bluuebunny/crossref_metadata_2025 huggingface dataset:
HS–SPME analysis of the volatile compounds from spices as a source of flavour in ‘Campo Real’ table olive preparations
Authors: Pérez R. A. , Navarro T. , Lorenzo C. de
Published: March 2007

The composition of volatile compounds in seven spices was analysed by means of headspace solid‐phase microextraction (HS–SPME) from aqueous solutions of the spices, in order to devise an effective method for the analysis of volatile compounds from aqueous preparations seasoned with spices. A PDMS–DVB fibre was used for the analysis of the main volatile compounds of a saline solution of the spice. The main volatile components identified in the spices tested were: linalool in oregano; t‐anethole in fennel; methyleugenol and eucalyptol in laurel; geraniol in coriander; terpinen‐4‐ol in marjoram; eucalyptol in thyme; and cuminaldehyde in cumin. Volatile profiles depended on the botanical species of the spice. Thus, thymol was the main volatile compound of a commercial thyme (Thymus sp.), whereas in the Thymus mastichina, which is usually used in the preparation of ‘Campo Real’ table olives, the main volatile component was eucalyptol. The effects of these spices in the characteristic aroma of ‘Campo Real’ table olive preparations have been evaluated and the results suggest that HS–SPME is a useful tool for the analysis of the spices aroma compounds in aqueous preparations. Copyright © 2007 John Wiley & Sons, Ltd.
Solution of the 2‐D shallow water equations with source terms in surface elevation splitting form
Authors: Ma Dong‐Jun , Sun De‐Jun , Yin Xie‐Yuan
Published: March 2007

A vertex‐centred finite‐volume/finite‐element method (FV/FEM) is developed for solving 2‐D shallow water equations (SWEs) with source terms written in a surface elevation splitting form, which balances the flux gradients and source terms. The method is implemented on unstructured grids and the numerical scheme is based on a second‐order MUSCL‐like upwind Godunov FV discretization for inviscid fluxes and a classical Galerkin FE discretization for the viscous gradients and source terms. The main advantages are: (1) the discretization of SWE written in surface elevation splitting form satisfies the exact conservation property (𝒞‐Property) naturally; (2) the simple centred‐type discretization can be used for the source terms; (3) the method is suitable for both steady and unsteady shallow water problems; and (4) complex topography can be handled based on unstructured grids. The accuracy of the method was verified for both steady and unsteady problems, including discontinuous cases. The results indicate that the new method is accurate, simple, and robust. Copyright © 2007 John Wiley & Sons, Ltd.
Optimal flow control for Navier–Stokes equations: drag minimization
Authors: Dedè L.
Published: March 2007

Optimal control and shape optimization techniques have an increasing role in Fluid Dynamics problems governed by partial differential equations (PDEs). In this paper, we consider the problem of drag minimization for a body in relative motion in a fluid by controlling the velocity through the body boundary. With this aim, we handle with an optimal control approach applied to the steady incompressible Navier–Stokes equations. We use the Lagrangian functional approach and we consider the Lagrangian multiplier method for the treatment of the Dirichlet boundary conditions, which include the control function itself. Moreover, we express the drag coefficient, which is the functional to be minimized, through the variational form of the Navier–Stokes equations. In this way, we can derive, in a straightforward manner, the adjoint and sensitivity equations associated with the optimal control problem, even in the presence of Dirichlet control functions. The problem is solved numerically by an iterative optimization procedure applied to state and adjoint PDEs which we approximate by the finite element method. Copyright © 2007 John Wiley & Sons, Ltd.
Profile of psychiatric disorders and life events in medically ill elderly: experiences from geriatric clinic in Northern India
Authors: Prakash Om , Gupta L. N. , Singh V. B. , Singhal A. K. , Verma K. K.
Published: March 2007

Background

Morbidity among elderly people has an important influence on their psychological well‐being. Evaluation of the morbidity profile and its determinants, which have implications for management of medical problems of elderly people, are scarce in developing countries. Even the physicians' detection rate of mental distress in elderly populations is low in medical outpatient clinics. This could be due to the large caseloads and also, importantly, underestimation of psychological concerns of the elderly. The objective of this study was to study the psychiatric co‐morbidity and life events among elderly medical outpatients.

Methods

One hundred medically ill elderly (>60 years) patients attending the Geriatric Clinic at Bikaner (North India) constituted the study population. The physical diagnosis was made by a physician based on reported illness, clinical examination and medical records. Psychiatric diagnosis was made by detailed clinical psychiatric interview using ICD‐10 guidelines. Life events were assessed by the Indian adaptation of Presumptive Stressful Life Events Scale.

Results

Hypertension was the most commonly reported physical diagnosis (50%), other specific medical illnesses were osteoarthritis (15%), diabetes (13%) and constipation (8%). The study found 18% subjects had depression and 11% had other mental disorders. Patients with mental disorders had suffered more recent stressful life events. Among life events, conflicts in family (16%); unemployment of self or children (9%) was reported by elderly psychiatric patients. Other reported life events in psychiatric diagnosed elderly were conflict in family (7%), illness of self (6%) or family members (5%) and death of family members (5%) or close relatives (4%).

