RF coil that minimizes electronic components while enhancing performance for rodent MRI at 7 Tesla.

This study introduces a novel volume coil design that features two slotted end-plates connected by six rungs, resembling the traditional birdcage coil. The end rings are equipped with six evenly distributed circular slots, inspired by Mansfield's cavity resonator theory, which suggests that circular slots can generate a baseline resonant frequency. One notable advantage of this proposed coil design is its reduced reliance on electronic components compared to other volume coils, making it more efficient. Additionally, the dimensions of the coil can be theoretically computed in advance, enhancing its practicality. To evaluate the performance and safety of the coil, electromagnetic field and specific absorption rate simulations were simulated using a cylindrical saline phantom and the finite element method. Furthermore, a transceiver coil prototype optimized for 7 Tesla and driven in quadrature was constructed, enabling whole-body imaging of rats. The resonant frequency of the coil prototype obtained through experimental measurements closely matched the theoretical frequency derived from Mansfield's theory. To validate the coil design, phantom images were acquired to demonstrate its viability and assess its performance. These images also served to validate the magnetic field simulations. The experimental results aligned well with the simulation findings, confirming the reliability of the proposed coil design. Importantly, the prototype coil showcased significant improvements over a similarly-sized birdcage coil, indicating its potential for enhanced performance. The noise figure was lower in the prototype versus the birdcage coil (NFbirdcage-NFslotcage= 0.7). Phantom image data were also used to compute the image SNR, giving SNRslotcage/SNRbirdcage= 34.36/24.34. By proving the feasibility of the coil design through successful rat whole-body imaging, the study provides evidence supporting its potential as a viable option for high-field MRI applications on rodents.

Induction avelumab followed by chemoimmunotherapy and maintenance versus chemotherapy alone as first-line therapy in cis-ineligible metastatic urothelial carcinoma (INDUCOMAIN): a randomized phase II study.

BACKGROUND: Platinum-based chemotherapy (ChT) has been the standard first-line treatment for metastatic urothelial carcinoma (mUC). The purpose of this study was to evaluate the use of induction avelumab followed by avelumab in combination with carboplatin-gemcitabine (carbo/gem) followed by avelumab maintenance. We tested the hypothesis that induction immunotherapy (IO) could enhance the response to ChT and prevent its detrimental effect on immune cells. MATERIALS AND METHODS: INDUCOMAIN is a multicenter, randomized, investigator-initiated, open-label phase II study evaluating the safety and efficacy of induction avelumab before carboplatin-gemcitabine-avelumab, followed by avelumab maintenance (arm A), compared to carbo/gem (arm B). Eligibility criteria included patients with mUC, no prior systemic therapy, and ineligibility for cisplatin by Galsky criteria. Patients were stratified by the presence/absence of visceral metastasis and Eastern Cooperative Oncology Group performance status 0-1 versus 2. The primary endpoint was objective response rate (ORR). Secondary endpoints included progression-free survival (PFS), overall survival (OS), and safety. RESULTS: Eighty-five patients were included and randomized to arm A (n = 42) and arm B (n = 43), respectively. ORR was similar between treatment arms: 59.5% in arm A and 53.5% in arm B (P = 0.57). Fourteen patients (33%) in arm A early progressed/died before or at first response assessment, compared to three patients (7%) in arm B. Median OS was 11.1 months in arm A and 13.2 months in arm B [hazard ratio (HR) 0.91, 95% confidence interval (CI) 0.57-1.46, P = 0.69]. Median PFS was 6.9 months in arm A versus 7.4 months in arm B (HR 0.99, 95% CI 0.61-1.60, P = 0.95). Treatment-related adverse events of grade 3-4 occurred in 70.7% of patients in arm A and in 72.1% in arm B. No predictive role of programmed death-ligand 1 expression was found. CONCLUSIONS: The hypothesis that induction avelumab could enhance the efficacy of subsequent ChT was not proven. Administering IO alone as induction before ChT is not an adequate strategy.

An oral cancer screening program in Brazil: Analysis of seven years of outcome after its implementation in the suburban cities of São Paulo.

