bluuebunny/crossref_metadata_2025_split huggingface dataset:
Myocardial T measurements in iron‐overloaded thalassemia: An in vivo study to investigate optimal methods of quantification
Authors: He Taigang , Gatehouse Peter D. , Smith Gillian C. , Mohiaddin Raad H. , Pennell Dudley J. , Firmin David N. 
Published: October 2008

AbstractReproducible and accurate myocardial T measurements are required for the quantification of iron in heart tissue in transfused thalassemia. The aim of this study was to determine the best method to measure the myocardial T from multi‐gradient‐echo data acquired both with and without black‐blood preparation. Sixteen thalassemia patients from six centers were scanned twice locally, within 1 week, using an optimized bright‐blood T sequence and then subsequently scanned at the standardization center in London within 4 weeks, using a T sequence both with and without black‐blood preparation. Different curve‐fitting models (monoexponential, truncation, and offset) were applied to the data and the results were compared by means of reproducibility. T measurements obtained using the bright‐ and black‐blood techniques. The black‐blood data were well fitted by the monoexponential model, which suggests that a more accurate measure of T can be obtained by removing the main source of errors in the bright‐blood data. For bright‐blood data, the offset model appeared to underestimate T values substantially and was less reproducible. The truncation model gave rise to more reproducible T measurements, which were also closer to the values obtained from the black‐blood data. Magn Reson Med 60:1082–1089, 2008. © 2008 Wiley‐Liss, Inc.
Efficient fat suppression by slice‐selection gradient reversal in twice‐refocused diffusion encoding
Authors: Nagy Zoltan , Weiskopf Nikolaus 
Published: October 2008

AbstractMost diffusion imaging sequences rely on single‐shot echo‐planar imaging (EPI) for spatial encoding since it is the fastest acquisition available. However, it is sensitive to chemical‐shift artifacts due to the low bandwidth in the phase‐encoding direction, making fat suppression necessary. Often, spectral‐selective RF pulses followed by gradient spoiling are used to selectively saturate the fat signal. This lengthens the acquisition time and increases the specific absorption rate (SAR). However, in pulse sequences that contain two slice‐selective 180° refocusing pulses, the slice‐selection gradient reversal (SSGR) method of fat suppression can be implemented; i.e., using slice‐selection gradients of opposing polarity for the two refocusing pulses. We combined this method with the twice‐refocused spin‐echo sequence for diffusion encoding and tested its performance in both phantoms and in vivo. Unwanted fat signal was entirely suppressed with this method without affecting the water signal intensity or the slice profile. Magn Reson Med 60:1256–1260, 2008. © 2008 Wiley‐Liss, Inc.
Linear phase‐error correction for improved water and fat separation in dual‐echo dixon techniques
Authors: Ma Jingfei , Slavens Zachary , Sun Wei , Bayram Ersin , Estowski Lloyd , Hwang Ken‐Pin , Akao James , Vu Anthony T. 
Published: October 2008

AbstractLarge and spatially‐linear phase errors along the frequency‐encode direction may be induced by several common and hard‐to‐avoid system imperfections such as eddy currents. For data acquired in dual‐echo Dixon techniques, the linear phase error can be more aggravated when compared to that acquired in a single echo and can pose challenges to a phase‐correction algorithm necessary for successful Dixon processing. In this work, we propose a two‐step process that first corrects the linear component of the phase errors with a modified Ahn‐Cho algorithm (Ahn CB and Cho ZH, IEEE Trans. Med. Imaging 6:32, 1987) and then corrects the residual phase errors with a previously‐developed region‐growing algorithm (Ma J, Magn. Res. Med. 52:415, 2004). We demonstrate that successive application of the two‐step process to data from a dual‐echo Dixon technique provides a “1‐2 punch” to the overall phase errors and can overcome local water and fat separation failures that are observed when the region‐growing–based algorithm is applied alone. Magn Reson Med 60:1250–1255, 2008. © 2008 Wiley‐Liss, Inc.
Cellular‐interstitial water exchange and its effect on the determination of contrast agent concentration in vivo: Dynamic contrast‐enhanced MRI of human internal obturator muscle
Authors: Buckley David L. , Kershaw Lucy E. , Stanisz Greg J. 
Published: October 2008

