bluuebunny/crossref_metadata_2025 huggingface dataset:
Keratins let liver live: Mutations predispose to liver disease and crosslinking generates Mallory-Denk bodies
Authors: Ku Nam-On , Strnad Pavel , Zhong Bi-Hui , Tao Guo-Zhong , Omary Bishr M.
Published: October 2007

Keratin polypeptides 8 and 18 (K8/K18) are the cytoskeletal intermediate filament proteins of hepatocytes while K8/K18/K19 are the keratins of hepatobiliary ductal cells. Hepatocyte K8/K18 are highly abundant and behave as stress proteins with injury-inducible expression. Human association studies show that K8/K18 germline heterozygous mutations predispose to end-stage liver disease of multiple etiologies (≈3 fold increased risk), and to liver disease progression in patients with chronic hepatitis C infection. These findings are supported by extensive transgenic mouse and

ex vivo

primary hepatocyte culture studies showing that K8 or K18 mutations predispose the liver to acute or subacute injury and promote apoptosis and fibrosis. Mutation-associated predisposition to liver injury is likely related to mechanical and nonmechanical keratin functions including maintenance of cell integrity, protection from apoptosis and oxidative injury, serving as a phosphate sponge, regulation of mitochondrial organization/function and protein targeting. These functions are altered by mutation-induced changes in keratin phosphorylation, solubility and filament organization/reorganization. Keratins are also the major constituents of Mallory-Denk bodies (MDBs). A toxin-induced K8>K18 ratio, and keratin crosslinking by transglutaminase-2 play essential roles in MDB formation. Furthermore, intracellular or cell-released K18 fragments, generated by caspase-mediated proteolysis during apoptosis serve as markers of liver injury. Therefore, K8 and K18 are cytoprotective stress proteins that play a central role in guarding hepatocytes from apoptosis. Keratin involvement in liver disease is multi-faceted and includes modulating disease progression upon mutation, formation of MDBs in response to unique forms of injury, and serving as markers of epithelial cell death.
Intrahepatic cholestasis of pregnancy: Amelioration of pruritus by UDCA is associated with decreased progesterone disulphates in urine
Authors: Glantz Anna , Reilly Sarah-Jayne , Benthin Lisbet , Lammert Frank , Mattsson Lars-Åke , Marschall Hanns-Ulrich
Published: October 2007

Intrahepatic cholestasis of pregnancy (ICP) is characterized by pruritus, elevated bile acids, and, specifically, elevated disulphated progesterone metabolites. We aimed to study changes in these parameters during treatment with dexamethasone or ursodeoxycholic acid (UDCA) in 40 out of 130 women included in the Swedish ICP intervention trial (26 randomized to placebo or UDCA, 14 randomized to dexamethasone). Serum bile acid profiles and urinary steroid hormone metabolites were analyzed using isotope-dilution gas chromatography–mass spectrometry and electrospray–mass spectrometry. We found that all patients displayed ICP-typical serum bile acid profiles with >50% cholic acid at baseline but almost 80% UDCA upon treatment with this bile acid. In UDCA-treated patients, relative amounts of disulphated progesterone metabolites in urine decreased by 34%, 48% (

P

< 0.05), and 55% (

P

< 0.05) after 1, 2, and 3 weeks of treatment, respectively, which was significantly correlated to improvements of pruritus scores but not to serum bile acid levels. In contrast, in patients randomized to dexamethasone or placebo, no changes in steroid metabolites or pruritus scores were observed.

Conclusion:

UDCA treatment in ICP decreased urinary excretion of disulphated progesterone metabolites, suggesting that amelioration of pruritus is connected to stimulation of hepatobiliary excretion of progesterone disulphates. (Hepatology 2008.)
Human skin fibroblasts: From mesodermal to hepatocyte-like differentiation
Authors: Lysy Philippe A. , Smets Françoise , Sibille Catherine , Najimi Mustapha , Sokal Etienne M.
Published: October 2007

The phenotypic homology of fibroblasts and mesenchymal stem cells (MSCs) has been recently described. Our study investigated the in vitro potential of human skin fibroblasts to differentiate into mesodermal (osteocyte and adipocyte) and endodermal (hepatocyte) cell lineages by comparison with human bone marrow (hBM) MSCs. The endodermal potential of fibroblasts was then explored in vivo in a mouse model of liver injury. Fibroblasts were able to acquire osteocyte and adipocyte phenotypes as assessed by cytochemistry and gene expression analyses. After exposure to a specific differentiation cocktail, these cells presented hepatocyte-like morphology and acquired liver-specific markers on protein and gene expression levels. Furthermore, these fibroblast-derived hepatocyte-like cells (FDHLCs) displayed the ability to store glycogen and synthesize small amounts of urea. By gene expression analysis, we observed that fibroblasts remained in a mesenchymal-epithelial transition state after hepatocyte differentiation. Moreover, FDHLCs lost their hepatocyte-like phenotype after dedifferentiation. In vivo, human fibroblasts infused directly into the liver of hepatectomized severe combined immunodeficient (SCID) mice engrafted in situ and expressed hepatocyte markers (albumin, alpha-fetoprotein, and cytokeratin 18) together with the mesodermal marker fibronectin. Despite lower liver-specific marker expression, the in vitro and in vivo differentiation profile of fibroblasts was comparable to that of mesenchymal-derived hepatocyte-like cells (MDHLCs). In conclusion, our work demonstrates that human skin fibroblasts are able to display mesodermal and endodermal differentiation capacities and provides arguments that these cells share MSCs features both on the phenotypic and functional levels.
How would I manage a case of essential thrombocythaemia presenting with an ischaemic toe
Authors: McLornan DP , McMullin MF
Published: October 2007