OBJECTIVE: To describe the implementation of an oral cancer screening program at the Barretos Cancer Hospital (BCH) and present the outcome based on data obtained from 2014 to 2020. MATERIALS AND METHODS: The residents of the Regional Health District of Barretos (DRS-V) were personally invited by community health agents or nurses, and among 13,973 people, 15,222 oral examinations were carried out over the years in 18 of its municipalities. Oral examinations were performed at the Mobile Dental Unit and at the Prevention Department of the BCH. Inclusion criteria were being 35 years of age or older, having a personal history of tobacco or alcohol consumption, or having a lesion in the oral cavity found by community health agent or self-reported, regardless of age or risk factors. RESULTS AND CONCLUSION: The main result of our study was the stages of oral cancer among screen detected cases were smaller compared to cases in the hospital registry, in the state and in Brazil. Oral cancer detection rate per 1,000 oral examinations was 10.7.The early stages of oral cancer found by screening in primary care facilities or using mobile units suggest that, when organized, screening may improve the prognosis of oral cancer.

Assessment of nitrification process in a sequencing batch reactor: Modelling and genomic approach.

Nitrification of ammoniacal nitrogen (N-NH4+) to nitrate (N-NO3-) was investigated in a lab-scale sequencing batch reactor (SBR) to evaluate its efficiency. During the nitrification process the removal of N-NH4+ reached 96%, resulting in 73% formation of N-NO3-. A lineal correlation (r2 = 0.9978) was obtained between the concentration of volatile suspended solids (VSS) and the maximal N-NO3- concentration at the end of each batch cycle under stationary state. The bacterial taxons in the initial inoculum were identified, revealing a complex diverse community mainly in the two major bacterial phyla Proteobacteria and Actinobacteria. The FAPROTAX algorithm predicted the presence in the inoculum of taxa involved in relevant processes of the nitrogen metabolism, highlighting the bacterial genera Nitrospira and Nitrosomonas that are both involved in the nitrification process. A kinetic model was formulated for predicting and validating the transformation of N-NH4+, N-NO2- and N-NO3- and the removal of organic and inorganic carbon (TOC and IC, respectively). The results showed how the increase in biomass concentration slowed down the transformation to oxidised forms of nitrogen and increased denitrification in the settling and filling stages under free aeration conditions.

Boar sperm motility is modulated by CCK at a low concentration of bicarbonate under capacitation conditions.

In a previous study, our group detected the cholecystokinin (CCK) protein in the porcine oviduct. This fact, together with the involvement of CCK in the regulation of sperm protein tyrosine phosphorylation by the modulation of HCO3 - uptake (in mice and humans) suggests a role for CCK during sperm capacitation. Therefore, on the one hand, the expression of CCK receptors (CCK1R and CCK2R) on boar testes has been investigated and probed; on the other hand, boar spermatozoa (from seminal doses of 1-day and 5-day storage) were exposed to different concentrations of CCK (0-control, 25 or 50 µM) in a medium supporting capacitation supplemented with 0, 5 or 25 mmol/L of HCO3 - for 1 h at 38.5°C. Sperm motion (total and progressive motility), kinetic parameters, viability, acrosome status, and mitochondrial activity were determined. No differences between groups (0, 25 or 50 µM of CCK) were observed when HCO3 - was absent in the media (p > .05). However, the results showed that when the media was supplemented with 5 mmol/L HCO3 - in 1-day seminal dose storage, the linearity index (LIN, %), straightness index (STR, %) and oscillation index (WOB, %) (sperm kinetics parameters) increased in the presence of CCK regardless the concentration (p < .05). Nevertheless, CCK in sperm from 5-day storage only increased the WOB parameter in comparison to the control (p < .05). Furthermore, the average amplitude of the lateral displacement of the sperm head (ALH, µm) and curvilinear velocity (VCL, µm/s) decreased when CCK was present, depending on its concentration and sperm aging (1-day vs. 5-days) (p < .05). In the case of the media supporting capacitation supplemented with 25 mmol/L HCO3 - , any differences were observed except for sperm viability in the 5-day seminal doses, which increased in the 50 µM-CCK group compared to the control (p < .05). In conclusion, these data suggest an implication of CCK protein during sperm capacitation under low bicarbonate concentration increasing the sperm linear trajectory.

Disordering two-dimensional magnet-particle configurations using bidispersity.

