bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnetization structure contrast based on intermolecular multiple‐quantum coherences
Authors: Bouchard Louis‐Serge , Rizi Rahim R. , Warren Warren S. 
Published: December 2002

AbstractIn vivo and ex vivo MRI based on intermolecular multiple‐quantum coherences (iMQC) is predicted to provide a fundamentally different source of contrast for MRI. This article investigates the dependence of image contrast upon the choice of correlation distance for a heterogeneous material. A closely packed array of parallel hollow cylinders was used to demonstrate signal intensity variations when the correlation distance becomes comparable to the gap size between the cylinders. The observed effects agree well with three‐dimensional calculations of the time evolution of magnetization under the nonlinear Bloch equations. Magn Reson Med 48:973–979, 2002. © 2002 Wiley‐Liss, Inc.
Mapping of the B1 field distribution of a surface coil resonator using EPR imaging
Authors: He Guanglong , Evalappan Sathesh P. , Hirata Hiroshi , Deng Yuanmu , Petryakov Sergey , Kuppusamy Periannan , Zweier Jay L. 
Published: December 2002

AbstractSurface coil resonators have been widely used to perform topical EPR spectroscopy. They are usually positioned adjacent to or implanted within the body. For EPR applications these resonators have a number of important advantages over other resonator designs due to their ease of sample accessibility, mechanical fabrication, implementation of electronic tuning and coupling functions, and low susceptibility to sample motions. However, a disadvantage is their B1 field inhomogeneity, which limits their usefulness for 3D imaging applications. We show that this problem can be addressed by mapping and correcting the B1 field distribution. We report the use of EPR imaging (EPRI) to map the B1 distribution of a surface coil resonator. We show that EPRI provides a fast, accurate, and reliable technique to evaluate the B1 distribution. 3D EPRI was performed on phantoms, prepared using three different saline concentrations, to obtain the B1 distribution. The information obtained from the phantoms was used to correct the images of living animals. With the use of this B1 correction technique, surface coil resonators can be applied to perform 3D mapping of the distribution of free radicals in biological samples and living systems. Magn Reson Med 48:1057–1062, 2002. © 2002 Wiley‐Liss, Inc.
Application of sensitivity‐encoded echo‐planar imaging for blood oxygen level‐dependent functional brain imaging †
Authors: de Zwart Jacco A. , van Gelderen Peter , Kellman Peter , Duyn Jeff H. 
Published: December 2002

AbstractThe benefits of sensitivity‐encoded (SENSE) echo‐planar imaging (EPI) for functional MRI (fMRI) based on blood oxygen level‐dependent (BOLD) contrast were quantitatively investigated at 1.5 T. For experiments with 3.4 × 3.4 × 4.0 mm3 resolution, SENSE allowed the single‐shot EPI image acquisition duration to be shortened from 24.1 to 12.4 ms, resulting in a reduced sensitivity to geometric distortions and T blurring. Finger‐tapping fMRI experiments, performed on eight normal volunteers, showed an overall 18% loss in t‐score in the activated area, which was substantially smaller than expected based on the image signal‐to‐noise ratio (SNR) and g‐factor, but similar to the loss predicted by a model that takes physiologic noise into account. Magn Reson Med 48:1011–1020, 2002. Published 2002 Wiley‐Liss, Inc.
Phased array ghost elimination (PAGE) for segmented SSFP imaging with interrupted steady‐state
Authors: Kellman Peter , Guttman Michael A. , Herzka Daniel A. , McVeigh Elliot R. 
Published: December 2002

AbstractSteady‐state free precession (SSFP) has recently proven to be valuable for cardiac imaging due to its high signal‐to‐noise ratio and blood‐myocardium contrast. Data acquired using ECG‐triggered, segmented sequences during the approach to steady‐state, or return to steady‐state after interruption, may have ghost artifacts due to periodic k‐space distortion. Schemes involving several preparatory RF pulses have been proposed to restore steady‐state, but these consume imaging time during early systole. Alternatively, the phased‐array ghost elimination (PAGE) method may be used to remove ghost artifacts from the first several frames. PAGE was demonstrated for cardiac cine SSFP imaging with interrupted steady‐state using a simple alpha/2 magnetization preparation and storage scheme and a spatial tagging preparation. Magn Reson Med 48:1076–1080, 2002. Published 2002 Wiley‐Liss, Inc.
RF heating due to conductive wires during MRI depends on the phase distribution of the transmit field
Authors: Yeung Christopher J. , Susil Robert C. , Atalar Ergin 
Published: December 2002