Essential thrombocythaemia (ET) is an acquired myeloproliferative disorder. The phenotypic and biological heterogeneity of ET can make management of individual cases problematic, especially in the era of changing ideas on the molecular pathogenesis of this disease process. This case discussion will explore the evidence base and rationale that guides treatment of a 46‐year‐old individual with ET presenting with an ischaemic episode. Copyright © 2007 John Wiley & Sons, Ltd.
Rainfall patterns and critical values associated with landslides in Povoação County (São Miguel Island, Azores): relationships with the North Atlantic Oscillation
Authors: Marques Rui , Zêzere José , Trigo Ricardo , Gaspar João , Trigo Isabel
Published: October 2007

São Miguel Island (Azores) has been affected by hundreds of destructive landslide episodes in the last five centuries, triggered either by earthquakes, volcanic eruptions or rainfall episodes, which were responsible for many deaths and very important economic losses.

Among the instability causes, meteorological factors are of primary importance on Povoação County, namely the high recurrence rate of calamitous rainfall triggering landslides. The most recent catastrophic episode took place on the 31st October 1997 when almost 1000 soil slips and debris flows were triggered, and 29 people died in the Ribeira Quente village.

The role of rainfall on regional landslide activity was analysed applying cumulative rainfall methods. The method comprises the reconstruction of both absolute and calibrated antecedent rainfalls associated with each major landslide event. The critical rainfall combination (amount‐duration) responsible for each landslide event was assessed and a rainfall critical threshold for landslide occurrence was calculated. Rainfall‐triggered landslides in the study area are ruled by the function I = 144·06 D−0·5551, and they are related both to short duration precipitation events (1–3 days) with high average intensity (between 78 and 144 mm/day) and long‐lasting rainfall episodes (1–5 months) with a lower intensity (between 9 and 22 mm/day).

The impact of the North Atlantic Oscillation (NAO) on the regional precipitation regime was evaluated. It is shown that the monthly precipitation of São Miguel is largely modulated by the NAO mode presenting a significant negative correlation with the NAO index. This result arises from the NAO control on the travelling latitude of most storm tracks that cross the Northern Atlantic Ocean. Copyright © 2007 John Wiley & Sons, Ltd.
Comment on ‘C.‐P. Tung, N.‐M. Hong, C.‐H. Chen and Y.‐C. Tan, Regional daily baseflow prediction. Hydrological Processes, 18(2004) 2147–2164’
Authors: Rupp David E. , Woods Ross A.
Published: October 2007

There are both practical and theoretical issues to consider when doing recession analyses of the type introduced by Brutsaert and Nieber (1977). Tung et al. (2004) point out a practical issue, which is the error introduced by using time‐averaged values of discharge. The issue, however, is probably not serious for many practical applications and the error can be made negligible by using time intervals that are appropriate to the time rate of change in discharge. Copyright © 2007 John Wiley & Sons, Ltd.
Should reciprocity be a part of the UNCITRAL Model Cross‐Border Insolvency Law?
Authors: Yamauchi Keith D.
Published: October 2007

In 1997, the United Nations Commission on International Trade Law adopted a Model Law on Cross Border Insolvency. Since then, many countries have passed it or a revised version of it. In many cases, the adopting country wrestled with the issue of whether to include a reciprocity provision in its version. Some have included such a provision, others have not. The inclusion of a reciprocity provision is not consistent. This article discusses the concept and argues that a reciprocity provision could be detrimental to the operation of the Model Law and prejudicial to the parties; especially those in the country whose legislation includes such a provision. Copyright © 2007 John Wiley & Sons, Ltd.
Effect of adsorbed von Willebrand factor and fibrinogen on platelet interactions with synthetic materials under flow conditions
Authors: Wu Yuguang , Zhang Min , Hauch Kip D. , Horbett Thomas A.
Published: October 2007

The effect of adsorbed fibrinogen (Fg) and von Willebrand factor (vWf) on platelet adhesion at low or high shear rate to several materials was studied. The materials studied were polyethylene terephthalate (PET), polystyrene (PS), glass, and tetraglyme‐coated PET. The materials were preadsorbed with normal plasma, serum, and Fg‐deficient plasma replenished with various amounts of Fg, and vWf‐deficient plasma with or without added vWf. Platelet adhesion to PET preadsorbed with Fg‐deficient plasma or serum was low at either low or high shear rate, but increased as Fg was added to the preadsorption media. However, the effect of added Fg on adhesion at the higher shear rate was much greater on surfaces preadsorbed with plasma than for serum, probably due to the much lower vWf concentration in serum in comparison to plasma. Platelet adhesion to either polystyrene or glass preadsorbed with normal plasma was much higher at high shear than low shear, but when vWf‐deficient plasma was used to preadsorb these surfaces, adhesion was much less at the higher shear rate than at low shear rate. Platelet adhesion to polystyrene preadsorbed with vWf‐deficient plasma to which vWf was added was higher at high shear rate than low shear rate. These results show that under high shear rate, both Fg and vWf are required for platelet adhesion on synthetic biomaterials. The results suggest that developing surfaces that adsorb low amounts of vWf is a good approach to improving the blood compatibility of biomaterials. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Structural stability and release profiles of proteins from core‐shell poly (DL‐lactide) ultrafine fibers prepared by emulsion electrospinning
Authors: Yang Ye , Li Xiaohong , Cui Wenguo , Zhou Shaobing , Tan Rui , Wang Chaoyang
Published: October 2007