In various types of many-particle systems, bidispersity is frequently used to avoid spontaneous ordering in particle configurations. In this study, the relation between bidispersity and disorder degree of particle configurations is investigated. By using magnetic dipole-dipole interaction, magnet particles are dispersed in a two-dimensional cell without any physical contact between them. In this magnetic system, bidispersity is introduced by mixing large and small magnets. Then, the particle system is compressed to produce a uniform particle configuration. The compressed particle configuration is analyzed by using Voronoi tessellation for evaluating the disorder degree, which strongly depends on bidispersity. Specifically, the standard deviation and skewness of the Voronoi cell area distribution are measured. As a result, we find that the peak of standard deviation is observed when the numbers of large and small particles are almost identical. Although the skewness shows a non-monotonic behavior, a zero skewness state (symmetric distribution) can be achieved when the numbers of large and small particles are identical. In this ideally random (disordered) state, the ratio between pentagonal, hexagonal, and heptagonal Voronoi cells becomes roughly identical, while hexagons are dominant under monodisperse (ordered) conditions. The relation between Voronoi cell analysis and the global bond orientational order parameter is also discussed.

Acid-base potentiometric titration using a stainless steel electrode without oxidative treatment.

An AISI 304 stainless steel laminar electrode without oxidative treatment was investigated for the potentiometric titration of hydrochloric acid with sodium hydroxide. The proposed electrode was obtained from metalworking cuttings. Scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray fluorescence spectroscopy and X-ray diffraction were used to study the surface morphology and chemical composition of the electrode. The electrode showed a sensitivity of 59.18 ± 0.37 mV/pH, which was reproducible under intermediate conditions. Potentiometric titration showed a curve with deviations from pH 9.5 with respect to the glass electrode. However, this did not affect the quantification as the jumps of the curves coincided. The endpoint was 9.25 mL for both electrodes and the hydrochloric acid concentration was 0.0845 mol/L, with a deviation of 0.0004 mol/L from the standard concentration of 0.0841 mol/L. The nonartificially oxidised electrode did not show any crystalline oxide phases, whereas after oxidation it showed semicrystalline phases of iron and chromium oxides and increased the crystallinity of the steel. Despite the low content of surface oxides, stainless steel electrodes can give a Nernstian response to pH, depending on the surface characteristics of the material. This leads to the need to calibrate any electrode prior to oxidative treatment to rule out a Nernstian response without surface modification.

Structural relaxation, dynamical arrest, and aging in soft-sphere liquids.

We investigate the structural relaxation of a soft-sphere liquid quenched isochorically (ϕ = 0.7) and instantaneously to different temperatures Tf above and below the glass transition. For this, we combine extensive Brownian dynamics simulations and theoretical calculations based on the non-equilibrium self-consistent generalized Langevin equation (NE-SCGLE) theory. The response of the liquid to a quench generally consists of a sub-linear increase of the α-relaxation time with system's age. Approaching the ideal glass-transition temperature from above (Tf > Ta), sub-aging appears as a transient process describing a broad equilibration crossover for quenches to nearly arrested states. This allows us to empirically determine an equilibration timescale teq(Tf) that becomes increasingly longer as Tf approaches Ta. For quenches inside the glass (Tf ≤ Ta), the growth rate of the structural relaxation time becomes progressively larger as Tf decreases and, unlike the equilibration scenario, τα remains evolving within the whole observation time-window. These features are consistently found in theory and simulations with remarkable semi-quantitative agreement and coincide with those revealed in a previous and complementary study [P. Mendoza-Méndez et al., Phys. Rev. 96, 022608 (2017)] that considered a sequence of quenches with fixed final temperature Tf = 0 but increasing ϕ toward the hard-sphere dynamical arrest volume fraction ϕHS a=0.582. The NE-SCGLE analysis, however, unveils various fundamental aspects of the glass transition, involving the abrupt passage from the ordinary equilibration scenario to the persistent aging effects that are characteristic of glass-forming liquids. The theory also explains that, within the time window of any experimental observation, this can only be observed as a continuous crossover.

Multi-Pulse Corona Discharges in Thunderclouds Observed in Optical and Radio Bands.

How lightning initiates inside thunderclouds remains a major puzzle of atmospheric electricity. By monitoring optical emissions from thunderstorms, the Atmosphere-Space Interactions Monitor (ASIM) onboard the International Space Station is providing new clues about lightning initiation by detecting Blue LUminous Events (BLUEs), which are manifestations of electrical corona discharges that sometimes precedes lightning. Here we combine optical and radio observations from a thunderstorm near Malaysia to uncover a new type of event containing multiple optical and radio pulses. We find that the first optical pulse coincides with a strong radio signal in the form of a Narrow Bipolar Event (NBE) but subsequent optical pulses, delayed some milliseconds, have weaker radio signals, possibly because they emanate from a horizontally oriented electrical discharges which does not trigger full-fledged lightning. Our results cast light on the differences between isolated and lightning-initiating electrical discharges.

