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1.
Microb Biotechnol ; 17(1): e14371, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38064205

RESUMO

Saprophytic fungi are able to catabolize many plant-derived aromatics, including, for example, gallate. The catabolism of gallate in fungi is assumed to depend on the five main central pathways, i.e., of the central intermediates' catechol, protocatechuate, hydroxyquinol, homogentisate and gentisate, but a definitive demonstration is lacking. To shed light on this process, we analysed the transcriptional reprogramming of the growth of Aspergillus terreus on gallate compared with acetate as the control condition. Surprisingly, the results revealed that the five main central pathways did not exhibit significant positive regulation. Instead, an in-depth analysis identified four highly expressed and upregulated genes that are part of a conserved gene cluster found in numerous species of fungi, though not in Aspergilli. The cluster comprises a monooxygenase gene and a fumarylacetoacetate hydrolase-like gene, which are recognized as key components of catabolic pathways responsible for aromatic compound degradation. The other two genes encode proteins with no reported enzymatic activities. Through functional analyses of gene deletion mutants in Aspergillus nidulans, the conserved short protein with no known domains could be linked to the conversion of the novel metabolite 5-hydroxydienelatone, whereas the DUF3500 gene likely encodes a ring-cleavage enzyme for 1,2,3,5-tetrahydroxybenzene. These significant findings establish the existence of a new 1,2,3,5-tetrahydroxybenzene central pathway for the catabolism of gallate and related compounds (e.g. 2,4,6-trihydroxybenzoate) in numerous fungi where this catabolic gene cluster was observed.


Assuntos
Fungos , Gentisatos , Fenóis , Fungos/genética
2.
medRxiv ; 2023 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-38105931

RESUMO

Development of innovative non-invasive neuroimaging methods and biomarkers are critical for studying brain disease. In this work, we have developed a methodology to characterize the frequency responses and spatial localization of oscillations and movements of cerebrospinal fluid (CSF) flow in the human brain. Using 7 Tesla human MRI and ultrafast echo-planar imaging (EPI), in-vivo images were obtained to capture CSF oscillations and movements. Physiological data was simultaneously collected and correlated with the 7T MR data. The primary components of CSF oscillations were identified using spectral analysis (with frequency bands identified around 0.3Hz, 1.2Hz and 2.4Hz) and were mapped spatially and temporally onto the MR image domain and temporally onto the physiological domain. The developed methodology shows a good consistency and repeatability (standard deviation of 0.052 and 0.078 for 0.3Hz and 1.2Hz bands respectively) in-vivo for potential brain dynamics and CSF flow and clearance studies.

3.
Cells ; 12(22)2023 11 20.
Artigo em Inglês | MEDLINE | ID: mdl-37998397

RESUMO

Bardet-Biedl syndrome (BBS) is an archetypal ciliopathy caused by dysfunction of primary cilia. BBS affects multiple tissues, including the kidney, eye and hypothalamic satiety response. Understanding pan-tissue mechanisms of pathogenesis versus those which are tissue-specific, as well as gauging their associated inter-individual variation owing to genetic background and stochastic processes, is of paramount importance in syndromology. The BBSome is a membrane-trafficking and intraflagellar transport (IFT) adaptor protein complex formed by eight BBS proteins, including BBS1, which is the most commonly mutated gene in BBS. To investigate disease pathogenesis, we generated a series of clonal renal collecting duct IMCD3 cell lines carrying defined biallelic nonsense or frameshift mutations in Bbs1, as well as a panel of matching wild-type CRISPR control clones. Using a phenotypic screen and an unbiased multi-omics approach, we note significant clonal variability for all assays, emphasising the importance of analysing panels of genetically defined clones. Our results suggest that BBS1 is required for the suppression of mesenchymal cell identities as the IMCD3 cell passage number increases. This was associated with a failure to express epithelial cell markers and tight junction formation, which was variable amongst clones. Transcriptomic analysis of hypothalamic preparations from BBS mutant mice, as well as BBS patient fibroblasts, suggested that dysregulation of epithelial-to-mesenchymal transition (EMT) genes is a general predisposing feature of BBS across tissues. Collectively, this work suggests that the dynamic stability of the BBSome is essential for the suppression of mesenchymal cell identities as epithelial cells differentiate.