This study was aimed at assessing the potential use of emulsion electrospinning to prepare core‐shell structured ultrafine fibers as carriers for therapeutic proteins. It focused on the effect of fiber structure on the release profiles and structural stability of encapsulated proteins. In the case of bovine serum albumin (BSA) which was selected as a model protein, poly‐DL‐lactide ultrafine fibers prepared by emulsion electrospinning using a lower volume ratio of aqueous to organic phase, showed higher structural integrity of core‐shell fiber as assessed by laser confocal scanning microscope (LCSM). This structural property can reduce the initial drug burst and improved the ability of the device to provide sustained therapeutic action. Fickian release was observed for the initial 60% of protein release. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) and size exclusion chromatography (SEC) were used to assess the primary structure of BSA. These studies indicated that ultra‐sonication caused denaturation of protein molecules, while the core‐shell structured electrospun fibers protected the structural integrity of encapsulated protein during incubation in the medium. Fourier transform infrared (FTIR) analyses showed that the electrospinning process had much less effect on the secondary structure of protein than ultra‐sonication. In vitro degradation study showed that the protein release from fibers led to more significant mass loss, higher molecular weight reduction and larger molecular weight distribution of the matrix residues, compared with fibers without protein inoculation. These data suggest that emulsion electrospinning can provide a useful core‐sheath structure, which may serve as a promising scaffold for sustainable, controllable, and effective release of bioactive proteins in tissue engineering and other applications. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Seamless tubular poly(glycerol sebacate) scaffolds: High‐yield fabrication and potential applications
Authors: Crapo Peter M. , Gao Jin , Wang Yadong
Published: October 2007

We have previously created scaffolds composed of a biodegradable elastomer, poly(glycerol sebacate) (PGS), which are tubular, seamless, and highly porous. Here we describe two scaffold fabrication methods developed subsequently and compare the advantages of these methods to the original by examining overall yields and scaffold characteristics, such as defect frequency and severity, wall thickness homogeneity, microstructure, porosity, and mechanical properties. Scaffolds fabricated with a heat‐shrinkable (HS) mandrel had higher yield, fewer defects, more homogeneous wall thickness and microstructure, and higher porosity. Improvements in yield and scaffold characteristics likely resulted from more uniform distribution of forces resulting in lower stress concentrations in the scaffolds during removal of HS mandrels. When seeded with smooth muscle cells in a bioreactor, the optimized scaffolds retained 74% of cells, which proliferated and formed a confluent cellular layer after 21 days of in vitro culture. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Three‐dimensional fabrication of engineered bone with human bio‐derived bone scaffolds in a rotating wall vessel bioreactor
Authors: Song Kedong , Liu Tianqing , Cui Zhanfeng , Li Xiangqin , Ma Xuehu
Published: October 2007

Bone tissue engineering has emerged as a promising strategy in the effort to regenerate and repair diseased or damaged bone. The bioreactor, within which engineered bone tissue is cultured, plays a key role in the development of engineered bone graphs. In this work, the potentials of the rotating wall vessel bioreactor (RWVB) and the human bio‐derived bone scaffolds (BDBS) for 3D bone culture are evaluated. The osteoblasts isolated from the cranium of neonatal Sprague‐Dawley (SD) rat of 3 days old were expanded firstly with microcarrier suspension culture in a RWVB. After the assessment of the biological functions of the expanded cells by histomorphometry, the cells were seeded at 2 × 106 and 1 × 106 cells/mL, respectively, onto the 3D human BDBS and cultured for 3 weeks in the RWVB. The cells metabolism and nutrient concentration were monitored in the whole culture processes. The structure of the harvested bone tissues was observed with optical microscope and scanning electron microscope (SEM). The biological properties of the engineered bone were detected by alkaline phosphatase (ALP) expression and alizarin red staining to visualize the newly formed bone. Acridine orange/ethidium bromide (AO/EB) double fluorescence staining was used to analyze the cell activity. For a comparative study, cell seeded constructs were also cultured in static conditions. The results indicate that the bone grafts cultured in RWVB with two different seeded cell densities grew well, and the cell number expanded in RWVB was five times as that in T‐flask and spinner flask. There were significantly more collagen fibers mineralized nodules and new osteoid tissue formed than those in T‐flask and spinner flask. It also demonstrated that with the stress stimulation inside the fluid in the RWVB, the ALP expression could be increased; the formation of mineralized nodules can be accelerated. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Navigator‐triggered oxygen‐enhanced MRI with simultaneous cardiac and respiratory synchronization for the assessment of interstitial lung disease.
Authors: Molinari Francesco , Eichinger Monika , Risse Frank , Plathow Christian , Puderbach Michael , Ley Sebastian , Herth Felix , Bonomo Lorenzo , Kauczor Hans‐Ulrich , Fink Christian
Published: October 2007

Purpose

To evaluate an optimized method for oxygen‐enhanced MRI of the lung, using simultaneous electrocardiograph (ECG) and navigator triggering. To correlate oxygen‐enhanced MRI with lung function tests assessing alveolar‐capillary gas exchange.