La unión de Candida albicans y Malassezia spp. a células de piel promueve cambios de expresión en los genes responsables de la síntesis de las cadenas de heparán y condroitín sulfato / Adherence of Candida albicans and Malassezia Species to Skin Cells Induces Changes in the Expression of Genes Responsible for Heparan and Chondroitin Sulfate Chain Synthesis

Las micosis superficiales son patologías prevalentes en dermatología, causadas frecuentemente por hongos oportunistas de los géneros Candida y Malassezia. El objetivo de este trabajo es analizar, mediante qRT-PCR, la existencia de alteraciones en la expresión génica de las enzimas biosintéticas de las cadenas de glicosaminoglicanos (GAGs) tras la adhesión de dichas levaduras a líneas celulares de piel. La interacción de C.albicans y Malassezia spp. produjo las siguientes modificaciones en genes implicados en la biosíntesis del heparán y condroitín sulfato: la subexpresión de CHPF en los queratinocitos y 4 subexpresiones (EXT1, EXT2, CHSY3 y CHPF) en los fibroblastos. Las enzimas implicadas en la modificación de las cadenas de dichos GAG se ven más alteradas en los fibroblastos, produciendo 13 subexpresiones y 2 sobreexpresiones (CHST15 y CHST7). Como consecuencia, la afinidad de las cadenas de GAGs por sus ligandos puede verse afectada, pudiendo alterar su papel como receptores de microorganismos, paso clave para el inicio de su proceso infeccioso (AU)

Superficial fungal infections are common in dermatology and are often caused by opportunistic species in the Candida and Malassezia genera. The aim of this study was to analyze changes in the expression of genes coding for enzymes involved in the biosynthesis of glycosaminoglycans (GAGs) chains following the adherence of Candida and Malassezia yeasts to skin cell lines. Gene expression was analyzed using reverse transcriptase–quantitative polymerase chain reaction assays. Interactions between the yeasts and the skin cells induced the following changes in genes involved in the biosynthesis of heparan sulfate and chondroitin sulfate: downregulation of CHPF in keratinocytes and downregulation of EXT1, EXT2, CHSY3, and CHPF in fibroblasts. Adherence to fibroblasts had an even greater effect on GAG biosynthetic enzymes, inducing the downregulation of 13 genes and the upregulation of two (CHST15 and CHST7). Interactions between yeasts and skin cells might affect the binding affinity of GAG chains, possibly changing their ability to function as receptors for pathogens and interfering with a key stage at the start of infection (AU)

[Translated article] Adherence of Candida albicans and Malassezia Species to Skin Cells Induces Changes in the Expression of Genes Responsible for Heparan and Chondroitin Sulfate Chain Synthesis / La unión de Candida albicans y Malassezia spp. a células de piel promueve cambios de expresión en los genes responsables de la síntesis de las cadenas de heparán y condroitín sulfato

Superficial fungal infections are common in dermatology and are often caused by opportunistic species in the Candida and Malassezia genera. The aim of this study was to analyze changes in the expression of genes coding for enzymes involved in the biosynthesis of glycosaminoglycans (GAGs) chains following the adherence of Candida and Malassezia yeasts to skin cell lines. Gene expression was analyzed using reverse transcriptase–quantitative polymerase chain reaction assays. Interactions between the yeasts and the skin cells induced the following changes in genes involved in the biosynthesis of heparan sulfate and chondroitin sulfate: downregulation of CHPF in keratinocytes and downregulation of EXT1, EXT2, CHSY3, and CHPF in fibroblasts. Adherence to fibroblasts had an even greater effect on GAG biosynthetic enzymes, inducing the downregulation of 13 genes and the upregulation of two (CHST15 and CHST7). Interactions between yeasts and skin cells might affect the binding affinity of GAG chains, possibly changing their ability to function as receptors for pathogens and interfering with a key stage at the start of infection (AU)

Las micosis superficiales son patologías prevalentes en dermatología, causadas frecuentemente por hongos oportunistas de los géneros Candida y Malassezia. El objetivo de este trabajo es analizar, mediante qRT-PCR, la existencia de alteraciones en la expresión génica de las enzimas biosintéticas de las cadenas de glicosaminoglicanos (GAGs) tras la adhesión de dichas levaduras a líneas celulares de piel. La interacción de C.albicans y Malassezia spp. produjo las siguientes modificaciones en genes implicados en la biosíntesis del heparán y condroitín sulfato: la subexpresión de CHPF en los queratinocitos y 4 subexpresiones (EXT1, EXT2, CHSY3 y CHPF) en los fibroblastos. Las enzimas implicadas en la modificación de las cadenas de dichos GAG se ven más alteradas en los fibroblastos, produciendo 13 subexpresiones y 2 sobreexpresiones (CHST15 y CHST7). Como consecuencia, la afinidad de las cadenas de GAGs por sus ligandos puede verse afectada, pudiendo alterar su papel como receptores de microorganismos, paso clave para el inicio de su proceso infeccioso (AU)

Secondary Fast Breakdown in Narrow Bipolar Events.

