T1 signal intensity in the dentate nucleus after the administration of the macrocyclic gadolinium-based contrast agent gadoterate meglumine: An observational study.

INTRODUCTION AND AIMS: Contradictory results have been reported about hyperintensity of the globus pallidus and/or dentate nucleus on unenhanced T1-weighted magnetic resonance (MR) images after exposure to various gadolinium-based contrast agents. This change in signal intensity varies with different gadolinium-based contrast agents. We aimed to determine whether signal intensity in the dentate nucleus is increased in unenhanced T1-weighted images in patients who have undergone multiple studies with the macrocyclic gadolinium-based contrast agent gadoterate meglumine. We thoroughly reviewed the literature to corroborate our results. MATERIALS AND METHODS: We included patients who had undergone more than 10 MR studies with gadoterate meglumine. We quantitatively analyzed the signal intensity in unenhanced T1-weighted MR images measured in regions of interest placed in the dentate nucleus and the pons, and we calculated the dentate nucleus-to-pons signal intensity ratios and the differences between the ratio in the first MR study and the last MR study. We used t-tests to evaluate whether the differences between the signal intensity ratios were different from 0. We also analyzed the subgroups of patients who had been administered <15 and ≥15 doses of gadoterate meglumine. We used Pearson correlation to determine the relationships between the differences in the signal intensity ratios and the number of doses of gadoterate meglumine administered. RESULTS: The 54 patients (26 men) had received a mean of 13.8±3.47 doses (range, 10-23 doses). The difference in the dentate nucleus-pons signal intensity ratio between the first and last MR study was -0.0275±0.1917 (not significantly different from 0; p=0.2968) in the entire group, -0.0357±0.2204 (not significantly different from 0; p = 0.351 in the patients who had received <15 doses (n=34), and -0.0135±0.1332 (not significantly different from 0; p = 0.655) in those who had received ≥15 doses (n=20). Differences in signal intensity ratios did not correlate significantly with the accumulated dose of gadoterate meglumine (P = 0.9064; ρ = -0.0164 [95%]). CONCLUSIONS: Receiving more than 10 doses of gadoterate meglumine was not associated with increased signal intensity in the dentate nucleus.

Intensidad de la señal en T1 en el núcleo dentado tras la administración del agente de contraste con gadolinio macrocíclico gadoterato de meglumina: un estudio observacional / T1 signal intensity in the dentate nucleus after the administration of the macrocyclic gadolinium-based contrast agent gadoterate meglumine: an observational study

Introducción y objetivo: Se han notificado resultados contradictorios sobre un aumento en la intensidad de la señal (IS) en las imágenes de resonancia magnética (RM) ponderadas en T1 no realzadas en el globo pálido y/o el núcleo dentado (ND) después de la exposición a varios agentes de contraste con gadolinio (ACG). Este cambio en la señal varía en función del ACG específico. Nuestro objetivo fue investigar si existe un aumento en la IS del ND en imágenes ponderadas en T1 no realzadas en pacientes sometidos a múltiples administraciones del ACG macrocíclico gadoterato de meglumina. Se realizó una revisión exhaustiva de la bibliografía para corroborar nuestros resultados. Materiales y métodos: Se incluyeron pacientes que se habían sometido a más de 10 estudios de RM con contraste y administración exclusiva de gadoterato de meglumina. Se llevó a cabo un análisis cuantitativo mediante el uso de mediciones de regiones de interés en el ND y el puente en imágenes no realzadas ponderadas en T1. Se calcularon las proporciones ND-puente y las diferencias en las proporciones entre el inicio y la última RM realizada. Se utilizó una prueba de la t de una muestra para evaluar si las diferencias en la proporción de la IS difieren de 0. Se realizó un análisis de subgrupos de pacientes con<15 y ≥15 dosis. Se utilizó el análisis de correlación de Pearson para determinar las correlaciones entre las diferencias de las proporciones de la IS y el número de administraciones del ACG.(AU)