AbstractIn many studies concerning wire heating during MR imaging, a “resonant wire length” that maximizes RF heating is determined. This may lead to the nonintuitive conclusion that adding more wire, so as to avoid this resonant length, will actually improve heating safety. Through a theoretical analysis using the method of moments, we show that this behavior depends on the phase distribution of the RF transmit field. If the RF transmit field has linear phase, with slope equal to the real part of the wavenumber in the tissue, long wires always heat more than short wires. In order to characterize the intrinsic safety of a device without reference to a specific body coil design, this maximum‐tip heating phase distribution must be considered. Finally, adjusting the phase distribution of the electric field generated by an RF transmit coil may lead to an “implant‐friendly” coil design. Magn Reson Med 48:1096–1098, 2002. © 2002 Wiley‐Liss, Inc.
Interleaved pulsed MAMBA: A new parallel slice imaging method
Authors: Paley Martyn N.J. , Lee Kuan J. , Wild James M. , Whitby Elspeth H. , Griffiths Paul D. 
Published: December 2002

AbstractA method of acquiring slices in parallel is described which uses interleaved sets of pulsed B0 field coils to generate discrete regions of uniform field within the main magnetic field known as interleaved MAMBA (multiple acquisition micro B0 array). Simulations of a number of coil designs were performed using the Biot‐Savart law. A six‐step coil was built and interfaced to a 0.17 T Niche MRI system and the field steps measured using an imaging technique. Measured field steps were in good agreement with the values predicted by simulation. The coil design was then scaled up by a factor of three, interfaced to a 1.5 T whole‐body MRI system, and scans of the hands and arms of volunteers were acquired from up to four field steps using standard spin and gradient echo sequences. Images were also acquired simultaneously from two field steps with no frequency encode aliasing and one excitation. The one‐dimensional interleaved pulsed MAMBA step field technique shows great promise for enabling many slices to be acquired simultaneously along the axis of the coil for rapid volumetric studies without the need for multiple shot Hadamard encoding. Extension of interleaved coil design to two or three dimensions is feasible, which could provide full spatial coverage combined with ultra‐rapid data acquisition. Magn Reson Med 48:1043–1050, 2002. © 2002 Wiley‐Liss, Inc.
Magnetic resonance relaxivity of dendrimer‐linked nitroxides
Authors: Winalski Carl S. , Shortkroff Sonya , Mulkern Robert V. , Schneider Erika , Rosen Gerald M. 
Published: December 2002

AbstractThe relaxivity and bioreduction rates of eight dendrimer‐linked nitroxides varying in the number of nitroxides per molecule were measured and the potential use of these compounds as MR contrast agents was demonstrated. The T1 and T2 relaxivities, measured at room temperature and 1.5 T, varied linearly with the number of nitroxides per molecule for compounds with up to 16 nitroxides per molecule. Fourth‐generation polypropylenimide‐ (DAB) and third‐generation polyamidoamine‐ (PAMAM) dendrimer‐linked nitroxides were found to have greater relaxivity than gadolinium diethylenetriaminepentaacetic acid (Gd‐DTPA). The greater number of nitroxides per dendrimer increased relaxivity over that of a single nitroxide, allowing a decreased dose to achieve differential contrast with MR evaluations. Rates of nitroxide bioreduction were below detection threshold using EPR spectroscopy for generation 2 dendrimers and higher. A pilot assessment of in vivo cartilage uptake that compared intraarticular injection of three structurally different dendrimer‐linked nitroxides with Gd‐DTPA and with saline demonstrated high affinity of the DAB‐dendrimer‐linked nitroxides for normal rabbit articular cartilage. From these results, it is evident that target‐specific dendrimer‐linked nitroxides can be designed. Magn Reson Med 48:965–972, 2002. © 2002 Wiley‐Liss, Inc.
Anomalous nuclear magnetic relaxation of aqueous solutions of ferritin: An unprecedented first‐order mechanism
Authors: Gossuin Yves , Roch Alain , Muller Robert N. , Gillis Pierre , Lo Bue Francesco 
Published: December 2002