The physical mechanism of Narrow bipolar events (NBEs) has been studied for decades but it still holds many mysteries. Recent observations indicate that the fast breakdown discharges that produce NBEs sometimes contain a secondary fast breakdown that propagates back in the opposite direction but this has not been fully addressed so far in electromagnetic models. In this study, we investigate fast breakdown using different approaches that employ a Modified Transmission Line with Exponential decay (MTLE) model and propose a new model, named "rebounding MTLE model," which reproduces the secondary fast breakdown current in NBEs. The model provides new insights into the physics of the fast breakdown mechanism.

Adherence of Candida albicans and Malassezia Species to Skin Cells Induces Changes in the Expression of Genes Responsible for Heparan and Chondroitin Sulfate Chain Synthesis. / La unión de Candida albicans y Malassezia spp. a células de piel promueve cambios de expresión en los genes responsables de la síntesis de las cadenas de heparán y condroitín sulfato.

Superficial fungal infections are common in dermatology and are often caused by opportunistic species in the Candida and Malassezia genera. The aim of this study was to analyze changes in the expression of genes coding for enzymes involved in the biosynthesis of glycosaminoglycans (GAGs) chains following the adherence of Candida and Malassezia yeasts to skin cell lines. Gene expression was analyzed using reverse transcriptase-quantitative polymerase chain reaction assays. Interactions between the yeasts and the skin cells induced the following changes in genes involved in the biosynthesis of heparan sulfate and chondroitin sulfate: downregulation of CHPF in keratinocytes and downregulation of EXT1, EXT2, CHSY3, and CHPF in fibroblasts. Adherence to fibroblasts had an even greater effect on GAG biosynthetic enzymes, inducing the downregulation of 13 genes and the upregulation of two (CHST15 and CHST7). Interactions between yeasts and skin cells might affect the binding affinity of GAG chains, possibly changing their ability to function as receptors for pathogens and interfering with a key stage at the start of infection.

Experimental manipulation of humidity in a cavity-nesting bird influences ectoparasites' abundance.

Climate change effects on host­parasite interactions have been poorly studied in arid or semi-arid habitats. Here, we conducted an experiment aimed to increase the temperature inside European roller Coracias garrulus nest boxes located in a semi-arid habitat on different nest-site types to look for effects on different ectoparasite abundances and nestling growth. Average nest temperature was slightly higher in heated nests than in control nests, although differences were not statistically significant. However, relative humidity was significantly lower at night in heated nests as compared to control nests. The abundance of sand flies, mites and carnid flies was significantly higher in heated, less humid, nests while biting midge abundance was significantly lower in heated nests. Other ectoparasites were not significantly affected by treatment. Relative humidity was high even in heated nests, reaching more than 60%. Sand fly abundance was higher in nests located in sandstone walls, while mite abundance was higher in isolated farmhouses. In addition, sand fly prevalence was higher in nests located in isolated farmhouses and sandstone walls. Heat treatment, nest-site type or ectoparasite abundances did not affect the nestling body mass, wing length or their growth at different nestling ages.

Kinetics and mathematical model of killer/sensitive interaction under different physicochemical conditions of must/wine: a study from a biological point of view.

Fermentation of grape must to wine is carried out by a complex microbial mixture, which also involves spoilage yeasts of wine. The latter yeasts produce organoleptic changes that cause significant economic losses to the wine industry. SO2 is traditionally used to control this spoilage populations, but because of its harmful effects on human health, biocontrol has emerged as an alternative treatment. Although studies have been carried out to select biocontroller yeasts and examine their underlying mechanisms of action, reports on their application have not been published yet. To better understand the interaction and the successful application of biocontrol, the use of mathematical models, among other methods, is important, as they facilitate the prediction of success or failure of the antagonist. The objective of the present study was to use an existing mathematical model to obtain information about the yeast's interaction assayed and to validate its predictive use under different physicochemical conditions during the wine fermentation, and eventually predict biocontrol kinetics. The mathematical model was applied to the fermentation conditions and provided information on the kinetic parameters of the biocontrol interaction and allowed interpretations about other parameters. The model was applied in the different physicochemical conditions for the biocontrol and did not fit correctly to experimental data, and therefore an improvement was proposed which was successful and presented new hypotheses.

