bluuebunny/crossref_metadata_2025_split huggingface dataset:
Proton magnetic resonance spectroscopy with metabolite nulling reveals regional differences of macromolecules in normal human brain
Authors: Mader Irina , Seeger Uwe , Karitzky Jochen , Erb Michael , Schick Fritz , Klose Uwe 
Published: November 2002

AbstractPurposeTo quantify the macromolecular content in different anatomic brain regions and to evaluate an age dependency of the macromolecular concentrations.Material and MethodsA short echo time Stimulated Echo Acquisition Mode (STEAM) sequence was used without and with inversion recovery metabolite nulling in 8–12 healthy volunteers. Quantitation was achieved by an extended LCModel, and macromolecular resonances at 0.9, 1.4, 2.1, and 3.0 ppm were evaluated.ResultsIn the cerebellum, the 1.4, 2.1, and 3.0 ppm resonances were highest compared to all other regions (P < 0.02); the 0.9 ppm resonance was significantly higher than that of pons (P < 0.01). In the motor cortex, the 0.9, 1.4, and 2.1 ppm resonances were higher than those of white matter and pons (P < 0.02). Pons and white matter did not differ significantly from each other. A significant correlation of the macromolecular concentrations with the age could not be found.ConclusionThere were higher macromolecular concentrations in the cerebellum and motor cortex than in pons or white matter. These were probably due to the higher portions of gray matter in these volumes of interest (VOIs) than in the other regions. J. Magn. Reson. Imaging 2002;16:538–546. © 2002 Wiley‐Liss, Inc.
Multiplanar MR temperature‐sensitive imaging of cerebral thermal treatment using interstitial ultrasound applicators in a canine model
Authors: Kangasniemi Marko , Diederich Chris J. , Price DVM Roger E. , Stafford R. Jason , Schomer Donald F. , Olsson Lars E. , Tyreus Per Daniel , Nau Will H. , Hazle John D. 
Published: November 2002

AbstractPurposeTo study the feasibility of an interleaved gradient‐echo, echo‐planar imaging (iGE‐EPI) sequence for multiplanar magnetic resonance temperature imaging (MRTI) to monitor intracerebral thermal treatment three‐dimensionally using multielement ultrasound applicators.Materials and MethodsTransmissible venereal tumor (TVT) fragments were injected into the right cerebral hemisphere of five dogs. Guided by MRI, an interstitial ultrasound applicator was inserted into the tumor or normal brain tissue. The iGE‐EPI sequence was used to estimate temperature changes by computing the complex phase‐difference induced by temperature‐dependent shifts in the proton resonance frequency of water. The thermal dose maps were updated every 6–8 seconds for five to seven image planes during treatment. The results of MRTI were compared with those of post‐treatment MRI and histologic analysis.ResultsThe multiplanar MRTI monitored temperature and thermal dose distributions in tumor and normal brain tissue over the entire user‐defined treatment volume. The ultrasound applicators produced contiguous areas of coagulative necrosis, resulting in 1.5–4.0 cm3 volumes of tissue necrosis. MRTI‐based assessments of thermal‐dose distributions were consistent with the results of post‐treatment MRI and histologic analysis.ConclusionMultiplanar MRTI is feasible for measuring necrosing thermal doses during intracerebral thermal delivery by interstitial ultrasound applicators. J. Magn. Reson. Imaging 2002;16:522–531. © 2002 Wiley‐Liss, Inc.
Changes in oxygenation of intracranial tumors with carbogen: A BOLD MRI and EPR oximetry study
Authors: Dunn Jeff F. , O'Hara Julia A. , Zaim‐Wadghiri Youssef , Lei Hao , Meyerand M. Elizabeth , Grinberg Oleg Y. , Hou Huagang , Hoopes P. Jack , Demidenko Eugene , Swartz Harold M. 
Published: November 2002

