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Ressonância magnética na avaliação das reações periosteais; Magnetic resonance imaging in the evaluation of periosteal reactions

NOGUEIRA-BARBOSA, Marcello Henrique; SÁ, José Luiz de; TRAD, Clóvis Simão; OLIVEIRA, Rodrigo Cecílio Vieira de; ELIAS JÚNIOR, Jorge; ENGEL, Edgard Eduard; SIMÃO, Marcelo Novelino; MUGLIA, Valdair Francisco
Fonte: Colégio Brasileiro de Radiologia e Diagnóstico por Imagem Publicador: Colégio Brasileiro de Radiologia e Diagnóstico por Imagem
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
96.18%
O objetivo deste ensaio iconográfico é estimular a avaliação cuidadosa das reações periosteais nas imagens de ressonância magnética. A abordagem inicial das lesões ósseas é realizada por meio das radiografias simples e pela avaliação destas se faz a classificação das reações periosteais em subtipos clássicos. Embora a ressonância magnética seja considerada o padrão ouro para o estadiamento regional das neoplasias ósseas, seu uso no estudo das reações periosteais relacionadas às lesões ósseas focais tem sido relativamente pouco enfatizado. A revisão da literatura evidencia um modelo experimental animal de osteomielite que sugere que a ressonância magnética seja superior às outras técnicas de imagem na identificação precoce das reações periosteais. Outro estudo encontrado na literatura sugere boa correlação entre as radiografias simples e as imagens de ressonância magnética na identificação e na classificação das reações periosteais no osteossarcoma. Neste ensaio foram ilustrados casos de reações periosteais observadas pela ressonância magnética, correlacionado-as com as radiografias convencionais ou com outros métodos de diagnóstico por imagem.; The objective of the present essay was to encourage a careful evaluation of periosteal reactions on magnetic resonance images. The initial approach to bone lesions is made by conventional radiography and...

Avaliação por ressonância magnética dos tumores de adrenal com correlação histológica; Evaluation of adrenal tumors by magnetic resonance imaging with histological correlation

MARTINS, Daniel Lahan; BARONI, Ronaldo Hueb; BLASBALG, Roberto; VIANA, Públio Cesar Cavalcanti; BEZERRA, Regis Otaviano Franca; DONATO JR., Francisco; MATTEDI, Romulo Loss; LUCON, Antonio Marmo; LEITE, Claudia da Costa; CERRI, Giovanni Guido
Fonte: Colégio Brasileiro de Radiologia e Diagnóstico por Imagem Publicador: Colégio Brasileiro de Radiologia e Diagnóstico por Imagem
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
96.12%
A ressonância magnética é ferramenta importante para a detecção e caracterização dos tumores adrenais. O conhecimento das diferentes apresentações dos tumores primários e secundários à ressonância magnética e sua correlação com dados da histologia são essenciais para o correto raciocínio diagnóstico. Este artigo revisa os aspectos que podem estreitar o diagnóstico diferencial dos tumores adrenais, dando ênfase à correlação histológica daqueles mais comuns.; Magnetic resonance imaging is an important tool for the detection and characterization of adrenal tumors. The knowledge about the different presentations of primary and secondary adrenal tumors at magnetic resonance imaging and their correlation with histological data are essential for the establishment of a correct diagnosis. The present study reviews magnetic resonance imaging aspects which may narrow the differential diagnosis of adrenal tumors, emphasizing the histological correlation of the most frequent ones.

Meduloblastoma: correlação entre ressonância magnética convencional, difusão e espectroscopia de prótons; Medulloblastoma: correlation among findings of conventional magnetic resonance imaging, diffusion-weighted imaging and proton magnetic resonance spectroscopy

