared to those expected for adolescents. Pediatr Blood Cancer 2009;53:152–155. © 2009 Wiley‐Liss, Inc.
Surface and interface characterization of untreated and SMA Imide‐treated hemp fiber/acrylic composites
Authors: Behzad Tayebeh , Sain Mohini 
Published: April 2009

AbstractThe hydrophilic nature of natural fibers adversely affects adhesion to a hydrophobic matrix, and consequently it may unfavorably influence the strength of the composite. Therefore, modifying the fiber or the matrix is essential to obtain optimum composite properties. In this work, hemp fibers were modified applying a paper sizing technique using SMA Imide resin (copolymer of styrene and dimethylaminopropylamine maleimide) as a surface modifying agent. The performance of the hemp/acrylic composite was improved significantly using the treated fibers. Inverse gas chromatography (IGC) and pull‐out test were employed to study the hemp fiber/matrix interface and the surface characteristics of untreated and treated hemp fibers. The IGC results demonstrated that treated fibers had slightly higher dispersive force compared with untreated fibers. Moreover, modification of fibers with SMA Imide resin slightly decreased the basic character and significantly increased the acid character of hemp fibers. From the pull‐out test, the average stress to pull the SMA‐treated fibers out was 71% higher than that calculated for untreated fibers. The higher interfacial strength for the treated fibers shows that the SMA treatment had a beneficial influence on the adhesion of the acrylic resin to the hemp fibers. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers