bluuebunny/crossref_metadata_2025_split huggingface dataset:
Compensation of slice profile mismatch in combined spin‐ and gradient‐echo echo‐planar imaging pulse sequences
Authors: Schmiedeskamp Heiko , Straka Matus , Bammer Roland 
Published: August 2011

AbstractCombined acquisition of gradient‐echo and spin‐echo signals in MRI time series reveals additional information for perfusion‐weighted imaging and functional MRI because of differences in the sensitivity of gradient‐echo and spin‐echo measurements to the properties of the underlying vascular architecture. The acquisition of multiple echo trains within one time frame facilitates the simultaneous estimation of the transversal relaxation parameters R2 and R. However, the simultaneous estimation of these parameters tends to be incorrect in the presence of slice profile mismatches between signal excitation and subsequent refocusing pulses. It is shown here that improvements in pulse design reduced R2 and R estimation errors. Further improvements were achieved by augmented parameter estimation through the introduction of an additional parameter δ to correct for discordances in slice profiles to facilitate more quantitative measurements. Moreover, the analysis of time‐resolved acquisitions revealed that the temporal stability of R2 estimates could be increased with improved pulse design, counteracting low contrast‐to‐noise ratios in spin‐echo‐based perfusion and functional MRI. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
A quantitative pressure and microbubble‐size dependence study of focused ultrasound‐induced blood‐brain barrier opening reversibility in vivo using MRI
Authors: Samiotaki Gesthimani , Vlachos Fotios , Tung Yao‐Sheng , Konofagou Elisa E. 
Published: August 2011

AbstractFocused ultrasound in conjunction with the systemic administration of microbubbles has been shown to open the blood‐brain barrier (BBB) selectively, noninvasively and reversibly. In this study, we investigate the dependence of the BBB opening's reversibility on the peak‐rarefactional pressure (0.30–0.60 MPa) as well as the microbubble size (diameters of 1–2, 4–5, or 6–8 μm) in mice using contrast‐enhanced T1‐weighted (CE‐T1) MR images (9.4 T). Volumetric measurements of the diffusion of Gd‐DTPA‐BMA into the brain parenchyma were used for the quantification of the BBB‐opened region on the day of sonication and up to 5 days thereafter. The volume of opening was found to increase with both pressure and microbubble diameter. The duration required for closing was found to be proportional to the volume of opening on the day of opening, and ranged from 24 h, for the smaller microbubbles, to 5 days at high peak‐rarefactional pressures. Overall, larger bubbles did not show significant differences. Also, the extent of BBB opening decreased radially towards the focal region until the BBB's integrity was restored. In the cases where histological damage was detected, it was found to be highly correlated with hyperintensity on the precontrast T1 images. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Understanding quantitative pulsed CEST in the presence of MT
Authors: Desmond Kimberly L. , Stanisz Greg J. 
Published: August 2011

AbstractPhantom experiments in agar and ammonium chloride were performed to evaluate a three‐pool model of magnetization transfer and chemical exchange saturation transfer (CEST) in a pulsed saturation transfer experiment. The utility of the pulsed CEST method was demonstrated by varying the pH of the phantoms and observing the effect upon the CEST spectra both with and without the solid agar (the magnetization transfer pool), while fitting the spectra to the Bloch equation model with exchange. Pulsed CEST could be used to robustly quantify parameters related to CEST, including the exchange rate constant describing proton exchange with free water and the concentration of exchanging protons. Furthermore, the exchange rate constant and the CEST pool offset frequency of the ammonium chloride remained unchanged in the presence of a magnetization transfer pool. The logarithm of the fitted exchange rate constant was linearly related to pH: this relationship was maintained in the presence of magnetization transfer. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Parallel magnetic resonance imaging using localized receive arrays with sinc interpolation (PILARS)
Authors: Feng Shuo , Ji Jim 
Published: August 2011

AbstractLarge arrays with localized coil sensitivity make it possible to use parallel imaging to significantly accelerate MR imaging speed. However, the need for auto calibration signals limits the actual acceleration factors achievable with large arrays. This paper presents a novel method for parallel imaging with large arrays. The method uses Sinc kernels for k‐space data interpolation that only requires one phase parameter to be estimated using a small size of calibration signals. Simulations based on synthetic array data and phantom experiments show that the new method can achieve higher actual acceleration factors with comparable reconstruction quality. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Time‐interleaved acquisition of modes: An analysis of SAR and image contrast implications
Authors: Orzada S. , Maderwald S. , Poser B. A. , Johst S. , Kannengiesser S. , Ladd M. E. , Bitz A. K. 
Published: August 2011

AbstractAs the magnetic field strength and therefore the operational frequency in MRI are increased, the radiofrequency wavelength approaches the size of the human head/body, resulting in wave effects which cause signal decreases and dropouts. Especially, whole‐body imaging at 7 T and higher is therefore challenging. Recently, an acquisition scheme called time‐interleaved acquisition of modes has been proposed to tackle the inhomogeneity problems in high‐field MRI. The basic premise is to excite two (or more) different B modes using static radiofrequency shimming in an interleaved acquisition, where the complementary radiofrequency patterns of the two modes can be exploited to improve overall signal homogeneity. In this work, the impact of time‐interleaved acquisition of mode on image contrast as well as on time‐averaged specific absorption rate is addressed in detail. Time‐interleaved acquisition of mode is superior in B homogeneity compared with conventional radiofrequency shimming while being highly specific absorption rate efficient. Time‐interleaved acquisition of modes can enable almost homogeneous high‐field imaging throughout the entire field of view in PD, T2, and T2*‐weighted imaging and, if a specified homogeneity criterion is met, in T1‐weighted imaging as well. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
A two‐stage approach for measuring vascular water exchange and arterial transit time by diffusion‐weighted perfusion MRI
Authors: St. Lawrence Keith S. , Owen Daron , Wang Danny J. J. 
Published: August 2011

AbstractChanges in the exchange rate of water across the blood‐brain barrier, denoted kw, may indicate blood‐brain barrier dysfunction before the leakage of large‐molecule contrast agents is observable. A previously proposed approach for measuring kw is to use diffusion‐weighted arterial spin labeling to measure the vascular and tissue fractions of labeled water, because the vascular‐to‐tissue ratio is related to kw. However, the accuracy of diffusion‐weighted arterial spin labeling is affected by arterial blood contributions and the arterial transit time (τa). To address these issues, a two‐stage method is proposed that uses combinations of diffusion‐weighted gradient strengths and post‐labeling delays to measure both τa and kw. The feasibility of this method was assessed by acquiring diffusion‐weighted arterial spin labeling data from seven healthy volunteers. Repeat measurements and Monte Carlo simulations were conducted to determine the precision and accuracy of the kw estimates. Average grey and white matter kw values were 110 ± 18 and 126 ± 18 min−1, respectively, which compare favorably to blood‐brain barrier permeability measurements obtained with positron emission tomography. The intrasubject coefficient of variation was 26% ± 23% in grey matter and 21% ± 17% in white matter, indicating that reproducible kw measurements can be obtained. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
A comparison of two methods for estimating refill adherence to statins in Sweden: the RARE project
Authors: Lesén Eva , Sandström Tatiana Z , Carlsten Anders , Jönsson Anna K , Mårdby Ann‐Charlotte , Sundell Karolina Andersson 
Published: August 2011

ABSTRACTPurposeTo analyse and compare refill adherence to statins estimated with two different methods with a focus on sensitivity to definitions.MethodsIndividuals aged 18–85 years who filled a statin prescription for the first time in 1.5 years during 1 January–30 June 2007 were followed until emigration or death or until 2 years after their first statin purchase. The data were collected via linkage between the Swedish Prescribed Drug Register, the National Patient Register and the Total Population Register. Days' supply was estimated based on amount dispensed and prescribed dosage. Refill adherence was estimated with the continuous measure of medication acquisition (CMA) and the maximum gap method (cut‐off 45 days). The impact of altering definitions, for example, regarding hospitalisations, length of observation period and management of overlapping supply, was analysed.ResultsThe study included 36 661 individuals (mean age 64 years, 47% women). The median proportion of days with statins was 95%, and 76% were classified as adherent with a cut‐off at ≥80% with CMA. With the maximum gap method, 65% were adherent. Disregarding hospitalisations did not alter the results. Emigration or death at least one year after statin initiation was associated with a lower adherence with both methods, and a shorter observation period and adding overlapping supply to the subsequent prescription increased the adherence estimates.ConclusionsThe choice of method and definitions, particularly regarding the management of overlapping supplies and the length of observation period, has a substantial impact on estimates of refill adherence to statins. Copyright © 2011 John Wiley & Sons, Ltd.
National changes in oral antipsychotic treatment for people with schizophrenia in primary care between 1998 and 2007 in the United Kingdom
Authors: Prah Philip , Petersen Irene , Nazareth Irwin , Walters Kate , Osborn David 
Published: August 2011