Conclusion

Mental disorders are common among medically ill elderly patients, but they are poorly recognized and treated. Assessment of the psychiatric morbidity will help in strengthening psycho‐geriatric services and thus, improve the quality of life of the elderly. Copyright © 2007 John Wiley & Sons, Ltd.
FMRI activations of amygdala, cingulate cortex, and auditory cortex by infant laughing and crying
Authors: Sander Kerstin , Frome Yvonne , Scheich Henning
Published: March 2007

One of the functions of emotional vocalizations is the regulation of social relationships like those between adults and children. Listening to infant vocalizations is known to engage amygdala as well as anterior and posterior cingulate cortices. But, the functional relationships between these structures still need further clarification. Here, nonparental women and men listened to laughing and crying of preverbal infants and to vocalization‐derived control stimuli, while performing a pure tone detection task during low‐noise functional magnetic resonance imaging. Infant vocalizations elicited stronger activation in amygdala and anterior cingulate cortex (ACC) of women, whereas the alienated control stimuli elicited stronger activation in men. Independent of listeners' gender, auditory cortex (AC) and posterior cingulate cortex (PCC) were more strongly activated by the control stimuli than by infant laughing or crying. The gender‐dependent correlates of neural activity in amygdala and ACC may reflect neural predispositions in women for responses to preverbal infant vocalizations, whereas the gender‐independent similarity of activation patterns in PCC and AC may reflect more sensory‐based and cognitive levels of neural processing. In comparison to our previous work on adult laughing and crying, the infant vocalizations elicited manifold higher amygdala activation. Hum Brain Mapp 2007. © 2006 Wiley‐Liss, Inc.
A multivariate non‐parametric model for synthetic generation of daily streamflow
Authors: Wang Wensheng , Ding Jing
Published: March 2007

Ap‐order multivariate kernel density model based on kernel density theory has been developed for synthetic generation of multivariate variables. It belongs to a kind of data‐driven approach and is able to avoid prior assumptions as to the form of probability distribution (normal or Pearson III) and the form of dependence (linear or non‐linear). Thep‐order multivariate kernel density model is a non‐parametric method for synthesis of streamflow. The model is more flexible than conventional parametric models used in stochastic hydrology. The effectiveness and satisfactoriness of this model are illustrated through its application to the simultaneous synthetic generation of daily streamflow from Pingshan station and Yibin‐Pingshan region (Yi‐Ping region) of the Jinsha River in China. Copyright © 2007 John Wiley & Sons, Ltd.
Evapotranspiration modelling from climatic data using a neural computing technique
Authors: Kisi Ozgur
Published: March 2007

Evapotranspiration is one of the basic components of the hydrologic cycle and essential for estimating irrigation water requirements. This paper investigates the modelling of evapotranspiration using the feed‐forward artificial neural network (ANN) technique with the Levenberg–Marquardt (LM) training algorithm. The LM algorithm has never been used in evapotranspiration estimation before. The LM is used for the optimization of network weights, since this algorithm is more powerful and faster than the conventional gradient descent. Various combinations of daily climatic data, i.e. wind speed, air temperature, relative humidity and solar radiation, from three stations in Los Angeles, USA, are used as inputs to the ANN so as to evaluate the degree of effect of each of these variables on evapotranspiration. A comparison is made between the estimates provided by the ANN and those of the following empirical models: Penman, Hargreaves, Turc. Mean square error, mean absolute error and determination coefficient statistics are used as comparing criteria for the evaluation of the models' performances. Based on the comparisons, it was found that the neural computing technique could be employed successfully in modelling evapotranspiration process from the available climatic data. The results also indicate that the Hargreaves method provides better performance than the Penman and Turc methods in estimation of the evapotranspiration. The accuracy of the ANN technique in evapotranspiration estimation using nearby station data was also investigated. Copyright © 2007 John Wiley & Sons, Ltd.
Racism in organizations: The case of a county public health department
Authors: Griffith Derek M. , Childs Erica L. , Eng Eugenia , Jeffries Vanessa
Published: March 2007

Racism is part of the foundation of U.S. society and institutions, yet few studies in community psychology or organizational studies have examined how racism affects organizations. This paper proposes a conceptual framework of institutional racism, which describes how, in spite of professional standards and ethics, racism functions within organizations to adversely affect the quality of services, the organizational climate, and staff job satisfaction and morale. Grounded in systems theory and organizational empowerment, the framework is based on data that describe how racism was made manifest in a county public health department. The findings highlight the importance of understanding how organizations are influenced by external forces and can negatively affect clients, communities, and their own staff members. © 2007 Wiley Periodicals, Inc.
Community organizational learning: Case studies illustrating a three‐dimensional model of levels and orders of change
Authors: Perkins Douglas D. , Bess Kimberly D. , Cooper Daniel G. , Jones Diana L. , Armstead Theresa , Speer Paul W.
Published: March 2007

We present a three‐dimensional cube framework to help community organizational researchers and administrators think about an organization's learning and empowerment‐related structures and processes in terms of firstorder (incremental or ameliorative) and second‐order (transformative) change at the individual, organizational, and community levels. To illustrate application of the framework, case studies of three different types of exemplary nonprofit organizations (a participatory neighborhood planning organization, a grassroots faith‐based social action coalition, and a larger community‐based human service agency) were based on qualitative interviews and participant observations. Our analysis, rooted in organizational learning theory, suggests that organizations that empower staff and volunteers through opportunities for learning and participation at theindividual levelare better able to succeed in terms oforganizational‐levellearning and transformation.Community‐levelchange is particularly difficult but must be made a more explicit goal. Learning that can lead to second‐order change at each level must help participants engage in critical analysis of (a) the organization's demonstrated goals and values; (b) the power relationships implicit in decision making at each level; (c) the interdependent role of participant stakeholders and organizations as part of a complex, community‐wide (or larger) system; and (d) how to work toward transformative change of all of the above. © 2007 Wiley Periodicals, Inc.
Community readiness as a multidimensional construct
Authors: Chilenski Sarah M. , Greenberg Mark T. , Feinberg Mark E.
Published: March 2007

