bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diffusion‐weighted imaging of normal and malignant prostate tissue at 3.0T
Authors: Pickles Martin D. , Gibbs Peter , Sreenivas Muthyala , Turnbull Lindsay W. 
Published: December 2005

AbstractPurposeTo measure the apparent diffusion coefficient (ADC) of normal and malignant prostate tissue at 3.0T using a phased‐array coil and parallel imaging, and determine the utility of ADC values in differentiating tumor from normal peripheral zone (PZ).Materials and MethodsADC values were calculated for 49 patients (tumor and PZ) with evidence of prostate cancer. Additionally, for nine asymptomatic volunteers, ADC values were determined for apparently normal central gland and PZ. A single‐shot EPI diffusion‐weighted imaging (DWI) technique with b = 0 and 500 seconds/mm2 was employed.ResultsADC values were significantly lower for tumor (1.38 ± 0.32 × 10−3 mm2/second) than for patient PZ (1.95 ± 0.50 × 10−3 mm2/second, P < 0.001) and volunteer PZ (1.60 ± 0.25 × 10−3 mm2/second, P = 0.031). A considerable overlap of ADC values was noted between patient tissue types.ConclusionDWI of the prostate at 3.0T in conjunction with a phased‐array coil and parallel imaging allows ADC calculation of the prostate. ADC values were lower for tumors compared to normal‐appearing PZ; however, there was considerable intersubject variability. J. Magn. Reson. Imaging 2006. © 2005 Wiley‐Liss, Inc.
Fully MR‐guided hepatic artery catheterization for selective drug delivery: A feasibility study in pigs
Authors: Seppenwoolde Jan‐Henry , Bartels Lambertus W. , van der Weide Remko , Nijsen Johannes F.W. , van het Schip Alfred D. , Bakker Chris J.G. 
Published: December 2005

AbstractPurposeTo demonstrate the feasibility of hepatic catheterization for selective delivery of therapeutic agents using a clinical MRI scanner for real‐time image guidance.Materials and MethodsExperiments were performed in three domestic pigs (70–80 kg) using a clinical 1.5‐T MR scanner. After abdominal three‐dimensional contrast‐enhanced MR angiography (3D‐CE‐MRA) was performed, endovascular devices with susceptibility markers were tracked with passive tracking techniques. Catheters were maneuvered into the primary and secondary hepatic arteries. Selective catheterization was verified using selective time‐resolved CE angiography. Paramagnetic microspheres were administered to a different region for each liver. The resulting biodistributions were investigated using MR images.ResultsSuccessful selective hepatic catheterization was repeatedly demonstrated using passive tracking techniques. 3D‐CE‐MRA significantly aided the interventional procedure by showing the vascular anatomy, and maximum‐intensity projections (MIPs) were used as roadmaps during the interventions. In all cases, microspheres were successfully delivered to the selected regions. The catheters were visualized at a maximum frame rate of five frames per second, allowing a good depiction of the devices and a reliable catheterization of the hepatic arteries.ConclusionFully MR‐guided real‐time navigation of endovascular devices permits complex procedures such as selective intra‐arterial delivery of therapeutic agents to parts of the liver. J. Magn. Reson. Imaging 2006. © 2005 Wiley‐Liss, Inc.
Proton magnetic resonance spectroscopic imaging to differentiate between nonneoplastic lesions and brain tumors in children
Authors: Hourani Roula , Horská Alena , Albayram Sait , Brant Larry J. , Melhem Elias , Cohen Kenneth J. , Burger Peter C. , Weingart John D. , Carson Benjamin , Wharam Moody D. , Barker Peter B. 
Published: December 2005

