bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative developmental toxicities of the three major metabolites of N‐methyl‐2‐pyrrolidone after oral administration in rats
Authors: Saillenfait A. M. , Sabaté J. P. , Gallissot F.
Published: March 2007

The developmental toxicity of the three main metabolites of N‐methyl‐2‐pyrrolidone (NMP) was studied in Sprague‐Dawley rats. Pregnant rats were given 5‐hydroxy‐N‐methyl‐2‐pyrrolidone (5‐HNMP; 0, 250, 500, 750 or 1000 mg kg−1 day−1), N‐methylsuccinimide (MSI; 0, 500, 750, 1000 or 1250 mg kg−1 day−1), or 2‐hydroxyN‐methylsuccinimide (2‐HMSI; 0, 250, 500, 1000 or 1500 mg kg−1 day−1), by gavage, on gestational days (GD) 6–20. No evidence of maternal toxicity was observed in dams given 5‐HNMP. Administration of 2‐HMSI resulted in overt maternal toxicity at 500 mg kg−1 day−1 and higher doses, as indicated by a significant reduction in weight gain and food consumption at the beginning of treatment. There was no evidence of embryo/fetal toxicity in any of the groups treated with 5‐HNMP or 2‐HMSI. MSI produced marked developmental toxicity in the presence of maternal effects. Maternal body weight gain and food consumption were affected at 750 mg kg−1 day−1 MSI, and above. A significant increase in post‐implantation loss occurred at 1250 mg kg−1 day−1 MSI, and the incidence of fetuses with external or with visceral malformations was significantly increased at 1000 and 1250 mg kg−1 day−1 MSI. Malformations mainly consisted of anasarca, cardiovascular defects and diaphragmatic hernia. Fetal weight was significantly reduced at 1000 and 1250 mg kg−1 day−1. The incidence of skeletal variations (predominantly cervical ribs, and delayed ossification of skull bones and sternebrae) was significantly elevated at 750 mg kg−1 day−1 and higher doses. However, MSI was much less potent than the parent compound.

These results indicate that the embryotoxic and teratogenic effects of NMP are not attributable to these metabolites. Copyright © 2007 John Wiley & Sons, Ltd.
Characterization of a lipopolysaccharide mediated neutrophilic hepatitis model in Sprague Dawley rats
Authors: Rose Robert , Banerjee Atrayee , Ramaiah Shashi K.
Published: March 2007

Several studies have investigated the role of neutrophils during endotoxin‐mediated liver injury, yet the precise mechanism for endotoxin‐mediated hepatic neutrophil transmigration is unknown. The primary objective of this study was to establish a reliable lipopolysaccharide (LPS)‐mediated necro‐hepatitis model to investigate the mechanisms of hepatic neutrophil infiltration following LPS administration. Male Sprague Dawley rats were administered a single (5 or 10 mg kg−1, i.v.) or repeated injection of LPS (10 mg kg−1, i.v., 24 h apart) with appropriate controls (i.v. saline) and were killed at various time points following LPS injection. Significant hematologic changes included neutrophilia, elevation of the neutrophil to lymphocyte ratio and toxic changes in neutrophils. Biochemical changes were observed in several liver (aspartate aminotransferase AST, gamma glutamyl transferase GGT) and kidney (blood urea nitrogen BUN) associated parameters generally at the earliest time points. Histopathology revealed a time‐dependent neutrophil and mononuclear infiltration around the periportal areas in the single dose study and multifocal midzonal coagulative necrosis in the repeated dose study. The neutrophil adhesion molecule, CD 11b was up‐regulated in single and repeat dose studies. Based on these studies, a reliable LPS‐mediated hepatitis model with necrosis was developed by intravenous administration of LPS in a repeat dose fashion. Midzonal hepatic necrosis, peripheral neutrophilia, hepatic neutrophil infiltration and up‐regulation of CD11b were the most significant and consistent markers of LPS mediated effects in this model. Copyright © 2007 John Wiley & Sons, Ltd.
Seasonal variations in spontaneous levels of DNA damage; implication in the risk assessment of environmental chemicals
Authors: Verschaeve L. , Koppen G. , Gorp U. Van , Schoeters G. , Jacobs G. , Zwijzen C.
Published: March 2007

The alkaline comet assay was used to investigate DNA damage levels in white blood cells of 45 normal healthy subjects. Therefore blood was sampled at four different periods, namely in February, June, August and November of the same year. Higher DNA damage levels were found in summertime, as well as higher levels of 1‐hydroxypyrene in urine in this period. This suggests a higher exposure to polycyclic hydrocarbons in the summer compared with other periods of the year. The observed seasonal variation in DNA damage levels is in agreement with some, but in contradiction with other data. Seasonal variations in DNA damage levels can easily be explained by the existence of different confounders that may influence the results of a biomonitoring study. Besides sunlight and environmental pollution, also diet, allergy and physical exercise, for example, were already identified as important influencing factors. The investigation confirms that the blood sampling period is crucial in the planning and interpretation of biomonitoring studies. Copyright © 2007 John Wiley & Sons, Ltd.
Sliding wear behavior of submicron‐grained alumina in biological environment
Authors: Singha Roy R. , Mondal A. , Chanda A. , Basu D. , Mitra M. K.
Published: March 2007