Both the organizational studies literature and the community psychology literature discuss the importance of readiness when implementing change. Although each area emphasizes different characteristics, several common themes are present within the literature. The current study integrates and applies organizational and community psychology literature in evaluating community readiness in the context of a school–community–university collaborative prevention model. Results demonstrate (a) that there is substantial agreement between members of community prevention teams on the level of readiness of a community; (b) that readiness is a cohesive, but multidimensional, construct related to hypothesized community and individual characteristics; and (c) that there is small to moderate agreement between members of prevention teams and their “agency directors.” These results support the notion that clear “theories of change” need to be formulated before deciding how to assess community readiness, as assessments will vary due to several factors: the type of respondent, the level in which analyses are conducted, and the specific community domain (i.e., school, workplace collaboration, collaboration experience) investigated. © 2007 Wiley Periodicals, Inc.
How settings change people: Applying behavior setting theory to consumer‐run organizations
Authors: Brown Louis D. , Shepherd Matthew D. , Wituk Scott A. , Meissen Greg
Published: March 2007

Self‐help initiatives stand as a classic context for organizational studies in community psychology. Behavior setting theory stands as a classic conception of organizations and the environment. This study explores both, applying behavior setting theory to consumer‐run organizations (CROs). Analysis of multiple data sets from all CROs in Kansas provide insight into how organizational size influences member participation, how members benefit from participation, and how behavior setting theory may need to be revised. Results suggest that members do benefit from participation. However, individual involvement in organizational planning and decision making does not appear to be the primary factor leading to member benefit. The predictions of behavior setting theory are found to be true, but results suggest that these predictions provide an incomplete picture of CROs. The incorporation of roles as a unit of analysis within behavior settings is suggested to improve the explanatory power of this theory. © 2007 Wiley Periodicals, Inc.
Evidence for positive and negative regulation of the mouse Cdx2 gene
Authors: Wang Wayne C.H. , Shashikant Cooduvalli S.
Published: March 2007

The caudal family of transcription factors specifies posterior structures during mouse development. We describe the cis‐regulatory regions that control mouse Cdx2 expression in the posterior neural tube and mesoderm. An 11.4 kb genomic fragment directs reporter gene expression in a pattern reflecting endogenous Cdx2 expression. A crucial enhancer is located in a 1 kb fragment upstream of the Cdx2 transcriptional start site. This enhancer by itself directs reporter gene expression to more anterior levels in the neural tube compared to the endogenous Cdx2 expression, suggesting the presence of negative regulatory elements outside the 1 kb fragment. A second enhancer, located in the first intron directs robust expression to the posterior two‐thirds of the developing embryo in a pattern that is ectopic to Cdx2 expression. The intronic enhancer activity is silenced in the context of the larger 11.4 kb reporter construct. Intron 1 contains two independent enhancers that specifically direct expression to mesoderm (MSE) and neural tube (NSE). Phylogenetic comparison of vertebrate Cdx2 sequences indicates several conserved regions of sequences within the three‐enhancer regions. A transcription factor database search suggests potential binding sites for factors involved in FGF and Wnt signaling pathways. J. Exp. Zool. (Mol. Dev. Evol.) 308B:308–321, 2007. © 2007 Wiley‐Liss, Inc.
Early developmental plasticity and integrative responses in arctic charr (Salvelinus alpinus): effects of water velocity on body size and shape
Authors: Grünbaum Thomas , Cloutier Richard , Mabee Paula M. , Le François Nathalie R.
Published: March 2007

Environmental conditions such as temperature and water velocity may induce changes among alternative developmental pathways, i.e. phenotypic responses, in vertebrates. However, the extent to which the environment induces developmental plasticity and integrated developmental responses during early ontogeny of fishes remains poorly documented. We analyzed the responses of newly hatched Arctic charr (Salvelinus alpinus) to four experimental water velocities during 100 days of development. To our knowledge, this work is the first to analyze developmental plasticity responses of body morphology to an experimental gradient of water velocities during early ontogeny of fish. Arctic charr body size and shape responses show first, that morphometric traits display significant differences between low and high water velocities, thus revealing directional changes in body traits. Secondly, trait variation allows the recognition of critical ontogenetic periods that are most responsive to environmental constraints (40–70 and 80–90 days) and exhibit different levels of developmental plasticity. This is supported by the observation of asynchronous timing of variation peaks among treatments. Third, morphological interaction of traits is developmentally plastic and time‐dependent. We suggest that developmental responses of traits plasticity and interaction at critical ontogenetic periods are congruent with specific environmental conditions to maintain the functional integrity of the organism. J. Exp. Zool. (Mol. Dev. Evol.) 308B:396–408, 2007. © 2007 Wiley‐Liss, Inc.
The future technical development of MRI
Authors: Riederer Stephen J.
Published: March 2007

