bluuebunny/crossref_metadata_2025 huggingface dataset:
Regression method for estimating rainfall recharge at unconfined sandy aquifers with an equatorial climate
Authors: Tan Stephen Boon Kean , Shuy Eng Ban , Chua Lloyd Hock Chye
Published: October 2007

A reliable estimate of rainfall recharge is essential for groundwater system managements. This study develops a method based on regression equations for estimating rainfall recharge at unconfined sandy aquifers with an equatorial climate. The developed method (GR‐I method) is generally efficient for estimating long‐term regional recharge, as the computational procedures could be formulated and executed easily using Microsoft's Excel spreadsheet. More importantly, its application could be extended to sand textures different from the sand texture used in developing the regression equations. To evaluate its reliability, the method was applied to estimate monthly gross recharge percentages at the Changi reclaimed land. When ignoring the effect of rainfall clusters, the GR‐I method was found to underestimate the monthly gross recharge percentages for those months with high monthly rainfall depths. By integrating the effect of rainfall clusters, the GR‐I method yields reliable estimates of monthly gross recharge percentages. By including daily potential evaporation as an additional input variable, the Extended GR‐I method was found to be not superior to the GR‐I method, implying that soil moisture availability is the major governing factor for actual soil evaporation in the highly porous sand medium, instead of atmospheric demand represented by the potential evaporation rate. Using the GR‐I method, the mean annual net recharge percentage of the study site was found to fall between 56·9 and 69·9%, which corresponds to a net recharge depth of 1073·8–1745·8 mm. Although the developed method provides a good alternative to other widely used methods, its recharge estimates still needs to be collaborated with estimates from other methods, as multiple techniques are highly recommended in any groundwater recharge estimations. Copyright © 2007 John Wiley & Sons, Ltd.
The effects of climate change on potential groundwater recharge in Great Britain
Authors: Herrera‐Pantoja M. , Hiscock K. M.
Published: October 2007

The predicted increase in mean global temperature due to climate change is expected to affect water availability and, in turn, cause both environmental and societal impacts. To understand the potential impact of climate change on future sustainable water resources, this paper outlines a methodology to quantify the effects of climate change on potential groundwater recharge (or hydrological excess water) for three locations in the north and south of Great Britain. Using results from a stochastic weather generator, actual evapotranspiration and potential groundwater recharge time‐series for the historic baseline 1961–1990 and for a future ‘high’ greenhouse gas emissions scenario for the 2020s, 2050s and 2080s time periods were simulated for Coltishall in East Anglia, Gatwick in southeast England and Paisley in west Scotland. Under the ‘high’ gas emissions scenario, results showed a decrease of 20% in potential groundwater recharge for Coltishall, 40% for Gatwick and 7% for Paisley by the end of this century. The persistence of dry periods is shown to increase for the three sites during the 2050s and 2080s. Gatwick presents the driest conditions, Coltishall the largest variability of wet and dry periods and Paisley little variability. For Paisley, the main effect of climate change is evident during the dry season (April–September), when the potential amount of hydrological excess water decreases by 88% during the 2080s. Overall, it is concluded that future climate may present a decrease in potential groundwater recharge that will increase stress on local and regional groundwater resources that are already under ecosystem and water supply pressures. Copyright © 2007 John Wiley & Sons, Ltd.
Using narratives to assess competencies and risks in young children: Experiences with high risk and normal populations
Authors: Holmberg John , Robinson Joann , Corbitt‐Price Jennifer , Wiener Pamela
Published: October 2007

The young child's mental representations convey a wealth of information about his/her early moral and emotional construction of reality. The MacArthur Story Stem Battery (MSSB) is a unique, child‐friendly tool for assessing socioemotional development in young children (3–6 years). The technique provides incomplete stories (stems), which are completed by the child using their own verbalizations and actions with doll figures. A sensitive examiner scaffolds appropriate boundaries for the task. The MSSB has demonstrated adequate psychometric properties and initial studies suggest the MSSB can tap important prosocial competencies as well as features indicative of psychopathology and distress. The MSSB has been translated and used in a number of countries across the world, in part due to the measure's clinical utility to quickly assess children at the level of representation. Current innovations reviewed emphasize the use of the MSSB for assessment in clinical and at‐risk populations. A table summarizing key clinically relevant articles on the MSSB is referenced throughout the paper.
Using accounts payable to improve cash flow
Authors: Schaeffer Mary S.
Published: October 2007

Accounts payable definitely has a cash flow/cash management component, the author reminds us. And there are several tactics accounts payable can use to improve your company's cash flow. What are they, and how can you use them effectively? © 2007 Wiley Periodicals, Inc.
Operating your business on a cash basis
Authors: Reider Rob
Published: October 2007

What are the keys to operating your business on a cash basis? The author tells you what you need to know—and supplies some very useful checklists to make your work easier. © 2007 Wiley Periodicals, Inc.
Opposing effects of glucocorticoids and Wnt signaling on Krox20 and mineral deposition in osteoblast cultures
Authors: Leclerc Nathalie , Noh Tommy , Cogan Jon , Samarawickrama Dilan B. , Smith Elisheva , Frenkel Baruch
Published: October 2007