Introduction and aims: Contradictory results have been reported about hyperintensity of the globus pallidus and/or dentate nucleus on unenhanced T1-weighted magnetic resonance (MR) images after exposure to various gadolinium-based contrast agents. This change in signal intensity varies with different gadolinium-based contrast agents. We aimed to determine whether signal intensity in the dentate nucleus is increased in unenhanced T1-weighted images in patients who have undergone multiple studies with the macrocyclic gadolinium-based contrast agent gadoterate meglumine. We thoroughly reviewed the literature to corroborate our results. Materials and methods: We included patients who had undergone more than 10 MR studies with gadoterate meglumine. We quantitatively analyzed the signal intensity in unenhanced T1-weighted MR images measured in regions of interest placed in the dentate nucleus and the pons, and we calculated the dentate nucleus-to-pons signal intensity ratios and the differences between the ratio in the first MR study and the last MR study. We used t-tests to evaluate whether the differences between the signal intensity ratios were different from 0. We also analyzed the subgroups of patients who had been administered<15 and ≥15 doses of gadoterate meglumine. We used Pearson correlation to determine the relationships between the differences in the signal intensity ratios and the number of doses of gadoterate meglumine administered.(AU)

T1 signal intensity in the dentate nucleus after the administration of the macrocyclic gadolinium-based contrast agent gadoterate meglumine: an observational study. / Intensidad de la señal en T1 en el núcleo dentado tras la administración del agente de contraste con gadolinio macrocíclico gadoterato de meglumina: un estudio observacional.

INTRODUCTION AND AIMS: Contradictory results have been reported about hyperintensity of the globus pallidus and/or dentate nucleus on unenhanced T1-weighted magnetic resonance (MR) images after exposure to various gadolinium-based contrast agents. This change in signal intensity varies with different gadolinium-based contrast agents. We aimed to determine whether signal intensity in the dentate nucleus is increased in unenhanced T1-weighted images in patients who have undergone multiple studies with the macrocyclic gadolinium-based contrast agent gadoterate meglumine. We thoroughly reviewed the literature to corroborate our results. MATERIALS AND METHODS: We included patients who had undergone more than 10 MR studies with gadoterate meglumine. We quantitatively analyzed the signal intensity in unenhanced T1-weighted MR images measured in regions of interest placed in the dentate nucleus and the pons, and we calculated the dentate nucleus-to-pons signal intensity ratios and the differences between the ratio in the first MR study and the last MR study. We used t-tests to evaluate whether the differences between the signal intensity ratios were different from 0. We also analyzed the subgroups of patients who had been administered<15 and ≥15 doses of gadoterate meglumine. We used Pearson correlation to determine the relationships between the differences in the signal intensity ratios and the number of doses of gadoterate meglumine administered. RESULTS: The 54 patients (26 men) had received a mean of 13.8±3.47 doses (range, 10-23 doses). The difference in the dentate nucleus-pons signal intensity ratio between the first and last MR study was -0.0275±0.1917 (not significantly different from 0; p=0.2968) in the entire group, -0.0357±0.2204 (not significantly different from 0; p=0.351 in the patients who had received <15 doses (n=34), and -0.0135±0.1332 (not significantly different from 0; p=0.655) in those who had received ≥15 doses (n=20). Differences in signal intensity ratios did not correlate significantly with the accumulated dose of gadoterate meglumine (P=0.9064; ρ=-0.0164 [95%]). CONCLUSIONS: Receiving more than 10 doses of gadoterate meglumine was not associated with increased signal intensity in the dentate nucleus.

The Diversity and Distribution of Wolbachia, Rhizobiales, and Ophiocordyceps Within the Widespread Neotropical Turtle Ant, Cephalotes atratus (Hymenoptera: Formicidae).

Ants are an ecologically and evolutionarily diverse group, and they harbor a wide range of symbiotic microbial communities that often greatly affect their biology. Turtle ants (genus Cephalotes) engage in mutualistic relationships with gut bacteria and are exploited by microbial parasites. Studies have shown that associations among these microbial lineages and the turtle ant hosts vary geographically. However, these studies have been limited, and thorough within-species analyses of the variation and structure of these microbial communities have yet to be conducted. The giant turtle ant, Cephalotes atratus (Linnaeus 1758), is a geographically widespread, genetically diverse Neotropical species that has been sampled extensively across its geographic range, making it ideal for analysis of microbial associations. In this study, we verified the presence, genetic variation, and geographic patterns at the individual, colony, and population level of three microbial groups associated with the giant turtle ant: Wolbachia, a genus of facultative bacteria which are often parasitic, affecting host reproduction; Rhizobiales, a mutualistic order of bacteria hypothesized to be an obligate nutritional symbiont in turtle ants; and Ophiocordyceps, a genus of endoparasitic fungi infecting many arthropod species by manipulating their behavior for fungal reproduction. In this study, we found varying degrees of prevalence for two distantly related genotypes (haplogroups) of Wolbachia and high degree of prevalence of Rhizobiales across colonies with little genetic variation. In addition, we found low occurrence of Ophiocordyceps. This study highlights a key first step in understanding the diversity, distribution, and prevalence of the microbial community of C. atratus.