AbstractPurposeTo investigate whether in vivo proton magnetic resonance spectroscopic imaging (MRSI) can differentiate between 1) tumors and nonneoplastic brain lesions, and 2) high‐ and low‐grade tumors in children.Materials and MethodsThirty‐two children (20 males and 12 females, mean age = 10 ± 5 years) with primary brain lesions were evaluated retrospectively. Nineteen patients had a neuropathologically confirmed brain tumor, and 13 patients had a benign lesion. Multislice proton MRSI was performed at TE = 280 msec. Ratios of N‐acetyl aspartate/choline (NAA/Cho), NAA/creatine (Cr), and Cho/Cr were evaluated in the lesion and the contralateral hemisphere. Normalized lesion peak areas (Chonorm, Crnorm, and NAAnorm) expressed relative to the contralateral hemisphere were also calculated. Discriminant function analysis was used for statistical evaluation.ResultsConsidering all possible combinations of metabolite ratios, the best discriminant function to differentiate between nonneoplastic lesions and brain tumors was found to include only the ratio of Cho/Cr (Wilks' lambda, P = 0.012; 78.1% of original grouped cases correctly classified). The best discriminant function to differentiate between high‐ and low‐grade tumors included the ratios of NAA/Cr and Chonorm (Wilks' lambda, P = 0.001; 89.5% of original grouped cases correctly classified). Cr levels in low‐grade tumors were slightly lower than or comparable to control regions and ranged from 53% to 165% of the control values in high‐grade tumors.ConclusionProton MRSI may have a promising role in differentiating pediatric brain lesions, and an important diagnostic value, particularly for inoperable or inaccessible lesions. J. Magn. Reson. Imaging 2006. Published 2005 Wiley‐Liss, Inc.
Shortened T2 after exercise in ischemic skeletal muscle
Authors: Nygren Anders T. 
Published: December 2005

AbstractPurposeTo detect skeletal muscle ischemia with transverse relaxometry after ischemic exercise.Materials and MethodsTen subjects with intermittent claudication were studied. T2 was measured in the gastrocnemius and soleus muscles (m. gastrocnemius and m. soleus) at rest and repeatedly after exercise during 45 minutes of recovery. Prior to MRI a symptom‐limited treadmill exercise was performed, and the ankle‐arm blood pressure index (AAI) was measured at rest and after exercise.ResultsIn the 14 legs with ischemic pain, a diverging response was found in the calf: T2 increased in m. gastrocnemius by 5.6% ± 4.9%, but decreased in m. soleus by –1.2% ± 4.4% (P < 0.001). Moreover, 13 regions in legs with ischemic pain and reduced AAI (from 0.7 ± 0.2 at rest to 0.31 ± 0.15 after exercise) had shortened T2 (–3.6% ± 1.8%) immediately after exercise. This finding was most frequent in m. soleus and two regions of m. gastrocnemius. Recovery was delayed in the latter two regions.ConclusionT2 may identify ischemic muscles after hypoxic exercise. Shortened T2 suggests a reduced water content (e.g., distribution volume of water) and may affect the upslope kinetics of an extravascular perfusion tracer. The different responses to ischemia by the soleus and gastrocnemius muscle may be due in part to their different fiber type compositions. J. Magn. Reson. Imaging 2006. © 2005 Wiley‐Liss, Inc.
Delayed contrast agent kinetics in ischemic skeletal muscle
Authors: Nygren Anders T. , Greitz Dan 
Published: December 2005