AbstractPurposeTo examine, using blood oxygen level dependent (BOLD) MRI and EPR oximetry, the changes in oxygenation of intracranial tumors induced by carbogen breathing.Materials and MethodsThe 9L and CNS‐1 intracranial rat tumor models were imaged at 7T, before and during carbogen breathing, using a multi‐echo gradient‐echo (GE) sequence to map R2*. On a different group of 9L tumors, tissue pO2 was measured using EPR oximetry with lithium phthalocyanine as the oxygen‐sensitive material.ResultsThe average decline in R2* with carbogen breathing was 13 ± 1 s−1 in the CNS‐1 tumors and 29 ± 4 s−1 in the 9L tumor. The SI vs. TE decay curves indicate the presence of multiple components in the tumor. Tissue pO2 in the two 9L tumors measured was 8.6 ± 0.5 and 3.6 ± 0.6 mmHg during air breathing, and rose to 20 ± 7 and 16 ± 4 mmHg (mean ± SE) with carbogen breathing. Significant changes were observed by 10 minutes, but changes in pO2 and R2* continued in some subjects over the entire 40 minutes.ConclusionEPR results indicate that glial sarcomas may be radiobiologically hypoxic. Both EPR and BOLD data indicate that carbogen breathing increases brain tumor oxygenation. These data support the use of BOLD imaging to monitor changes in oxygenation in brain tumors. J. Magn. Reson. Imaging 2002;16:511–521. © 2002 Wiley‐Liss, Inc.
Structure of the water resonance in small voxels in rat brain detected with high spectral and spatial resolution MRI
Authors: Fan Xiaobing , Du Weiliang , MacEneaney Peter , Zamora Marta , Karczmar Gregory 
Published: November 2002

AbstractPurpose:To acquire high spectral and spatial resolution (HiSS) MR images of the water resonance in rat brain, evaluate the lineshape of the water resonance in small voxels, and compare images derived from HiSS data with conventional images.Materials and Methods:Spectroscopic images of rat brain were obtained at 4.7 Tesla using phase encoding gradients only. Spectral resolution in each voxel was ∼8 Hz and bandwidth was 1000 Hz. Spatial resolution was ∼250 microns in 1‐mm slices. Images were synthesized to show the water signal integral, peak height, linewidth, resonance frequency, and asymmetry.Results:Two or more resolved components of the water resonance were detected in ∼14% ± 6% of voxels in the brains of eight rats. The water resonances in ∼20% ± 10% of voxels (n = 8) were highly asymmetric. Images with intensity proportional to water signal peak height, T2*, or to selected components of the water resonance showed features that were not evident in conventional images.Conclusions:The complexity of the water signal reflects the anatomy and physiology of the sub‐voxelar environment, and may be a useful source of image contrast. HiSS imaging of brain provides accurate anatomic information, and may improve image contrast and delineation of subtle anatomic features. J. Magn. Reson. Imaging 2002;16:547–552. © 2002 Wiley‐Liss, Inc.
Preoperative evaluation of patients awaiting liver transplantation: Comparison of multiphasic contrast‐enhanced 3D magnetic resonance to helical computed tomography examinations
Authors: Eubank William B. , Wherry Kimberly L. , Maki Jeff H. , Sahin Hakan , Funkhouser Charles P. , Schmiedl Udo P. 
Published: November 2002

AbstractPurposeTo determine the feasibility of using a multiphasic magnetic resonance (MR) examination to evaluate the hepatic arterial anatomy and parenchyma in patients awaiting orthotopic liver transplantation (OLT).Materials and MethodsTwenty consecutive patients awaiting OLT underwent multiphasic MR (using a T1‐weighted 3D gadolinium‐enhanced gradient‐echo (GRE) sequence and two separate injections of contrast material) and computed tomography (CT) imaging; both imaging studies were performed within a 1‐week period for each patient. Quantitative and qualitative assessment of the hepatic arterial system on MR data was performed. Two independent observers classified the hepatic arterial anatomy and evaluated the hepatic parenchyma from the MR data. The prospective CT interpretation was used as the gold standard.ResultsOverall qualitative rating of hepatic arterial system‐to‐background contrast on MR data was good to excellent (average pooled score of 2.00 ± 0.27), with no significant difference between the two observers after the first or second injections of contrast material. Classification of hepatic arterial anatomy by MR angiography (MRA) and CT angiography (CTA) was concordant in 85% (17/20) of patients and discordant in 15% (3/20) of patients. Focal parenchymal lesions were detected in 25% (5/20) of patients by MR and CT; however, two lesions in one patient with multiple lesions were detected only with MR.ConclusionMultiphasic T1‐weighted 3D gadolinium‐enhanced MR examination can provide comprehensive evaluation of the hepatic arterial anatomy and parenchyma in patients awaiting OLT. MR may offer an advantage over CT in the detection of focal parenchymal lesions. J. Magn. Reson. Imaging 2002;16:565–575. Published by Wiley‐Liss, Inc.
Combined high‐resolution and real‐time imaging: A technical feasibility study on coronary magnetic resonance angiography
Authors: Eggers Holger , Koken Peter , Manke Dirk , Boesiger Peter , Boernert Peter 
Published: November 2002