AbstractThe purpose of this study was to assess the effects of cellular‐interstitial water exchange on estimates of tracer kinetics parameters obtained using rapid dynamic contrast‐enhanced (DCE) MRI. Data from the internal obturator muscle of six patients were examined using three models of water exchange: no exchange (NX), fast exchange limit (FXL), and intermediate rate (shutter‐speed [SS]). In combination with additional multiple flip angle (FA) data, a full two‐pool exchange model was also used. The results obtained using the NX model (transfer constant, Ktrans = 0.049 ± 0.027 min–1, apparent interstitial volume, ve = 0.14 ± 0.04) were marginally higher than those obtained using the FXL model (Ktrans = 0.045 ± 0.025 min–1, ve = 0.13 ± 0.04), but the error bars overlapped in two‐thirds of these parameter estimate pairs. Estimates of Ktrans and ve obtained using the SS model exceeded those obtained using the NX model in half the patients, and many estimates, including all those of intracellular residence time of water, ti, were imprecise. Results obtained using the full two‐pool model fell between those obtained using FXL and NX models, and estimates of ti were also imprecise. The results suggest that data obtained using clinically relevant DCE‐MRI are exchange‐insensitive and unsuitable for the assessment of cellular‐interstitial water exchange. Magn Reson Med 60:1011–1019, 2008. © 2008 Wiley‐Liss, Inc.
Four‐pool modeling of proton exchange processes in biological systems in the presence of MRI–paramagnetic chemical exchange saturation transfer (PARACEST) agents
Authors: Li Alex X. , Hudson Robert H.E. , Barrett John W. , Jones Craig K. , Pasternak Stephen H. , Bartha Robert 
Published: October 2008

AbstractSignal loss due to magnetization transfer (MT) from the macromolecular protons of biological tissues is an important consideration for the in vivo detection of paramagnetic chemical exchange saturation transfer (PARACEST) agents. In this study, a four‐pool model is presented that is based on the modified Bloch equations and incorporates terms for the proton exchange processes that occur in biological systems in the presence of MRI‐PARACEST contrast agents. The effect of the exchangeable proton chemical shift and PARACEST agent concentration are modeled in the presence of macromolecule‐derived MT. Experimental validation of the model was performed at 9.4 Tesla using Eu3+‐DOTAM‐glycine (Gly)‐phenylalanine (Phe) in both aqueous solution and samples containing 10% bovine serum albumin (BSA). The model was then used to measure the agent‐bound‐water chemical shift and the transverse relaxation time of macromolecular protons of a sample of Vero (nonhuman primate) cells labeled with Eu3+‐DOTAM‐Gly‐Phe and a phantom containing mouse brain tissue and 7 mM Eu3+‐DOTAM‐Gly‐Phe. In the brain tissue phantom, a chemical shift map with standard deviation (SD) < 0.7 ppm and a T2 map with SD < 0.6 μs were obtained. The results demonstrate the feasibility of in vivo temperature measurement based on the bound‐water chemical shift of Eu3+‐DOTAM‐Gly‐Phe in combination with this four‐pool model despite the inherent MT effect. Magn Reson Med 60:1197–1206, 2008. © 2008 Wiley‐Liss, Inc.
Comparison of BOLD and direct‐MR neuronal detection (DND) in the human visual cortex at 3T
Authors: Chow Li Sze , Dagens Andrew , Fu Ying , Cook Greg G. , Paley Martyn N.J. 
Published: October 2008