AbstractPurposeTo detect skeletal muscle ischemia with first‐pass gadolinium (Gd) kinetics after exercise.Materials and MethodsEleven subjects with intermittent claudication performed a symptom‐limited bilateral plantar flexion exercise in the magnet. Regional ROIs were placed bilaterally in the gastrocnemius and soleus muscles, and a signal intensity (SI) time‐curve analysis was performed. Induced ischemia was validated prior to the MRI with the systolic ankle‐arm blood pressure index (AAI) measured after a symptom‐limited treadmill exercise.ResultsExercise induced ischemic pain in 16 of 22 legs with a significantly reduced AAI (0.31 ± 0.15). The time to contrast arrival (TCA) was delayed in symptomatic ischemic legs vs. asymptomatic legs (16.3 ± 6.9 seconds vs. 11.1 ± 2.7 seconds, P < 0.05). The maximum SI during recovery was higher in the soleus muscle than in the gastrocnemius muscle in ischemic legs (1.55 ± 0.1 vs. 1.44 ± 0.1, P < 0.05). Symptomatic regions had a less steep upslope than asymptomatic regions (43 ± 15 vs. 63 ± 14, P < 0.001), with a graded upslope response to ischemia. However, a normal upslope was found in 10 of 29 ischemic regions, and some of the regions showed delayed contrast arrival, suggesting a pseudonormal upslope in ischemic regions.ConclusionExercise‐induced ischemia was detected with the use of an SI time‐curve analysis. However, disregarding the arterial input function and distribution volume of the tracer may lead to misinterpretation of some ischemic regions. J. Magn. Reson. Imaging 2006. © 2005 Wiley‐Liss, Inc.
Cardiac CINE MR imaging with a 32‐channel cardiac coil and parallel imaging: Impact of acceleration factors on image quality and volumetric accuracy
Authors: Wintersperger Bernd J. , Reeder Scott B. , Nikolaou Konstantin , Dietrich Olaf , Huber Armin , Greiser Andreas , Lanz Titus , Reiser Maximilian F. , Schoenberg Stefan O. 
Published: December 2005

AbstractPurposeTo assess the impact of parallel imaging algorithms on image quality and volumetric accuracy of CINE magnetic resonance imaging (MRI) with high temporal and spatial resolution using a new 32‐channel dedicated cardiac phased array coil.Materials and MethodsFourteen individuals underwent steady‐state free precession (SSFP) CINE MRI using a 32‐element phased‐array coil and parallel imaging acceleration using spatiotemporal sensitivity encoding (TSENSE). Acquisition acceleration ranged from R = 2 to 7. In conjunction with data extracted from phantom measurements, contrast‐to‐noise ratio (CNR) performance was evaluated for each acceleration factor and subjective image quality was evaluated by two independent readers. In addition, volumetric assessment was performed for each acceleration factor based on a single breath‐hold multi‐slice data acquisition. Results were compared to nonTSENSE measurements.ResultsCNR for non‐accelerated CINE (R = 1) was 45.7 ± 12.8 and showed a constant decrease with increase in acceleration of 51% at R = 4 and 86% at R = 7. CNR losses accompanied reductions in subjective image quality. Volumetric evaluation was accurate for R ≤ 4, with significant underestimation of ejection fraction (EF) at higher accelerations.ConclusionThis study shows that one‐dimensional acceleration factors up to R = 4 allow accurate SSFP CINE MRI even though CNR is significantly reduced. This allows for a marked reduction in scan time and allows for multi‐slice CINE imaging with high spatial and temporal resolution. J. Magn. Reson. Imaging 2006. © 2005 Wiley‐Liss, Inc.
Exposure, health complaints and cognitive performance among employees of an MRI scanners manufacturing department
Authors: de Vocht Frank , van Drooge Hinkelien , Engels Hans , Kromhout Hans 
Published: December 2005

AbstractPurposeTo assess sensory effects and other health complaints that are reported by system testers working near magnetic resonance imaging (MRI) magnets, realizing that it is believed that exposure up to 8 T is safe for humans.Materials and MethodsLevels of exposure to static magnetic fields (SMFs), movement speed during exposure, health complaints, and cognitive performance among employees in an MRI‐manufacturing department and at a reference department have been analyzed. Mercury concentrations in urine samples were determined to analyze whether they depend on exposure to SMFs.ResultsAverage exposure of system testers was 25.9 mT/8 hours at a 1.0‐T system and 40.4 mT/8 hours at a 1.5‐T system. Vertigo, metallic taste, and concentration problems were more reported among workers of MRI‐fabrication than in the reference department. Cognitive performance was tested outside the SMF, and no significant changes were detected.ConclusionThis study suggests that any effects on cognitive functions are acute and transient and disappear rapidly after exposure has ended. All complaints, except for headaches, were more frequently reported by “fast movers” than by “slow movers,” and depended on field strength and duration of exposure. Mercury‐levels in urine were not affected. J. Magn. Reson. Imaging 2006. © 2005 Wiley‐Liss, Inc.
A polymer‐based MR‐compatible guidewire: A study to explore new prospects for interventional peripheral magnetic resonance angiography (ipMRA)
Authors: Mekle Ralf , Hofmann Eugen , Scheffler Klaus , Bilecen Deniz 
Published: December 2005