Krox20 is expressed in osteoblasts and chondrocytes, and is required for trabecular bone formation during embryogenesis. Here we show by RT‐qPCR and Western blot analysis that Krox20 is up‐regulated during late stages of osteoblast differentiation in culture. Glucocorticoids (GCs) rapidly inhibit the expression of Krox20 as well its co‐activator, HCF‐1, resulting in inhibition of the Osteocalcin Krox20‐binding Enhancer (OKE). GCs also inhibit expression of EGR1, EGR3, and EGR4. OKE activity, which is dependent on the presence of Runx2, was independent of the osteocalcin promoter Runx2 binding site. In contrast to GCs, activation of the Wnt, but not the BMP or the PTH signaling pathways, stimulated Krox20 expression as well as activity of the OKE. GC‐mediated suppression of Krox20 expression was compromised, albeit not completely, in the presence of DKK1, suggesting that the inhibition occurs in both Wnt‐dependent and Wnt‐independent manners. Furthermore, Wnt3A partially rescued Krox20 expression in GC‐arrested osteoblast cultures and this was accompanied by rescue of mineralization. These findings are consistent with a role for Krox20 in osteoblast function and suggest that this transcription factor may contribute to the opposing effects of GCs and Wnt signaling on bone formation. J. Cell. Biochem. 103: 1938–1951, 2007. © 2007 Wiley‐Liss, Inc.
An initial evaluation of a mindful parenting program
Authors: Altmaier Elizabeth , Maloney Raelynn
Published: October 2007

A growing number of children are experiencing marital transition. The effects of divorce on children have typically been considered deleterious, although factors can buffer the difficulty of postdivorce adjustment. One of these factors is a positive relationship with a parental figure. Unfortunately, divorce often overwhelms parents with a series of changes that compromise their parenting skills. One new approach to improving parenting after divorce is mindful parenting, which aims to enhance interpersonal and emotional connection in the parent–child relationship. This program is intended to facilitate parents' self‐awareness, their mindfulness, and their intentionality in responding to their child's needs. The present study reports on the implementation of the Mindful Parenting Program, delivered in two groups to 12 recently divorced parents with preschool‐aged children. Program effectiveness was conducted on two levels. First, mindfulness measured by the Toronto Mindfulness Scale revealed significant increases over the intervention and posttest period. Second, in‐home behavioral observations conducted pre‐ and postintervention revealed no changes in parent–child relationships. These findings are discussed within the larger context of facilitating effective parenting postdivorce. © 2007 Wiley Periodicals, Inc. J Clin Psychol 63: 1231–1238, 2007.
Perceived criticism only matters when it comes from those you live with
Authors: Renshaw Keith D.
Published: October 2007

Perceived criticism (PC) is the amount of criticism that a respondent perceives from another individual, typically a relative with whom the respondent lives. Measured in this way, PC has been shown to predict symptom fluctuation, treatment outcome, and relapse rates across many disorders. Three recent studies failed to replicate these results, but in all three studies, investigators did not require patients to rate people with whom they lived on the measure of PC, which may have changed the overall meaning of the construct. To address this possibility, the current study examined change in depressive symptoms in relation to ratings of PC from multiple individuals who did and did not live with respondents. Only PC from family members or romantic partners who lived with participants predicted change in depressive symptoms. Perceived criticism from friends and PC from individuals ranked as most influential did not. These findings suggest that PC is most meaningful and informative when viewed in its original conceptual form, as a reflection of the family home environment. © 2007 Wiley Periodicals, Inc. J Clin Psychol 63: 1171–1179, 2007.
Top producers of scholarly publications in clinical psychology PhD programs
Authors: Stewart Peter K. , Wu Yelena P. , Roberts Michael C.
Published: October 2007

Publication productivity of 1,927 core faculty members in clinical psychology training programs was tallied over a 5‐year period (2000–2004) from their PsycINFO database entries (http://www.apa.org/psycinfo/). The top‐producing faculty members are presented with rank by total number of publications and rank by number of peer‐reviewed journal articles. In this report, the authors recognize those productive clinical psychologists in accredited clinical programs who have advanced the field through their substantial contributions to the literature base. © 2007 Wiley Periodicals, Inc. J Clin Psychol 63: 1209–1215, 2007.
Obsessive–compulsive disorder and romantic functioning
Authors: Abbey Richard D. , Clopton James R. , Humphreys Joy D.
Published: October 2007

The current study examined the romantic relationships of individuals with obsessive–compulsive disorder (OCD). Participants were 64 individuals recruited from a national conference who completed measures of OCD symptoms, depressive symptoms, intimacy, self‐disclosure, relationship satisfaction, and relationship worry. Severity of obsessions was negatively correlated with intimacy, relationship satisfaction, and self‐disclosure. In contrast, two compulsive behaviors (washing and neutralizing) were positively correlated with several relationship variables. Fears of contamination from sexual activity were positively correlated with the severity of OCD symptoms. The clinical implications of the findings from this study and suggestions for future research are presented. © 2007 Wiley Periodicals, Inc. J Clin Psychol 63: 1181–1192, 2007.
Perceived costs and benefits of behavioral change: Reconsidering the value of ambivalence for psychotherapy outcomes
Authors: McEvoy Peter M. , Nathan Paula
Published: October 2007