AbstractFerritin, the iron‐storing protein, speeds up proton transverse magnetic relaxation in aqueous solutions. This T2 shortening is used in MRI to quantify iron in the brain and liver. Current theoretical models underestimate the relaxation enhancement by ferritin at imaging fields, and they do not predict the measured dependence of the rate enhancement on the magnetization of the particles. Here it is shown that a proton exchange dephasing model (PEDM) overcomes these limitations by allowing a first‐order relaxation mechanism. The PEDM considers proton exchange between bulk water and exchangeable protons located at the surface of the hydrated iron oxide nanometric core of the protein. Relaxation is shown to depend on the distribution of the frequency shifts of the adsorption sites; the observed properties agree with a Lorentzian distribution. Computer simulations utilizing recent Mössbauer spectroscopy data show that the distribution of these shifts is effectively Lorentzian. Magn Reson Med 48:959–964, 2002. © 2002 Wiley‐Liss, Inc.
How does blood oxygen level‐dependent (BOLD) contrast correlate with oxygen partial pressure (pO2) inside tumors?
Authors: Baudelet Christine , Gallez Bernard 
Published: December 2002

AbstractBlood oxygen level‐dependent (BOLD) contrast‐based functional MRI (fMRI) has been reported as a method to assess the evolution of tumor oxygenation after hyperoxic treatments, because of its sensitivity to changes in blood flow and deoxyhemoglobin content. However a number of questions remain: 1) In view of tumor heterogeneity, how good is the correlation between the MR parameters in gradient‐echo imaging (signal intensity (SI) or effective transverse relaxation time (T)) and local tumor oxygen partial pressure (pO2)? 2) Is the magnitude of the change in SI or T a quantitative marker for variation in pO2? 3) Is initial T a good marker for initial pO2? To address these questions, murine tumors were imaged during respiratory challenges at 4.7 Tesla, using fiber‐optic microprobes to simultaneously acquire tumor pO2 and erythrocyte flux. The BOLD signal response (SI and T) was temporally correlated with changes in pO2. However, the magnitude of the signal bore no absolute relation to pO2 across tumors, i.e., a given change in SI corresponded to a 25 mmHg pO2 change in one tumor, but to a 100 mmHg change in another. The initial T value did not reliably predict tumor oxygenation at the beginning of the experiment. In conclusion, the major advantages of the technique include noninvasiveness, high spatial resolution, and real‐time detection of pO2 fluctuations. Information afforded by the BOLD imaging technique is qualitative in nature and may be combined with other techniques capable of providing an absolute measure of pO2. Magn Reson Med 48:980–986, 2002. © 2002 Wiley‐Liss, Inc.
Dynamic activity‐induced manganese‐dependent contrast magnetic resonance imaging (DAIM MRI)
Authors: Aoki Ichio , Tanaka Chuzo , Takegami Tetsuro , Ebisu Toshihiko , Umeda Masahiro , Fukunaga Masaki , Fukuda Kohji , Silva Afonso C. , Koretsky Alan P. , Naruse Shoji 
Published: December 2002

AbstractActivity‐induced manganese‐dependent contrast (AIM) MRI is a hemodynamic‐independent functional MRI method that used manganese ion as an MR‐detectable contrast agent. In AIM, MnCl2 is infused intra‐arterially after the blood‐brain barrier (BBB) is opened with a hyperosmolar agent. Upon functional stimulation of the brain, Mn2+ accumulates in the active region(s) by entering active cells through voltage‐gated Ca2+ channels, causing local signal increases in T1‐weighted images. The contrast of AIM MRI depends strongly on the depth of anesthesia, and the low levels used in somatosensory stimulation studies can lead to significant nonspecific accumulation of manganese ion throughout the brain. The purpose of this study was to produce an AIM functional map of somatosensory stimulation, which separates the stimulation‐specific signal increase from the nonspecific activation due to light anesthesia. A dynamic AIM (DAIM) paradigm was developed, which used sequential MR scans during MnCl2 infusion, prior to and following functional stimulation of the brain. Stimulation‐specific functional maps were produced using time‐course analysis. The new method was tested during glutamate administration and electric stimulation of the rat forepaw. It was shown that DAIM maps are better confined to the specific region of brain activated by somatosensory stimulation as compared to AIM MRI. Magn Reson Med 48:927–933, 2002. © 2002 Wiley‐Liss, Inc.
Experimental confirmation of the von Neumann
theory of shock wave reflection transition
Authors: BARBOSA FILIPE J. , SKEWS BERIC W. 
Published: December 2002