AbstractPurposeTo introduce a newly developed polymer‐based and magnetic resonance (MR)‐compatible guidewire and to explore its capabilities with respect to interventional peripheral magnetic resonance angiography (ipMRA) in a flow phantom.Materials and MethodsThe guidewire is based on a polyetheretherketone (PEEK) polymer core, and small iron particles are embedded in its coating. A passive device tracking technique was designed utilizing a susceptibility artifact induced by the wire in images acquired with a balanced steady‐state free precession (b‐SSFP) sequence using small flip angles. The position of the guidewire tip was determined from image intensity maxima and overlayed onto a roadmap in near real‐time. Guidewire tracking and balloon angioplasty of an artificial stenosis were attempted in two configurations of a flow phantom.ResultsSuccessful passive guidewire tracking was performed for all phantom configurations. Robustness and accuracy of the tracking technique were sufficient for phantom studies. A balloon catheter was placed into the stenosis using the guidewire under complete MR guidance, and subsequent balloon angioplasty yielded improved flow conditions.ConclusionThe new guidewire is well‐suited for clinical application due to an absence of the risk of core fracture and its atraumatic flexible tip. It opens novel prospects for the realization of ipMRA in humans that need to be explored in further studies. J. Magn. Reson. Imaging 2006. © 2005 Wiley‐Liss, Inc.
Determination of thigh muscle stiffness using magnetic resonance elastography
Authors: Bensamoun Sabine F. , Ringleb Stacie I. , Littrell Laurel , Chen Qingshan , Brennan Michael , Ehman Richard L. , An Kai‐Nan 
Published: December 2005

AbstractPurposeTo measure the elastic properties of the vastus lateralis (VL), vastus medialis (VM), and sartorius (Sr) muscles using magnetic resonance elastography (MRE).Materials and MethodsTo obtain a normative database of the aforementioned muscles, oblique scan directions were prescribed passing through each muscle. Shear waves were induced into the muscles using pneumatic and mechanical drivers at 90 and 120 Hz, respectively. These drivers were attached to the distal end of the right thigh with the knee flexed at 30°. The foot was placed in a footplate containing MR‐compatible load cells to record the force during a contraction (10% and 20% of the maximum voluntary contraction).ResultsThe shear moduli measured at rest in the VL (N = 12), VM (N = 14), and Sr (N = 13) were 3.73 ± 0.85 kPa, 3.91 ± 1.15 kPa, and 7.53 ± 1.63 kPa, respectively. The stiffness of both vasti increased with the level of contraction, while the stiffness of the Sr remained the same.ConclusionThe MRE technique was able to approximate the stiffness of different thigh muscles. Furthermore, the wave length was sensitive to the morphology (unipennate or longitudinal) and fiber composition (type I or II) in each muscle. J. Magn. Reson. Imaging 2006. © 2005 Wiley‐Liss, Inc.
Line scan diffusion tensor MRI at low magnetic field strength: Feasibility study of cervical spondylotic myelopathy in an early clinical stage
Authors: Hori Masaaki , Okubo Toshiyuki , Aoki Shigeki , Kumagai Hiroshi , Araki Tsutomu 
Published: December 2005