Self-efficacy profile in daily activities: Children at risk and with developmental coordination disorder.

AIM: The objectives of this study were: 1) to compare the perceptions of self-efficacy in the daily activities (self-care, schoolwork, and leisure) of boys and girls with DCD, or in children at risk for DCD (r-DCD) and in typical children (TD); 2) to investigate if a self-efficacy assessment could be a support tool in the establishment of children with the DCD profile. METHODS: Children between 6 to 8 years old (N=115: 35 with DCD, 40 with r-DCD, 40 with TD) were assessed using the Movement Assessment Battery for Children (MABC-2) and the Perceived Efficacy and Goal Setting System (PEGS). A two-way MANOVA showed significant effect for the perceived self-efficacy group. RESULTS: The Bonferroni post hoc test indicated that in the self-care, schoolwork, leisure, and general self-efficacy dimensions the children with DCD presented significantly lower scores compared to children with r-DCD and TD (p < 0.001). A similar result was observed for r-DCD children in comparison with TD (p < 0.001). The discriminate analysis showed that perceived self-efficacy in leisure activities was the variable that most contributed to the discrimination of the groups. CONCLUSION: The judgment of children with DCD and r-DCD on the effectiveness of the execution of schoolwork and leisure activities may have been influenced by the motor skill difficulties showed by the children.

Receptor-mediated PLGA nanoparticles for glioblastoma multiforme treatment.

Glioblastoma multiforme is the most lethal type of brain tumor and the established therapy only extends patients survival to approximately one year. Its first-line treatment is based on of chemotherapy with the alkylating agent temozolomide (TMZ). As many other chemotherapeutic drugs, TMZ presents several limitations as high toxicity and low bioavailability. The delivery of TMZ using poly(lactic-co-glycolic acid) nanoparticles is proposed in this work. Stable nanoparticles functionalized with a OX26 type monoclonal antibody for transferrin receptor were developed, targeting the glioblastoma tumor cells, since these cells are known for overexpressing this receptor. The release profile of TMZ from the nanoparticles was studied mimicking physiological conditions, and targeted cellular internalization was also investigated. Two glioblastoma cell lines - U215 and U87 - were used to evaluate the in vitro cytotoxicity of the drug, showing that the prepared nanocarriers enhance the anticancer activity of TMZ. The functionalization with the monoclonal antibody for transferrin receptor proved to be advantageous in enhancing the cellular internalization in glioblastoma cells.

Genetic control of number of flowers and pod set in common bean.

This article aimed to study the genetic control of some flowers and pod set of common bean and to verify if its estimate varies with environmental conditions and gene pool. A complete diallel was used among six lines, but no reciprocal ones. The treatments were evaluated in three harvests/generations - F2, F3, and F4 - in 2015/2016, in a randomized complete block design with four replications. The plot consisted of 3 lines with 4 m. In the center line, a receptacle to collect the aborted flowers/pods was placed. The traits considered were the number of flowers/plant (N), the percentage of pod set (V), and the production of grain/plant (W). A joint diallel analysis was performed, and the correlations between N, V, ​​and W were estimated. N was 31.9 on average, and V was 40.4%. The average of Mesoamerican parents, for N and V, was higher than for Andean. Specific combining ability explained most of the variation for N, evidencing predominance of dominance effect. For V, specific combining ability was slightly lower than general combining ability, indicating additive loci and also dominance effects. These two traits were very influenced by environment and should be considered a strategy for greater grain yield stability of common bean.

Genetic progress estimation strategy for upright common bean plants using recurrent selection.