Assuntos
Síndrome de Bardet-Biedl , Humanos , Camundongos , Animais , Síndrome de Bardet-Biedl/genética , Síndrome de Bardet-Biedl/metabolismo , Síndrome de Bardet-Biedl/patologia , Camundongos Knockout , Proteínas/metabolismo , Cílios/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo
4.
Artigo em Inglês | MEDLINE | ID: mdl-37107740

RESUMO

Traditionally, studies that associate air pollution with health effects relate individual pollutants to outcomes such as mortality or hospital admissions. However, models capable of analyzing the effects resulting from the atmosphere mixture are demanded. In this study, multilayer perceptron neural networks were evaluated to associate PM10, NO2, and SO2 concentrations, temperature, wind speed, and relative air humidity with cardiorespiratory mortality among the elderly in São Paulo, Brazil. Daily data from 2007 to 2019 were considered and different numbers of neurons on the hidden layer, algorithms, and a combination of activation functions were tested. The best-fitted artificial neural network (ANN) resulted in a MAPE equal to 13.46%. When individual season data were analyzed, the MAPE decreased to 11%. The most influential variables in cardiorespiratory mortality among the elderly were PM10 and NO2 concentrations. The relative humidity variable is more important during the dry season, and temperature is more important during the rainy season. The models were not subjected to the multicollinearity issue as with classical regression models. The use of ANNs to relate air quality to health outcomes is still very incipient, and this work highlights that it is a powerful tool that should be further explored.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Poluentes Ambientais , Humanos , Idoso , Poluentes Atmosféricos/análise , Poluentes Ambientais/análise , Dióxido de Nitrogênio/análise , Brasil/epidemiologia , Poluição do Ar/análise , Redes Neurais de Computação , Material Particulado/análise
5.
Case Rep Gastrointest Med ; 2023: 8635340, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36818745

RESUMO

Anisakiasis of the gastrointestinal tract is caused by the consumption of raw or undercooked seafood infected with Anisakis larvae. Penetration of Anisakis larvae into the gastrointestinal mucosa leads to severe epigastric pain, nausea, and vomiting, usually within hours of ingestion of the parasite. Suspicion for gastrointestinal Anisakiasis should be raised in patients with a compatible dietary history. Definitive diagnosis can be made by direct visualization of larvae via endoscopic examination. Although symptoms are self-limiting, the removal of larvae by gastroscopy can hasten relief of symptoms. There are a large number of cases of gastric anisakiasis reported from Japan, Korea, and Western Europe, where it is customary to consume raw fish. Cases reported from the United States are less common, and given the nonspecific symptoms of anisakiasis, the diagnosis can be missed. We report a patient who presented with gastroesophageal reflux disease like symptoms that started after ingesting raw fish. He was found by esophagogastroduodenoscopy to have white, filiform worms penetrating into the wall of his stomach, consistent with a diagnosis of gastric anisakiasis.

6.
Echocardiography ; 40(3): 252-258, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36597560

RESUMO

INTRODUCTION: Pneumopericardium is a dreaded complication in esophageal carcinoma. CASE DESCRIPTION: We report a case of a 62 year old patient with past history of esophageal cancer with pneumopericardium, without hemodynamic compromise. Admission echocardiogram that revealed a pneumopericadium with the presence of the "swirling bubbles" and the "air gap" sign. A small esophagopericardial fistula was postulated as the cause of the pneumopericardium. He underwent esophageal stent placement with almost complete resolution of the pneumopericardium. DISCUSSION: Pneumopericardium is usually a sign of marked clinical deterioration in neoplasia and leads to patients' death few weeks. Here we presented a case, in which a more fortunate and unusual outcome happened. CASE DESCRIPTION: We present a case of a 62 year old patient, with a past history of esophageal cancer with pulmonary metastases undergoing palliative chemotherapy treatment and with two palliative esophageal stents. Other past medical history included active hepatitis B, arterial hypertension and dyslipidaemia. He was an ex smoker of 80 pack-year units.