In this essay the author makes predictions on how the future of MRI will develop for the short term, the intermediate term, and the long term; these periods of time are defined as the present to the next 3 years, 3 to 5 years, and beyond 5 years, respectively. For each time period, general scientific trends and specific applications are presented. Despite about 15 years of extensive scientific research and significant application to clinical imaging, there continue to be many opportunities for additional technical development in MRI as its role in clinical use and the extent of its scientific significance expand.
Respiratory and postprandial changes in portal flow rate: Assessment by phase contrast MR imaging
Authors: Sadek Ahmed G. , Mohamed Feroze B. , Outwater Eric K. , El‐Essawy Saleh S. , Mitchell Donald G.
Published: March 2007

The objective of this study was to investigate the variability of several different phase contrast (PC) magnetic resonance techniques and duplex Doppler imaging (DDI) for measuring portal flow rate (PFR) with different patterns of respiration before and after a standard meal. PFR was measured in nine normal volunteers in both fasting and postprandial states, using both 2D and cine PC MR techniques. Two‐dimensional PC technique was performed with and without breathhold (BH). Four different patterns of BH (relaxed maximal inspiration, expiration, Valsalva maneuver, and Müller or reversed Valsalva) were used. Cine PC technique was performed without BH. DDI measurement of PFR was done in the fasting state with relaxed inspiration. PFR measurements made by means of PC MR techniques varied, depending on BH method, and were systematically less than those obtained by DDI. PFR measured during inspiration was significantly less than that measured during expiration and other respiratory maneuvers (P < .03). PFR increased significantly after a meal for PC and Doppler measurements, with a range of mean increases of 24 to 74%. Two‐dimensional PC MR imaging techniques yielded differing measurements of PFR, depending on whether they were done with or without BH, as well as on the pattern of BH. PC mean measures of PFR were consistently less than those of DDI. The physiologic inspiratory decreases and postprandial increases of the PFR were evident from 2D and cine PC MRI techniques, as well as with DDI.
Abdominal phase‐contrast MR angiography: Breath‐Hold versus non‐breath‐hold techniques
Authors: Hara Amy K. , Burkart David J. , Johnson C. Daniel , Ehman Richard L. , Ilstrup Duane M.
Published: March 2007

Breath‐hold magnetic resonance (MR) imaging is now replacing many non‐breath‐hold pulse sequences in the upper abdomen because of faster imaging times and improved image quality. The authors compared non‐breath‐hold cine phase‐contrast (PC) and breath hold 2D phase‐contrast (2DPC) magnetic resonance (MR) angiograms of the main portal vein (MPV) and superior mesenteric artery (SMA) in 12 volunteers. All angiograms were graded in overall image quality, vessel conspicuity, and signal‐to‐noise ratios (SNR). In the MPV MR angiograms, the breath‐hold 2DPC sequence produced better images than the non‐breath‐hold cine PC sequence as graded by overall image quality (P=.016) and SNR (P=.004). Conversely, in the SMA MR angiograms, the non‐breath‐hold cine PC sequence produced better images than the breath‐hold sequence in terms of overall image quality (P=.008) and SNR (P=.008). By reducing the most significant cause of image artifacts, (ie, using a breath‐hold 2DPC sequence to decrease respiratory misregistration of the MPV, and using a cardiac‐gated cine PC sequence to minimize pulsatile artifacts of the SMA), one can clearly optimize the quality of MR angiography.
Effects of through‐plane myocardial motion on phase‐difference and complex‐difference measurements of absolute coronary artery flow
Authors: Polzin Jason A. , Korosec Frank R. , Wedding Kristin L. , Grist Thomas M. , Frayne Richard , Peters Dana C. , Mistretta Charles A.
Published: March 2007

We have previously reported on a complex‐difference (CD) flow measurement technique that produces more accurate results than the phase‐difference (PD) flow measurement technique due to the greater immunity of the former method to partial volume effects. We report here on some of the ways in which through‐plane myocardial motion affects the accuracy of absolute coronary artery flow measurements obtained using the PD and CD techniques. We also discuss motion correction schemes that can be applied to the PD and CD processing methods to improve their accuracy. Computer simulations have been performed to assess the magnitude of the errors associated with these flow measurement techniques when they are applied to small vessels that are attached to a moving background. Laminar and plug flow, with and without complete background suppression, have been considered. Experiments with a moving vessel phantom have been conducted to test the performance of the PD and CD flow measurement techniques in circumstances similar to those simulated. The simulations and the experiments showed that, after corrections for throughplane motion are made, the CD method generally yields more accurate flow results than the PD method. As shown by the simulations, however, both methods yield compromised results due to subtle saturation effects that occur when the direction of myocardial motion is opposite the direction of blood flow. Unvalidated PD and CD measurements of coronary artery flow waveforms in human volunteers are presented to illustrate the magnitude of the proposed throughplane motion effects in vivo.
Dynamic MR imaging of recurrent postoperative cervical cancer
Authors: Yamashita Yasuyuki , Harada Mikihiko , Torashima Miyuki , Takahashi Mutsumasa , Miyazaki Kohji , Tanaka Nobuyuki , Okamura Hitoshi
Published: March 2007