Common bean producers in Brazil tend to grow plants as upright as possible. Because the control of this trait involves a large number of genes, recurrent selection (RS) is the best approach for successful plant improvement. Because plant architecture (PA) is evaluated using scores and usually has high heritability, RS for PA is performed through visual selection in generation S0. The aim of the present study was to evaluate selection progress and investigate whether this progress varies with the number of selected progenies or the generation evaluated. In addition, the effect of RS for the upright (PA) trait on progeny grain yield (GY) was investigated. Data of progenies S0:3 and S0:4 of the fifth, eighth, and twelfth cycles were used. A combined analysis of variance was performed using the adjusted means of the 47 best progenies from each generation and cycle, using two control cultivars as reference. A joint analysis of the two generations used during the evaluation of progenies for the different cycles was also performed. The genetic progress (GP) was estimated by fitting a linear regression equation to the relationship between the adjusted mean of each cycle and the number of cycles. We found that RS was efficient and the estimated GP of the evaluated progenies was 4.5%. Based on the GY heritability estimates, in more advanced generation selection for GY can be successfully performed on progenies. Thus, the selection already done for PA in F2 could be associated to the most productive progenies.

Genotype x environment interaction and its implication in identification of common bean populations with high calcium content.

The common bean is a food with high mineral content. Of the various types of beans cultivated in Brazil, carioca type beans are the most consumed. The aim of this study was to identify promising common bean populations with an emphasis toward the selection of carioca type bean lines with high calcium content. We also aimed to verify whether and how the crop season and the genotype (parental line and hybrid populations) x crop season interaction affect calcium content. A group of 3 lines of good agronomic characteristics were crossed with a group of 4 lines with high calcium content in a 3 x 4 partial diallel design. Great variability was identified among both the parental lines and the hybrid populations derived from the diallel crosses among the parental lines. We found significant interactions between crop season and both parental line and hybrid population. In the diallel analysis, only the general combining ability was significant, explaining 89.4% of the sum of squares. The RP-1, CNF05, and Safira lines exhibited the greatest calcium contents and a positive GCA. RP-1 is a line that presents high calcium content, in addition to having carioca type beans and an upright plant with high yield. To further increase the calcium content of the RP-1 line, we suggest crossing it with the CNF05 and Safira lines. Although there was a hybrid population x crop season interaction, it was possible to identify populations that performed best in terms of calcium content in both crop seasons.

Geometry applied to breeding common beans (Phaseolus vulgaris).

The primary components of common bean (Phaseolus vulgaris) grain yield (W) are the number of pods (X), the number of grains per pod (Y), and the weight of the grains (Z). In 1964, Grafius suggested using geometry in plant breeding; W corresponds to the volume of a parallelepiped with three axes, X, Y, and Z. Because the cube is the largest parallelepiped by volume, maximum yield is obtained when the relative contributions of X, Y, and Z are the same. We evaluated individual plants of a 'Talismã' x 'L.59583' cross in two sowing periods. The sum of squares of deviations from the ideal plant (GI), i.e., the plant in which the X, Y, and Z contributions were the same, was estimated. Mean and variance genetic components, and genetic and phenotypic correlations between the characteristics were also estimated. Good concordance was observed in the magnitude and direction of the genetic and phenotypic correlation estimates of the paired characteristics. However, a low GI heritability (h(2)r = 6.7%) indicated that success due to selection should be small. Ninety-four progenies of 'Pérola' x 'ESAL 686' crosses were also evaluated, where X, Y, Z, and W were obtained and GI was estimated. The h(2) estimate was higher, but still low (h(2) = 39.0%). Therefore, the selection of individuals to obtain plants in which the X, Y, and Z products tend to the cube is unfeasible, because the sums of X, Y, and Z vary between individuals. In addition, the GI h2 value was low.

T1 Signal-Intensity Increase in the Dentate Nucleus after Multiple Exposures to Gadodiamide: Intraindividual Comparison between 2 Commonly Used Sequences.