FONTE, Mariana Vieira de Melo da; AMARAL, Raquel Portugal Guimarães; COSTA, Maria Olívia Rodrigues; OTADUY, Maria Concepción Garcia; LUCATO, Leandro Tavares; REED, Umbertina Conti; ROSEMBERG, Sergio; LEITE, Claudia da Costa
Fonte: Colégio Brasileiro de Radiologia e Diagnóstico por Imagem Publicador: Colégio Brasileiro de Radiologia e Diagnóstico por Imagem
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
96.21%
OBJETIVO: Correlacionar os achados de ressonância magnética convencional, difusão e espectroscopia de prótons nos meduloblastomas, e compará-los aos dados da literatura. MATERIAIS E MÉTODOS: Análise retrospectiva de exames de ressonância magnética pré-operatórios de nove pacientes na faixa pediátrica com diagnóstico histológico de meduloblastoma (oito desmoplásicos e um de células gigantes). Foram considerados dados demográficos e características do tumor como localização, característica morfológica, intensidade de sinal, realce, disseminação e achados na difusão e espectroscopia. RESULTADOS: Na maioria dos casos os tumores apresentaram epicentro no vermis cerebelar (77,8%), sendo predominantemente sólido (88,9%), com hipossinal nas seqüências ponderadas em T1 e iso/hipersinal nas seqüências ponderadas em T2 e FLAIR, realce heterogêneo (100%), sinais de disseminação/extensão tumoral (77,8%) e restrição à movimentação das moléculas de água (100%). A espectroscopia de prótons pela técnica STEAM (n = 6) demonstrou redução da relação Naa/Cr (83,3%) e aumento de Co/Cr (100%) e mI/Cr (66,7%), e pela técnica PRESS (n = 7) evidenciou pico de lactato (57,1%). CONCLUSÃO: O conjunto dos achados macroscópicos obtidos pela ressonância magnética...

Clinically low-risk prostate cancer: evaluation with transrectal doppler ultrasound and functional magnetic resonance imaging

NOVIS, Maria Inês; BARONI, Ronaldo Hueb; CERRI, Luciana Mendes de Oliveira; MATTEDI, Romulo Loss; BUCHPIGUEL, Carlos Alberto
Fonte: Faculdade de Medicina / USP Publicador: Faculdade de Medicina / USP
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
96.23%
OBJECTIVES: To evaluate transrectal ultrasound, amplitude Doppler ultrasound, conventional T2-weighted magnetic resonance imaging, spectroscopy and dynamic contrast-enhanced magnetic resonance imaging in localizing and locally staging low-risk prostate cancer. INTRODUCTION: Prostate cancer has been diagnosed at earlier stages and the most accepted classification for low-risk prostate cancer is based on clinical stage T1c or T2a, Gleason score <6, and prostate-specific antigen (PSA) <10 ng/ml. METHODS: From 2005 to 2006, magnetic resonance imaging was performed in 42 patients, and transrectal ultrasound in 26 of these patients. Seven patients were excluded from the study. Mean patient age was 64.94 years and mean serum PSA was 6.05 ng/ml. The examinations were analyzed for tumor identification and location in prostate sextants, detection of extracapsular extension, and seminal vesicle invasion, using surgical pathology findings as the gold standard. RESULTS: Sixteen patients (45.7%) had pathologically proven organ-confined disease, 11 (31.4%) had positive surgical margin, 8 (28.9%) had extracapsular extension, and 3 (8.6%) presented with extracapsular extension and seminal vesicle invasion. Sensitivity, specificity, positive predictive value (PPV)...

Ressonância magnética de alta resolução na avaliação do carcinoma ductal in situ mamário.; High resolution magnetic resonance imaging of ductal carcinoma in situ of the breast

Mendonça, Maria Helena Siqueira
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 13/07/1999 PT
Relevância na Pesquisa
96.18%
O método mais eficaz para detecção de carcinoma mamário ductal in situ é a mamografia, que apesar de apresentar alta sensibilidade, possui baixa especificidade e não demonstra todos os casos deste tipo de lesão. Assim sendo, pesquisadores têm desenvolvido modalidades por imagem adjuntas à mamografia, das quais a mais promissora talvez seja a ressonância magnética mamária de alta resolução. Neste estudo investigou-se a capacidade da ressonância magnética, realizada em aparelho de 1,5 Tesla, com gradientes de alto desempenho, uso de bobina de superfície dedicada para mama e agente paramagnético por via endovenosa, em demonstrar focos de carcinoma ductal in situ em sua forma pura. Realizou-se análise retrospectiva em 24 pacientes que apresentaram este diagnóstico histológico e haviam sido submetidas à mamografia e à ressonância magnética. Evidenciou-se baixa reprodutibilidade entre os achados mamográficos e os da ressonância magnética mamaria, com discordância em 13 dos 24 casos (54%). Mesmo assim, concluiu-se que a ressonância magnética mamária foi valiosa, pois apesar de ter sido negativa em 5 dos 16 casos mamograficamente detectados (20,83%) revelou 8 focos de carcinoma ductal in situ não vistos à mamografia (33...