AbstractDirect‐MR neuronal detection (DND) of transient magnetic fields has recently been investigated as a novel imaging alternative to the conventional BOLD functional MRI (fMRI) technique. However, there remain controversial issues and debate surrounding this methodology, and this study attempts clarification by comparing BOLD responses in the human visual system with those of DND. BOLD relies on indirectly measuring blood oxygenation and flow changes as a result of neuronal activity, whereas the putative DND method is based on the hypothesis that the components of the in vivo neuronal magnetic fields, which lie parallel to the B0 field, can potentially modulate the MR signal, thus providing a means of direct detection of nerve impulses. Block paradigms of checkerboard patterns were used for visual stimulation in both DND and BOLD experiments, allowing detection based on different frequency responses. This study shows colocalization of some voxels with slow BOLD responses and putative fast DND responses using General Linear Model (GLM) analysis. Frequency spectra for the activated voxel cluster are also shown for both stimulated and control data. The mean percentage signal change for the DND responses is 0.2%, corresponding to a predicted neuronal field of 0.14 nT. Magn Reson Med 60:1147–1154, 2008. © 2008 Wiley‐Liss, Inc.
Inhibition of carbohydrate oxidation during the first minute of reperfusion after brief ischemia: NMR detection of hyperpolarized 13CO2 and H13CO
Authors: Merritt Matthew E. , Harrison Crystal , Storey Charles , Sherry A. Dean , Malloy Craig R. 
Published: October 2008

AbstractIsolated rat hearts were studied by 31P NMR and 13C NMR. Hyperpolarized [1‐13C]pyruvate was supplied to control normoxic hearts and production of [1‐13C]lactate, [1‐13C]alanine, 13CO2 and H13CO was monitored with 1‐s temporal resolution. Hearts were also subjected to 10 min of global ischemia followed by reperfusion. Developed pressure, heart rate, oxygen consumption, [ATP], [phosphocreatine], and pH recovered within 3 min after the ischemic period. During the first 90 s of reperfusion, [1‐13C]alanine and [1‐13C]lactate appeared rapidly, demonstrating metabolism of pyruvate through two enzymes largely confined to the cytosol, alanine aminotransferase, and lactate dehydrogenase. 13CO2 and H13CO were not detected. Late after ischemia and reperfusion, the products of pyruvate dehydrogenase, 13CO2 and H13CO were easily detected. Using this multinuclear NMR approach, we established that during the first 90 s of reperfusion PDH flux is essentially zero and recovers within 20 min in reversibly‐injured myocardium. Magn Reson Med 60:1029–1036, 2008. © 2008 Wiley‐Liss, Inc.
A human ferritin iron oxide nano‐composite magnetic resonance contrast agent
Authors: Uchida Masaki , Terashima Masahiro , Cunningham Charles H. , Suzuki Yoriyasu , Willits Deborah A. , Willis Ann F. , Yang Philip C. , Tsao Philip S. , McConnell Michael V. , Young Mark J. , Douglas Trevor 
Published: October 2008

AbstractMacrophages play important roles in the immunological defense system, but at the same time they are involved in inflammatory diseases such as atherosclerosis. Therefore, imaging macrophages is critical to assessing the status of these diseases. Toward this goal, a recombinant human H chain ferritin (rHFn)‐iron oxide nano composite has been investigated as an MRI contrast agent for labeling macrophages. Iron oxide nanoparticles in the form of magnetite (or maghemite) with narrow size distribution were synthesized in the interior cavity of rHFn. The composite material exhibited the R2 relaxivity comparable to known iron oxide MRI contrast agents. Furthermore, the mineralized protein cages are readily taken up by macrophages in vitro and provide significant T2* signal loss of the labeled cells. These results encourage further investigation into the development of the rHFn‐iron oxide contrast agent to assess inflammatory disease status such as macrophage‐rich atherosclerotic plaques in vivo. Magn Reson Med 60:1073–1081, 2008. © 2008 Wiley‐Liss, Inc.
Steady state free precession magnetization transfer imaging
Authors: Bieri Oliver , Mamisch Tallas C. , Trattnig Siegfried , Scheffler Klaus 
Published: October 2008