Assuntos
Neoplasias Esofágicas , Pneumopericárdio , Humanos , Masculino , Pessoa de Meia-Idade , Fístula Esofágica/complicações , Neoplasias Esofágicas/complicações , Pericárdio , Pneumopericárdio/etiologia , Stents/efeitos adversos
8.
Sensors (Basel) ; 22(20)2022 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-36298371

RESUMO

The Zero Trust concept is being adopted in information technology (IT) deployments, while human users remain to be the main risk for operational technology (OT) deployments. This article proposes to enhance the new Modbus/TCP Security protocol with authentication and authorization functions that guarantee security against intentional unauthorized access. It aims to comply with the principle of never trusting the person who is accessing the network before carrying out a security check. Two functions are tested and used in order to build an access control method that is based on a username and a password for human users with knowledge of industrial automation control systems (IACS), using simple means, low motivation, and few resources. A man-in-the-middle (MITM) component was added in order to intermediate the client and the server communication and to validate these functions. The proposed scenario was implemented using the Node-RED programming platform. The tests implementing the functions and the access control method through the Node-RED software have proven their potential and their applicability.


Assuntos
Segurança Computacional , Telemedicina , Humanos , Confidencialidade , Software
9.
J Med Internet Res ; 24(9): e39452, 2022 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-36178720

RESUMO

BACKGROUND: American Academy of Sleep Medicine guidelines suggest that clinical prediction algorithms can be used to screen patients with obstructive sleep apnea (OSA) without replacing polysomnography, the gold standard. OBJECTIVE: We aimed to identify, gather, and analyze existing machine learning approaches that are being used for disease screening in adult patients with suspected OSA. METHODS: We searched the MEDLINE, Scopus, and ISI Web of Knowledge databases to evaluate the validity of different machine learning techniques, with polysomnography as the gold standard outcome measure and used the Prediction Model Risk of Bias Assessment Tool (Kleijnen Systematic Reviews Ltd) to assess risk of bias and applicability of each included study. RESULTS: Our search retrieved 5479 articles, of which 63 (1.15%) articles were included. We found 23 studies performing diagnostic model development alone, 26 with added internal validation, and 14 applying the clinical prediction algorithm to an independent sample (although not all reporting the most common discrimination metrics, sensitivity or specificity). Logistic regression was applied in 35 studies, linear regression in 16, support vector machine in 9, neural networks in 8, decision trees in 6, and Bayesian networks in 4. Random forest, discriminant analysis, classification and regression tree, and nomogram were each performed in 2 studies, whereas Pearson correlation, adaptive neuro-fuzzy inference system, artificial immune recognition system, genetic algorithm, supersparse linear integer models, and k-nearest neighbors algorithm were each performed in 1 study. The best area under the receiver operating curve was 0.98 (0.96-0.99) for age, waist circumference, Epworth Somnolence Scale score, and oxygen saturation as predictors in a logistic regression. CONCLUSIONS: Although high values were obtained, they still lacked external validation results in large cohorts and a standard OSA criteria definition. TRIAL REGISTRATION: PROSPERO CRD42021221339; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=221339.


Assuntos
Apneia Obstrutiva do Sono , Adulto , Teorema de Bayes , Humanos , Aprendizado de Máquina , Redes Neurais de Computação , Polissonografia/métodos , Apneia Obstrutiva do Sono/diagnóstico
10.
Int J Mol Sci ; 23(15)2022 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-35955863

RESUMO

Advances in research have boosted therapy development for congenital disorders of glycosylation (CDG), a group of rare genetic disorders affecting protein and lipid glycosylation and glycosylphosphatidylinositol anchor biosynthesis. The (re)use of known drugs for novel medical purposes, known as drug repositioning, is growing for both common and rare disorders. The latest innovation concerns the rational search for repositioned molecules which also benefits from artificial intelligence (AI). Compared to traditional methods, drug repositioning accelerates the overall drug discovery process while saving costs. This is particularly valuable for rare diseases. AI tools have proven their worth in diagnosis, in disease classification and characterization, and ultimately in therapy discovery in rare diseases. The availability of biomarkers and reliable disease models is critical for research and development of new drugs, especially for rare and heterogeneous diseases such as CDG. This work reviews the literature related to repositioned drugs for CDG, discovered by serendipity or through a systemic approach. Recent advances in biomarkers and disease models are also outlined as well as stakeholders' views on AI for therapy discovery in CDG.