The value of dynamic‐contrast enhanced MR imaging using FLASH technique was studied in 13 patients with postoperative recurrent cervical cancer verified histopathology and in 9 patients without recurrence. Dynamic FLASH imaging and conventional spin‐echo T1‐ and T2‐weighted sequences were compared in a prospective fashion with regard to accuracy of the diagnosis of recurrent tumor using biopsy results as the gold standard. The contrast between the recurrent tumor and the surrounding pelvic tissues was also analyzed. The accuracy of depicting recurrent tumor on dynamic images (82%) was superior to that of pre‐ and postcontrast T1‐weighted images and T2‐weighted images (64%, 68%, and 64%, respectively). The contrast between the recurrent tumor and pelvic fat was greater on precontrast T1‐weighted and dynamic images than on T2‐weighted and postcontrast T1‐weighted images. The dynamic images clearly showed involvement of the surrounding pelvic organs, because enhancement was observed exclusively in the tumor in the early dynamic phase. Accuracy regarding involvement of the urinary bladder or rectal wall on pre‐ and postcontrast T1‐weighted images and T2‐weighted images was lower than that on the dynamic images. Dynamic MR imaging has potential for use in the detection and evaluation of the extent of recurrent postoperative cervical cancer.
High‐resolution magnetic resonance imaging of normal porcine cartilaginous epiphyseal maturation
Authors: Babyn Paul S. , Kim Harry K. W. , Lemaire Claude , Gahunia Harpal K. , Cross Albert , Denanassy Joseph , Pritzker Kenneth P. H.
Published: March 2007

The aim of this study was to determine whether highresolution magnetic resonance (MR) imaging could differentiate epiphyseal and articular cartilage in the cartilaginous epiphysis and demonstrate its developmental changes. T1‐ and T2‐weighted (T1W and T2W) spin‐echo sequences at 50‐mm field of view (FOV) of hip joints were obtained from 14 piglets (newborn to 6 months). Subsequently, high‐resolution MR images (15‐mm FOV) of a biopsy core of the proximal femoral cartilaginous epiphysis were correlated with histology. Newborn cartilaginous epiphysis demonstrated homogeneous signal intensity on T1W and T2W imaging with abundant cartilage canals. From 2 weeks of age, the cartilaginous epiphysis showed a diminution of cartilage canals, with three zones evident on T2W imaging consisting of a low‐signal middle zone separating two higher signal zones. Histologic evaluation demonstrated four distinct morphologic laminas with a decrease in overall cartilage thickness with age. The laminas were not as well defined in the newborn compared with the older piglets. No simple correlation was found between the MR zonal pattern and the morphological laminas on histology. No distinct demarcation between the articular cartilage and epiphyseal cartilage was present. MR can visualize cartilage canals and demonstrate changes in the cartilaginous epiphysis that occur with maturation. What component of the cartilaginous epiphysis that accounts for the MR differences seen between newborn and older piglets remains unclear.
Incidental magnetization transfer contrast in fast spin‐echo imaging of cartilage
Authors: Yao Lawrence , Gentili Amilcare , Thomas Albert
Published: March 2007

In this article, the authors illustrate the contributions of incidental magnetization transfer contrast (MTC) to the signal characteristics of patellar cartilage on routine, multiplanar fast spin‐echo (FSE) images. Incidental MTC diminishes the signal of patellar cartilage by 30% on routine FSE scans. Spectral fat saturation does not significantly increase incidental MTC on multislice FSE acquisitions. By increasing the contrast between synovial fluid and patellar cartilage, incidental MTC may account for greater conspicuousness of chondromalacia on FSE as compared to conventional spin‐echo images. Incidental MTC may also alter or obscure the normal, laminar appearance of hyaline cartilage on short‐TE, FSE images.
MR imaging of tuberculous arthritis: Clinical and experimental studies
Authors: Suh Jin‐Suck , Lee Jong Doo , Cho Jae‐Hyun , Kim Myung Joon , Han Dae Yong , Cho Nam Hoon
Published: March 2007

Signal‐intensity characteristics of magnetic resonance (MR) images were assessed in five patients and in 10 rabbits with tuberculous arthritis. MR imaging findings were compared with histologic findings in the animal study. In both of clinical and experimental cases, tuberculous lesions showed both intermediate and high signal intensity on T2‐weighted images, while they showed heterogeneously intermediate signal intensity on T1‐weighted images. As T2‐weighted images were compared with pathologic specimens, intermediate signal intensity corresponded to caseous necrosis, whereas high signal intensity related to granulomas or effusion. Postcontrast T1‐weighted images showed enhancement at the peripheries rather than the centers of tuberculous lesions. These results indicate that tuberculous arthritis should be included in the differential diagnosis when intra‐articular lesions with low or intermediate signal intensity are found on T2‐weighted images.
Angiogenic response of MCF7 human breast cancer to hormonal treatment: Assessment by dynamic GdDTPA‐enhanced MRI at high spatial resolution
Authors: Furman‐Haran Edna , Margalit Raanan , Maretzek António F. , Degani Hadassa
Published: March 2007