This study examined the measurement of ambivalence toward change, and the predictive utility of ambivalence in terms of psychotherapy outcomes. Ambivalent individuals were defined as those acknowledging both costs and benefits to change. Two competing hypotheses were tested. The first, based on the transtheoretical model (C. C. DiClemente & J. O. Prochaska, 1998), predicted that ambivalent individuals would experience less symptom change than those who predominantly acknowledge benefits to change. The second, based on evidence that acknowledging the costs of change is associated with better outcomes, predicted that ambivalence would be associated with more change. Patients (n = 173) with anxiety and affective disorders completed unitary and multidimensional measures of perceived costs and benefits to change, with a subset (n = 115) completing a course of cognitive–behavioral therapy. Results suggested that ambivalence was best measured within a multidimensional framework. Patients who acknowledged both costs and benefits to change (i.e., ambivalent) achieved better outcomes than those acknowledging predominantly benefits, or few costs and benefits, to change. © 2007 Wiley Periodicals, Inc. J Clin Psychol 63: 1217–1229, 2007.
Could you be more specific, please: Self‐discrepancies, affect, and variation in specificity and relevance
Authors: Rodebaugh Thomas L. , Donahue Kelly L.
Published: October 2007

Multiple studies have suggested that the use of the Selves Questionnaire to assess self‐discrepancies related to specific forms of affect may be problematic. The authors tested whether greater specificity in participant characteristics, study context, and form of assessment would increase the ability to detect the hypothesized differences. The Selves Questionnaire failed to show the hypothesized relations. A modified version of the Selves Questionnaire did show some of the hypothesized relationships; however, these relationships were stronger in regard to depression than anxiety, which also contradicted hypotheses. The results provide more evidence that the Selves Questionnaire, especially when used alone, may be of limited use in assessing self‐discrepancies as described by self‐discrepancy theory. © 2007 Wiley Periodicals, Inc. J Clin Psychol 63: 1193–1207, 2007.
Posttraumatic distress in security guards and the various effects of social support
Authors: Declercq Frédéric , Vanheule Stijn , Markey Samuel , Willemsen Jochem
Published: October 2007

This study investigates the effects of six types of social support on distress and posttraumatic stress disorders in security guards who did and did not encounter a critical incident. Three types of social support were significantly related to distress and posttraumatic stress disorder: emotional support in problem situations, instrumental support, and social companionship. Emotional support in problem situations paradoxically appeared to have an aggravating effect on distress and posttraumatic stress, whereas instrumental support and social companionship had a mitigating outcome. © 2007 Wiley Periodicals, Inc. J Clin Psychol 63: 1239–1246, 2007.
Florida obsessive–compulsive inventory: Development, reliability, and validity
Authors: Storch Eric A. , Kaufman David A.S. , Bagner Daniel , Merlo Lisa J. , Shapira Nathan Andrew , Geffken Gary R. , Murphy Tanya K. , Goodman Wayne K.
Published: October 2007

David A.S. Kaufman, M.S. was accidentally omitted from the order of authorship for the manuscript that appeared in Volume 63, Issue 9, pages 851–859. Mr. Kaufman was the second author of this paper.
Health disparities and culturally specific treatment: Perspectives and expectancies of African American smokers
Authors: Webb Monica S. , Francis Joan , Hines Bill C. , Quarles Frankie B.
Published: October 2007

When the following article originally appeared in the Journal of clinical Psychology (Volume 63, number 6, june 2007), a number of author corrections were omitted. We regret this oversight and now reprint the article in full.

Researchers suggest that culturally specific (CS) interventions are important in addressing smoking‐related health disparities. Yet, little research has examined the perspectives of African American smokers regarding these efforts. This qualitative study sought to gain insight into perceptions related to (a) the smoking prevalence among African Americans, (b) smoking‐related health disparities, (c) expectancies for CS interventions, (d) methods of recruiting research participants, and (e) key intervention components. Six focus groups were conducted with 41 African American smokers (aged 21–64) at a community health center. Content analyses revealed several themes, including the perception that smoking is normative among African Americans, limited knowledge of racial health disparities, mixed perceptions regarding race as a risk factor for illness, and mixed expectancies for the efficacy of CS interventions. In conclusion, individual differences, such as smoking norms, knowledge of health disparities, and intervention expectations may influence receptivity to CS treatments. Implications for tobacco interventions among African Americans are discussed. © 2007 Wiley Periodicals, Inc. J Clin Psychol 63: 1247–1263, 2007.
Cell surface protein detection with immunogold labelling in ESEM: Optimisation of the method and semi‐quantitative analysis
Authors: Muscariello Livio , Rosso Francesco , Marino Gerardo , Barbarisi Manlio , Cafiero Gennaro , Barbarisi Alfonso
Published: October 2007

In this work we used a combination of immunogold labelling (IGL) and environmental scanning electron microscopy (ESEM) to detect the presence of a protein on the cell surface. To achieve this purpose we chose as experimental system 3T3 Swiss Albino Mouse Fibroblasts and galectin‐3. This protein, whose sub‐cellular distribution is still under discussion, is involved in a large number of cell physiological and pathological processes. IGL technique has been utilised by many authors in combination with SEM and TEM to obtain the identification/localisation of receptors and antigens, both in cells and tissues. ESEM represents an important tool in biomedical research, since it does not require any severe processing of the sample, lowering the risk of generating artefacts and interfere with IGL procedure. The absence of metal coating could yield further advantages for our purpose as the labelling detection is based on the atomic number difference between Nanogold spheres and the biological material. Using the gaseous secondary electron detector (GSED) compositional contrast is easily revealed by the backscattered electrons component of the signal. In spite of this fact, only few published papers present a combination of ESEM and IGL. Hereby we present our method, optimised to improve the intensity and the specificity of the labelling signal, in order to obtain a semi‐quantitative evaluation of the labelling signal. J. Cell. Physiol. 214: 769–776, 2008. © 2007 Wiley‐Liss, Inc.
Cholesterol modulates cellular TGF‐β responsiveness by altering TGF‐β binding to TGF‐β receptors
Authors: Chen Chun‐Lin , Huang Shuan Shian , Huang Jung San
Published: October 2007