Assuntos
Defeitos Congênitos da Glicosilação , Inteligência Artificial , Biomarcadores , Defeitos Congênitos da Glicosilação/genética , Reposicionamento de Medicamentos , Humanos , Doenças Raras
11.
J Eng Sci Med Diagn Ther ; 5(2): 021002, 2022 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-35833206

RESUMO

As machine learning is used to make strides in medical diagnostics, few methods provide heuristics from which human doctors can learn directly. This work introduces a method for leveraging human observable structures, such as macroscale vascular formations, for producing assessments of medical conditions with relatively few training cases, and uncovering patterns that are potential diagnostic aids. The approach draws on shape grammars, a rule-based technique, pioneered in design and architecture, and accelerated through a recursive subgraph mining algorithm. The distribution of rule instances in the data from which they are induced is then used as an intermediary representation enabling common classification and anomaly detection approaches to identify indicative rules with relatively small data sets. The method is applied to seven-tesla time-of-flight angiography MRI (n = 54) of human brain vasculature. The data were segmented and induced to generate representative grammar rules. Ensembles of rules were isolated to implicate vascular conditions reliably. This application demonstrates the power of automated structured intermediary representations for assessing nuanced biological form relationships, and the strength of shape grammars, in particular for identifying indicative patterns in complex vascular networks.

12.
Pharmaceutics ; 14(7)2022 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-35890283

RESUMO

The need for new therapeutic approaches for triple-negative breast cancer is a clinically relevant problem that needs to be solved. Using a multi-targeting approach to enhance cancer cell uptake, we synthesized a new family of ruthenium(II) organometallic complexes envisaging simultaneous active and passive targeting, using biotin and polylactide (PLA), respectively. All compounds with the general formula, [Ru(η5-CpR)(P)(2,2'-bipy-4,4'-PLA-biotin)][CF3SO3], where R is -H or -CH3 and P is P(C6H5)3, P(C6H4F)3 or P(C6H4OCH3)3, were tested against triple-negative breast cancer cells MDA-MB-231 showing IC50 values between 2.3-14.6 µM, much better than cisplatin, a classical chemotherapeutic drug, in the same experimental conditions. We selected compound 1 (where R is H and P is P(C6H5)3), for further studies as it was the one showing the best biological effect. In a competitive assay with biotin, we showed that cell uptake via SMVT receptors seems to be the main transport route into the cells for this compound, validating the strategy of including biotin in the design of the compound. The effects of the compound on the hallmarks of cancer show that the compound leads to apoptosis, interferes with proliferation by affecting the formation of cell colonies in a dose-dependent manner and disrupts the cell cytoskeleton. Preliminary in vivo assays in N: NIH(S)II-nu/nu mice show that the concentrations of compound 1 used in this experiment (maximum 4 mg/kg) are safe to use in vivo, although some signs of liver toxicity are already found. In addition, the new compound shows a tendency to control tumor growth, although not significantly. In sum, we showed that compound 1 shows promising anti-cancer effects, bringing a new avenue for triple-negative breast cancer therapy.

13.
Case Rep Gastrointest Med ; 2022: 5703407, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35669380

RESUMO

Malignancies of the small intestine are rare. Signet-ring cell carcinoma (SRCC) is one of the rarest forms of adenocarcinoma that can arise in the small intestines. We present a case of a patient who originally presented with abdominal pain and radiographic findings suggestive of ileal congestion. The ileal biopsy specimens were nonspecific, and the patient began a trial of corticosteroid treatment for suspected Crohn's disease. A repeat colonoscopy yielded biopsies that were positive for malignancy. The patient then underwent an exploratory laparotomy which led to the diagnosis of SRCC. Given their similar presentations and the extreme rarity of this unusual malignancy, it can be difficult to differentiate between new-onset Crohn's disease and SRCC. A review of the literature was conducted to provide us with an improved understanding of previously documented cases of SRCC.

14.
Polymers (Basel) ; 13(7)2021 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-33805231

RESUMO

Combining organic and inorganic components at a nanoscale is an effective way to obtain high performance coating materials with excellent chemical and physical properties. This review focuses on recent approaches to prepare hybrid nanostructured waterborne coating materials combining the mechanical properties and versatility of silica as the inorganic filler, with the flexural properties and ease of processing of the polymer matrix. We cover silica-polymer coupling agents used to link the organic and inorganic components, the formation of hybrid films from these silica-polymer nanostructures, and their different applications. These hybrid nanostructures can be used to prepare high performance functional coatings with different properties from optical transparency, to resistance to temperature, hydrophobicity, anti-corrosion, resistance to scratch, and antimicrobial activity.