Dynamic gadolinium diethylenetriamine pentaacetic acid (Gd‐DTPA)‐enhanced MRI was followed during growth and regression of MCF7 human breast tumors implanted in nude mice in the presence of estrogen and tamoxifen, respectively. Gradient‐echo and spinecho sequences were applied at a temporal resolution of 12 and 100 seconds, respectively, and a spatial resolution of 195 × 390 × 1000 μm. Maps of initial rates of contrast enhancement demonstrated stimulation of local growth of permeable microcapillaries at regions bordering necrotic areas, resulting from tamoxifen treatment. This localized angiogenic stimulation was confirmed by immunohistochemical staining of endothelial cells. After 1 week of tamoxifen treatment, the fraction of tumor pixels exhibiting rapid initial rate of contrast enhancement increased significantly from .28 ± .05 to .46 ± .06. In parallel, the fraction of tumor area showing contrast enhancement 3 minutes after Gd‐DTPA injection also increased significantly, from .42 ± .06 to .58 ± .06. On the basis of these changes, it was possible to assess the response to tamoxifen therapy at an early stage.
MR imaging of silicone breast implants: Evaluation of prospective and retrospective interpretations and interobserver agreement
Authors: Quinn Stephen F. , Neubauer Nancy M. , Sheley Robert C. , Demlow Thomas A. , Szumowski Jerzy
Published: March 2007

MR imaging was used to evaluate the integrity of silicone breast implants in 54 women with 108 implants. MR images were interpreted by relatively inexperienced readers who tried to reproduce the experiences reported in the literature. The study examines the interobserver agreement using different diagnostic signs and the influence of experience on interpretation errors. Prospective and retrospective interpretations were compared with surgical findings at the time of explantation. Diagnostic indicators, including the linguine sign, the inverted tear drop sign, the C sign, water droplets mixed with silicone, and extracapsular globules of silicone, were evaluated for diagnostic efficacy and interobserver agreement. The prospective sensitivity and specificity were 87% and 78%, respectively. With the retrospective interpretations, the sensitivity and specificity increased to 93% and 92%, respectively. Most of the prospective false‐positive interpretations were due to misinterpreting radial folds as signs of implant rupture. Six implants interpreted retrospectively as false positives had gross amounts of silicone around the implants at surgery but there were no obvious rents in the implant shells. There was fair to excellent interobserver agreement with the individual diagnostic signs except for extracapsular globules of silicone. All of the signs had specificities of greater than 90%. The sensitivities of the individual signs were less than the overall retrospective sensitivity. With experience, the sensitivity improved from 87% to 93% and the specificity improved from 78% to 92%. This study helps substantiate the use of diagnostic signs used by other authors to detect silicone loss from breast implants by MR imaging; however, questions remain as to the clinical role of MR imaging in evaluating implants for silicone loss.
High resolution 3D imaging of the inner ear with a modified fast spin‐echo pulse sequence
Authors: Lee James N. , King Brian D. , Parker Dennis L. , Buswell Henry R. , Harnsberger H. Ric
Published: March 2007

A fast spin‐echo pulse sequence is described that produces high resolution images of the inner ear without susceptibility artifacts. It uses thin overlapping slices that can be reformatted in multiple projections to provide a view of the 3D geometry of inner ear structures, such as the cochlea, vestibule, semicircular canals, and internal auditory canal. It has proven useful in screening adults for the presence of acoustic schwannoma and in identifying structural congenital lesions in children with sensorineural hearing loss.
Determination of H relaxation times of water in human bone marrow by fat‐suppressed turbo spin echo in comparison to MR spectroscopic methods
Authors: Träber Frank , Block Wolfgang , Layer Günter , Bräucker Gitte , Gieseke Jürgen , Kretzer Sonja , Hasan Ibrahim , Schild Hans H.
Published: March 2007

Relaxation times of water were measured in human vertebral bodies by a fat‐suppressed dual‐echo turbo spin echo/turbo inversion recovery MRI sequence. Comparison was made with T1 and T2 values obtained by localized 1H‐MR spectroscopy. The accuracy of the results and the diagnostic potential of the fast quantitative MRI technique were evaluated in 20 volunteers, 11 patients with osteoporosis, 6 patients with lymphoma, and 6 patients with bone marrow metastasis. No significant alterations of T1 and T2 relaxation times of water and fat were found in osteoporosis. With both methods, an increase in the T1 values of the water resonance by 16% was observed in lymphomas, which was highly significant (P < .001) in the MRS measurements, and an elevation by the same amount was obtained by the MRI sequence for the metastases (P = .040). A strong reduction of fat fraction was quantified by MRS in the tumorous cases. T2 of the water resonance increased by more than 30% (P < .003) in metastases. Water T2 values obtained by the MRI sequence showed systematic deviations from the MRS results, especially at short echo spacings.
Investigation of MR decay rates in microphantom models of trabecular bone
Authors: Selby Kathy , Majumdar Sharmila , Newitt David C. , Genant Harry K.
Published: March 2007

MR measurements of transverse relaxation time, T2*, in trabecular bone may provide both structural and density‐related information for assessment of bone mineral status in osteoporosis. Using submillimeter scale glass phantoms as simplified models of trabecular bone, we have made a quantitative investigation of the dependence of T2* decay on modeled trabecular microstructure and MR image resolution. The experimental MR data are in excellent agreement with predictions from a computer simulation. Decreasing the modeled trabecular bone volume fraction, ζ, decreases the decay rate, as expected. However, if trabecular width and spacing are both increased without changing ζ, the decay rate is unchanged. The measured decay curves closely follow the predicted dependence on trabecular orientation. The decay rates are independent of image resolution, provided that the pixel dimensions are larger than the intertrabecular spacing. For smaller pixel sizes, the decay rate decreases with decreasing pixel size.
An infrared device for monitoring the respiration of small rodents during magnetic resonance imaging
Authors: Lemieux Susan K. , Glover Gary H.
Published: March 2007