Transforming growth factor‐β (TGF‐β) responsiveness in cultured cells can be modulated by TGF‐β partitioning between lipid raft/caveolae‐ and clathrin‐mediated endocytosis pathways. The TβR‐II/TβR‐I binding ratio of TGF‐β on the cell surface has recently been found to be a signal that controls TGF‐β partitioning between these pathways. Since cholesterol is a structural component in lipid rafts/caveolae, we have studied the effects of cholesterol on TGF‐β binding to TGF‐β receptors and TGF‐β responsiveness in cultured cells and in animals. Here we demonstrate that treatment with cholesterol, alone or complexed in lipoproteins, decreases the TβR‐II/TβR‐I binding ratio of TGF‐β while treatment with cholesterol‐lowering or cholesterol‐depleting agents increases the TβR‐II/TβR‐I binding ratio of TGF‐β in all cell types studied. Among cholesterol derivatives and analogs examined, cholesterol is the most potent agent for decreasing the TβR‐II/TβR‐I binding ratio of TGF‐β. Cholesterol treatment increases accumulation of the TGF‐β receptors in lipid rafts/caveolae as determined by sucrose density gradient ultracentrifugation analysis of cell lysates. Cholesterol/LDL suppresses TGF‐β responsiveness and statins/β‐CD enhances it, as measured by the levels of P‐Smad2 and PAI‐1 expression in cells stimulated with TGF‐β. Furthermore, the cholesterol effects observed in cultured cells are also found in the aortic endothelium of atherosclerotic ApoE‐null mice fed a high cholesterol diet. These results indicate that high plasma cholesterol levels may contribute to the pathogenesis of certain diseases (e.g., atherosclerosis) by suppressing TGF‐β responsiveness. J. Cell. Physiol. 215: 223–233, 2008. © 2007 Wiley‐Liss, Inc.
The sea spider's contribution to T.H. Morgan's (1866–1945) development
Authors: Maxmen Amy
Published: October 2007

Over a century ago, T.H. Morgan helped foundThe Journal of Experimental Zoölogy, a series devoted to emerging investigations in development and evolution, variation and heredity, adaptation and ecology. T.H. Morgan initially encountered these topics in his graduate research on the ontogeny and phylogeny of the sea spiders. His Ph.D. thesis, written in 1891, reflects in interesting ways the conceptual shifts in evolutionary biology in the late 1800s. Embryology had become a major criterion in using morphological similarity to speculate on phylogenetic relationships. Yet, when Morgan studied the development of sea spiders to draw conclusions about their relatedness, he struggled with the incompleteness of knowledge about the role of inheritance and variation of ontogenetic processes. This can best be seen in his discussions of the properties of conservation during embryonic cleavage, varied development of supposedly homologous appendages, and the evolvability of larval stages. After his dissertation, Morgan never returned to phylogenetic analysis. He had been dissatisfied with the plethora of untestable phylogenetic hypotheses based on comparing complicated embryological phenomenon, and joined an experimental movement in which systems were explicitly chosen and constructed to test hypotheses about developmental processes.J. Exp. Zool. (Mol. Dev. Evol.) 310B:203–215, 2008. © 2007 Wiley‐Liss, Inc.
External genital morphology of the ring‐tailed lemur (Lemur catta): Females are naturally “masculinized”
Authors: Drea Christine M. , Weil Anne
Published: October 2007

The extravagance and diversity of external genitalia have been well characterized in male primates; however, much less is known about sex differences or variation in female form. Our study represents a departure from traditional investigations of primate reproductive anatomy because we 1) focus on external rather than internal genitalia, 2) measure both male and female structures, and 3) examine a strepsirrhine rather than an anthropoid primate. The subjects for morphological study were 21 reproductively intact, adult ring‐tailed lemurs (Lemur catta), including 10 females and 11 males, two of which (one per sex) subsequently died of natural causes and also served as specimens for gross anatomical dissection. Male external genitalia presented a typical masculine configuration, with a complex distal penile morphology. In contrast, females were unusual among mammals, presenting an enlarged, pendulous external clitoris, tunneled by the urethra. Females had a shorter anogenital distance and a larger urethral meatus than did males, but organ diameter and circumference showed no sex differences. Dissection confirmed these characterizations. Noteworthy in the male were the presence of a “levator penis” muscle and discontinuity in the corpus spongiosum along the penile shaft; noteworthy in the female were an elongated clitoral shaft and glans clitoridis. The female urethra, while incorporated within the clitoral body, was not surrounded by erectile tissue, as we detected no corpus spongiosum. The os clitoridis was 43% the length and 24% the height of the os penis. On the basis of these first detailed descriptions of strepsirrhine external genitalia (for either sex), we characterize those of the female ring‐tailed lemur as moderately “masculinized.” Our results highlight certain morphological similarities and differences between ring‐tailed lemurs and the most male‐like of female mammals, the spotted hyena (Crocuta crocuta), and call attention to a potential hormonal mechanism of “masculinization” in female lemur development. J. Morphol., 2008. © 2007 Wiley‐Liss, Inc.
Biochemical safety profiles of gadolinium‐based extracellular contrast agents and nephrogenic systemic fibrosis
Authors: Ersoy Hale , Rybicki Frank J.
Published: October 2007