15.
Sci Rep ; 11(1): 3370, 2021 02 09.
Artigo em Inglês | MEDLINE | ID: mdl-33564013

RESUMO

Recently cleared by the FDA, 7 Tesla (7 T) MRI is a rapidly growing technology that can provide higher resolution and enhanced contrast in human MRI images. However, the increased operational frequency (~ 297 MHz) hinders its full potential since it causes inhomogeneities in the images and increases the power deposition in the tissues. This work describes the optimization of an innovative radiofrequency (RF) head coil coupled design, named Tic Tac Toe, currently used in large scale human MRI scanning at 7 T; to date, this device was used in more than 1,300 neuro 7 T MRI scans. Electromagnetic simulations of the coil were performed using the finite-difference time-domain method. Numerical optimizations were used to combine the calculated electromagnetic fields produced by these antennas, based on the superposition principle, resulting in homogeneous magnetic field distributions at low levels of power deposition in the tissues. The simulations were validated in-vivo using the Tic Tac Toe RF head coil system on a 7 T MRI scanner.


Assuntos
Campos Eletromagnéticos , Desenho de Equipamento , Modelos Teóricos
17.
mSystems ; 6(1)2021 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-33500329

RESUMO

In fungi, salicylate catabolism was believed to proceed only through the catechol branch of the 3-oxoadipate pathway, as shown, e.g., in Aspergillus nidulans However, the observation of a transient accumulation of gentisate upon the cultivation of Aspergillus terreus in salicylate medium questions this concept. To address this, we have run a comparative analysis of the transcriptome of these two species after growth in salicylate using acetate as a control condition. The results revealed the high complexity of the salicylate metabolism in A. terreus with the concomitant positive regulation of several pathways for the catabolism of aromatic compounds. This included the unexpected joint action of two pathways-3-hydroxyanthranilate and nicotinate-possibly crucial for the catabolism of aromatics in this fungus. Importantly, the 3-hydroxyanthranilate catabolic pathway in fungi is described here for the first time, whereas new genes participating in the nicotinate metabolism are also proposed. The transcriptome analysis showed also for the two species an intimate relationship between salicylate catabolism and secondary metabolism. This study emphasizes that the central pathways for the catabolism of aromatic hydrocarbons in fungi hold many mysteries yet to be discovered.IMPORTANCE Aspergilli are versatile cell factories used in industry for the production of organic acids, enzymes, and pharmaceutical drugs. To date, bio-based production of organic acids relies on food substrates. These processes are currently being challenged to switch to renewable nonfood raw materials-a reality that should inspire the use of lignin-derived aromatic monomers. In this context, aspergilli emerge at the forefront of future bio-based approaches due to their industrial relevance and recognized prolific catabolism of aromatic compounds. Notwithstanding considerable advances in the field, there are still important knowledge gaps in the central catabolism of aromatic hydrocarbons in fungi. Here, we disclose a novel central pathway, 3-hydroxyanthranilate, defying previously established ideas on the central metabolism of the aromatic amino acid tryptophan in Ascomycota We also observe that the catabolism of the aromatic salicylate greatly activated the secondary metabolism, furthering the significance of using lignin-derived aromatic hydrocarbons as a distinctive biomass source.

18.
Environ Sci Pollut Res Int ; 28(21): 27318-27332, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33511534

RESUMO

Fabric dyeing produces high amounts of wastewater containing organic and inorganic pollutants such as reactive dyes that are the most common textile dyes employed by the industry. Three vinylsulfonic reactive dyes, blue 19 (B-19), red 198 (R-198), and yellow 15 (Y-15), were removed from effluents of industrial-like dyeing processes employing three adsorbents: (1) magnetite nanoparticles (MNP), (2) yeast waste obtained after ß-glucan removal from yeast biomass (YW), and (3) nanomagnetic composite produced from YW and MNP (YW-MNP). The non-linear kinetic pseudo-second-order and two-stage models best explained the experimental phenomena for the majority of adsorbate:adsorbent systems. The theoretical isotherm models were fitted to experimental isotherms obtained from experiments conducted with appropriated dilutions of effluents, which have a specific condition, limited by the maximum dye concentration established by the dye recipe. Thus, the saturation of adsorbents was not reached for all adsorbate:adsorbent systems. In this way, the best conditional sorption capacities (SCcond) were obtained by YW (1.7, 2.3, and 2.5 g/kg for B-19, R-198, and Y-15, respectively). The SIPS model best described all dyes adsorbed by YW, while the D-R model best described the phenomena for MNP and YW-MNP.