Sliding wear behavior of sintered alumina with grain sizes between 0.45 and 4 μm was studied in bovine serum environment with unidirectional pin‐on‐disc wear testing machine. Submicron grained alumina of average grain size of G = 0.45 μm exhibits lowest wear factor among the others. It was found that grain pull out or localized grain dislodgement caused by coalescence of grain boundary microcracks is the basic wear mechanism of submicron grained alumina though the extent of cracking and pull‐out was substantially less than that with higher grained material. However, in few cases, some areas where substantial volume of material was removed following pull‐out of cluster of grains have also been observed. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Micro‐CT based quantification of non‐mineralized tissue on cultured hydroxyapatite scaffolds
Authors: Hilldore Amanda , Wojtowicz Abigail , Johnson Amy Wagoner
Published: March 2007

An improved method to determine material volumes from microcomputed tomography (micro‐CT) data is presented. In particular, the method can account for materials with significantly overlapping peaks and small volumes. The example case is a hydroxyapatite scaffold cultured with osteoprogenitor cells. The histogram obtained from the micro‐CT data is decomposed into a Gaussian attenuation distribution for each material in the sample, including scaffold, pore and surface tissue, and background. This is done by creating a training set of attenuation data to find initial parameters and then using a nonlinear curve fit, which produced R2 values greater than 0.998. To determine the material volumes, the curves that simulated each material are integrated, allowing small volume fractions to be accurately quantified. Thresholds for visualizing the samples are chosen based on volume fractions of the Gaussian curves. Additionally, the use of dual‐material regions helps accurately visualize tissue on the scaffold, which is otherwise difficult because of the large volume fraction of scaffold. Finally, the curve integration method is compared with Bayesian estimation and intersection thresholding methods. The pore tissue is not represented at all by the Bayesian estimation, and the intersection thresholding method is less accurate than the curve integration method. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
PD98059 enhanced insulin, cytokine, and growth factor activation of xanthine oxidoreductase in epithelial cells involves STAT3 and the glucocorticoid receptor
Authors: Roberts Laura E. , Fini Mehdi A. , Derkash Noi , Wright Richard M.
Published: March 2007

PD98059 and U0126 are organic compound inhibitors frequently used to block the activity of the MEK‐1/2 protein kinase. In the present work, promoter activation analyses of xanthine oxidoreductase (XOR) in epithelial cells uncovered the unexpected opposite effect of these inhibitors on activation of XOR. Activation of an XOR‐luciferase fusion gene was studied in stably transfected epithelial cells. The XOR reporter gene was activated by the epidermal growth factors (EGF), prolactin, and dexamethasone and by the acute phase cytokines (APC) IL‐1, IL‐6, and TNFα as previously reported for its native gene, and insulin further stimulated activation induced with acute phase cytokines or growth factors. Activation of the proximal promoter was blocked by inhibitors of the glucocorticoid receptor (GR), p38 MAP kinase, and U0126. Unexpectedly, PD98059 activated the promoter and significantly enhanced expression induced by insulin, APC, or growth factors. Analysis of the XOR upstream DNA and proximal promoter revealed primary roles for the GR and STAT3 in mediating the effects of PD98059 on XOR activation and protein complex formation with the promoter. STAT3 phosphotyrosine‐705 was rapidly induced by PD98059, dexamethasone, and insulin. XOR activation by PD98059, dexamethasone, or insulin was superinduced by a constitutively active derivative of STAT3, while a dominant negative derivative of STAT3 blocked the enhancing effect of PD98059 on XOR activation. These data demonstrate a previously unrecognized effect of PD98059 on STAT3 and the GR that could have unanticipated consequences when used to infer the involvement of the MEK‐1/2 protein kinase. J. Cell. Biochem. 101: 1567–1587, 2007. © 2007 Wiley‐Liss, Inc.
PI‐3K/Akt signal pathway plays a crucial role in arsenite‐induced cell proliferation of human keratinocytes through induction of cyclin D1
Authors: Ouyang Weiming , Li Jingxia , Zhang Dongyun , Jiang Bing‐Hua , Huang Dr Chuanshu
Published: March 2007

Exposure of arsenite can induce hyperproliferation of skin cells, which is believed to play important roles in arsenite‐induced carcinogenesis by affecting both promotion and progression stages. However, the signal pathways and target genes activated by arsenite exposure responsible for the proliferation remain to be defined. In the present study, we found that: (1) exposure of human keratinocytic HaCat cells to arsenite caused an increase in cell proliferation, which was significantly inhibited by pretreatment of wortmannin, a specific chemical inhibitor of PI‐3K/Akt signal pathway; (2) arsenite exposure was also able to activate PI‐3K/Akt signal pathway, which thereby induced the elevation of cyclin D1 expression level in both HaCat cells and human primary keratinocytes based on that inhibition of PI‐3K/Akt pathway by either pretreatment of wortmannin or the transfection of their dominant mutants, significantly inhibited cyclin D1 expression upon arsenite exposure; (3) PI‐3K/Akt pathway is implicated in arsenite‐induced proliferation of HaCat cells through the induction of cyclin D1 because either knockdown of cyclin D1 by its siRNA or inhibition of PI‐3K/Akt signal pathway by their dominant mutants markedly impaired the proliferation of HaCat cells induced by arsenite exposure. Taken together, we provide the direct evidence that PI‐3K/Akt pathway plays a role in the regulation of cell proliferation through the induction of cyclin D1 in human keratinocytes upon arsenite treatment. Given the importance of aberrant cell proliferation in cell transformation, we propose that the activation of PI‐3K/Akt pathway and cyclin D1 induction may be the important mediators of human skin carcinogenic effect of arsenite. J. Cell. Biochem. 101: 969–978, 2007. © 2007 Wiley‐Liss, Inc.
Ear mesenchymal stem cells (EMSC) can differentiate into spontaneously contracting muscle cells
Authors: Gawronska‐Kozak Barbara , Manuel Jessica A. , Prpic Veronica
Published: March 2007