Gadolinium (Gd)‐based paramagnetic contrast agents are relatively safe when used in clinically recommended doses. However, with the rapidly expanding body of literature linking Gd‐based paramagnetic contrast agents and nephrogenic systemic fibrosis (NSF), awareness of the potential side effects and adverse reactions from Gd is now an important requirement for practicing radiologists. In addition to the ongoing accumulation and analyses of clinical NSF data, it is also essential for the practicing radiologist to understand the biochemical characteristics of the extracellular Gd‐chelates. The purpose of this review is to consolidate and update the available information on known side effects, adverse reactions, and toxicity of the Gd chelates, with particular emphasis on the potential mechanisms of NSF. J. Magn. Reson. Imaging 2007;26:1190–1197. © 2007 Wiley‐Liss, Inc.
Detection of DNA double‐strand breaks using γh2AX after MRI exposure at 3 Tesla: An in vitro study
Authors: Schwenzer Nina F. , Bantleon Rüdiger , Maurer Brigitte , Kehlbach Rainer , Schraml Christina , Claussen Claus D. , Rodegerdts Enno
Published: October 2007

Purpose

To evaluate the effects of the static magnetic field and typical imaging sequences of a high‐field magnetic resonance scanner (3 Tesla) on the induction of double‐strand breaks (DSBs) in two different human cell lines.

Materials and Methods

Human promyelocytic leukemia cells (HL‐60) and human acute myeloid leukemia cells (KG‐1a) were exposed to the static magnetic field alone and to turbo spin‐echo (TSE) and gradient‐echo (GE) sequences. Flow cytometry was used to quantify γH2AX (serine 139 phosphorylated form of histone H2AX) expression of antibody‐stained cells as a marker for deoxyribonucleic acid (DNA) DSBs one hour and 24 hours after magnetic field exposure. X‐ray–treated cells were used as positive control.

Results

Neither exposure to the static magnetic field alone nor to the applied imaging sequences showed significant differences in γH2AX expression between exposed and sham‐exposed cells. X‐ray–treated cells as positive control showed a significant increase in γH2AX expression.

Conclusion

The static magnetic field alone and MRI sequences at 3 Tesla have no effect on the induction of DSBs in HL‐60 and KG‐1a cells. J. Magn. Reson. Imaging 2007;26:1308–1314. © 2007 Wiley‐Liss, Inc.
Measurements of occupational exposure to switched gradient and spatially‐varying magnetic fields in areas adjacent to 1.5T clinical MRI systems
Authors: Riches Sophie F. , Collins David J. , Charles‐Edwards Geoffrey D. , Shafford Jonathan C. , Cole Jonathan , Keevil Stephen F. , Leach Martin O.
Published: October 2007

Purpose

To determine if magnetic field exposure close to two clinical 1.5T magnetic resonance imaging (MRI) scanners during image acquisition and when moving in the spatially‐varying static magnetic field is compliant with European Union (EU) Directive 2004/40/EC (the Directive).

Materials and Methods

Using commercially available equipment we measured the magnetic flux density around the scanners during two clinical pulse sequences. The data was compared with frequency‐dependent limits that will limit occupational exposure following transposition of the Directive into national law in 2008. The static magnetic field was measured around the scanners and the exposure from movement within this field was simulated.

Results

The whole‐body exposure experienced when standing close to the face of the magnet exceeds the limits in the Directive on the two scanners tested during clinical sequences. Simulation of movement toward the scanner shows that speeds must be restricted to 1/5 of normal walking speed to comply with the Directive.

Conclusion

EU Directive 2004/40/EC will have a major impact on the current use and future development of MRI due to limitations on exposure to time‐varying gradient fields and movement within the spatially‐varying static field. This will make interventional work impossible and routine MRI use impracticable in Europe. J. Magn. Reson. Imaging 2007;26:1346–1352. © 2007 Wiley‐Liss, Inc.
Standards for medical devices in MRI: Present and future
Authors: Woods Terry O.
Published: October 2007

The purpose of this review is to define the current standards addressing safety of medical devices in MRI and to describe ongoing standards development efforts. The American Society for Testing and Materials (ASTM International) began developing standard test methods for determining the MR safety of medical devices in MRI in 1997. To date, five ASTM standards addressing testing and marking medical devices and other items for use in the MR environment have been published. International Standards Organization (ISO) 14630, the general requirements standard for nonactive surgical implants, is currently being revised to include information about MR safety of passive implants and to reference the ASTM standards. To address the unique safety issues of active implants, and in particular, active implants with leads, like pacemakers and neurostimulators, a joint working group between ISO TC150/SC6 on active implants and International Electrotechnical Commission (IEC) SC 62B MT40 on magnetic resonance equipment for medical diagnosis is working to develop a technical specification for active implantable medical devices (AIMDs) in MRI. While much progress has been made, work still needs to continue to develop a complete body of test methods to allow the evaluation of the safety of medical devices in the MR environment. J. Magn. Reson. Imaging 2007;26:1186–1189. © 2007 Wiley‐Liss, Inc.
A prototype RF dosimeter for independent measurement of the average specific absorption rate (SAR) during MRI
Authors: Stralka John P , Bottomley Paul A
Published: October 2007

Purpose

To develop a scanner‐independent dosimeter for measuring the average radio frequency (RF) power deposition and specific absorption rates (SAR) for human MRI exposure.