Assuntos
Indústria Têxtil , Poluentes Químicos da Água , Adsorção , Biomassa , Corantes , Concentração de Íons de Hidrogênio , Cinética , Saccharomyces cerevisiae , Têxteis , Termodinâmica , Poluentes Químicos da Água/análise
19.
Ophthalmic Genet ; 42(1): 71-74, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-32940091

RESUMO

BACKGROUND: Classic homocystinuria (HCU), or cystathionine beta-synthase (CBS) deficiency, is a rare inborn error of methionine metabolism. Main clinical features may include skeletal and vascular manifestations, developmental delay, intellectual disability and eye disorders. MATERIAL AND METHODS: This is an observational and retrospective study aiming at describing eye abnormalities presented by a cohort of late-diagnosed HCU patients. Data regarding ophthalmological evaluation included visual acuity, refraction, biomicroscopy, Perkins tonometry, fundus examination, retinography, biometry, ocular ultrasound, optical coherence tomography, anterior segment photography and topography. RESULTS: Ten patients with HCU (20 eyes) were included. The most frequent findings were ectopia lentis(n = 20) and myopia (n = 9). Biometry, ultrasound, OCT and topography findings were available for four patients. One patient had keratoconus; one had abnormal retinal pigmentation; and two had lens surgery scars with irregular astigmatism. CONCLUSIONS: Eye abnormalities are very frequent in late-diagnosed HCU patients. The presence of ectopia lentis should always raise the diagnostic hypothesis of HCU.


Assuntos
Astigmatismo/patologia , Ectopia do Cristalino/patologia , Homocistinúria/complicações , Miopia/patologia , Adolescente , Adulto , Astigmatismo/etiologia , Ectopia do Cristalino/etiologia , Feminino , Humanos , Masculino , Miopia/etiologia , Prognóstico , Estudos Retrospectivos , Adulto Jovem
20.
NMR Biomed ; 34(3): e4441, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33354828

RESUMO

Electromagnetic simulations are an important tool for the safety assessment of RF coils. They are a useful resource for MRI RF coil designers, especially when complemented with experimental measurements and testing using physical phantoms. Regular-shaped (spherical/cylindrical) homogeneous phantoms are the MRI standard for RF testing but are somewhat inaccurate when compared with anthropomorphic anatomies, especially at high frequencies. In this work, using a recently developed anthropomorphic heterogeneous human head phantom, studies were performed to analyze the scattering parameters (S-parameters) and the electric and magnetic field distributions using (1) the B1+ field mapping method on a 7 T human MRI scanner and (2) numerical full-wave electromagnetic simulations. All studies used the following: a recently developed six-compartment refillable 3D-printed anthropomorphic head phantom (developed from MRI scans obtained in vivo), where the phantom itself is filled in its entirety with either heterogeneous loading, or homogeneous brain or water loading, in vivo imaging, and a commercial homogeneous spherical water phantom. Our results determined that the calculated S-parameters for all the anthropomorphic head phantom models were comparable to the model that is based on the volunteer (within 17% difference of the reflection coefficient value) but differed for the commercial homogeneous spherical water phantom (within 45% difference). The experimentally measured B1+ field maps of the anthropomorphic heterogeneous and homogeneous brain head phantoms were most comparable to the in vivo measured values. The numerical simulations also show that both the anthropomorphic homogeneous water and brain phantom models were less accurate in terms of electric field intensities/distributions when compared with the segmented in-vivo-based head model and the anthropomorphic heterogeneous head phantom model. The presented data highlights the differences between the physical phantoms/phantom models, and the in vivo measurements/segmented in-vivo-based head model. The results demonstrate the usefulness of 3D-printed anthropomorphic phantoms for RF coil evaluation and testing.


Assuntos
Campos Eletromagnéticos , Imageamento por Ressonância Magnética , Imagens de Fantasmas , Eletricidade , Cabeça , Humanos , Análise Numérica Assistida por Computador
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