AbstractThe formerly proposed concept for magnetization transfer imaging (MTI) using balanced steady‐state free precession (SSFP) image acquisitions is in this work extended to nonbalanced protocols. This allows SSFP‐based MTI of targets with high susceptibility variation (such as the musculoskeletal system), or at ultra‐high magnetic fields (where balanced SSFP suffers from considerable off‐resonance related image degradations). In the first part, SSFP‐based MTI in human brain is analyzed based on magnetization transfer ratio (MTR) histograms. High correlations are observed among all different SSFP MTI protocols and thereby ensure proper conceptual extension to nonbalanced SSFP. The second part demonstrates SSFP‐based MTI allowing fast acquisition of high resolution volumetric MTR data from human brain and cartilage at low (1.5T) to ultra‐high (7.0T) magnetic fields. Magn Reson Med 60:1261–1266, 2008. © 2008 Wiley‐Liss, Inc.
Detection of targeted perfluorocarbon nanoparticle binding using 19F diffusion weighted MR spectroscopy
Authors: Waters Emily A. , Chen Junjie , Yang Xiaoxia , Zhang Huiying , Neumann Robert , Santeford Andrea , Arbeit Jeffrey , Lanza Gregory M. , Wickline Samuel A. 
Published: October 2008

AbstractReal‐time detection of targeted contrast agent binding is challenging due to background signal from unbound agent. 19F diffusion weighted MR spectroscopy (DWS) could selectively detect binding of angiogenesis‐targeted perfluorocarbon nanoparticles in vivo. Transgenic K14‐HPV16 mice with epidermal squamous carcinomas exhibiting up‐regulated neovasculature were used, with nontransgenic littermates as controls. Mice were treated with αvβ3‐integrin targeted perfluorocarbon nanoparticles. 19F DWS (b‐values from 0 to 16,000 s/mm2) was performed on mouse ears in vivo at 11.74 Tesla. Progressive decay of 19F signal with increased diffusion weighting at low b‐values (< 1500 s/mm2) was observed in ears of both K14‐HPV16 and control mice, demonstrating suppression of background 19F signal from unbound nanoparticles in the blood. Much of the 19F signal from ears of K14‐HPV16 mice persisted at high b‐values, indicating a stationary signal source, reflecting abundant nanoparticle binding to angiogenesis. 19F signal in controls decayed completely at high b‐values (> 1500 s/mm2), reflecting a moving signal source due to absence of angiogenesis (no binding sites). Estimated ADCs of nanoparticles in K14‐HPV16 and control mice were 33.1 ± 12.9 μm2/s and 19563 ± 5858 μm2/s (p < 0.01). In vivo 19F DWS can be used for specific detection of bound perfluorocarbon nanoparticles by selectively suppressing background 19F signal from nanoparticles flowing in blood. Magn Reson Med 60:1232–1236, 2008. © 2008 Wiley‐Liss, Inc.
Focal reversible deactivation of cerebral metabolism affects water diffusion
Authors: Khachaturian Mark H. , Arsenault John , Ekstrom Leeland B. , Tuch David S. , Vanduffel Wim 
Published: October 2008

AbstractThe underlying biophysical mechanisms which affect cerebral diffusion contrast remain poorly understood. We hypothesized that cerebral metabolism may affect cerebral diffusion contrast. The purpose of this study was to develop the methodology to reversibly deactivate cerebral metabolism and measure the effect on the diffusion MRI signal. We developed an MRI‐compatible cortical cooling system to reversibly deactivate cortical metabolism in rhesus monkey area V1 and used MR thermometry to calculate three‐dimensional temperature maps of the brain to define the extent of deactivated brain in vivo. Significant changes in the apparent diffusion coefficient (ADC) wereonlyobserved during those experiments in which the cortex was cooled below the metabolic cutoff temperature of 20°C. ADC decreases (12–20%) were observed during cortical cooling in regions where the temperature did not change. The normalized in vivo ADC as function of temperature was measured and found to be equivalent to the normalized ADC of free water at temperatures above 20°C, but was significantly decreased below 20°C (20–25% decrease). No changes in fractional anisotropy were observed. In future experiments, we will apply this methodology to quantify the effect of reversible deactivation on neural activity as measured by the hemodynamic response and compare water diffusion changes with hemodynamic changes. Magn Reson Med 60:1178–1189, 2008. © 2008 Wiley‐Liss, Inc.
Antitussiva und Expektorantien. Medizinisch‐chemische Aspekte
Authors: Sander Kerstin , Zettl Heiko , Schubert‐Zsilavecz Manfred , Stark Holger 
Published: October 2008