AbstractPurposeTo implement line scan diffusion tensor MR imaging (LSDTI) on a 0.2 Tesla MR imager, and investigate the findings in the spinal cord of patients with cervical spondylotic myelopathy in an early clinical stage.Materials and MethodsFourteen patients with clinical symptoms of cervical myelopathy underwent LSDTI. The signal‐to‐noise ratio (SNR) in the spinal cord and cerebrospinal fluid (CSF) was evaluated. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were measured. We classified the ROIs into two groups: 1) unaffected (no clinical symptoms and no abnormality on conventional images) and 2) affected (some clinical symptoms but no abnormal signal on conventional images). Three‐dimensional (3D) fiber‐tracking was also studied.ResultsThe isotropic ADC values (10–3mm2/sec) were 1.28 ± 0.11 in group 1 and 1.59 ± 0.23 in group 2. The FAs were 0.55 ± 0.07 in group 1, and 0.47 ± 0.11 in group 2. The ADC value in group 2 increased (P < .001, Mann‐Whitney U‐test) and the FA in group 2 decreased (P = 0.24) on average, compared to those in group 1. 3D fiber‐tracking was successful in 64% (9/14) of the cases.ConclusionLSDT images at low field strength may be a sensitive method for elucidating the structural characteristics of spinal cord pathology in vivo. However, clinical correlation and a long‐term follow‐up study will be needed. J. Magn. Reson. Imaging 2006. © 2005 Wiley‐Liss, Inc.
R2 relaxometry with MRI for the quantification of tissue iron overload in β‐thalassemic patients
Authors: Alexopoulou Efthymia , Stripeli Fotini , Baras Panagiotis , Seimenis Ioannis , Kattamis Antonis , Ladis Vasilis , Efstathopoulos Efstathios , Brountzos Elias N. , Kelekis Alexis D. , Kelekis Nikolaos L. 
Published: December 2005

AbstractPurposeTo evaluate the usefulness of a time‐efficient MRI method for the quantitative determination of tissue iron in the liver and heart of β‐thalassemic patients using spin‐spin relaxation rate, R2, measurements.Materials and MethodsImages were obtained at 1.5 T from aqueous Gd‐DTPA solutions (0.106–8 mM) and from the liver and heart of 46 β‐thalassemic patients and 10 controls. The imaging sequence used was a respiratory‐triggered 16‐echo Carr‐Purcell‐Meiboom‐Gill (CPMG) spin‐echo (SE) pulse sequence (TR = 2000 msec, TEmin = 5 msec, echo spacing (ES) = 5 msec, matrix = 192 × 256, slice thickness = 10 mm). Liver iron concentration (LIC) measurements were obtained for 22 patients through biopsy specimens excised from the relevant liver segment. Biopsy specimens were also evaluated regarding iron grade and fibrosis. Serum ferritin (SF) measurements were obtained in all patients.ResultsA statistically significant difference was found between patients and healthy controls in mean liver (P < 0.004) and myocardium (P < 0.004) R2 values. The R2 values correlated well with Gd DTPA concentration (r = 0.996, P < 0.0001) and LIC (r = 0.874, P < 0.0001). A less significant relationship (r = 0.791, P < 0.0001) was found between LIC measurements and SF levels. R2 measurements appear to be significantly affected (P = 0.04) by different degrees of hepatic fibrosis. The patients' liver R2 values did not correlate with myocardial R2 values (r = 0.038, P < 0.21).ConclusionTissue iron deposition in β‐thalassemic patients may be adequately quantified using R2 measurements obtained with a 16‐echo MRI sequence with short ES (5 msec), even in patients with a relatively increased iron burden. J. Magn. Reson. Imaging 2006. © 2005 Wiley‐Liss, Inc.
Paraglacial response of steep, sediment‐mantled slopes to post‐‘Little Ice Age’ glacier recession in the central Swiss Alps
Authors: Curry A. M. , Cleasby V. , Zukowskyj P. 
Published: December 2005