Materials and Methods

A prototype dosimeter has a transducer with orthogonal conducting loops surrounding a small signal‐generating MRI sample. The loops contain resistors whose values are adjusted to load the scanner's MRI coils equivalent to an average head or body during MRI. The scanner adjusts its power output to normal levels during setup, using the MRI sample. Following calibration, the total power and average SAR deposited in the transducer are measured from the root‐mean‐square (rms) power induced in the transducer during MRI.

Results

A 1.5 Tesla head transducer was adjusted to elicit the same load as the average of nine adult volunteers. Once adjusted, the transducer loads other head coils the same as the head does. The dosimeter is calibrated at up to 20 W total deposited power and 4.5 W/kg SAR in the average head, with about 5% accuracy.

Conclusion

This dosimeter provides a simple portable means of measuring the power deposited in a body‐equivalent sample load, independent of the scanner. Further work will develop SAR dosimetry for the torso and for higher fields. J. Magn. Reson. Imaging 2007;26:1296–1302. © 2007 Wiley‐Liss, Inc.
Pooled analyses of effects on visual and visuomotor performance from exposure to magnetic stray fields from MRI scanners: Application of the Bayesian framework
Authors: de Vocht Frank , Glover Paul , Engels Hans , Kromhout Hans
Published: October 2007

Purpose

To pool measurement data from individual studies on acute and temporal neurobehavioral effects of stray fields and reanalyze these using a Bayesian framework.

Materials and Methods

Data from tests assessing effects of exposure to stray fields (<1600 mT) from MRI systems (1.5–7.0 T) on visuomotor and visual sensory systems collected in three relatively small case‐crossover studies of volunteers seated in the magnet stray field were analyzed together using hierarchical regression models. Bayesian prior distributions were specified such that a priori an association with electromagnetic field (EMF) exposure was absent, and were updated with measurement data into posterior distributions.

Results

The posterior distributions suggested that visuomotor speed, but not precision, was affected by exposure (−0.2% to −0.7% per 100 mT). The visual contrast threshold at stronger contrasts also increased with increased EMF exposure (−1%/100 mT).

Conclusion

Using a Bayesian framework with conservative priors appeared to be an effective technique to assess subtle effects of exposure to stray magnetic fields. The posterior distributions were dominated by the observed data, which provides additional compelling evidence that the visuomotor domain and the visual contrast threshold level are negatively affected in the presence of stray fields of 1.5‐T to 7.0‐T MRI systems. J. Magn. Reson. Imaging 2007;26:1255–1260. © 2007 Wiley‐Liss, Inc.
Do static or time‐varying magnetic fields in magnetic resonance imaging (3.0 T) alter protein–gene expression?—A study on human embryonic lung fibroblasts
Authors: Schwenzer Nina F. , Bantleon Rüdiger , Maurer Brigitte , Kehlbach Rainer , Schraml Christina , Claussen Claus D. , Rodegerdts Enno
Published: October 2007

Purpose

To evaluate the influence of magnetic resonance imaging (MRI) on gene expression in embryonic human lung fibroblasts (Hel 299).

Materials and Methods

The cells were exposed to the static magnetic field and to a turbo spin‐echo sequence of an MR scanner at 3.0 Tesla. An MR group (exposed) and a control group (sham‐exposed) were set up using a special MR‐compatible incubation system. The exposure time was two hours. Gene expression profiles were studied using a complementary deoxyribonucleic acid (cDNA) microarray containing 498 known genes involved in transcription, intracellular transport, structure/junction/adhesion or extracellular matrix, signaling, host defense, energetics, metabolism, cell shape, and death.

Results

No changes in gene expression were found in either group (exposed or sham‐exposed cells) at the end of a two‐hour exposure for any of the 498 tested protein genes.

Conclusion

The results suggest that MRI has no influence on protein–gene expression in eugenic human lung cells. J. Magn. Reson. Imaging 2007;26:1210–1215. © 2007 Wiley‐Liss, Inc.
A novel method for measuring the torque on implantable cardiovascular devices in MR static fields
Authors: D'Avenio Giuseppe , Canese Rossella , Podo Franca , Grigioni Mauro
Published: October 2007

Purpose

To propose a novel quantitative method for measuring the torque acting on mechanical heart valve prostheses subjected to a high static magnetic field in a MR scanner.

Materials and Methods

Torque measurements were performed with a torsion balance, implemented with a copper wire. The reaction torque exerted by the static magnetic field on the device was measured optically from the deflection angle of a laser beam spot on a graduate scale. Three different types of mechanical valves (two bileaflet and one monoleaflet) were tested at different locations of a small bore 4.7 tesla system.

Results

The method proved to be particularly sensitive (detectability limit lower than 10−6 N · m), reliable and yielded quantitative reproducible results. The equivalent force of the torque measured for the three valves was at least 103‐fold lower than the force exerted by the beating heart.