We have previously shown that cells isolated from the outer ears of adult mice are a source of mesenchymal stem cells that can be induced to differentiate into adipo‐, osteo‐, and chondrocytes. In this study, we demonstrate that ear mesenchymal stem cells (EMSC) express stromal cell‐associated markers (CD44, CD73) and stem cell marker Sca‐1 and can be differentiated into spontaneously contracting muscle cells. Treatment of cells with epidermal growth factor (EGF) change their morphology from fibroblast shapes into stick‐like structures that show repeated spontaneous contractions. Under conditions that promote myogenic differentiation, EMSC expressed mRNA for myoD and ventricular specific myosin light chain (MLC‐2v) and protein for connexin 43, sarcomeric α‐actinin, myocyte enhancer factor 2c (MEF2c), myosin heavy chain (MyHC), myogenin, and sarco‐endoplasmic reticulum Ca2+ATPase (SERCA) 1. However, the cells were negative for Nkx2.5, GATA4, and ANP. Intracellular Ca2+ transients in spontaneously beating EMSC, visualized by Fluo‐3AM, showed a frequency of Ca2+ oscillations ranging over 28–59/min (mean 41.17 ± SEM 1.54). We also demonstrated that small pieces of ear tissues (ear punches) collected from live mice provide sufficient numbers of EMSC to isolate, culture and differentiate them into myocytes. Due to the ease of acquiring an expanding repertoire of differentiated EMSC cell types by a noninvasive surgical procedure, we conclude that the ear may prove to be a potential source of autologous cells for regenerative medicine, as supported by the fact that ears are one of the best sources of cells for somatic cell nuclear transfer (SCNT). J. Cell. Biochem. 102: 122–135, 2007. © 2007 Wiley‐Liss, Inc.
Improving access to reproductive and child health services in developing countries: are competitive voucher schemes an option?
Authors: Bhatia M. R. , Gorter A. C.
Published: March 2007

Reducing maternal and child mortality is an important goal of the Millennium declaration and a major concern for policy makers in developing countries. One of the important barriers to reducing maternal mortality is the low utilisation of maternal health services provided by the public health system through it supply side mechanisms.

Demand side financing is increasingly being proposed as one of the options to increase access to reproductive and child health services and is generating great interest in a number of developing countries. Demand side financing not only promotes equity through improved access and better targeting of subsidies, but also provides incentives for efficiency and provider choice by involving the private sector. This paper discusses the concept of demand side financing, and analyses its strengths and limitations. Copyright © 2007 John Wiley & Sons, Ltd.
Multilocular cystic nephroma: MR imaging appearance with current techniques, including gadolinium enhancement
Authors: Kettritz Ute , Semelka Richard C. , Siegelman Evan S. , Shoenut J. Patrick , Mitchell Donald G.
Published: March 2007

The purpose of the study was to define the MRI appearance of multilocular cystic nephroma (MLCN), using current MR techniques, including gadolinium (Gd)‐enhanced sequences. Seven patients with MLCN underwent MR imaging with the following sequences: T1‐weighted spin echo with fat suppression (TIFS, five patients), T1‐weighted spoiled gradient echo (SGE, seven patients), T2‐weighted fast spin echo (two patients), and Gd‐enhanced TIFS (seven patients) and SGE (seven patients). MLCN was histologically proven by resection of the mass in six patients and by observation of typical imaging features with stability in appearance over a 6‐month period in one patient. Lesion morphology and signal intensity (SI) features were retrospectively evaluated. MRI features of MLCN included a solitary cystic lesion with thin internal septations in six patients and a cluster of closely grouped cysts similar in size in one patient. Individual cystic spaces demonstrated SI, varying from low to high on T1‐weighted images in three patients and demonstrated low‐to‐intermediate SI in four patients. Herniation of the lesions into the renal collecting system and thin enhancing septa were demonstrated in all patients. A complex cystic renal lesion with enhancing septa and herniation into the renal collecting system are the characteristic MR findings of MLCN. The direct multiplanar capability of MR may optimally show the relationship of MLCN to the renal pelvis and, thus, facilitate correct diagnosis.
Gd‐DOTA tubular transit asymmetry induced by angiotensin‐converting enzyme inhibitor in experimental renovascular hypertension
Authors: Trillaud Hervé , Roques François , Degrèze Philippe , Combe Christian , Grenier Nicolas
Published: March 2007

In stenosis of a renal artery, angiotensin‐converting enzyme inhibitor (ACEI) can induce a decrease in ipsilateral glomerular filtration. Dynamic MR imaging with gadolinium chelate enhancement was tested to detect this glomerular filtration reduction in experimental renovascular hypertension in the rat. Thirteen rats, with surgically induced left renal artery stenosis, developed hypertension and were studied before and after intravenous injection of ACEI with sequential Gd‐DOTA‐enhanced MR imaging. The time to onset of the tubular phase, the time of the maximal drop of signal, and the medullary signal‐time curves of both kidneys were compared. Before ACEI, tubular phases were symmetric in 11 rats and slightly asymmetric in 2. Twelve rats showed ACEI‐induced changes (positive test): absence of tubular phase on the left side (n=8) or delay (n=4) with significant differences (P<.01). Tubular phases remained symmetric in one (negative test). Dynamic MR imaging can identify ACEI‐induced Gd‐DOTA tubular transit asymmetry, indicative of functionally significant renal artery stenoses, in rats.
Design of gradient coils for permanent magnets
Authors: Wang Jingguo , Abele Manlio G. , Rusinek Henry
Published: March 2007