BACKGROUND AND PURPOSE: Different T1-weighted sequences have been used for qualitative and quantitative evaluation of T1 signal intensity related to gadolinium deposition in the dentate nucleus in patients who underwent several enhanced MR imaging studies. Our purpose was to perform an intraindividual qualitative and quantitative comparison between T1-weighted spin-echo and 3D magnetization-prepared rapid acquisition of gradient echo sequences in patients who had multiple exposures to gadodiamide. MATERIALS AND METHODS: Our retrospectively selected population included 18 patients who underwent at least 3 administrations of gadodiamide and had a baseline and a final MR imaging performed with both T1-weighted sequences. Qualitative and quantitative analyses were independently performed. Dentate nucleus/middle cerebellar peduncle signal-intensity ratios and signal changes between the baseline and final examinations were compared by using the Wilcoxon signed rank test. Correlation between quantitative and qualitative evaluations was assessed by using a polyserial correlation test. RESULTS: The differences between the 2 sequences for both baseline and last examination dentate nucleus/middle cerebellar peduncle ratios were statistically significant (P = .008 and P = .006, respectively); however, the signal-intensity changes of the ratios with time were not (P = .64). The correlation between the qualitative and quantitative analysis was very strong (near-perfect) (r = 0.9) for MPRAGE and strong (r = 0.63) for spin-echo sequences. CONCLUSIONS: T1-weighted spin-echo and MPRAGE sequences cannot be used interchangeably for qualitative or quantitative analysis of signal intensity in the dentate nucleus in patients who received gadodiamide. Baseline and final examination ratios should be evaluated across time by using the same sequence. Qualitative analysis performed with MPRAGE correlated better with quantitative analysis and may offer advantages over spin-echo sequences for research purposes.

Molecular Profile of the Brazilian Weaver Ant Camponotus textor Forel (Hymenoptera, Formicidae).

Camponotus textor Forel is, to date, the only weaver ant recorded from Brazil, and all existing studies on the species are restricted to describing its weaving and nesting behaviors. The aim of this work is to establish the molecular profile of the species. We sampled eight different colonies by sequencing mitochondrial genes (COI, transfer DNA (tRNA), and an intergenic spacer) and the nuclear gene 28S ribosomal DNA (rDNA). We then assessed haplotype diversity and also analyzed distribution patterns of this species based on the correlation between genetic and geographic distances. Our results provide an additional tool for species identification by identifying new regions that can be used as molecular markers for barcoding (such as the intergenic spacer (IGS) and tRNA-Leu). In addition, the phylogenetic analysis revealed that C. textor has features that could be associated with deep population divergences. We identified a wide range of mitotypes and three distinct groups, suggesting a possible reduction of gene flow between colonies.

Epistasis in intra- and inter-gene pool crosses of the common bean.

Epistasis has been shown to have an important role in the genetic control of several quantitative traits in the common bean. This study aimed to investigate the occurrence of epistasis in intra- and inter-pool gene crosses of the common bean. Four elite lines adapted to Brazilian conditions were used as parents, two from the Andean gene pool (ESAL 686; BRS Radiante) and two from the Mesoamerican gene pool (BRSMG Majestoso; BRS Valente). Four F2 populations were obtained: "A" (ESAL 686 x BRS Radiante), "B" (BRSMG Majestoso x BRS Valente), "C" (BRS Radiante x BRSMG Majestoso), and "D" (BRS Valente x ESAL 686). A random sample of F2 plants from each population was backcrossed to parents and F1 individuals, according to the triple test cross. Three types of progenies from each population were evaluated in contiguous trials. Seed yield and 100-seed weight were evaluated. Dominance genetic variance was predominant in most cases. However, the estimates of genetic variance may be biased by the occurrence of linkage disequilibrium and epistasis. Epistasis was detected for both traits; however, the occurrence differed among the populations and between the two traits. The results of this study reinforce the hypothesis that epistasis is present in the genetic control of traits in the common bean and suggest that the phenomenon is more frequent in inter-gene pool crosses than in intra-gene pool crosses.

Non-parametric approach to the study of phenotypic stability.

The aim of this study was to undertake the theoretical derivations of non-parametric methods, which use linear regressions based on rank order, for stability analyses. These methods were extension different parametric methods used for stability analyses and the result was compared with a standard non-parametric method. Intensive computational methods (e.g., bootstrap and permutation) were applied, and data from the plant-breeding program of the Biology Department of UFLA (Minas Gerais, Brazil) were used to illustrate and compare the tests. The non-parametric stability methods were effective for the evaluation of phenotypic stability. In the presence of variance heterogeneity, the non-parametric methods exhibited greater power of discrimination when determining the phenotypic stability of genotypes.

Gadolinium-Based Contrast Agent Accumulation and Toxicity: An Update.