Localização e estadiamento local do adenocarcinoma prostático por ressonância magnética com estudo perfusional e espectroscopia: correlação com resultados histopatológicos; Localization and local staging of prostate cancer with magnetic resonance imaging using perfusion study and spectroscopy: comparison with histopathological results

Oliveira, Maria Ines Novis de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 05/11/2010 PT
Relevância na Pesquisa
96.13%
O adenocarcinoma prostático (CaP) é o tumor que ocupa a segunda posição em incidência e em mortalidade dentre as neoplasias malignas masculinas, tendo aumentado a detecção de tumores em estágios precoces da sua história natural nas últimas décadas, frequentemente pequenos e pouco agressivos. A definição clínica mais aceita de tumor de baixo risco foi proposta por DAmico e consiste em PSA 10 ng/ml, Gleason 6 e não ser palpável ou não acometer mais de um lobo prostático no toque retal. A localização do tumor na próstata, bem como o seu estadiamento local através da detecção de extensão extracapsular (EEC) e/ou invasão de vesículas seminais (IVS) têm importância fundamental na opção e adequação terapêuticas. O objetivo deste trabalho foi avaliar a ultrassonografia transretal (USTR), a ultrassonografia com Doppler de amplitude (USDA), a ressonância magnética (RM), a espectroscopia de prótons por RM (RMS) e a RM dinâmica com contraste endovenoso (RMD) na localização tumoral e estadiamento local do CaP de baixo risco, em comparação com resultados anatomopatológicos. Este foi um estudo prospectivo realizado entre os anos de 2005 e 2009, que avaliou 35 pacientes por RM, RMS e RMD, dos quais 26 foram também submetidos a USTR e USDA. Após a prostatectomia radical...

Prostate Cancer: The Role of Multiparametric Magnetic Resonance Imaging

Lopes Dias, J; Magalhães Pina, J; João, R; Fialho, J; Carmo, S; Leal, C; Bilhim, T; Mateus Marques, R; Campos Pinheiro, L
Fonte: Centro Editor e Livreiro da Ordem dos Médicos Publicador: Centro Editor e Livreiro da Ordem dos Médicos
Tipo: Artigo de Revista Científica
Publicado em //2015 ENG
Relevância na Pesquisa
96.22%
Multiparametric Magnetic Resonance Imaging has been increasingly used for detection, localization and staging of prostate cancer over the last years. It combines high-resolution T2 Weighted-Imaging and at least two functional techniques, which include Dynamic Contrast–Enhanced Magnetic Resonance Imaging, Diffusion-Weighted Imaging, and Magnetic Resonance Imaging Spectroscopy. Although the combined use of a pelvic phased-array and an Endorectal Coil is considered the state-of-the-art for Magnetic Resonance Imaging evaluation of prostate cancer, Endorectal Coil is only absolute mandatory for Magnetic Resonance Imaging Spectroscopy at 1.5 T. Sensitivity and specificity levels in cancer detection and localization have been improving with functional technique implementation, compared to T2 Weighted-Imaging alone. It has been particularly useful to evaluate patients with abnormal PSA and negative biopsy. Moreover, the information added by the functional techniques may correlate to cancer aggressiveness and therefore be useful to select patients for focal radiotherapy, prostate sparing surgery, focal ablative therapy and active surveillance. However, more studies are needed to compare the functional techniques and understand the advantages and disadvantages of each one. This article reviews the basic principles of prostatic mp-Magnetic Resonance Imaging...