Designing gradient coils for permanent magnets requires modeling the interaction between the currents and the ferromagnetic material. We have developed and tested an iterative design approach based on the boundary element method. The power dissipated by the gradient coil is treated as a constraint of the minimization problem. The technique is illustrated on a magnet with a rectangular prismatic cavity and two ferromagnetic plates adjacent to the coil. The procedure improved the linearity of the field from 10.5% to 3.4% and reduced the power dissipation to 63% of the power of the unoptimized coil. The optimized distribution of currents has been transformed to variable locations of coil windings without loss of gradient uniformity. The new approach significantly reduces computation time and memory storage and yields practical designs of gradient coils for permanent magnets.
Interaction between paramagnetic metal complexes and intracellular water of single cells
Authors: Päuser Sabine , Zschunke Adolf , Keller Konrad
Published: March 2007

Oocytes from Xenopus laevis were used as a well‐established model to investigate spatially resolved changes in relaxation time (T1) within a cell during exposure to copper complexes by means of 'H‐NMR‐microscopy. T1 relaxation of intracellular water was shortened in dependence on the complex concentration, the water content, and the water mobility in various cell compartments. A relatively constant T1 decrease was observed in the cytoplasm of the vegetal pole, irrespective of the type and concentration of the permeable complexes used. Since the lowest content of free mobile water molecules was detected at the vegetal pole, we concluded that this quantity was as important for the relaxation time decrease as that of the chelated paramagnetic ions. Experiments using 14C‐labeled inulin demonstrated that the paramagnetic metal complexes entered the oocytes without gross injury to their plasma membranes.
Safety of gadodiamide injection in two different age groups
Authors: Högström Barry , Kristoffersen Doris T. , Lundby Bjørg , Svaland Marit G.
Published: March 2007

A meta‐analyses was performed to evaluate the safety of gadodiamide injection (OMNISCAN®) for magnetic resonance imaging in two different age groups (< 65 years; ≥ 65 years). Data on vital signs, clinical laboratory parameters, and subjectively experienced adverse events were reviewed for 734 patients included in 19 European Phase II and III trials with gadodiamide injection (0.1 mmol/kg body weight or 0.3 mmol/kg body weight) used in magnetic resonance imaging. One hundred sixty‐four patients were 65 years of age or older. No statistically significant differences were shown between this population and the population younger than 65 years of age with respect to vital signs or clinical laboratory parameters. A total of 48 adverse events, discomfort excluded, were reported, with no significant difference in frequency between the two age groups. Injection‐associated discomfort was significantly (P=.0025) more frequent in the younger (9.2%) than in the older group (2.5%). Gadodiamide injection is in conclusion a safe contrast medium in older as well as in younger patients.
Feasibility of overhauser‐enhanced MR imaging with nitroxide free radicals
Authors: Lee James N.
Published: March 2007

Overhauser enhancement can increase the signal available in low‐field imaging systems. If the signal is enhanced by a factor of 40, low‐field Overhauser‐enhanced imaging may produce contrast equivalent to that achieved in subtraction MR mammography performed at 1.5 T. This article describes experiments in which Overhauser enhancement is performed with nitroxide free radicals at field strengths near 100 G. The enhanced signal is much less than 40, and less than the equilibrium signal at 0.25 T, in spite of absorbed power levels greater than 100 W/kg. Although the signal enhancement for nitroxides is disappointing, it is likely that other free radical contrast agents will be developed that offer higher Overhauser enhancement.
MR arterial portography with gadolinium‐DOTA: Analysis of nontumoral perfusion abnormalities
Authors: Soyer Philippe , Laissy Jean‐Pierre
Published: March 2007

The purpose of this article was to determine the frequency and imaging characteristics of nontumoral perfusion abnormalities observed on magnetic resonance imaging (MRI) obtained during arterial portography (MRAP). MRAP examinations done in 23 consecutive patients with malignant hepatic tumors were retrospectively and blindly reviewed by two readers for the presence of nontumoral perfusion abnormalities. MR images were assessed for the presence, location, shape, and type of nontumoral perfusion abnormalities, and correlated with intraoperative findings or follow‐up imaging studies. Fourteen nontumoral perfusion abnormalities were found in 10 patients (43%). Nontumoral perfusion abnormalities were categorized into these five types: triangular nontumoral perfusion defects not associated with a more proximal tumor (n = 6), triangular nontumoral perfusion abnormalities distal to a tumor (n = 2), hypoperfusion involving 1 or >1 segment (n = 2), hyperenhancement of the posterior part of the right hemiliver (n = 2), and gravity‐effect‐related perfusion abnormality (n = 2). Nontumoral perfusion abnormalities are seen frequently on MRAP examination. Recognition of these abnormalities remains crucial to avoid misdiagnosis.
Use of magnetization transfer contrast to improve single breath‐hold three‐dimensional MR‐portography with bolus injection of gadopentetate dimeglumine: A preliminary report
Authors: Suto Yuji , Kato Takashi , Kimura Toshihiko , Takizawa Osamu
Published: March 2007

We investigated whether better visualization of the intrahepatic portal system could be obtained by adding magnetization transfer contrast (MTC) to three‐dimensional MR portography (3D‐MRP). In 15 healthy volunteers, 3D fast low‐angle shot images combined with an off‐resonance pulse were obtained after bolus injection of gadopentetate dimeglumine during one period of breath‐holding. Within 1 week after injection, MR images without MTC were obtained using the same scanning condition. MRPs with and without the MTC pulse were compared quantitatively and qualitatively. The contrast‐to‐noise ratio of the portal vein–liver was significantly higher in the group imaged with the addition of MTC. Qualitatively, the use of MTC improved peripheral portal branch depiction on maximum‐intensity projection images. Even when the MTC pulse was added to the conventional method of 3D data collection, it was possible to obtain images within one period of breath‐holding. In conclusion, the use of MTC can substantially enhance the quality of 3D‐MRPs.
Dialysis and transplantation affect cerebral abnormalities of end‐stage renal disease
Authors: Michaelis Thomas , Videen John S. , Linsey Michael S. , Ross Brian D.
Published: March 2007