Materials and Methods

A total of 12 healthy volunteers (aged 20–32 years) and 10 patients (aged 37–87 years) with interstitial lung diseases (ILD) underwent oxygen‐enhanced MRI and pulmonary functional tests (PFTs) assessing alveolar‐capillary gas exchange. The paradigm room‐air–oxygen–room‐air was acquired with a nonselective inversion‐recovery half‐Fourier single‐shot turbo spin‐echo sequence (inversion time = 1200 msec; acquisition time = 134.5 msec; slice thickness = 20 mm; matrix size = 128 × 128), using simultaneous double triggering (navigator plus ECG trigger). Cross‐correlation was performed in regions of interest (ROIs) encompassing both lungs. The number of oxygen‐activated pixels over the total number of pixels in the ROIs (OAP%) of volunteers and patients was compared. OAP%s were correlated with PFTs.

Results

The mean OAP% of patients was significantly lower than that of volunteers (36.7 vs. 81.7, P = 0.001). OAP% correlated with the transfer lung factor for carbon monoxide (Tlco) (r = 0.64; P = 0.002), the transfer coefficient (Kco) (r = 0.75; P = 0.001), the arterial partial pressure (r = 0.77; P < 0.001), and the saturation (r = 0.70; P < 0.001) of oxygen.

Conclusion

Navigator‐triggered oxygen‐enhanced MRI of the lung may have a potential role in the quantitative assessment of lung function in ILD. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Apparent diffusion coefficients in oligodendroglial tumors characterized by genotype
Authors: Jenkinson Michael D. , Smith Trevor S. , Brodbelt Andrew R. , Joyce Kathy A. , Warnke Peter C. , Walker Carol
Published: October 2007

Purpose

To investigate whether oligodendroglial tumors with or without 1p/19q loss differ in their diffusion‐weighted imaging characteristics. Oligodendroglial tumors with or without 1p/19q loss differ in their therapeutic responsiveness and prognosis, and recent reports also suggest that these tumors may differ in their magnetic resonance characteristics and blood volume.

Materials and Methods

Apparent diffusion coefficients (ADCs) were assessed in three grade II oligodendrogliomas, nine grade II and five grade III oligoastrocytomas with known 1p/19q status. Regions of interest (ROIs) were placed on ADC maps: 1) around tumor margins to generate pixel histograms; 2) over minimum and maximum tumor ADC; 3) on areas comparable to the highest choline (Cho)/creatine (Cr) ratio determined from chemical shift imaging (CSI); and 4) across tumor margins to measure the ADC transition coefficient (ATC).

Results

Tumor ADC was significantly different from normal brain (P < 0.001). ADC in regions of highest Cho/Cr was greater than minimum ADC and did not correlate with the Cho/Cr ratio. ADC and ATC were not significantly different between oligodendroglial subtypes or grades. Tumors with intact 1p/19q had higher maximum (P = 0.021) and histogram ADC (P = 0.015), and greater ATC (P = 0.001) compared to those with 1p/19q loss, which may reflect differences in edema and cellularity.

Conclusion

This preliminary study identified differences in ADC and ATC between oligodendroglial tumor genotypes that may reflect underlying biology. Confirmation in a larger series is warranted. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Orthogonal measurement of thoracic aorta luminal diameter using ECG‐gated high‐resolution contrast‐enhanced MR angiography
Authors: Bireley William R. , Diniz Lincoln O. , Groves Elliott M. , Dill Karin , Carroll Timothy J. , Carr James C.
Published: October 2007

Purpose

To compare orthogonal measurements of the thoracic aortic luminal diameter to standard axial measurements within the same patient population using ECG‐gated high‐resolution contrast‐enhanced MR angiography (CE‐MRA).

Materials and Methods

In all, 45 consecutive patients who had undergone CE‐MRA for suspected disease of the thoracic aorta were evaluated retrospectively. Two diameter measurement techniques were performed for each patient's thoracic aorta: standard axial and orthogonal to the aorta. Seven anatomic locations along the thoracic aorta were used for measurement. The data obtained were compared using a paired, two‐tailed t‐test.

Results

We found that the aorta diameter measurements acquired from axial MRA images were significantly greater (P < 0.05) than those acquired from images orthogonal to the course of the aorta at six of seven anatomic sites. Overall, standard axial measurements were found to overestimate luminal diameter of the thoracic aorta by 0.24 cm (95% confidence interval [CI]: 0.14, 0.33) compared to orthogonal measurements. 13.3% of the patients were placed into a greater aorta size classification based on the axial versus the orthogonal measurements.

Conclusion

Standard axial measurements can overestimate vessel size of the thoracic aorta. ECG‐gated high‐resolution CE‐MRA can be used to measure orthogonal diameters of the thoracic aorta. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Mechanical dyssynchrony or myocardial shortening as MRI predictor of response to biventricular pacing?
Authors: Rüssel Iris K. , Zwanenburg Jaco J.M. , Germans Tjeerd , Marcus J. Tim , Allaart Cornelis P. , de Cock Carel C. , Götte Marco J.W. , van Rossum Albert C.
Published: October 2007

Purpose

To investigate whether mechanical dyssynchrony (regional timing differences) or heterogeneity (regional strain differences) in myocardial function should be used to predict the response to cardiac resynchronization therapy (CRT).

Materials and Methods

Baseline mechanical function was studied with MRI in 29 patients with chronic heart failure. Using myocardial tagging, two mechanical dyssynchrony parameters were defined: the standard deviation (SD) in onset time (Tonset) and in time to first peak (Tpeak,first) of circumferential shortening. Electrical dyssynchrony was described by QRS width. Further, two heterogeneity parameters were defined: the coefficient of variation (CV) in end‐systolic strain and the difference between peak septal and lateral strain (DiffSLpeakCS). The relative increase in maximum rate of left ventricle pressure rise (dP/dtmax) quantified the acute response to CRT.