A device that uses infrared reflectometry for monitoring the respiratory waveform of small rodents during MRI was developed. This system uses a photoplethysmograph coupled to the animal by a light pipe to detect movements as small as 1.0 mm. This device can also be used for monitoring larger animals or for controlling respiratory‐compensated or respiratory‐triggered MRI.
Functional MRI in human somatosensory cortex activated by touching textured surfaces
Authors: Lin Weili , Kuppusamy Karthikeyan , Haacke E. Mark , Burton Harold
Published: March 2007

MRI revealed activation foci in human somatosensory cortex during protocols involving stimulation of the fingertips with a textured surface. A 2D T2*‐weighted gradient echo sequence was used to acquire images. The imaging protocol included acquiring images while subjects performed specific tactile stimulation paradigms (activation scans) or rested. Three different paradigms were used to produce functional activation using a textured surface to rub the fingertips of one hand. First, motor sensory activation was produced by rubbing the textured surface held in one hand against the fingertips of the opposite hand only during the activation scans. Second, the hand holding the textured surface moved throughout the experiment but touched the fingertips of the opposite hand only during the activation scans. Third, subjects remained still in the magnet throughout the entire study while an investigator rubbed the textured surface against the subjects' fingertips during the activation scans. Images were postprocessed using a cross‐correlation scheme. The results revealed multiple foci of motor sensory activation near the central sulcus, postcentral sulcus, and prefrontal cortex.
Pancreatic masses with inconclusive findings on spiral CT: Is there a role for MRI?
Authors: Semelka Richard C. , Kelekis Nikolaos L. , Molina Paul L. , Sharp Tonya J. , Calvo Benjamin
Published: March 2007

This prospective study evaluates the ability of MRI using T1‐weighted fat‐suppressed spin‐echo (T1FS) and dynamic gadolinium chelate (Gd) enhanced spoiled‐gradient echo (SGE) to detect the presence of pancreatic tumor in patients in whom spiral CT findings are inconclusive.

Sixteen consecutive patients who underwent spiral CT and had findings that were considered inconclusive for pancreatic tumor underwent MR within 2 weeks of CT. Spiral CT and MR images were interpreted in a prospective fashion by separate individual investigators blinded to the results of the other imaging modality. CT was performed on a spiral CT scanner. MRI was performed on a 1.5‐T MR machine. Imaging sequences included T1FS pre‐Gd and post‐Gd and SGE pre‐Gd and immediately post‐Gd. Data were analyzed using receiver operating characteristic (ROC) analysis. Confirmation was obtained by pancreatic biopsy (n = 4), surgical resection (n = 1), and clinical imaging (n = 4) or clinical follow‐up (n = 7).

MRI was superior to spiral CT (P = .027) in this selected patient group at detecting or excluding pancreatic tumor by ROC analysis, with areas under the curve of .982 and .764, respectively, which was significant (P = .041). The greatest advantage of MRI was in patients in whom spiral CT demonstrated enlargement of the pancreatic head without clear definition of tumor, which was significant (P = .033). In 10 patients with this CT appearance, MRI demonstrated a high confidence for presence of tumor in four and a high confidence of absence in six. Association of imaging findings with patient diagnosis was significant for MRI (P = .001) but not significant for CT (P = .148).

The results of our study suggest that MRI may add significant diagnostic information in patients in whom spiral CT is inconclusive for the presence of pancreatic tumor. The greatest advantage of MRI was in the evaluation of patients in whom spiral CT findings revealed an indeterminate enlarged pancreatic head.
MR of focal liver lesions: Comparison of breath‐hold and non‐breath‐hold hybrid rare and conventional spin‐echo T2‐weighted pulse sequences
Authors: Carpenter Kenneth D. , Macaulay Shane E. , Schulte Scott J. , Obregon Richard G. , Nelson Rendon C. , Simon Howard E. , Schmiedl Udo P.
Published: March 2007

To compare liver lesion detection rates, tissue signal and noise data, and qualitative parameters for breathhold (BH) and non‐breath‐hold (NBH) hybrid rapid acquisition with relaxation enhancement (RARE) and conventional spin‐echo (CSE) T2‐weighted (CSE‐T2) MR sequences, 20 patients were imaged using all three sequences. Lesion detection rates were 73.5% for the CSE‐T2 sequence and 81.1% and 88.6% for the BH‐RARE and NBH‐RARE sequences, respectively (P = .027). Mean lesion‐to‐liver signal‐difference‐to‐noise ratio for the NBH‐RARE sequence was 14.0 ± 11.5, significantly greater than 9.8 ± 7.8 obtained for the BH‐RARE sequence (P = .050) and 9.0 ± 6.2 obtained for the CSE‐T2 sequence (P = .015). The NBH‐RARE sequence demonstrated fewer artifacts and greater overall image quality compared to the CSE‐T2 sequence. The NBH‐RARE sequence is a useful alternative to the CSE‐T2 sequence providing a higher mean lesion‐to‐liver signal‐difference‐to‐noise ratio and lesion detection rate and better overall image quality.
Comparison of conventional single echo and multi‐echo sequences with a fast spin‐echo sequence for quantitative T2 mapping: Application to the prostate
Authors: Liney Gary P. , Knowles Adrian J. , Manton David J. , Turnbull Lindsay W. , Blackband Stephen J. , Horsman Anthony
Published: March 2007