Localized short echo time proton magnetic resonance spectroscopy was performed to determine whether chronic and end‐stage renal failure, hemodialysis, continuous ambulatory peritoneal dialysis, or renal transplantation result in alterations of cerebral water and metabolites in humans. Hemodialysis patients show an increased cerebral concentration of myo‐inositol (+ 14%; P < .05). Increased metabolite ratios are found for myo‐inositol/creatine (+ 14%; P < .01) and choline‐containing compounds choline/creatine (+ 10%; P < .01) and are more marked in gray than in white matter. N‐acetylaspartate and total creatine concentrations are unaffected. Compared to hemodialysis, continuous ambulatory peritoneal dialysis patients show a larger increase in choline and less elevated myo‐inositol. Acutely, hemodialysis significantly decreases the cerebrospinal fluid content of the examined brain regions, but metabolite changes are small compared to the persistent alterations in patients receiving hemodialysis or continuous ambulatory peritoneal dialysis. Undialyzed patients with chronic renal failure do not differ from patients on hemodialysis, but cerebral metabolite changes are completely reversed by transplantation.

Cerebral metabolic effects of end‐stage renal disease differ from Alzheimer's disease, which is associated with markedly reduced N‐acetylaspartate, increased myo‐inositol, and normal choline concentrations. The small but significant cerebral metabolic disorders associated with renal failure and dialysis may be a consequence of osmotic dysregulation.
T1‐Weighted MR imaging of the brain using a fast inversion recovery pulse sequence
Authors: Rydberg John N. , Hammond Charlotte A. , Iii John Huston , Jack Clifford R. , Grimm Roger C. , Riederer Stephen J.
Published: March 2007

The purpose of this paper was to develop and evaluate a fast inversion recovery (FIR) technique for T1‐weighted MR imaging of contrast‐enhancing brain pathology. The FIR technique was developed, capable of imaging 24 sections in approximately 7 minutes using two echoes per repetition and an alternating echo phase encoding assignment. Resulting images were compared with conventional T1‐weighted spin echo (T1SE) images in 18 consecutive patients. Compared with corresponding T1SE images, FIR images were quantitatively comparable or superior for lesion‐to‐background contrast and contrast‐to‐noise ratio (CNR). Gray‐to‐white matter and cerebrospinal fluid (CSF)‐to‐white matter contrast and CNR were statistically superior in FIR images. Qualitatively, the FIR technique provided comparable lesion detection, improved lesion conspicuity, and superior image contrast compared with T1SE images. Although FIR images had greater amounts of image artifacts, there was not a statistically increased amount of interpretation‐interfering image artifact. FIR provides T1‐weighted images that are superior to T1SE images for a number of image quality criteria.
Magnetic resonance imaging of the brain: Blood partition coefficient for water: Application to spin‐tagging measurement of perfusion
Authors: Roberts David A. , Rizi Rahim , Lenkinski Robert E. , Leigh John S.
Published: March 2007

We describe the use of relative proton density imaging to obtain spatially resolved measurements of the brain:blood partition coefficient for water. Values of relative proton density and apparent‐T1 were calculated by performing a multidimensional nonlinear least squares fit of progressive saturation image data. Correction for magnetic field inhomogeneity was included. The partition coefficient was calculated by dividing the relative proton density of brain by the relative proton density of blood water. Results obtained from healthy volunteers demonstrate significant spatial variation in the partition coefficient in brain. Direct measurement of this parameter eliminates a source of error in the calculation of regional perfusion using arterial spin‐tagging techniques.
Line scan imaging of brain metabolites with CPMG sequences at 1.5 tesla
Authors: Mulkern Robert V. , Meng Jiqun , Oshio Koichi , Tzika A. Aria
Published: March 2007

A line scan Carr‐Purcell‐Meiboom‐Gill (CPMG) spectroscopic imaging sequence has been implemented on a standard 1.5 T clinical scanner to map metabolite signals at multiple echo times from voxels along selected tissue columns through the brain. The CPMG multi‐echo spectroscopic image data sets are used to estimate brain metabolite T2 decay parameters in a group of healthy volunteers and in one tumor patient. Inherent trade‐offs between T2 decay, spectral resolution, and echo spacing prove to be important limiting factors. In particular, separate quantitation of choline and creatine resonances at 1.5 T was not achieved in the present implementation. However, the ability to collect data sets suitable for T2 decay analyses of combined choline and creatine resonances and N‐acetyl aspartate resonances in under 10 minutes may prove of clinical utility in the study of brain pathology.
Effects of intravoxel velocity distributions on the complex difference method of phase‐contrast MR angiography
Authors: Hamilton Craig A.
Published: March 2007

The complex difference method of phase‐contrast MR angiography is affected not only by the degree of velocity encoding applied during the scan but also by the variance of the intravoxel velocity distribution. The reconstructed intensities of voxels with the same average flow rate but different variances of the velocity distribution can differ significantly. Mathematical analysis and scanner phantom experiments confirm this conclusion.
Magnetic resonance imaging of the brain with gadopentetate dimeglumine‐DTPA: Comparison of T1‐weighted spin‐echo and 3D gradient‐echo sequences
Authors: Li Debiao , Haacke E. Mark , Tarr Robert W. , Venkatesan Ramesh , Lin Weili , Wielopolski Piotr
Published: March 2007