Conclusion

The proposed method provides a quantitative evaluation of the torque induced on prosthetic device by a MR scanner operating at high magnetic field. J. Magn. Reson. Imaging 2007;26:1368–1374. © 2007 Wiley‐Liss, Inc.
Patient safety concept for multichannel transmit coils
Authors: Seifert Frank , Wübbeler Gerd , Junge Sven , Ittermann Bernd , Rinneberg Herbert
Published: October 2007

Purpose

To propose and illustrate a safety concept for multichannel transmit coils in MRI based on finite‐differences time‐domain (FDTD) simulations and validated by measurements.

Materials and Methods

FDTD simulations of specific absorption rate (SAR) distributions in a cylindrical agarose phantom were carried out for various radio frequency (RF) driving conditions of a four‐element coil array. Additionally, maps of transmit amplitude, signal phase, and temperature rise following RF heating were measured by MRI.

Results

Quantitative agreement was achieved between simulated and measured field distributions, thus validating the numerical modeling. When applying the same RF power to each element of the coil array but systematically varying the RF phase between its elements, the maximum of the SAR distribution was found to vary by a factor of about 15.

Conclusion

Our results demonstrate that current RF safety approaches are inadequate to deal with the new challenge of multichannel transmit coils. We propose a new concept based on a systematic investigation of the parameter space for RF phases and amplitudes. In this way the driving conditions generating the highest local SAR values per unit power can be identified and appropriately considered in the RF safety concept of a given MRI system. J. Magn. Reson. Imaging 2007;26:1315–1321. © 2007 Wiley‐Liss, Inc.
Observation of changes in neural activity due to the static magnetic field of an MRI scanner
Authors: Toyomaki Atsuhito , Yamamoto Toru
Published: October 2007

Purpose

To clarify whether a strong static magnetic field affects brain activity such as arousal level.

Materials and Methods

We compared the electroencephalography (EEG) inside an MRI scanner in the presence/absence of the static magnetic field in two different arousal levels of task and rest conditions. Cardiac‐related pulsations of head and blood flow induce an electric voltage at each EEG electrode in a static magnetic field. This induced voltage overlaps with the intrinsic EEG signal and becomes a large confounding factor. To extract the information of the intrinsic EEG from the contaminated EEG data measured in a static magnetic field, we developed a new analysis method.

Results

No significant difference was observed in the intrinsic EEG in the absence of a magnetic field, whereas in the presence of the static magnetic field, the theta frequency band of the intrinsic EEG increased, especially during the task condition, but other frequency bands did not change.

Conclusion

Our results demonstrate that a static magnetic field affects brain activity. J. Magn. Reson. Imaging 2007;26:1216–1221. © 2007 Wiley‐Liss, Inc.
Occupational exposure to static and time‐varying gradient magnetic fields in MR units
Authors: Bradley Jill K. , Nyekiova Matilda , Price David L. , Lopez Lindsay D'jon , Crawley Therese
Published: October 2007

Purpose

To assess exposure of MR staff to static and time‐varying gradient magnetic fields by direct measurement and questionnaire and to compare these to the action values and exposure limits stated in published guidance.

Materials and Methods

Instantaneous and time‐averaged exposure to static magnetic fields were measured on clinical and research MR scanners. A questionnaire was sent to 100 clinical MR centers to estimate the average static field exposure. Instantaneous measurements of the time‐varying magnetic field were conducted on a 1.5T conventional and a 0.6T open‐bore MR system.

Results

The 24‐hour time‐averaged static field exposure was measured to be 1.8 ± 1 mT and the questionnaire produced a 24‐hour time‐average of 2.3 mT. The maximum static field strength recorded during patient set up was 554 mT. Time‐varying gradient field exposure was found to exceed the action values up to 30 cm from the bore entrance or magnet rim.

Conclusion

The time‐varying gradient field exposure limit is the only limit to be exceeded. The time‐averaged static field exposure to staff was found to be 100 times lower than the recommended guidelines. J. Magn. Reson. Imaging 2007;26:1204–1209. © 2007 Wiley‐Liss, Inc.
British association of MR radiographers (BAMRR) safety survey 2005: Potential impact of European Union (EU) Physical Agents Directive (PAD) on electromagnetic fields (EMF)
Authors: Moore Elizabeth A. , Scurr Erica D.
Published: October 2007

Purpose

To measure the potential impact on clinical MRI practice in the UK of the European Union (EU) Physical Agents Directive (PAD) on electromagnetic fields (EMF). There is evidence that the exposure limit values contained in the PAD will make it impossible for members of staff to stand close to the magnet during scanning; currently this is common practice in order to provide care and support for vulnerable patients. Interventional MR procedures will also be impossible.

Materials and Methods

Members of the British Association of MR Radiographers (BAMRR) were sent a questionnaire to assess the impact of the PAD and related safety issues.

Results

A total of 25% of responding sites have at least one sedation/general anesthesia (GA) session per week, while only 3% reported any interventional practice. A total of 29% of respondents reported that operators give a bolus injection by hand during contrast‐enhanced magnetic resonance angiography (CE‐MRA) scans. Overall it is estimated that 3% of all MR examinations in the UK are performed with a staff member in the magnet room. Some of these examinations would be impossible without staff in the room and it would be necessary for patients to have computed tomography (CT) instead of MRI. The additional radiation dose of substituting CT for MRI is estimated at 224 man‐sievert per year.