For many years there has been debate regarding why shock wave reflection off a
solid surface has allowed regular reflection to persist beyond the incidence angles
where it becomes theoretically impossible. Theory predicts that at some limiting angle
the reflection point will move away from the wall and Mach reflection will occur.
Previous studies have suggested that the paradox could be due to the presence of the
growing viscous boundary layer immediately behind the point of reflection, and some
numerical studies support this view. This paper takes the approach of establishing
an experimental facility in which the theoretical assumptions regarding the surface of
reflection are met, i.e. that the reflecting surface is perfectly smooth, perfectly rigid,
and adiabatic. This is done by constructing a bifurcated shock tube facility in which
a shock wave is split into two plane waves that are then allowed to reflect off each
other at the trailing edge of wedge. The plane of symmetry between the waves then
acts as the perfect reflection surface.Through a careful set of visualization experiments, and the use of multivariate
analysis to take account of the uncertainty in shock Mach number, triple-point
trajectory angle, and slightly different shock wave arrival times at the trailing edge,
the current work shows that the transition from one type of reflection to the other
does indeed occur at the theoretical value. Conventional tests of reflection off a solid
wall show significantly different transition results. Furthermore, it is also shown that
the thermal boundary layer plays an important role in this regard. It is thus confirmed
that viscous and thermal effects are the reason for the paradox. Reasons are also
suggested for the counter-intuitive behaviour of the reflected shock wave angle.
Spouse similarity for antisocial behaviour in the general population
Authors: GALBAUD DU FORT G. , BOOTHROYD L. J. , BLAND R. C. , NEWMAN S. C. , KAKUMA R. 
Published: December 2002

Background. In contrast with the large amount of research on the familial transmission of antisocial behaviour, few studies have investigated similarity between spouses for such behaviour. In addition, none of these studies have examined child conduct disorder (CCD) and adult antisocial behaviour (AAB) separately.Method. We studied 519 pairs of spouses who completed the Diagnostic Interview Schedule. In each pair, one spouse belonged to a random subsample of persons who had participated in a large population survey and was re-interviewed. Association between spouses for lifetime symptoms and DSM-III criteria of CCD, AAB, antisocial personality disorder and co-morbid psychiatric diagnoses was examined with bivariate and multivariate logistic regression analyses.Results. We observed a moderate association between spouses for the presence of CCD (OR=4·02, 95% CI=2·03–7·96), and a strong association for the presence of AAB (OR=20·1, 95% CI=5·97–67·5). This similarity for AAB was independent of the similarity for CCD and persisted after adjustment for spousal similarity for disorders co-morbid with AAB. An examination of the relationship between marital status and the presence of CCD and/or AAB in the general population sample (from which originated our sample of couples) suggested that the spousal similarity for AAB was more likely attributable to assortative mating rather than marital contamination.Conclusion. Our finding of a strong similarity between spouses for AAB has significant implications for both clinicians and researchers. It also suggests that adult antisocial behaviour should be considered as a distinct diagnostic entity, an approach which diverges from DSM-IV diagnostic criteria.
Childhood trauma and neuroticism as an adult: possible implication for the development of the common psychiatric disorders and suicidal behaviour
Authors: ROY ALEC 
Published: December 2002

Background. Neuroticism is an important personality dimension associated with depressive and anxiety disorders. Both genetic and social factors are thought to contribute to neuroticism. This study aims to examine whether early childhood adversity may be a determinant of neuroticism.Method. Five hundred and thirty-two abstinent substance dependent patients completed both the Childhood Trauma Questionnaire (CTQ) and the Eysenck Personality Questionnaire (EPQ).Results. There was a significant relationship between total childhood trauma scores on the CTQ and neuroticism scores on the EPQ. There were also significant relationships between neuroticism and CTQ subscores for emotional abuse, physical abuse, sexual abuse, emotional neglect and physical neglect.Conclusions. Childhood trauma may be a determinant of neuroticism. This may be one way in which childhood trauma plays a role in the development of psychiatric disorders. General population studies are needed.
Neurocognitive deficits in decision-making and planning of patients with DSM-III-R borderline personality disorder
Authors: BAZANIS E. , ROGERS R. D. , DOWSON J. H. , TAYLOR P. , MEUX C. , STALEY C. , NEVINSON-ANDREWS D. , TAYLOR C. , ROBBINS T. W. , SAHAKIAN B. J. 
Published: December 2002