AbstractHusten – ein weit verbreitetes Symptom von unterschiedlicher Genese – resultiert am häufigsten als Folge von viralen und bakteriellen Infekten der oberen Atemwege. Je nach Ausprägung sind zur Behandlung dieses Symptoms Antitussiva und/oder Expektorantien indiziert. Trotz des großen Bedarfs an medikamentöser Therapie sind sowohl im verschreibungspflichtigen als auch im OTC‐Bereich die Möglichkeiten auf dem deutschen Markt eher übersichtlich und hinsichtlich einer signifikanten Wirksamkeit einiger Substanzgruppen kritisch zu beurteilen.
Stellenwert chemisch‐synthetischer Antitussiva und Expektorantien. Waisenkinder der pharmakologischen Forschung?
Authors: Kardos Peter 
Published: October 2008

AbstractObwohl Husten einer der häufigsten Beschwerden ist, verfügen wir nicht über effektive und nebenwirkungsarme Medikamente zur Therapie. Falls eine kausale Therapie (z.B. Operation des Bronchialkarzinoms) nicht möglich ist, oder die eingeleitete kausale Therapie nur langsam wirkt (z.B. die Tuberkulosetherapie) benötigen wir symptomatisch wirkende Medikamente zur Linderung. Es haben sich zwei therapeutische Ansätze eingebürgert: die antitussive Therapie für den nicht produktiven Reizhusten und die protussive Therapie mit Expektorantien zur Linderung des produktiven Hustens. Chemisch definierte Antitussiva werden aus Alkaloiden des Schlafmohns abgeleitet und haben mehr oder weniger ausgeprägt die Nebenwirkungen der Morphinderivate, die Addiktionsgefahr sollte keinesfalls unterschätzt werden. Ein objektiver Wirksamkeitsnachweis für die besonders in Deutschland beliebten Expektorantien fehlt, subjektiv werden sie jedoch häufig als hilfreich empfunden.
Stellenwert pflanzlicher Antitussiva und Expektorantien. Symptomatische Phytotherapie bei Husten
Authors: Kraft Karin 
Published: October 2008

AbstractDie Inzidenz von Erkrankungen des Respirationstraktes steigt in Deutschland stark an, dies betrifft insbesondere die chronischen Erkrankungen wie die chronisch obstruktive Lungenerkrankung und das Asthma bronchiale. Der Stellenwert von pflanzlichen Drogen und ihren Zubereitungen ist bei diesen Erkrankungen bisher kaum zu beurteilen, da das Spektrum an verfügbaren Expektorantien und Antitussiva zwar relativ breit ist, diese jedoch ganz überwiegend bei akuten unkomplizierten Erkrankungen des Respirationstraktes eingesetzt werden und zwar immer mehr im Bereich der Selbstmedikation. Ein kompetenter Umgang mit Phytopharmaka ist jedoch bei allen Atemwegserkrankungen essenziell; die infolge der fehlenden Erstattungsfähigkeit mittlerweile überwiegende Selbstmedikation sollte arztgestützt erfolgen.
Inhalationstherapie bei Hustenerkrankungen: Methoden und Techniken. Wirkungsvolle Hustentherapie mit geeigneten Inhalationsgeräten
Authors: Berzel Hans Günter , Berzel Simon Gunter 
Published: October 2008