ABSTRACTPurposeThere is little information regarding antipsychotic prescription in primary care, despite general practitioners issuing most ongoing prescriptions. We sought to investigate changes in oral antipsychotic prescriptions in primary care from January 1998 to December 2007.MethodsWe conducted a cohort analysis of patients diagnosed with schizophrenia in primary care in the United Kingdom, using The Health Improvement Network database, to determine the proportions of prescribed antipsychotics. We investigated the yearly estimates of the overall time patients spent in treatment with any antipsychotic as well as the class of antipsychotic and individual antipsychotic agent.ResultsWe found that in any one calendar year, approximately 24% of patients previously prescribed antipsychotics do not receive treatment in primary care. Over the last decade, people with schizophrenia have been prescribed antipsychotic treatment for greater proportions of time. The greatest increase was observed in older women. The overall increase in treatment time can be attributed to the increased prescription of second‐generation antipsychotics (SGAs). The annual proportion of time in SGA treatment increased from 16.6% to 51.2% within the study period, whereas time in first‐generation antipsychotic treatment reduced from 37.1% to 15.0%. Overall, olanzapine, risperidone and sulpiride were prescribed for the longest periods of time.ConclusionsOver the last decade, the general practice of prescribing SGAs has increased whereas first‐generation antipsychotic prescriptions have declined. By 2007, patients with schizophrenia were prescribed antipsychotics for greater proportions of time, perhaps reflecting the greater acceptability of SGAs or a shift from secondary to primary care prescription. Copyright © 2011 John Wiley & Sons, Ltd.
Insecticide selectivity to two species of Trichogramma in three different hosts, as determined by IOBC/WPRS methodology
Authors: Goulart Roberto M , Volpe Haroldo XL , Vacari Alessandra M , Thuler Robson T , De Bortoli Sergio A 
Published: August 2011

AbstractBACKGROUND: The use of Trichogramma species is a potential key strategy in integrated pest management. However, its effectiveness depends on the use of chemicals that do not interfere with parasitism and parasite population growth. Here, a study was made of the effects of synthetic insecticides on Trichogramma pretiosum and Trichogramma exiguum in different hosts (Ephestia kuehniella, Plutella xylostella and Spodoptera frugiperda) and the influence of International Organisation for Biological Control (IOBC/WPRS) methodology in selectivity studies using different Trichogramma species. The insecticides used were commercial formulations (triflumuron at a concentration of 0.2 mL L−1 water, etofenprox at a concentration of 0.47 mL L−1 water and endosulfan at a concentration of 7.5 mL L−1 water); the control treatment consisted of distilled water. Eggs attached to cardboard cards were offered to parasitoids inside glass cages. Parasitised eggs, parasitism and adult emergence rates and parasitism reduction were evaluated.RESULTS: Endosulfan and etofenprox, classified as class‐4 toxic products, were extremely toxic to the parasitoids. Triflumuron, classified as a non‐toxic product, was selective to the parasitoids in eggs of all hosts.CONCLUSIONS: The methodology recommended by IOBC/WPRS influenced results regarding the use of different species of parasitoids, and the use of a single parasitoid species in their experiment is questionable. Copyright © 2011 Society of Chemical Industry
Cross‐resistance patterns and fitness in fufenozide‐resistant diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae)
Authors: Sun Jingyan , Liang Pei , Gao Xiwu 
Published: August 2011