AbstractPurposeTo propose a new approach to combining high‐resolution and real‐time imaging and to show its technical feasibility on the example of coronary magnetic resonance angiography.Materials and MethodsThe insertion of fast two‐dimensional (2D) acquisitions into time intervals that have not been utilized by triggered or gated 2D or three‐dimensional (3D) acquisitions so far is suggested, as well as the immediate reconstruction and display of the additional data. For a technical validation of this concept, a 2D ventricular function protocol was interleaved into a cardiac‐triggered and respiratory‐gated 3D coronary angiography protocol. Dedicated hardware was employed to rapidly process the data originating from the former. Since the sampling of the latter was restricted to intervals with minimal motion, remaining periods of time could be used to simultaneously image the cardiac and respiratory motion.ResultsThe technical feasibility of the proposed approach was demonstrated by successful measurements with the combined high‐resolution and real‐time protocol in volunteers. All examinations provided short axis views during the acquisition and angiograms of selected parts of the coronary system after its completion.ConclusionThe investigated concept allows high‐resolution measurements to be complemented with real‐time imaging functionality without affecting the scan time or image quality. In the particular application considered, an image‐based patient monitoring or motion correction is enabled, indicating potential benefits of combining two very dissimilar methods of data acquisition in one measurement. J. Magn. Reson. Imaging 2002;16:584–590. © 2002 Wiley‐Liss, Inc.
Magnetic resonance safety update 2002: Implants and devices
Authors: Shellock Frank G. 
Published: November 2002

AbstractThe preservation of a safe magnetic resonance (MR) environment requires constant vigilance by MR healthcare professionals, particularly with regard to the management of patients with metallic biomedical implants or devices. The variety and complexity of implants and devices constantly changes, requiring continuous attention and diligence with regard to obtaining the most current and accurate information about these objects relative to the MR environment. This review article discusses MR safety and MR compatibility issues and presents important information for a variety of implants and devices, with an emphasis on those objects that have recently undergone evaluation or that require additional consideration because of existing controversy or confusion. J. Magn. Reson. Imaging 2002;16:485–496. © 2002 Wiley‐Liss, Inc.
MR assessment of left ventricular function: Quantitative comparison of fast imaging employing steady‐state acquisition (FIESTA) with fast gradient echo cine technique
Authors: Li Wei , Stern Jessica S. , Mai Vu M. , Pierchala Linda N , Edelman Robert R , Prasad Pottumarthi V. 
Published: November 2002

AbstractPurposeTo evaluate the agreement of fast imaging employing steady‐state acquisition (FIESTA) cine technique with segmented k‐space fast gradient echo (GRE) cine technique when using them for assessment of cardiac function.Materials and MethodsEleven MR cine studies were performed on six healthy volunteers and five patients, using FIESTA and fast GRE techniques. The quantitative measurements of ventricular function obtained from the two techniques were compared. The data analysis was performed by two observers independently.ResultsCompared to fast GRE cine technique, FIESTA cine technique consistently resulted in higher end‐diastolic volume (10.2%) and end‐systolic volume (21.6%), but lower myocardial mass of left ventricle (19.2%) and ejection fraction (9.9%). The stroke volume obtained from the two techniques was very close. The primary explanation for this variability is that the two techniques have different mechanisms on establishing signal contrast.ConclusionCompared to fast GRE technique, FIESTA provides significantly different results when using it for assessment of left ventricular function. It is important to consider this difference in the assessment of cardiac function. J. Magn. Reson. Imaging 2002;16:559–564. © 2002 Wiley‐Liss, Inc.
MR‐guided microwave thermocoagulation therapy of liver tumors: Initial clinical experiences using a 0.5 T open MR system
Authors: Morikawa Shigehiro , Inubushi Toshiro , Kurumi Yoshimasa , Naka Shigeyuki , Sato Koichiro , Tani Tohru , Yamamoto Ikuo , Fujimura Masaki 
Published: November 2002