Short TR, short TE, high resolution, 3D gradient‐recalled echo (GRE) imaging was evaluated for lesion detection in the brain. High resolution 3D GRE data acquisition was used to reduce partial volume effects and flow artifacts, to better visualize smaller structures, to minimize signal losses caused by field inhomogeneities, and to allow better image reformatting. Spin‐echo (SE) and 3D GRE approaches were compared for lesion detection after the administration of an MR contrast agent, gadopentetate dimeglumine. Preliminary clinical studies demonstrated that the signal‐to‐noise ratio (SNR) in each slice of the GRE scan was worse than that of the SE scan because of the much thicker slices acquired with the SE technique. However, by averaging two adjacent 3D slices, the SNR of the two methods was essentially equivalent. In the averaged GRE slices, large lesions were seen just as well as in the SE images. More importantly, small lesions were better visualized in the thin 3D GRE images than in the thick SE images for the lesions studied in this work and the protocols used. These observations were confirmed by theoretical simulations.
Classification of 1H MR spectra of human brain neoplasms: The influence of preprocessing and computerized consensus diagnosis on classification accuracy
Authors: Somorjai Ray L. , Dolenko Brion , Nikulin Alexander K. , Pizzi Nicolino , Scarth Gordon , Zhilkin Peter , Halliday William , Fewer Derek , Hill Norman , Ross Ian , West Michael , Smith Ian C. P. , Donnelly S. Maureen , Kuesel Annette C. , Brière Kathleen M.
Published: March 2007

We study how classification accuracy can be improved when both different data preprocessing methods and computerized consensus diagnosis (CCD) are applied to 1H magnetic resonance (MR) spectra of astrocytomas, meningiomas, and epileptic brain tissue. The MR spectra (360 MHz, 37°C) of tissue specimens (biopsies) from subjects with meningiomas (95; 26 cases), astrocytomas (74; 26 cases), and epilepsy (37; 8 cases) were preprocessed by several methods. Each data set was partitioned into training and validation sets. Robust classification was carried out via linear discriminant analysis (LDA), artificial neural nets (NN), and CCD, and the results were compared with histopathological diagnosis of the MR specimens. Normalization of the relevant spectral regions affects classification accuracy significantly. The spectra‐based average three‐class classification accuracies of LDA and NN increased from 81.7% (unnormalized data sets) to 89.9% (normalized). CCD increased the classification accuracy of the normalized sets to an average of 91.8%. CCD invariably decreases the fraction of unclassifiable spectra. The same trends prevail, with improved results, for casebased classification. Preprocessing the 1H MR spectra is essential for accurate and reliable classification of astrocytomas, meningiomas, and nontumorous epileptic brain tissue. CCD improves classification accuracy, with an attendant decrease in the fraction of unclassifiable spectra or cases.
Localized 2D J‐resolved H MR spectroscopy of human brain tumors in vivo
Authors: Thomas M. Albert , Ryner Lawrence N. , Mehta Minesh P. , Turski Patrick A. , Sorenson James A.
Published: March 2007

Application of two‐dimensional (2D) J‐resolved MR spectroscopy, fully localized in three dimensions to monitor the metabolites in human brain tumors in vivo on a whole body MR scanner is presented. A modified PRESS sequence with [90° – 180° – t1/2 – 180° – t1/2‐acquisition] was used for voxel localization (2D J point‐resolved spectroscopy [PRESS]); chemical shift selective (CHESS) sequence was used for suppression of water. The incremental delay (t1/2) added to the intervals before and after the last slice‐selective 180° RF pulse allowed the monitoring of the J‐evolution in a localized 2D NMR spectrum. The addition of the second frequency dimension in 2D J‐resolved spectroscopy to encode the indirect spin‐spin coupling allowed the visualization of lactate peaks not observed in the 1D MR spectrum because of severe overlap with lipid peaks. 2D spectra of a two‐layer phantom with 100 mM alanine and corn oil and also from three patients with tumors are presented here. The 2D spectra show that the J‐coupled lactate peaks could be separated even when the lipids peaks severely overlap.
MR perfusion imaging of the kidney pre‐ and post‐dipyridamole stress
Authors: Tello Richard , Hartnell George G. , Hill Thomas , Volpe Joanne , Finn J. Paul , Cohen Mylan
Published: March 2007

Animal studies have demonstrated that renal MR contrast enhancement depends on the timing of image acquisition. Limited human studies have demonstrated effects of dipyidamole (DP) on total renal perfusion. This study assessed the effect of DP on total and regional renal perfusion using gated perfusion MRI for patients undergoing DP stress. Five subjects with no evidence of renal ischemia were examined at rest and after DP stress. Rest MRI images in the left kidney were acquired using electrocardiogram (ECG)‐gated MR: turbo fast low‐angle shot (FLASH); echo time (TE) = 12, repetition time (TR) = 6. flip angle = 12, inversion time (TI) = (100) 10 to 45 seconds after injection of gadopentetate dimeglumine. Stress was induced in the MRI scanner (DP, .56 mg/kg over 4 minutes) followed by stress MRI after a second bolus of gadopentetate dimeglumine in the same position and identical time intervals. MR signal in the whole left kidney and renal medulla and cortex pre‐ and post‐DP demonstrated a 70% depression of total renal perfusion with relative preservation of cortical perfusion at the expense of medullary perfusion. Post‐DP MR images demonstrated a decrease in cortical perfusion with an additional 29% depression of medullary perfusion (P < .001) with respect to cortical perfusion. Turbo FLASH MRI can provide adequate time and spatial resolution to demonstrate changes in renal perfusion. Depression of renal medullary perfusion after DP appears to be caused by the intrarenal effect of DP and may have clinical impact.
Contrast enhancement with GD‐EOB‐DTPA in MR imaging of hepatocellular carcinoma in mice: A comparison with superparamagnetic iron oxide
Authors: Fujita Makoto , Yamamoto Reiko , Fritz‐Zieroth Bernhard , Yamanaka Tsuyoshi , Takahashi Masaya , Miyazawa Tomoaki , Tatsuta Masaharu , Terada Nobuyuki , Hosomi Naohiro , Inoue Etsuo , Kuroda Chikazumi
Published: March 2007