In current practice, gadolinium-based contrast agents have been considered safe when used at clinically recommended doses in patients without severe renal insufficiency. The causal relationship between gadolinium-based contrast agents and nephrogenic systemic fibrosis in patients with renal insufficiency resulted in new policies regarding the administration of these agents. After an effective screening of patients with renal disease by performing either unenhanced or reduced-dose-enhanced studies in these patients and by using the most stable contrast agents, nephrogenic systemic fibrosis has been largely eliminated since 2009. Evidence of in vivo gadolinium deposition in bone tissue in patients with normal renal function is well-established, but recent literature showing that gadolinium might also deposit in the brain in patients with intact blood-brain barriers caught many individuals in the imaging community by surprise. The purpose of this review was to summarize the literature on gadolinium-based contrast agents, tying together information on agent stability and animal and human studies, and to emphasize that low-stability agents are the ones most often associated with brain deposition.

Evidence levels for neuroradiology articles: low agreement among raters.

BACKGROUND AND PURPOSE: Because evidence-based articles are difficult to recognize among the large volume of publications available, some journals have adopted evidence-based medicine criteria to classify their articles. Our purpose was to determine whether an evidence-based medicine classification used by a subspecialty-imaging journal allowed consistent categorization of levels of evidence among different raters. MATERIALS AND METHODS: One hundred consecutive articles in the American Journal of Neuroradiology were classified as to their level of evidence by the 2 original manuscript reviewers, and their interobserver agreement was calculated. After publication, abstracts and titles were reprinted and independently ranked by 3 different radiologists at 2 different time points. Interobserver and intraobserver agreement was calculated for these radiologists. RESULTS: The interobserver agreement between the original manuscript reviewers was -0.2283 (standard error = 0.0000; 95% CI, -0.2283 to -0.2283); among the 3 postpublication reviewers for the first evaluation, it was 0.1899 (standard error = 0.0383; 95% CI, 0.1149-0.2649); and for the second evaluation, performed 3 months later, it was 0.1145 (standard error = 0.0350; 95% CI, 0.0460-0.1831). The intraobserver agreement was 0.2344 (standard error = 0.0660; 95% CI, 0.1050-0.3639), 0.3826 (standard error = 0.0738; 95% CI, 0.2379-0.5272), and 0.6611 (standard error = 0.0656; 95% CI, 0.5325-0.7898) for the 3 postpublication evaluators, respectively. These results show no-to-fair interreviewer agreement and a tendency to slight intrareviewer agreement. CONCLUSIONS: Inconsistent use of evidence-based criteria by different raters limits their utility when attempting to classify neuroradiology-related articles.

Genetic control of inflorescence in common bean.

The number of pods per common bean plant is a primary component of grain yield, which depends on the number of flowers produced and on the flower set. Thus, a larger number of flowers per plant would increase yield. Lines with inflorescences that had a large number of flowers compared to common bean plants now under cultivation were identified. We analyzed the genetic control of this trait and its association with grain yield. The cultivar BRSMG Talismã was crossed with 2 lines, L.59583 and L.59692, which have a large number of flowers. The F1, F2, and F3 generations were obtained. These generations were assessed together with the parents in a randomized block experimental design with 2 replications. The traits assessed included length of inflorescence, number of pods per inflorescence, number of pods per plant, number of grains per plant, 100-grain weight, and grain yield per plant. Mean genetic components and variance were estimated. The traits length of inflorescence and number of pods per inflorescence exhibited genetic control with predominance that showed an additive effect. In the 2 crosses, genetic control of grain yield and of its primary components showed that the allelic interaction of dominance was high. The wide variability in the traits assessed may be used to increase yield of the common bean plant by increasing the number of flowers on the plant.

Comparación de una secuencia en 3D con eco de gradiente potenciada en T1 con 3 factores de reducción de imagen en paralelo diferentes, en apnea y respiración libre, utilizando una bobina de 32 canales a 1,5T. Estudio preliminar / A comparison of a T1 weighted 3D gradient-echo sequence with three different parallel imaging reduction factors, breath hold and free breathing, using a 32 channel coil at 1.5T. A preliminary study