AbstractBACKGROUND: Fufenozide is a novel non‐steroidal ecdysone agonist with good efficacy against diamondback moth (DBM), Plutella xylostella (Lepidoptera: Plutellidae). At present, it is widely applied for the control of a range of lepidopterous pests in China. This study compared the activities of fufenozide and 12 other insecticides against unselected and fufenozide‐selected strains of DBM to examine potential patterns of cross‐resistance. The relative fitness of the fufenozide‐selected strain was assessed to provide information pertinent to insecticide resistance management.RESULTS: Compared with the susceptible strain (JSS), the fufenozide‐resistant strain (JSR) showed high cross‐resistance to dibenzoylhydrazines and benzoylphenylureas, low cross‐resistance to abamectin and no cross‐resistance to organophosphates, carbamates and pyrethroids. JSR had a lower reproductive ability and a relative fitness of 0.5 compared with JSS.CONCLUSION: P. xylostella has the potential to develop resistance to fufenozide, albeit at the expense of fitness. Cross‐resistance between the same and other classes of insecticides is of concern, and should be a key consideration when implementing fufenozide‐based control strategies for this species. Copyright © 2011 Society of Chemical Industry
Acromyrmex octospinosus (Hymenoptera: Formicidae) management. Part 1: Effects of TRAMIL's insecticidal plant extracts
Authors: Boulogne Isabelle , Germosen‐Robineau Lionel , Ozier‐Lafontaine Harry , Jacoby‐Koaly Christina , Aurela Lucie , Loranger‐Merciris Gladys 
Published: August 2011

AbstractBACKGROUND: Leaf‐cutting ants are considered to be one of the most important pest species of the New World. Until now, control strategies against these leaf‐cutting ants have mainly been synthetic chemicals. The aim of the present study was to test the action of several plant extracts quoted as an example by TRAMIL participative surveys for their insecticidal properties on adult major workers of Acromyrmex octospinosus. Three tests were used to that end: contact toxicity, repellent test and ingestion bioassay. Six traditional plant uses recommended by interviewed people in surveys were tested: (1) maceration of Mammea americana fresh crushed seeds; (2) decoction of Nerium oleander fresh leaves; (3) Nerium oleander dried leaf water juice; (4) decoction of Nicotiana tabacum dried leaves; (5) Trichillia pallida dried leaf water juice; (6) decoction of Rollinia mucosa dried seeds.RESULTS: Two plant extracts with contact toxicity (Mammea americana and Nicotiana tabacum), six plant extracts with repellent activity and four plant extracts with ingestion toxicity (Mammea americana, Nicotiana tabacum and both extracts of Nerium oleander) were found.CONCLUSION: The data presented in this study showed that plant extracts cited by TRAMIL ethnopharmacological surveys have the potential to control the leaf‐cutting ant, Acromyrmex octospinosus. In particular, the Mammea americana extract, with its natural low repellent effect and its high toxicity by ingestion, and Nerium oleander extracts, with their natural delay action, are possibly the best extracts for the control of these ants. Copyright © 2011 Society of Chemical Industry
Gate hysteresis originating from atomic layer deposition of Al2O3 onto suspended carbon nanotube field‐effect transistors
Authors: Muoth Matthias , Döring Valentin , Hierold Christofer 
Published: August 2011

AbstractWhile hysteretic effects upon gate sweeps in carbon nanotube transistors can be useful for memory devices, they may hamper the reliable readout of CNFET‐based sensors. Here, we demonstrate the use of our recent hysteresis‐free, suspended nanotube transistor fabrication method to evaluate the influence of dielectric layers on gate characteristics. The atomic layer deposition of Al2O3 induced substantial hysteresis in a previously hysteresis‐free device. The extraction of electrical device properties before and after an individual processing step provides an insight into the fundamental issue of hysteresis, which is of particular relevance for nanoscale devices with electrical field‐strength enhancement due to nanoscale dimensions.magnified imageGate hysteresis appears after atomic layer deposition of Al2O3 onto the previously hysteresis‐free carbon nanotube transistor.
Performance of third‐trimester ultrasound for prediction of small‐for‐gestational‐age neonates and evaluation of contingency screening policies
Authors: Souka A. P. , Papastefanou I. , Pilalis A. , Michalitsi V. , Kassanos D. 
Published: August 2011