AbstractThis research assesses the morphological consequences of recent (post‐‘Little Ice Age’) paraglacial reworking of valley‐side sediment mantles in the European Alps. It aims to identify the extent and conditioning factors of slope adjustment at sites in the Swiss Alps, model the temporal pattern, and assess the rates of sediment reworking involved. Gully systems have cut into steep, high‐level lateral moraines, and debris cones have accumulated downslope. Debris flow is the dominant agent of sediment transfer. Factors controlling the extent of this activity include moraine slope gradient, relief and moisture availability. Gullies appear to have reached their maximum dimensions within ca. 50 yr of deglaciation, after which gully relief is reduced by removal of inter‐gully slopes and gully infilling (within 80–140 yr). On the most recently deglaciated terrain, minimum erosion rates average ca. 95 mm yr−1 since gully initiation, greatly exceeding ‘normal’ erosion rates in other environments. Mean annual accumulation of a single debris cone since ice retreat was calculated to be ca. 30 mm yr−1. Implications of these findings are applied to patterns of paraglacial sediment‐mantled slope adjustment, conceptualising paraglacial landscape response in terms of a sediment release exhaustion model, and paraglacial landform succession. Copyright © 2005 John Wiley & Sons, Ltd.
Sea‐level changes, river activity, soil development and glaciation around the western margins of the southern North Sea Basin during the Early and early Middle Pleistocene: evidence from Pakefield, Suffolk, UK
Authors: Lee Jonathan R. , Rose James , Candy Ian , Barendregt Rene W. 
Published: December 2005

AbstractThis paper outlines evidence from Pakefield (northern Suffolk), eastern England, for sea‐level changes, river activity, soil development and glaciation during the late Early and early Middle Pleistocene (MIS 20–12) within the western margins of the southern North Sea Basin. During this time period, the area consisted of a low‐lying coastal plain and a shallow offshore shelf. The area was drained by major river systems including the Thames and Bytham. Changes in sea‐level caused several major transgressive–regressive cycles across this low‐relief region, and these changes are identified by the stratigraphic relationship between shallow marine (Wroxham Crag Formation), fluvial (Cromer Forest‐bed and Bytham formations) and glacial (Happisburgh and Lowestoft formations) sediments. Two separate glaciations are recognised—the Happisburgh (MIS 16) and Anglian (MIS 12) glaciations, and these are separated by a high sea level represented by a new member of the Wroxham Crag Formation, and several phases of river aggradation and incision. The principal driving mechanism behind sea‐level changes and river terrace development within the region during this time period is solar insolation operating over 100‐kyr eccentricity cycles. This effect is achieved by the impact of cold climate processes upon coastal, river and glacial systems and these climatically forced processes obscure the neotectonic drivers that operated over this period of time. © British Geological Survey/Natural Environment Research Council copyright 2005. Reproduced with the permission of BGS/NERC. Published by John Wiley & Sons, Ltd.
Climatic cycles inferred from the aminostratigraphy and aminochronology of Quaternary dunes and palaeosols from the eastern islands of the Canary Archipelago
Authors: Ortiz J. E. , Torres T. , Yanes Y. , Castillo C. , Nuez J. De La , Ibáñez M. , Alonso M. R. 
Published: December 2005

AbstractAminochronological and aminostratigraphical methods have been used to study the Quaternary aeolian deposits from the islands located east of the Canary Archipelago (Fuerteventura and Lanzarote islands and La Graciosa, Montaña Clara and Alegranza islets). The extent of racemisation/epimerisation of four amino acids (isoleucine, aspartic acid, phenylalanine and glutamic acid) was measured in land snail shells of the genus Theba. The age calculation algorithms of these amino acids have been determined to permit the numerical dating of these deposits. Eight Aminozones, each defining dune/palaeosol‐formation episodes, have been distinguished and dated at 48.6 ± 6.4, 42.5 ± 6.0, 37.8 ± 4.6, 29.4 ± 4.8, 22.4 ± 4.5, 14.9 ± 3.6, 11.0 ± 4.0 and 5.4 ± 1.1 ka BP, the first five of them defining cycles of 5–7 ka.The alternation of palaeosols and aeolian deposits, which are related to abrupt transitions from humid to arid conditions, are the reflection of globally induced changes in North Africa palaeoenvironmental conditions linked to the effect of African palaeomonsoons on the trade winds and the Saharan Air Layer. Probably these aeolian cycles, with a recurrence period of 5–7 ka, are the expression of multiples of the ∼2.4 ka solar‐cycle. Copyright © 2005 John Wiley & Sons, Ltd.