Conclusion

While the financial costs of implementing the PAD (EMF) are relatively low, the social costs are difficult to quantify but potentially more alarming. J. Magn. Reson. Imaging 2007;26:1303–1307. © 2007 Wiley‐Liss, Inc.
Measurement of visual evoked potential during and after periods of pulsed magnetic field exposure
Authors: Glover Paul M. , Eldeghaidy Sally , Mistry Tejal R. , Gowland Penny A.
Published: October 2007

Purpose

To study the effect of switched magnetic fields used in MR scanners on the visual evoked potential (VEP) in human subjects.

Materials and Methods

We have used an MRI gradient coil, remote from an MRI magnet to produce a time‐varying magnetic field (0.5 kHz, peak field ∼8.7 T/second) in the human brain without the confounding effects of static field exposure or accompanying acoustic noise. The VEP response to a 2‐Hz reversal, 8 × 8 checkerboard, occupying 20 degrees of the visual field was recorded from occipital locations O1 and O2. VEP recordings were made every five minutes before, during, and after a 10‐minute magnetic field exposure period for seven subjects.

Results

In contradiction to studies previously reported in the literature for fields of 50 Hz and 60 mT, no significant effects on the peak amplitude or latency of the VEP P100 O1 and O2 responses were found.

Conclusion

Switched magnetic fields of a level and frequency comparable to those used in MRI do not have a significant effect on primary retinal or visual processing. J. Magn. Reson. Imaging 2007;26:1353–1356. © 2007 Wiley‐Liss, Inc.
Tissue warming and regulatory responses induced by radio frequency energy deposition on a whole‐body 3‐Tesla magnetic resonance imager
Authors: Boss Andreas , Graf Hansjörg , Berger Alexander , Lauer Ulrike A. , Wojtczyk Hanne , Claussen Claus D. , Schick Fritz
Published: October 2007

Purpose

To quantify the B1‐field induced tissue warming on a 3T‐whole‐body scanner, to test whether the patient is able to sense the temperature change, and to evaluate whether the imaging procedure constitutes a significant cardiovascular stress.

Materials and Methods

A total of 18 volunteers were divided into three equal groups for 3.0T MRI of the pelvis, the head, or the knee. An imaging protocol operating at first level mode was applied, allowing radio frequency (RF) irradiation up to the legal specific absorption rate (SAR) limits. An identical placebo protocol with active gradient switching but without RF transmission was used. Temperature changes were measured with a fiber‐optic thermometer (FO) and an infrared camera (IR).

Results

Temperature differences to the placebo were highest for imaging of the pelvis (FO: ΔT = 0.88 ± 0.13°C, IR: ΔT = 1.01 ± 0.15°C) as compared to the head (FO: ΔT = 0.46 ± 0.12°C, IR: ΔT = 0.47 ± 0.10°C) and the knee (FO: ΔT = 0.33 ± 0.11°C, IR: ΔT = 0.37 ± 0.09°C). The volunteers were able to discriminate between imaging and placebo for pelvic (P < 0.0001) and head (P = 0.0005) imaging but not for knee imaging (P = 0.209). No changes in heart rate or blood pressure were detected.

Conclusion

The 3.0T MRI in the first operational mode may lead to measurable and perceptible thermal energy deposition. However, it may be regarded as safe concerning the thermoregulatory cardiovascular stress. J. Magn. Reson. Imaging 2007;26:1334–1339. © 2007 Wiley‐Liss, Inc.
Heating of metallic implants and instruments induced by gradient switching in a 1.5‐Tesla whole‐body unit
Authors: Graf Hansjörg , Steidle Günter , Schick Fritz
Published: October 2007

Purpose

To examine gradient switching–induced heating of metallic parts.

Materials and Methods

Copper and titanium frames and sheets (≈50 × 50 mm2, 1.5 mm thick, frame width = 3 mm) surrounded by air were positioned in the scanner perpendicular to the static field horizontally 20 cm off‐center. During the execution of a sequence (three‐dimensional [3D] true fast imaging with steady precession [True‐FISP], TR = 6.4 msec) exploiting the gradient capabilities (maximum gradient = 40 mT/m, maximum slew rate = 200 T/m/second), heating was measured with an infrared camera. Radio frequency (RF) amplitude was set to zero volts. Heating of a copper frame with a narrowing to 1 mm over 20 mm at one side was examined in air and in addition surrounded by several liters of gelled saline using fiber‐optic thermography. Further heating studies were performed using an artificial hip made of titanium, and an aluminum replica of the hip prosthesis with the same geometry.

Results

For the copper specimens, considerable heating (>10°C) in air and in gelled saline (>1.2°C) could be observed. Heating of the titanium specimens was markedly less (≈1°C in air). For the titanium artificial hip no heating could be detected, while the rise in temperature for the aluminum replica was approximately 2.2°C.

Conclusion

Heating of more than 10°C solely due to gradient switching without any RF irradiation was demonstrated in isolated copper wire frames. Under specific conditions (high gradient duty cycle, metallic loop of sufficient inductance and low resistance, power matching) gradient switching–induced heating of conductive specimens must be considered. J. Magn. Reson. Imaging 2007;26:1328–1333. © 2007 Wiley‐Liss, Inc.