Reliability of a computer-aided system in the evaluation of indeterminate ultrasound images of thyroid nodules.

Introduction: Computer-aided diagnostic (CAD) programs for malignancy risk stratification from ultrasound (US) imaging of thyroid nodules are being validated both experimentally and in real-world practice. However, they have not been tested for reliability in analyzing difficult or unclear images. Methods: US images with indeterminate characteristics were evaluated by five observers with different experience in US examination and by a commercial CAD program. The nodules, on which the observers widely agreed, were considered concordant and, if there was little agreement, not concordant or difficult to assess. The diagnostic performance of the readers and the CAD program was calculated and compared in both groups of nodule images. Results: In the group of concordant thyroid nodules (n = 37), the clinicians and the CAD system obtained similar levels of accuracy (77.0% vs 74.2%, respectively; P = 0.7) and no differences were found in sensitivity (SEN) (95.0% vs 87.5%, P = 0.2), specificity (SPE) (45.5 vs 49.4, respectively; P = 0.7), positive predictive value (PPV) (75.2% vs 77.7%, respectively; P = 0.8), nor negative predictive value (NPV) (85.6 vs 77.7, respectively; P = 0.3). When analyzing the non-concordant nodules (n = 43), the CAD system presented a decrease in accuracy of 4.2%, which was significantly lower than that observed by the experts (19.9%, P = 0.02). Conclusions: Clinical observers are similar to the CAD system in the US assessment of the risk of thyroid nodules. However, the AI system for thyroid nodules AmCAD-UT® showed more reliability in the analysis of unclear or misleading images.

Global Distribution of Key Features of Streamer Corona Discharges in Thunderclouds.

We present nighttime worldwide distributions of key features of Blue LUminous Events (BLUEs) detected by the Modular Multispectral Imaging Array of the Atmosphere-Space Interaction Monitor. Around 10% of all detected BLUEs exhibit an impulsive single pulse shape. The rest of BLUEs are unclear (impulsive or not) single, multiple or with ambiguous pulse shapes. BLUEs exhibit two distinct populations with peak power density <25 µWm-2 (common) and ≥25 µWm-2 (rare) with different rise times and durations. The altitude (and depth below cloud tops) zonal distribution of impulsive single pulse BLUEs indicate that they are commonly present between cloud tops and a depth of ≤4 km in the tropics and ≤1 km in mid and higher latitudes. Impulsive single pulse BLUEs in the tropics are the longest (up to ∼4 km height) and have the largest number of streamers (up to ∼3 × 109). Additionally, the analysis of BLUEs has turned out to be particularly complex due to the abundance of radiation belt particles (at high latitudes and in the South Atlantic Anomaly [SAA]) and cosmic rays all over the planet. True BLUEs can not be fully distinguished from radiation belt particles and cosmic rays unless other ground-based measurements associated with the optically detected BLUEs are available. Thus, the search algorithm of BLUEs presented in Soler et al. (2021), https://doi.org/10.1029/2021gl094657 is now completed with a new additional step that, if used, can considerably smooth the SAA shadow but can also underestimate the number of BLUEs worldwide.

External waveguide magnetic resonance imaging for lower limbs at 3 T.

PURPOSE: We report a method based on the traveling-wave MRI approach, in order to acquire images of human lower limbs with an external waveguide at 3 T. METHODS: We use a parallel-plate waveguide and an RF surface coil for reception, while a whole-body birdcage is used for transmission. The waveguide and the surface coil are located right outside the magnet, in the magnetic resonance (MR) conditional devices zone. We ran numerical simulations to investigate the B 1 field generated by the surface coil located at one of the waveguides, as well as a saline-solution phantom positioned on the opposite side (150 cm away) inside the magnet. RESULTS: We obtained phantom images by varying the distance between the coil and the phantom, in order to investigate the signal-to-noise ratio and to validate our numerical simulations. Lower limb images of a healthy volunteer were also acquired, demonstrating the viability of this approach. Standard pulse sequences were used and no physical modifications were made to the MR imager. CONCLUSIONS: These numerical and experimental results show that traveling-wave MRI can produce high-quality images with only a simple waveguide and an RF coil located outside the magnet. This can be particularly favorable when acquiring images of lower limbs requiring a larger field of view.