Results

The heterogeneity parameters correlated better with acute response (CV: r = 0.58, DiffSLpeakCS: r = 0.63, P < 0.005) than the mechanical dyssynchrony parameters (SD(Tonset): r = 0.36, SD(Tpeak,first) r = 0.47, P = 0.01, but similar to electrical dyssynchrony (r = 0.62, P < 0.001). When a heterogeneity parameter was combined with electrical dyssynchrony, the correlation increased (r > 0.70, Pincr < 0.05).

Conclusion

Regional heterogeneity in myocardial shortening correlates better with response to CRT than mechanical dyssynchrony, but should be combined with electrical dyssynchrony to improve prediction of response beyond the prediction from electrical dyssynchrony only. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
In vivo proton magnetic resonance spectroscopy in patients with mood disorders: A technically oriented review
Authors: Capizzano Aristides A. , Jorge Ricardo E. , Acion Laura C. , Robinson Robert G.
Published: October 2007

Proton MR spectroscopy (1HMRS) has been extensively used among mood disorders patients. A review of the published literature in 1HMRS studies of mood disorders was carried out for the period 1991 to July 2006. Of 71 1HMRS studies, 77.5% were done at 1.5T and 66.2% used single voxel sequences (SVS), implying limitations of spectral resolution and anatomic coverage, respectively. In all, 47.9% of studies relied on creatine (Cr) as internal signal standard, although Cr changes were reported in major depression (MD). Most reported metabolic alterations related to mood state affected the left frontal lobe. Depressed adult and pediatric MD patients had reduced glutamate (Glu) in frontal lobe regions, which reversed with successful treatment. A consistent reduction of N‐acetyl‐aspartate (NAA) was reported in the hippocampal formation among bipolar disorder (BD) patients, along with an increment in frontal Glu. The differences in results of 1HMRS studies in mood disorders reflect heterogeneity of technical factors and subject selection. Future studies should benefit from higher spectral resolution and more extensive anatomic coverage as well as standardized data‐processing protocols and subject selection criteria. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Exposure of workers to pulsed gradients in MRI
Authors: Crozier Stuart , Wang Hua , Trakic Adnan , Liu Feng
Published: October 2007

Purpose

To numerically evaluate the electric field/current density magnitudes and spatial distributions in healthcare workers when they are standing close to the gradient coil windings near the magnetic resonance imaging (MRI) scanner ends.

Materials and Methods

Anatomically realistic, whole‐body male and female voxel phantoms are engaged to model the workers at various positions near the ends of three cylindrical gradient coils (x‐, y‐, and z‐axis gradients). The numerical calculations of induced fields are based on an efficient, quasistatic finite‐difference method.

Results

The simulations show that it is possible to induce electric fields/current densities above levels recommended by the International Commission for Non‐ionizing Radiation Protection (ICNIRP) and the Institute of Electrical and Electronics Engineers (IEEE) standards when the workers are standing close to the gradient coils and when two or three gradients are switched simultaneously, as is often the case.

Conclusion

The longitudinal gradient tends to induce more fields in workers than the transverse coils. The strongest levels of field exposure are observed when all three gradients are operated simultaneously and can be above regulations when the healthcare worker is close to the gradient coils. Other postures such as bending into the magnet shall be investigated in further studies. J. Magn. Reson. Imaging 2007;26:1236–1254. © 2007 Wiley‐Liss, Inc.
Chronic postinfarction pseudo‐pseudoaneurysm diagnosed by cardiac MRI
Authors: Faludi Réka , Tóth Levente , Komócsi András , Varga‐Szemes Ákos , Papp Lajos , Simor Tamás
Published: October 2007

Left ventricular pseudo‐pseudoaneurysm is an extremely rare complication of myocardial infarction. In this condition the postinfarction rupture of the myocardium is not transmural, but remains circumscribed within the ventricular muscle itself as a cavity joining to the left ventricle through a narrow neck. The differentiation between postinfarction pseudoaneurysms and pseudo‐pseudoaneurysms may be very difficult using conventional imaging techniques, such as transthoracic, or transesophageal echocardiography and left ventricular angiography. Cardiac MRI (CMR), however, is capable of distinguishing among anatomical structures such as pericardium, thrombus, and myocardium. In our report a chronic postinfarction pseudo‐pseudoaneurysm is described by CMR in a patient with an old myocardial infarction. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Detecting groups of coherent voxels in functional MRI data using spectral analysis and replicator dynamics
Authors: Müller Karsten , Neumann Jane , Grigutsch Maren , von Cramon D. Yves , Lohmann Gabriele
Published: October 2007

Purpose

To investigate the relationship between functional MRI (fMRI) time series in the human brain, combining fMRI spectral analysis and replicator dynamics.

Materials and Methods

Simulated and real fMRI time courses were investigated using the bivariate spectral coherence. Coherence values were placed in coherence matrices encoding the relationship between the time courses. Groups of maximally coherent voxels were detected using replicator dynamics. Results were compared to a former approach called number of coherent voxels (NCV).

Results

NCV critically depends on a threshold that has to be chosen in advance. The lower this threshold, the larger the detected group. Using higher NCV thresholds in our simulations, the method did not detect all voxels that were constructed to have a high coherence among each other. In contrast, the replicator process found the whole group in all simulations.