The purpose of this study was to evaluate the ability of the new liver‐specific magnetic resonance contrast agent gadolinium‐ethoxybenzyl‐diethylenetriamine penta‐acetic acid (Gd‐EOB‐DTPA) to detect hepatocellular carcinoma (HCC). Seventeen mice with 66 chemically induced HCCs underwent magnetic resonance imaging with both Gd‐EOB‐DTPA (30 μmol/kg) and superparamagnetic iron oxide (SPIO; 10 μmol/kg). After enhancement, lesion‐to‐liver contrast‐to‐noise ratios (CNRs) of 47 detected HCCs increased negatively from 3.7 ± 10.7 (mean ± SD) to –55.1 ± 25.8 with Gd‐EOB‐DTPA (P < .001) and increased positively from 10.4 ± 10.4 to 26.1 ± 16.3 with SPIO (P < .001). The improvement of CNR after administration of SPIO was less in smaller lesions (< 4 mm), whereas that after administration of Gd‐EOB‐DTPA was independent of lesion size. However, Gd‐EOB‐DTPA positively enhanced four HCCs (8.5%), both highly differentiated (grade 1) and moderately differentiated (grade 2). Gd‐EOB‐DTPA allows the conspicuous detection of small HCCs; however, moderately differentiated HCCs occasionally may be positively enhanced.
Magnetic resonance imaging evaluation of the ascending aorta after graft‐inclusion surgery: Comparison between an ultrafast contrast‐enhanced MR sequence and conventional cine‐MRI
Authors: Loubeyre Pierre , Delignette Alexandra , Bonefoy Laurence , Douek Philippe , Amiel Michel , Revel Didier
Published: March 2007

The aim of this study was to compare the value of two magnitude‐based MR sequences, a contrast‐enhanced ultrafast MR sequence and a cine MR sequence, for the detection of flow around the graft in the postoperative ascending thoracic aorta. Thirteen patients who underwent ascending aortic surgery for dissection (n = 11) and aneurysm (n = 2) were enrolled. They were referred to MRI for mediastinum enlargement on the chest x‐ray or mediastinal symptoms. All patients had replacement of the diseased ascending aorta using a graft‐inclusion technique (with wrapping of the native aorta over the graft). Delays between surgery and MRI ranged from 15 days to 8 years (mean: 10 months). All patients were examined using a T1‐weighted spin‐echo sequence, a magnitude‐based cine gradient‐echo sequence, and an ultrafast contrast‐enhanced MR sequence. MR images of the cine and the contrast‐enhanced sequences were retrospectively and independently analyzed by two qualified radiologists for evidence of flow or thrombus around the graft, including perigraft structure and aneurysmal formations. Evidence of flow was detected by both methods in all aneurysmal formations of the ascending aorta located at suture level (n = 6). Evidence of flow in the perigraft structure was found in seven cases by contrast‐enhanced MR sequence and in only four cases by cine MR sequence. Contrast‐enhanced ultrafast MR sequence could be proposed as a minimally invasive and fast modality for assessing the perigraft structure, in graft‐in‐clusion surgical procedures of the ascending aorta, when noncontrast enhanced MR sequences do not exclude the possibility of flowing blood in this structure.
Papillary projections in ovarian neoplasms: Appearance on MRI
Authors: Outwater Eric K. , Huang Abbott B. , Dunton Charles J. , Talerman Alexander , Capuzzi David M.
Published: March 2007

Papillary projections are distinctive pathologic features of epithelial ovarian neoplasms. We sought to determine whether these structures have recognizable features on MRI. A search of a database of 125 patients on whom MRI was performed with pelvic phased‐array coil and abdominal surgical exploration was performed for suspected gynecologic disease identified 15 patients who had either MRI reports or pathology reports mentioning papillary projections in an adnexal mass. The MR images were reviewed to characterize the size, structure, and signal intensity of papillary projections. Pathologic correlation was performed on these and on four surgical specimens imaged with high resolution technique. Pathologic correlation showed that larger papillary projections had a distinctive structure of a fibrous stalk supporting clumps of edematous papillae with signal intensity similar to that of fluid on T2‐weighted images. Smaller papillae showed nondescript intracystic projections of intermediate signal intensity on T2‐weighted images. All papillary projections in vivo enhanced after injection of gadopentetate dimeglumine. Papillary projections have an appearance on MRI that reflects their histologic structure.
Pharmacokinetic Analysis of Gd‐DTPA Enhancement in dynamic three‐dimensional MRI of breast lesions
Authors: Den Boer Jacques A. , Hoenderop Ruud K. K. M. , Smink Jouke , Dornseiffen Gerard , Koch Paul W. A. A. , Mulder Jan H. , Slump Cornelis H. , Volker Edo D. P. , De Vos Rob A. I.
Published: March 2007