Objetivo. Analizar si el aumento de la resolución temporal utilizando mayores factores de reducción (FR) de imagen en paralelo (IP), tanto en apnea como con respiración libre, utilizando una secuencia 3D con eco de gradiente (EG) potenciada en T1, sin contraste y una bobina de múltiples elementos (phased array) de 32 canales, proporciona una calidad de imagen diagnóstica, con posibilidad de ser aplicada en pacientes que no puedan cooperar para mantener la apnea. Material y métodos. Se incluyeron en el estudio 9 sujetos sanos (5 mujeres y 4 varones; rango de edad: 20-49; media: 36 años). Se les realizó un estudio de RM abdominal con secuencias 3D EG en un equipo de 1,5T con bobina de múltiples elementos (phased-array) de 32 canales con FR de imagen en paralelo de 2, 4 y 6, en apnea y con respiración libre. Dos revisores evaluaron retrospectiva y cualitativamente la calidad de imagen de las secuencias, la magnitud de los artefactos, incluyendo los artefactos de movimiento por reducción de señales, de solapamiento (aliasing), de granulado de los píxeles y la heterogeneidad de la señal. Los resultados se compararon mediante la prueba de Wilcoxon de los rangos con signo y la corrección de Bonferroni para comparaciones múltiples. Resultados. La adquisición en apnea proporcionó mejor calidad de imagen y menos artefactos que la adquisición con respiración libre. La tasa de artefactos fue mayor para FR más altos. La mejor calidad se obtuvo con secuencias en apnea con un FR = 2. Un FR = 4 presentó tasas menores pero diagnósticas (p = 0,004). La severidad de los artefactos, en especial el granulado de los píxeles (p = 0,004), hizo que las secuencias con un FR = 6 no fueran diagnósticas. Ninguna de las secuencias obtenidas con respiración libre fue diagnóstica. Conclusión. Las secuencias obtenidas en apnea con un FR = 2 presentaron una calidad de imagen excelente, y aquellas con un FR = 4 presentaron una calidad buena y potencialmente se pueden aplicar en pacientes poco colaboradores. Ninguna de las secuencias obtenidas con respiración libre se consideró diagnóstica (AU)

Purpose. To investigate whether increasing temporal resolution with higher parallel imaging (PI) reduction factors (RF) in both breath-hold and free breathing approaches, using a non-contrast T1-weighted 3D gradient echo (GRE) sequence and a 32-channel phased array coil, permits diagnostic image quality, with potential application in patients unable to cooperate with breath-hold requirements. Materials and methods. The 9 healthy subjects (5 females and 4 males; age range was 20-49, mean 36 yrs) were recruited. A 3D GRE MR imaging of the abdomen was performed on 1.5T MR system using a 32-element phased-array torso coil with PI RFs of 2, 4 and 6, breath hold and free breathing. Two reviewers retrospectively qualitatively evaluated all sequences for image quality, extent of artifacts, including motion, truncation, aliasing, pixel graininess and signal heterogeneity. The results were compared using Wilcoxon signed rank and a Bonferroni adjustment was applied for multiple comparisons. Results. Image quality and extent of artifacts were better with breath hold than with free breathing acquisitions. The rate of artifacts increased with higher RF. The best quality was acquired with breath hold sequence using RF=2. RF=4 had lower but diagnostic rates (P=.004). The severity of artifacts, mainly pixel graininess (P=.004), rendered sequences with RF=6 non-diagnostic. All sequences were non-diagnostic in free breathing acquisitions. Conclusion. Breath hold sequences with RF=2 had excellent quality and RF=4 had good quality and may be potentially used in partially cooperative patients. None of the sequences was considered diagnostic in free breathing acquisitions (AU)

Experimental strategies in performing value for cultivation and use experiments for the tobacco crop II: dimension of the experimental network.

In this study, we aimed to establish strategies for value for cultivation and use (VCU) experiments for the tobacco crop in the southern region of Brazil with respect to the number of environments used to assess tobacco lines. Trials of the Virginia (18 sites) and Burley (17 sites) varietal groups were conducted in the three states of the southern region of Brazil in the 2009-2010 crop season. The experiment was conducted in a completely randomized block design with four replications of 10 tobacco lines in the final stage of evaluation; the plots had 6 rows of 7 plants each, or 42 plants per plot. The cured leaf weight per hectare (kg/ha) was obtained. To evaluate stability, the ecovalence and additive main effects and multiplicative interaction models were adopted. In addition, joint analyses of variance were carried out considering different site numbers by simulating resampling. The site number ranged from 2 to 17 or 2 to 16, depending on the varietal group, and sites were selected at random without replacement. The process was repeated 2000 times for each number of sites. All analyses were performed using the R software. The results are very similar for both varietal groups. There is no advantage of using a large number of sites for VCU experiments in the southern region of Brazil because many sites contributed little to the interaction or did not discriminate the tobacco lines. Furthermore, the classification of the best lines is very similar to that obtained in the total number of evaluated sites.