Conclusion

The application of replicator dynamics to spectral matrices is a reliable method for detecting groups of maximally coherent voxels. A replicator process is able to determine groups of voxels with the property that each voxel in the group exhibits a high coherence with every other group member. In contrast to the NCV approach, this method is parameter‐free and does not require the a priori selection of a reference voxel. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
MR imaging of the female pelvis at 3 Tesla: Evaluation of image homogeneity using different dielectric pads
Authors: Kataoka Masako , Isoda Hiroyoshi , Maetani Yoji , Nakamoto Yuji , Koyama Takashi , Umeoka Shigeaki , Tamai Ken , Kido Aki , Morisawa Nobuko , Saga Tsuneo , Togashi Kaori
Published: October 2007

Purpose

To evaluate improvements in image homogeneity in pelvic MR imaging at 3 Tesla (T) using two different dielectric pads.

Materials and Methods

A total of eight healthy females were scanned using a 3T MR scanner equipped with a body‐array coil. Axial and sagittal fast spin‐echo T2‐weighted images (T2WI) (TR/TE = 3200 msec/94 msec), axial fast spin‐echo T1‐weighted images (T1WI) (TR/TE = 700 msec/11 msec), and sagittal half‐Fourier acquisition single‐shot turbo spin‐echo (HASTE) images (TR/TE = 3000 msec/100 msec) were performed for pelvic imaging. Sequences were repeated with dielectric pads (consisting of either ultrasound [US] gel or water), and without pads. Three or four regions of interest (ROIs) were placed on fatty tissues and the ratio of minimum to maximum signal intensity (RSI) was calculated as a marker of image homogeneity.

Results

RSI was significantly higher on T2WI and T1WI when using dielectric pads than when no pad was used. A similar tendency was observed in RSI on HASTE. No significant difference was found between images with US gel pads and those with water pads.

Conclusion

Dielectric pads consisting of either US gel or water are effective in improving image homogeneity of the pelvis on 3T MRI. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Laser Doppler velocimetry (LDV) and 3D phase‐contrast magnetic resonance angiography (PC‐MRA) velocity measurements: Validation in an anatomically accurate cerebral artery aneurysm model with steady flow
Authors: Hollnagel Dorothea I. , Summers Paul E. , Kollias Spyros S. , Poulikakos Dimos
Published: October 2007

Purpose

To verify the accuracy of velocity mapping with three‐dimensional (3D) phase‐contrast magnetic resonance angiography (PC‐MRA) for steady flow in a realistic model of a cerebral artery aneurysm at a 3T scanner.

Materials and Methods

Steady flow through an original geometry model of a cerebral aneurysm was mapped at characteristic positions by state‐of‐the‐art laser Doppler velocimetry (LDV) as well as 3D PC‐MRA at 3T. The spatial distributions and local values of two velocity components obtained with these two measurement methods were compared.

Results

The 3D PC‐MRA velocity field distribution and mean velocity values exhibited only minor differences to compare to the LDV measurements in straight artery regions for both main and secondary velocities. The differences increased in regions with disturbed flow and in cases where the measurement plane was not perpendicular to the main flow direction.

Conclusion

3D PC‐MRA can provide reliable measurements of velocity components of steady flow in small arteries. The accuracy of such measurements depends on the artery size and the measurement plane positioning. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Opposed phase imaging in lumbar disc disease: An option providing faster image acquisition times
Authors: Yagmurlu Banu , Erden Ilhan , Tanju Sumru , Genc Yasemin
Published: October 2007

Purpose

To investigate the utility of opposed phase imaging (OPI) (in‐phase and out‐of‐phase) in lumbar disc disease.

Materials and Methods

A total of 127 patients suspected of disc disease were examined with both traditional lumbar spine protocol (fast spin‐echo [FSE] T1‐weighted, T2‐weighted sagittal, and T2‐weighted axial) and OPI. Images were evaluated to detect the disc disease and to assess the anatomical clarity of certain spinal structures by two different radiologists using a four‐point scale (1 = inadequate, 2 = adequate, 3 = good, and 4 = optimal). Results of two methods in terms of pathologic conditions and anatomical structures were compared. Comparison of the methods and the interpretations of two radiologists were performed by using kappa statistics. The difference among two methods in terms of anatomic clarity was assessed by using Wilcoxon analysis.

Results

Disc disease detected by each technique demonstrated concurrence (agreement was 82.4% and 93.1% for two radiologists; P < 0.05). OPI received similar scores with conventional sequences for disc disease (P > 0.05). OPI was optimal in displaying disc, marrow, osteophytes, and hemangiomas, where other structures got higher scores on conventional images (P > 0.05 and P > 0.001). But these structures had equal scores at least in one of the opposed‐phase images. Acquisition time for OPI and conventional images were 4.46 and 9.01 minutes, respectively.

Conclusion

OPI can be a faster backup technique in evaluating the lumbar disc disease. It has a shorter image acquisition time with adequate diagnostic quality. It can be a “time saver” option for busy MR centers or may be used for patients who cannot tolerate longer acquisition times. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Planimetric and continuity equation assessment of aortic valve area: Head to head comparison between cardiac magnetic resonance and echocardiography
Authors: Pouleur Anne‐Catherine , le Polain de Waroux Jean‐Benoît , Pasquet Agnès , Vancraeynest David , Vanoverschelde Jean‐Louis J. , Gerber Bernhard L.
Published: October 2007

Purpose

To compare the accuracy of planimetric and continuity equation measurements of aortic valve area (AVA) by cardiac MR (cMR) to each other and against transthoracic (TTE) and transesophageal (TEE) echocardiography.

Materials and Methods

A total of 31 patients (21 men, mean age = 67 ± 13 years) with aortic stenosis (AS) and 16 controls (12 men, mean age = 57 ± 14 years) underwent measurement of AVA by planimetric and continuity equation cMR. Measurements were compared to TEE planimetry and continuity equation TTE.