AbstractPurposeTo utilize a microwave coagulator for MR‐guided interstitial thermal therapy of liver tumors as a clinically feasible heating device.Materials and MethodsMR‐guided microwave thermocoagulation therapy was carried out 34 times in 30 patients with liver tumors (eight hepatocellular carcinoma, 22 metastatic tumors) using a 0.5 T open configuration MR system.ResultsPercutaneous puncture could be accomplished both accurately and safely while monitoring real‐time magnetic resonance imaging (MRI). Using a notch filter, MR images could be observed without electromagnetic interference even during microwave ablation. Temperature monitoring during ablation was possible using the proton resonance frequency method. All procedures could be successfully carried out without any complications, and the therapeutic effects were deemed satisfactory.ConclusionMR‐guided microwave thermocoagulation therapy could be one promising procedure of minimally invasive treatment for liver tumors. J. Magn. Reson. Imaging 2002;16:576–583. © 2002 Wiley‐Liss, Inc.
Tissue thermal conductivity by magnetic resonance thermometry and focused ultrasound heating
Authors: Cheng Hai‐Ling Margaret , Plewes Donald B. 
Published: November 2002

AbstractPurposeTo investigate the combined use of magnetic resonance (MR) temperature imaging and focused ultrasound (FUS) for the noninvasive determination of tissue thermal properties.Materials and MethodsBrief, spatial impulses of temperature elevation were created in tissue using a spherical, air‐backed transducer operating at 1.68 MHz and measured using MR temperature imaging in a 1.5‐Tesla clinical scanner. A novel technique based on thermal washout is applied in an analysis of the acquired MR temperature images to estimate tissue thermal conductivity and perfusion.ResultsNumerical simulations and experiments in vitro and in vivo demonstrate that thermal conductivity can be measured to within 10% of the true value with MR thermometry at 1.5 Tesla. With the temperature precision available at 1.5 Tesla, however, robust perfusion estimation is feasible only in highly perfused organs or tumors.ConclusionThis study has developed a method for determining tissue thermal properties specific to the patient and organ at the site of interest, and allows repeated application. This capability is relevant in thermal therapy planning of tumor ablation using MR‐guided FUS systems. J. Magn. Reson. Imaging 2002;16:598–609. © 2002 Wiley‐Liss, Inc.
Modern distribution of saltmarsh testate amoebae: regional variability of zonation and response to environmental variables
Authors: Charman Dan J. , Roe Helen M. , Roland Gehrels W. 
Published: November 2002

AbstractSea‐level reconstruction from biological indicators in saltmarsh sediments requires an understanding of the modern ecology of the organisms concerned. Previous work suggested that testate amoebae are a potential new group of organisms to use for sea‐level reconstruction, especially combined with diatoms and foraminifera. This paper analyses data from three saltmarshes on the Taf estuary, South Wales, the River Erme, Devon, and at Brancaster, Norfolk (UK) to (i) test for the presence and zonation of testate amoebae in relation to elevation; (ii) examine the similarity of zonation patterns between marshes; and (iii) explore the relationship between assemblage composition and a wider range of environmental variables. In addition we provide an update on the identification of testate amoebae on saltmarshes. Our results confirm that at all sites the primary environmental gradient is tidal inundation. Major changes in taxa along the tidal gradient are similar except for the lowest elevations, where different taxa become dominant at different sites. Canonical correspondence analysis (CCA) shows that assemblage composition is also strongly related to other variables, independent of the tidal position. Salinity, particle size and organic matter content are particularly important, and there is a statistically significant geographical effect on assemblages. Relationships between sea‐level and assemblage composition are often stronger for individual sites, suggesting that local data sets should be used for quantitative sea‐level reconstructions. However, the combined data set would provide more robust estimates of past sea‐level change from fossil data. Other environmental variables explain as much of the variability in species assemblages as tidal parameters and should be considered more often in sea‐level reconstructions based on microfossil indicators. Copyright © 2002 John Wiley & Sons, Ltd.
Fossil testate amoebae in coastal deposits in the UK: implications for studies of sea‐level change
Authors: Roe Helen M. , Charman Dan J. , Roland Gehrels W. 
Published: November 2002