AbstractObjectivesTo assess the performance of third‐trimester fetal biometry and fetal Doppler studies for the prediction of small‐for‐gestational‐age (SGA) neonates, and to explore contingency strategies using a first‐trimester prediction model based on maternal and fetal parameters and third‐trimester ultrasound.MethodsThis was an observational cross‐sectional study of uncomplicated singleton pregnancies. Risk assessment for chromosomal abnormality was carried out in 4702 pregnancies using a combination of ultrasound markers (fetal nuchal translucency thickness (NT) and nasal bone assessment) and biochemistry (free beta‐human chorionic gonadotropin (β‐hCG) and pregnancy‐associated plasma protein‐A (PAPP‐A)) at 11 to 13 + 6 weeks. Maternal demographic characteristics and method of conception were recorded. Third‐trimester (30–34 weeks) fetal biometry (biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL)) and umbilical artery (UA) and middle cerebral artery Doppler studies were performed routinely in a subgroup (n = 2310). Reference ranges for birth weight were constructed using the cohort of 4702 women, and neonates were classified as small (SGA, ≤ 5th centile) or appropriate (AGA) for gestational age. First‐trimester, third‐trimester and integrated first‐ and third‐trimester prediction models for SGA were constructed using regression analysis and three different contingency strategies of rescanning in the third trimester were investigated.ResultsAccording to the areas under the receiver–operating characteristics curves (AUCs), AC (AUC = 0.85) and ultrasound‐estimated fetal weight (EFW, AUC = 0.87) were equally good predictors of SGA. The model was marginally improved by the addition of UA Doppler, smoking status and first‐trimester indices (free β‐hCG and PAPP‐A multiples of the median) (combined model, AUC = 0.88), but the difference was not statistically significant. A contingency strategy of rescanning 50% of the population in the third trimester according to the risk estimated by a first‐trimester prediction model yielded a detection rate of 79% for a 25% screen‐positive rate.ConclusionThird‐trimester ultrasound is effective in screening for SGA in uncomplicated pregnancies. The use of a contingency screening policy can reduce the need for unnecessary examinations. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.
The Extended Indication of Parotidectomy Using the Modified Facelift Incision in Benign Lesions: Retrospective Analysis of a Single Institution
Authors: Lee So‐Yoon , Koh Yoon Woo , Kim Bo Gyung , Hong Hyun Jun , Jeong Jun Hui , Choi Eun Chang 
Published: August 2011

AbstractBackgroundRecently, the modified facelift incision (FLI) has gained increasing popularity for its cosmetic benefits in parotidectomy. However, many surgeons remain concerned with the adequacy of the exposure and are unwilling to use the FLI for anterior or superior tumors of the parotid gland because these tumors are closer to the superficially positioned facial nerve branch. To evaluate the changing trends in parotidectomy incisions for benign lesions at a single institute, and to compare the surgical outcomes between the modified Blair incision (BI) and FLI, and determine the adequacy and possible indications or limitations of the FLI, especially for tumors located in the anterior or superior parotid gland.Materials and methodsRetrospective study analyzed 357 patients who had various benign parotid diseases and underwent parotidectomy at Severance Hospital between January 2005 and December 2009. Revisions or recurrences and histologically confirmed malignancies were excluded. Tumor location was divided into superficial and deep lobes. The superficial lobe was subdivided into anterior, superior, inferior, and middle portions. Patients’ profiles, surgical outcomes, and cosmetic satisfaction score on a scale of 0 (extremely dissatisfied) to 10 (extremely satisfied) were compared.ResultsIn all, 344 patients underwent BI or FLI. The FLI was performed increasingly each year. For anterior (n = 58) or superior tumors (n = 32), there was no significant difference between the type of incision and tumor size or complications. No facial nerve palsy occurred in either group. For deep‐lobe tumors (n = 67), the mean tumor size was significantly larger in the BI group (p = 0.025). There was a significant difference between facial nerve palsy and tumor size (p < 0.001) but no significant difference between facial nerve palsy and tumor location (p = 0.145) or the type of incision (p = 0.530). The mean scar satisfaction score was significantly higher in the FLI group (p <0.001). There was a positive correlation between the scar and deep hollow satisfaction score (Pearson coefficient of correlation = 0.547; p < 0.001)ConclusionsThe modified facelift incision is feasible for most benign parotid lesions regardless of tumor location, even for anterior or superior tumors. Using the modified facelift incision may be extended with a surgeon’s accumulated experience, but for a large deep‐lobe tumor, the modified Blair incision is still considered useful.