AbstractIn der Pneumologie spielt die Inhalationstherapie von Atemwegserkrankungen mit geeigneten Inhalationsgeräten und atemwegsgängigen Medikamenten eine bedeutungsvolle Rolle. Ein ausschließlich für alle Altersgruppen zu empfehlendes Inhalationsgerät gibt es nicht, vielmehr muss je nach Alter ein geeignetes Inhalationsinstrument ausgewählt werden. Es sollte leicht zu handhaben, gut pflegbar und transportabel sein und keine zu großen Anforderungen an Koordination und Compliance stellen. Gründliche Unterrichtungen über die Zielsetzung der Therapie, Applikationsform und Behandlungsdauer sind eminent wichtig. Frustrationen und Misserfolge durch ineffiziente Inhalationstherapien sind durch regelmäßige Schulungen und Kontrolldemonstrationen zu korrigieren.Bei konsequenter praktischer Umsetzung ist eine wirkungsvolle Inhalationstherapie in allen Altersgruppen gut möglich. Dies beinhaltet nicht zuletzt auch den Einsatz topisch inhalierbarer Kortikosteroide über Dosieraerosole mit ventilgesteuerten Spacern selbst im Säuglings‐ und Kleinkindesalter. Kinder sollten ermutigt werden, Dosieraerosole mit einem vorgeschalteten Spacersystem über den Mund zu inhalieren, höhere Medikamentendepositionen werden hierdurch erreicht. Eine Gesichtsmaske für Säuglinge und Kleinkinder erleichtert die Behandlung auch unter dem Aspekt, dass Wirkverluste einzukalkulieren sind. Mit dem Einsatz effizienter Spacer‐ und Trockenpulver‐Inhaliersysteme hat sich die Notwendigkeit der Ausstattung mit Feuchtverneblern vermindert.Druckluftgesteuerte Inhaliersysteme, verbesserte Pulverapplikatoren, fein‐ und langsam vernebelnde Lösungsaerosole sind neu eingeführt worden. Dosimetrisch gesteuerte und atemzugverstärkte Vernebler erhöhen bei kontrollierter Atmung nachhaltig die Wirksamkeit und Lungendeposition, so dass Patienten mit schweren chronischen Lungenkrankheiten auch mit dosiskritischen Medikamenten wirkungsvoll behandelt werden können. Sehr intensiv wird an neuen Methoden zur Erzeugung ultrafeiner Aerosole wie auch an Aerosolen selbst geforscht. Dies wird die Lebensperspektive chronisch atemwegskranker Patienten durch innovative Inhalationsmethoden auch in Zukunft erheblich verbessern.
Cocain‐Bindungsstelle am Dopamintransporter geklärt
Authors: Wenzel E. , Stark H. 
Published: October 2008

AbstractDer Bindungsmechanismus des Cocains am Wiederaufnahmeprotein wurde als allosterische Bindungsstelle diskutiert. Umfangreiche Mutations‐ und Modellingstudien belegen ein mit Dopamin überlappendes Bindungsverhalten.
Safer Sex auch unter antiretroviraler Therapie?
Authors: Winckler Thomas 
Published: October 2008

AbstractEin Ziel der modernen hoch‐aktiven, antiretroviralen Therapie (HAART) von HIV‐Infizierten ist die Senkung der Viruslast unter die Nachweisbarkeitsgrenze. Wie groß unter diesen Bedingungen das Risiko der Übertragung des HI‐Virus auf den Sexualpartner ist, wird von Fachleuten kontrovers diskutiert.
Non‐Hodgkin‐Lymphom: Personalisierte Therapie aus Pflanzen
Authors: Reichwein Simone , Warzecha Heribert 
Published: October 2008

AbstractDie Therapie verschiedener Krebsformen durch die spezifische Stimulation des körpereigenen Immunsystems hat in den letzten Jahren großes Interesse geweckt. Besonders bei der Therapie von Lymphomen hat sich hier ein vielversprechender Therapieansatz entwickelt.