The accuracy of water T2 maps generated from a fast spin‐echo (FSE) sequence was compared with data obtained by conventional single and multi‐echo spin‐echo pulse sequences using a commercial gel phantom. Spatially localized stimulated echo acquisition mode (STEAM) proton spectroscopy was also used to confirm the reported water T2 values of the gels contained in the phantom. The FSE sequence was shown to be superior in accuracy to both the single and multi‐echo spin echo sequences and comparable to STEAM, producing results that were within 10% of known values. The effectiveness of the FSE sequence was further demonstrated by generating T2 maps of the normal and diseased prostate in clinically acceptable imaging times, resulting in comparable T2 values to those obtained using STEAM. Accurate quantitative T2 maps can be produced with the FSE sequence.
Comparison of single‐breath‐hold fast spin‐echo sequences with routine non‐breath‐hold techniques: Application to MRI of renal masses
Authors: Melki Philippe S. , Argaud Christophe , Suminski Matt , Hélénon Olivier , Belin Xavier , Millet Patrick , Chrétien Yves , Zannoli Guillermo , Moreau Jean‐François
Published: March 2007

In 24 patients presenting with 55 renal lesions (mean size, 20.8 mm), single‐breath‐hold (SBH) fast spin‐echo (FSE) techniques allowing T1 and T2 images to be produced within 20 and 23 sec, respectively, were compared with routine non‐breath‐hold (NBH) spin‐echo (SE) T1 and NBH‐FSE T2 sequences. Contrast‐to‐noise ratios (CNRs) measured from SBH‐FSE T1 images were an average of 97% higher than their NBH counterparts (P = .0001) and allowed an improved lesion conspicuity in 80% of the cases (P = .0001). For T2 imaging, SBH‐FSE and NBH‐FSE sequences were not statistically different with respect to lesion conspicuity (P = .55) and CNR values (P = .19). This was observed despite a 35% average decrease in CNR of SBH‐FSE compared to NBH‐FSE images. By reducing respiratory motion artifacts while preserving SE‐like image contrast, SBH‐FSE techniques have the potential to replace routine NBH sequences for an optimal diagnosis of renal masses.
MR imaging characterization of postischemic myocardial dysfunction („stunned myocardium”︁): Relationship between functional and perfusion abnormalities
Authors: Szolar Dieter H. , Saeed Maythem , Wendland Michael F. , Sakuma Hajime , Roberts Timothy P. L. , Stiskal Michael A. , Derugin Nikita , Higgins Charles B.
Published: March 2007

Stunned myocardium has been detected in patients treated successfully with thrombolytic agents. The hypothesis of this study was that fast gradient echo (GRE) imaging could be used to characterize the regional functional and perfusion abnormalities that are indicative of myocardial stunning. This study was designed to monitor and correlate the extent of wall thickness and perfusion abnormalities as determined by fast (segmented k space) cine and contrast enhanced GRE imaging, respectively. Dogs were subjected to left circumflex (LCX) coronary artery occlusion (15 min) followed by 30‐minute reperfusion (n= 8). Perivascular flow probes were used to continuously measure flow in left anterior descending (LAD) and LCX coronary arteries. Short‐axis inversion recovery prepared fast GRE and cine images were acquired at baseline, at occlusion, and at 1, 10, and 30 minutes of reflow. Regional signal intensity and percent systolic wall thickening were determined at 26 equally spaced circumferential positions to compare the extent of functional and perfusion abnormalities. During occlusion and reperfusion, the ischemic region was demonstrated on contrast‐enhanced images as a hypointense and hyperintense region, respectively. During occlusion, the extent of the perfusion defect (32% ± 2% of the circumference of the equatorial slice) correlated closely (r= .74) with the extent of contractile dysfunction (35% ± 2%). After reperfusion, there was transient recovery in the percent wall thickening (26% ± 4% vs 36% ± 4% normal), coinciding with the reactive hyperemic response, but this was followed by a significant decline in wall thickening at 10 minutes (19% ± 4%) and 30 minutes (12% ± 2%). Fast MR imaging may be useful to monitor postischemic myocardial abnormalities after thrombolytic therapy and the response to pharmacologic interventions.
Determination of the optimal imaging parameters of the RODEO pulse sequence by computer simulation
Authors: Miller Ira , Gao Jia‐Hong , Fox Peter T.
Published: March 2007

A computer program has been developed for evaluating the NMR signal response of various imaging parameters and its efficiency in fat suppression of the RODEO (ROtating Delivery of Excitation Off‐resonance) pulse sequence. Both spoiled and refocused RODEO pulse sequences have been considered. By numerically solving the Bloch equation modified for a three‐dimensional volume of spins, for realistic RF excitations and Lorentzian distribution of the frequency spectrum for both fat and water, the program permits the imaging contrast and fat suppression of the RODEO pulse sequences to be assessed quantitatively. We have found that excellent fat suppression can be achieved by choosing appropriate imaging parameters. Imaging contrast for different tissues can be enhanced by using longer repetition time (TR) in the spoiled scheme. The complex pattern of the NMR signal response and imaging contrast has been observed in the refocused scheme.