Results

AVA by continuity equation cMR correlated highly to continuity equation TTE (r = 0.98) and was not significantly different (1.8 ± 1.3 cm2 vs. 1.8 ± 1.4 cm2, P = 0.62). Similarly, AVA by cMR planimetry was not statistically different from TEE planimetry (2.1 ± 1.7 cm2 vs. 2.1 ± 1.6 cm2, P = 0.34) and correlated highly (r = 0.98). Yet planimetric measurements of AVA by cMR and TEE were significantly higher than AVA by continuity equation cMR (P < 0.001 and P < 0.001, respectively) and TTE (P < 0.001 and P < 0.001, respectively).

Conclusion

Both planimetry and continuity equation–based measurements of AVA by cMR are equally accurate. However, similar to TEE, cMR AVA is larger by planimetry than by continuity equation. This is consistent with the contention that the anatomical maximum opening of a stenotic aortic valve is larger than the size of the functional vena contracta. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Correlation of lung parenchymal MR signal intensity with pulmonary function tests and quantitative computed tomography (CT) evaluation: A pilot study
Authors: Iwasawa Tae , Takahashi Hiroshi , Ogura Takashi , Asakura Akira , Gotoh Toshiyuki , Kagei Seiichiro , Nishimura Jun‐ichi , Obara Makoto , Inoue Tomio
Published: October 2007

Purpose

To evaluate the effect of ventilatory impairment on MR signal intensity of the lung parenchyma.

Materials and Methods

Subjects were five normal volunteers (age = 30 ± 7.9 years, mean ± SD) and 19 male patients with chronic obstructive lung disease (COPD) (mean age = 70.4 ± 6.5 years). Coronal MR images were obtained over entire lung fields at full inspiration and full expiration with cardiac triggering on a 1.5T system. Changes in the mean lung intensity between the two respiratory states were normalized by each intercept of the linear regression lines of the signal changes, and the slope of the relationship was calculated. Computed tomography (CT) images were also obtained in COPD patients at full inspiration using a multidetector row CT scanner. Attenuation values less than −950 Hounsfield units (HU) (RA‐950) represented the percentage of relative lung area on the CT.

Results

The mean slope of COPD patients (0.365 ± 0.074) was less steep than that of the normal subjects (0.570 ± 0.124, P < 0.001). In COPD patients, the slope correlated significantly with forced expiratory volume in one second (FEV1, r = 0.508, P = 0.026), but not with RA‐950.

Conclusion

In COPD patients, lung signal change measured by MRI correlates with airflow obstruction, but not with volume of the emphysema measured by lung CT. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Line scan diffusion spectrum of the denervated rat skeletal muscle
Authors: Yamabe Eiko , Nakamura Toshiyasu , Oshio Koichi , Kikuchi Yoshito , Toyama Yoshiaki , Ikegami Hiroyasu
Published: October 2007

Purpose

To detect the earlier changes of the skeletal muscle of rats after peripheral nerve injury by measuring the apparent diffusion coefficient (ADC) on diffusion MR spectroscopy.

Materials and Methods

The posterior tibial nerve was transected in six rats (nerve transection group) and was only dissected in six rats (control group). At one, three, five, seven, 14, and 28 days after the surgery, both the T2 value and the ADC of gastrocnemius muscle were measured using a line‐scan diffusion spectrum on a 1.5T clinical MR imager on both groups.

Results

In the nerve transection group, the T2 ratio compared to the contralateral side increased gradually over four weeks after the transection, while the ADC ratio increased right after the surgery and began to decrease at five days. Four weeks after the transection, the ADC ratio returned to normal while the T2 ratio stayed at a high value. The control group indicated an almost constant T2 and ADC ratio during the experimental periods.

Conclusion

The ADC of the skeletal muscle increased quickly after the transection of the dominant peripheral nerve and was detectable one day after the surgery. Diffusion MRI can be a useful tool for early detection of peripheral nerve injury instead of T2‐weighted MRI or electromyography (EMG). J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
MRI appearance of perianal carcinoma in Crohn's disease
Authors: Lad Shilpa V. , Haider Masoom A. , Brown Carl J. , Mcleod Robin S.
Published: October 2007

Detection of carcinoma in perianal Crohn's disease can be difficult. The purpose of this study was to describe the MRI appearance of anorectal cancer in patients with perianal Crohn's disease. A total of six patients with anorectal carcinoma (four mucinous adenocarcinoma, two squamous) in Crohn's disease were retrospectively reviewed. Axial T2 and dynamic postcontrast fat‐suppressed T1‐weighted gradient echo sequences were performed, and findings were compared with 18 noncancer patients with perianal fistulae in Crohn's disease. MRI characteristics of carcinoma were irregular inner wall contours and delayed mild enhancement of internal tissue. The combined features of an irregular internal wall and delayed enhancing tissue were seen exclusively in cancer patients. The four cases of mucinous adenocarcinoma all displayed a pattern of lobulated fluid‐filled cavities with delayed internal tissue enhancement. This pattern was not seen in any of the control cases. The presence of a double‐layered enhancement pattern was seen in both cases of squamous carcinoma and in only one of four cases of mucinous adenocarcinoma and one of 18 noncancer cases. The pattern of contrast enhancement is valuable in the MRI diagnosis of carcinoma in perianal Crohn's disease. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Diagnostic performance of MRI relative to CT for metastatic nodes of head and neck squamous cell carcinomas
Authors: Sumi Misa , Kimura Yasuo , Sumi Tadateru , Nakamura Takashi
Published: October 2007

Purpose

To compare the diagnostic abilities of magnetic resonance imaging (MRI) and computed tomography (CT) based on the architectural changes in the nodal parenchyma.