AbstractAssemblages of testate amoebae in UK saltmarshes are strongly correlated with elevation and flooding duration, suggesting that if adequately preserved in sediments they may be used as accurate sea‐level indicators. To examine the preservation of testate amoebae in the fossil record in coastal environments, subsamples were collected from a range of coastal sites around Britain, including saltmarsh, coastal reedswamp, isolation basin, back‐barrier and coastal raised bog sites. The results showed that testate amoebae are present in the fossil record, although in variarble species diversities, concentrations and states of preservation. Testate amoebae were found to be well preserved in isolation basin infills and coastal raised bog deposits, where diverse assemblages (>20 taxa) were recorded. In the upper part of the isolation basin sequence from Loch nan Corr, northwest Scotland, the testate amoebae assemblages showed a greater degree of sensitivity to transitional salinity changes than existing foraminferal and larger testate amoebae data sets. This implies that testate amoebae, particularly small to medium‐sized specimens (15–300 µm), may hold considerable potential for sea‐level reconstruction in these environments. Preservation of testate amoebae in a freshly sampled core of saltmarsh sediment from South Wales was reasonable, although test distribution decreased significantly in abundance below 18 cm. The assemblage composition was similar to that found in the contemporary surface environment. The preservation of testate amoebae in saltmarsh and coastal reedswamp deposits of mid‐Holocene age was variable and generally poor. Partial dehydration of the sediment samples may account for this. Further studies are required to examine the palaeoecology and distribution of testate amoebae in similar coastal settings, to strengthen these preliminary findings. Copyright © 2002 John Wiley & Sons, Ltd.
A revised chronology for the ‘Fjord Stade’ moraine in Disko Bugt, west Greenland
Authors: Long Antony J. , Roberts David H. 
Published: November 2002

AbstractThis paper re‐evaluates the age of the ‘Fjord Stade’ moraine in Disko Bugt, a large marine embayment in west Greenland. Previous work suggests that this moraine is part of a widespread moraine complex present throughout west Greenland, which formed ca. 9300 cal. yr BP in response to either a regional climate change or the effects of topographic controls on ice‐sheet recession. We present the results of a relative sea‐level study using data from eight isolation basins that straddle the ‘Fjord Stade’ moraine in southeast Disko Bugt. Our results suggest that the moraine here formed between ca. 8400 and 7700 cal. yr BP. This is later than previously thought, and similar in timing to a widespread cooling event recorded in the Greenland ice‐core records. This chronological similarity raises the possibility that the ‘Fjord Stade’ moraine in the study area records an ice marginal response to a major short‐lived climatic cooling during the early Holocene (the so‐called ‘8200 event’). Copyright © 2002 John Wiley & Sons, Ltd.
The marine Eemian of the Baltic: new pollen and diatom data from Peski, Russia, and Põhja‐Uhtju, Estonia
Authors: Miettinen Arto , Rinne Katja , Haila Heikki , Hyvärinen Hannu , Eronen Matti , Delusina Irina , Kadastik Ene , Kalm Volli , Gibbard Philip 
Published: November 2002

AbstractSeveral relatively well‐preserved last interglacial (Eemian, marine oxygen isotope substage 5e; ca. 130–116 ka) deposits containing marine diatom flora have been found in Finland. In addition to these Finnish sites, more numerous Eemian (Mikulino) marine deposits are known from the northwestern part of Russia and from Estonia.Two new clayey and silty deposits covered by till, one at Peski, Russia, and the other Põhja‐Uhtju, Estonia, were studied for pollen and diatom content. At Peski, the deposit representing the Eemian interglacial is 3.8 m thick. The polyhalobous diatom flora in the Corylus and Carpinus zones indicates the maximum of the marine transgression during the climatic optimum. Later, the increasing proportion of brackish water diatom flora indicates a lowering in the relative sea‐level, and finally, during a very late phase of the Eemian, the sharply increasing proportion of freshwater species indicates the isolation of the sedimentary basin from the Eemian Sea.At Põhja‐Uhtju, according to the pollen, the Eemian deposit is 3.5 m thick. Diatoms occur only in a layer 1.6 m thick, which represents the period of Corylus and Carpinus zones, and thus the period of the climatic optimum. The brackish–marine diatom flora consists mainly of littoral, shallow‐water species.Although Peski is situated at a higher altitude than Põhja‐Uhtju at present, the diatom stratigraphy at Peski indicates deeper and more saline conditions than at Põhja‐Uhtju during the Eemian. This probably is the result of variations in glacio‐isostatic rebound between these sites, which can be accounted for by differences of the ice load during the final phase of the Saalian glaciation. Copyright © 2002 John Wiley & Sons, Ltd.