Background. Repeated, self-damaging behaviour occurring in the context of borderline personality disorder (BPD) may reflect impairments in decision-making and planning cognition. However, there has been no systematic neuropsychological examination of these particular cognitive functions in patients diagnosed with BPD. Such investigations may improve our understanding of the possible role of brain dysfunction in BPD and improve the characterization of the psychological difficulties associated with this disorder.Method. Forty-two psychiatric patients with a diagnosis of DSM-III-R BPD (41 of whom gave a history of self-harm), without a history of specified ‘psychoses’ or current major affective disorder, were clinically assessed before completing computerized tasks of decision-making and planning previously shown to be sensitive to frontal lobe dysfunction, and tests of spatial and pattern visual recognition memory previously shown to be sensitive to frontal lobe damage and temporal lobe damage respectively. The performance of the BPD patient group was compared with that of a non-clinical control group consisting of 42 subjects.Results. The performance of the BPD patients on the decision-making task was characterized by a pattern of delayed and maladaptive choices when choosing between competing actions, and by impulsive, disinhibited responding when gambling on the outcome of their decisions. BPD patients also showed impairments on the planning task. There was no evidence of impaired visual recognition memory. Additional analyses suggested only limited effects of current medication and history of previous substance use disorder.Conclusions. These findings suggest that BPD is associated with complex impairments in dissociable cognitive processes mediated by circuitry encompassing the frontal lobes. These impairments may mediate some of the behavioural changes evident in BPD. Further work is needed to examine the specificity of these findings.
Adding to our understanding of Gulf War health issues
Authors: HYAMS KENNETH C. , SCOTT KEN 
Published: December 2002

In this edition of Psychological Medicine, research findings are reported from two studies of British Gulf War veterans (David et al. 2002; Everitt et al. 2002). Both studies were carried out at King's College ‘Gulf War Illness Research Unit’, which was established in 1996. The two studies were conducted to examine the causes of unexplained symptoms among Gulf War veterans. The results presented in these papers are important because they were derived from well-designed studies that employed a randomized sample of Gulf War veterans and two control populations of non-deployed ‘era’ veterans who served in the early 1990s and troops who participated in another hazardous deployment to Bosnia.In one study, cognitive function and mood disturbances were evaluated using a comprehensive battery of neuropsychological tests and rating scales (David et al. 2002). A significant proportion of Gulf War veterans reporting ill health were found to have both lower cognitive function scores and depressed mood compared to well Gulf War veterans, era veterans and Bosnia troops. Importantly, a strong association was found between depressed mood and poor performance on cognitive function tests. It is noteworthy that among ill Gulf War veterans, most cognitive function measures were within the normal range, although they were significantly lower than those of controls.Based on these and related research findings, the study investigators concluded that lower performance on cognitive function tests could be explained primarily by mood disturbances. However, they could not rule out the possibility that cognitive difficulties had led to depressed mood or that a neurotoxic environmental exposure had caused both health problems.
Three cases of tetrasomy 9p
Authors: Dhandha S. , Hogge W. A. , Surti U. , McPherson E. 
Published: December 2002

AbstractWe report three cases of tetrasomy 9p, two of which were confirmed prenatally. All three had characteristic findings on ultrasound and at birth. We also present a review of the literature, which suggests that a recognizable phenotype for this condition is emerging. Common findings on prenatal ultrasound include intrauterine growth restriction, ventriculomegaly, cleft lip or palate, and renal anomalies. These findings can provide a clue toward the prenatal diagnosis of this condition. There is also a clearly recognizable phenotype at birth. Facial characteristics include hypertelorism, broad nasal bridge/bulbous or beaked nose, cleft lip/palate, ear anomalies, and micrognathia. The exact extent of the isochromosome does not seem to predict severity, but mosaic cases are less severe, or at least have a greater probability of survival. © 2002 Wiley‐Liss, Inc.