The purpose of this study was to demonstrate that dynamic MRI covering both breasts can provide sensitivity for tumor detection as well as specificity and sensitivity for differentiation of tumor malignancy. Three‐dimensional gradient echo scans were used covering both breasts. Before Gd‐DTPA bolus injection, two scans were obtained with different flip angles, and after injection, a dynamic series followed. Thirty‐two patients were scanned according to this protocol. From these scans, in addition to enhancement, the value of T1 before injection was obtained. This was used to estimate the concentration of Gd‐DTPA as well as the pharmacokinetic parameters governing its time course. Signal enhancement in three‐dimensional dynamic scanning was shown to be a sensitive basis for detection of tumors. In our series, all but two mam‐mographically suspicious lesions did enhance, and in three cases, additional enhancing lesions were found, two of which were in the contralateral breast. The parameter most suited for classification of breast lesions into benign or malignant was shown to be the pharmacokinetically defined permeability k31, which, for that test, gave a sensitivity of 92% and a specificity of 70%. Our three‐dimensional dynamic MRI data are sensitive for detection of mammographically occult breast tumors and specific for classification of these as benign or malignant.
Limitations of the keyhole technique for quantitative dynamic contrast‐enhanced breast MRI
Authors: Bishop Jonathan E. , Santyr Giles E. , Kelcz Frederick , Plewes Donald B.
Published: March 2007

The effect of keyhole data acquisition on quantitative analysis of dynamic MRI was examined. Experiments were performed retrospectively on raw data obtained from clinical dynamic contrast‐enhanced breast imaging procedures. The effects of keyhole phase‐encoding acquisition and type of reconstruction algorithm on the accuracy of derived quantitative parameters was assessed. Results indicate that the minimum keyhole size used should be restricted by the approximate minimum size of the expected lesions. Furthermore, reconstruction algorithms that offer improved image resolution do not circumvent this restriction.
Improved solvent suppression and increased spatial excitation bandwidths for three‐dimensional press CSI using phase‐compensating spectral/spatial spin‐echo pulses
Authors: Star‐Lack Josh , Vigneron Daniel B. , Pauly John , Kurhanewicz John , Nelson Sarah J.
Published: March 2007

Dual phase‐compensating spectral/spatial echo‐planar (EP) spin‐echo (SE) pulses were incorporated into the point resolved spectroscopy (PRESS) excitation sequence to improve water and lipid suppression for 1H chemical shift imaging (CSI) and to decrease the dependence of the PRESS box location upon chemical shift. The asymmetric EPSE pulses (either minimum or maximum phase in the chemical shift domain) were substituted for the two PRESS SE pulses to yield zero phase spectra. Three different pulses were designed and tested at 1.5 T. Pulse 1, targeted for brain CSI (TE > 85 msec), passed choline to lipid resonances, suppressed water, and rephased the methyl lactate doublet independently of TE. Pulse 2, targeted for general purpose shorter TE PRESS, possessed both high chemical shift and spatial domain bandwidths. Pulse 3, designed for prostate CSI, passed choline to citrate resonances while suppressing lipids and water. The three pulses possessed spatial bandwidths ranging between 3.3 and 5.0 kHz, more than three times higher than that offered by one‐dimensional SE pulses of equivalent maximum B1 amplitude. Phantom and in vivo experimental results demonstrated that, for EPSE pulses 1 and 2, suppression factors higher than 104 were achieved. The increased spatial bandwidths resulted in less contamination by signals from outside the designated PRESS excited region and a significant improvement in the uniformity of metabolite intensities for voxels located near edges of the PRESS box.
Massive edema of the ovary: High resolution MR findings using a phased‐array pelvic coil
Authors: Kramer Larry A. , Lalani Tasneem , Kawashima Akira
Published: March 2007

We report a rare premenarchal case of massive ovarian edema in which high resolution MRI findings more accurately reflected characteristic pathologic changes of this condition compared with CT and ultrasound. A potential role of MR in preoperative diagnosis of massive ovarian edema is suggested.
Xenon effects on regional cerebral blood flow assessed by 15O‐H2O positron emission tomography: Implications for hyperpolarized xenon MRI
Authors: Liotti Mario , Martin Charles C. , Gao Jia‐Hong , Roby John W. , Mayberg Helen S. , Zamarripa Frank , Jerabek Paul A. , Fox Peter T.
Published: March 2007

Subjective and physiologic effects of 33% inhaled Xe were measured with 15O‐water positron emission tomography (PET) in 3 subjects at rest and during visual stimulation. The procedure was well tolerated. Robust functional activations of the visual cortex were obtained after xenon (Xe) inhalation as well as air breathing. However, Xe inhalation was followed by smaller size, but significant decreases of regional cerebral blood flow (rCBF) in visual cortex relative to the air‐breathing baseline, both during visual stimulation and at rest. No such decreases were found in other sensory or motor regions.
Use of an intravascular T1 contrast agent to improve MR cine myocardial‐blood pool definition in man
Authors: Stillman Arthur E. , Wilke Norbert , Jerosch‐Herold Michael
Published: March 2007

The feasibility of improving myocardial/blood pool contrast in MR cine images through use of an intravascular contrast agent (Ferumoxtran, Advanced Magnetics, Inc., Cambridge, MA) was tested in four subjects. The contrast‐to‐noise ratio (CNR) demonstrated a trend toward improvement in the short axis and improved significantly in the long axis cine by an average of 128% (P < .05). Image intensity gradients at the myocardial/blood pool interface increased significantly in both the short and long axis (P < .01). It is expected that larger image intensity gradients at the endocardial border should improve the capabilities of automated segmentation algorithms, reducing the uncertainty and need for manual editing.