Materials and Methods

We retrospectively studied histologically proven 70 metastatic and 52 reactive nodes in the necks of 38 patients with head and neck squamous cell carcinomas who had undergone both CT and MRI. We assessed the detectability of the architectural changes in the nodal parenchyma that were suggestive of cancer focus (cancer nest, necrosis, and keratinization). The diagnostic abilities of CT and MRI were assessed by three observers separately for the small (<10 mm in minimum axis diameter) and large (≥10 mm) nodes.

Results

MRI was significantly more effective than CT in diagnosing small metastatic nodes, yielding 83% sensitivity, 88% specificity, and 86% accuracy. However, the diagnostic abilities of MRI and CT were similar for large metastatic nodes; MRI yielded 100% sensitivity, 98% specificity, and 99% accuracy. receiver operating characteristic analysis also indicated that the Az values were significantly higher for MRI than for CT (0.927 vs. 0.822, P = 0.00054) for the detection of small nodes.

Conclusion

MRI is superior to CT in the diagnosis of metastatic nodes from head and neck squamous cell carcinomas. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Alteration of blood oxygenation level‐dependent signaling by local circulatory condition
Authors: Kamba Masayuki , Sung Yul‐Wan , Ogawa Seiji
Published: October 2007

Purpose

To determine regional differences in the relationship between neuronal activation and blood oxygenation level‐dependent (BOLD) signal changes.

Materials and Methods

We performed BOLD and perfusion‐based studies on healthy adult volunteers (40 for BOLD and 20 for perfusion‐based studies) with visual stimulation of varied extent in the visual field of subjects.

Results

Regions with a significant negative correlation between the extent of visual stimuli and BOLD and perfusion responses were found bilaterally on the lateral surface of the occipital lobe just anterior to the occipital pole. These regions were located in the border zone between the territories of the middle and posterior cerebral arteries.

Conclusion

Insufficient perfusion pressure in these regions may have led to attenuation of BOLD and perfusion responses to stimulation of a large portion of the visual field, or a condition in which a large extent of the visual areas was activated in the proximal regions of the territories perfused by the middle and posterior cerebral arteries. This finding supports the hypothesis that regional differences in circulatory condition can result in alterations of the relationship between neuronal activation and BOLD signal changes in the normal human brain. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Coating thickness of magnetic iron oxide nanoparticles affects R2 relaxivity
Authors: LaConte Leslie E.W. , Nitin Nitin , Zurkiya Omar , Caruntu Daniela , O'Connor Charles J. , Hu Xiaoping , Bao Gang
Published: October 2007

Purpose

To evaluate the effect of coating thickness on the relaxivity of iron oxide nanoparticles.

Materials and Methods

Monocrystalline superparamagnetic iron oxide nanoparticles (MIONs), coated with a polyethylene glycol (PEG)‐modified, phospholipid micelle coating, with different PEG molecular weights, were prepared. The particle diameters were measured with dynamic light scattering (DLS) and electron microscopy (EM). The R1 and R2 of MIONs were measured using a bench‐top nuclear magnetic resonance (NMR) relaxometer. pH was varied for some measurements. Monte Carlo simulations of proton movement in a field with nanometer‐sized magnetic inhomogeneities were performed.

Results

Increasing the molecular weight of the PEG portion of the micelle coating increased overall particle diameter. As coating thickness increases, the R2 decreases and the R1 increases. Changing pH has no effect on relaxivity. The Monte Carlo simulations suggest that the effect of coating size on R2 relaxivity is determined by two competing factors: the physical exclusion of protons from the magnetic field and the residence time for protons within the coating zone.

Conclusion

Coating thickness can significantly impact the R2, and the R2/R1 ratio, of a MION contrast agent. An understanding of the relationship between coating properties and changes in relaxivity is critical for designing magnetic nanoparticle probes for molecular imaging applications using MRI. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Long and short echo time proton magnetic resonance spectroscopic imaging of the healthy aging brain
Authors: McIntyre Dominick J.O. , Charlton Rebecca A. , Markus Hugh S. , Howe Franklyn A.
Published: October 2007

Purpose

To investigate the relationship between subject age and white matter brain metabolite concentrations and R2 relaxation rates in a cross‐sectional study of human brain.

Materials and Methods

Long‐ and short‐echo proton spectroscopic imaging were used to investigate concentrations and R2 relaxation rates of N‐acetyl aspartate (NAA) + N‐acetyl aspartyl glutamate (NAAG), choline (Cho), creatine (Cr), and myoinositol (mI) in the white matter of the centrum semiovale of 106 healthy volunteers aged 50–90 years; usable data were obtained from 79 subjects. A major aim was to identify which parameters were most sensitive to changes with age. Spectra were analyzed using the LCModel method.

Results

The apparent R2 of NAA and the LCModel concentration of Cr at short echo time were significantly correlated with age after multiplicity correction. Large lipid resonances were observed in the brain midline of some subjects, the incidence increasing significantly with age. We believe this to result from lipid deposits in the falx cerebri.

Conclusion

Since only short‐echo spectroscopy showed a robust relationship between Cr and subject age, and detects more metabolites than long echo time, we conclude that short‐echo is superior to long‐echo for future aging studies. Future studies could usefully determine whether the Cr–age relationship is due to changes in concentration, T1, or both. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.