Prostate Cancer: The Role of Multiparametric Magnetic Resonance Imaging

Lopes Dias, J; Magalhães Pina, J; João, R; Fialho, J; Carmo, S; Leal, C; Bilhim, T; Mateus Marques, R; Campos Pinheiro, L
Fonte: Centro Editor e Livreiro da Ordem dos Médicos Publicador: Centro Editor e Livreiro da Ordem dos Médicos
Tipo: Artigo de Revista Científica
Publicado em //2015 ENG
Relevância na Pesquisa
96.22%
Multiparametric Magnetic Resonance Imaging has been increasingly used for detection, localization and staging of prostate cancer over the last years. It combines high-resolution T2 Weighted-Imaging and at least two functional techniques, which include Dynamic Contrast–Enhanced Magnetic Resonance Imaging, Diffusion-Weighted Imaging, and Magnetic Resonance Imaging Spectroscopy. Although the combined use of a pelvic phased-array and an Endorectal Coil is considered the state-of-the-art for Magnetic Resonance Imaging evaluation of prostate cancer, Endorectal Coil is only absolute mandatory for Magnetic Resonance Imaging Spectroscopy at 1.5 T. Sensitivity and specificity levels in cancer detection and localization have been improving with functional technique implementation, compared to T2 Weighted-Imaging alone. It has been particularly useful to evaluate patients with abnormal PSA and negative biopsy. Moreover, the information added by the functional techniques may correlate to cancer aggressiveness and therefore be useful to select patients for focal radiotherapy, prostate sparing surgery, focal ablative therapy and active surveillance. However, more studies are needed to compare the functional techniques and understand the advantages and disadvantages of each one. This article reviews the basic principles of prostatic mp-Magnetic Resonance Imaging...

Advanced techniques in magnetic resonance imaging of the brain in children with ADHD

Pastura,Giuseppe; Mattos,Paulo; Gasparetto,Emerson Leandro; Araújo,Alexandra Prufer de Queiroz Campos
Fonte: Academia Brasileira de Neurologia - ABNEURO Publicador: Academia Brasileira de Neurologia - ABNEURO
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2011 EN
Relevância na Pesquisa
96.15%
Attention deficit hyperactivity disorder (ADHD) affects about 5% of school-aged child. Previous published works using different techniques of magnetic resonance imaging (MRI) have demonstrated that there may be some differences between the brain of people with and without this condition. This review aims at providing neurologists, pediatricians and psychiatrists an update on the differences between the brain of children with and without ADHD using advanced techniques of magnetic resonance imaging such as diffusion tensor imaging, brain volumetry and cortical thickness, spectroscopy and functional MRI. Data was obtained by a comprehensive, non-systematic review of medical literature. The regions with a greater number of abnormalities are splenium of the corpus callosum, cingulated girus, caudate nucleus, cerebellum, striatum, frontal and temporal cortices. The brain regions where abnormalities are observed in studies of diffusion tensor, volumetry, spectroscopy and cortical thickness are the same involved in neurobiological theories of ADHD coming from studies with functional magnetic resonance imaging.

Is magnetic resonance imaging a plausible biomarker for upper motor neuron degeneration in amyotrophic lateral sclerosis/primary lateral sclerosis or merely a useful paraclinical tool to exclude mimic syndromes? A critical review of imaging applicability in clinical routine

Rocha,Antonio José da; Maia Júnior,Antonio Carlos Martins
Fonte: Academia Brasileira de Neurologia - ABNEURO Publicador: Academia Brasileira de Neurologia - ABNEURO
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2012 EN
Relevância na Pesquisa
96.13%
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that affects motor neurons in the cerebral cortex, brainstem, and spinal cord, brain regions in which conventional magnetic resonance imaging is often uninformative. Although the mean time from symptom onset to diagnosis is estimated to be about one year, the current criteria only prescribe magnetic resonance imaging to exclude "ALS mimic syndromes". Extensive application of non-conventional magnetic resonance imaging (MRI) to the study of ALS has improved our understanding of the in vivo pathological mechanisms involved in the disease. These modern imaging techniques have recently been added to the list of potential ALS biomarkers to aid in both diagnosis and monitoring of disease progression. This article provides a comprehensive review of the clinical applicability of the neuroimaging progress that has been made over the past two decades towards establishing suitable diagnostic tools for upper motor neuron (UMN) degeneration in ALS.

Assessment of Myocardial Infarction by Cardiac Magnetic Resonance Imaging and Long-Term Mortality

Petriz,João Luiz Fernandes; Gomes,Bruno Ferraz de Oliveira; Rua,Braulio Santos; Azevedo,Clério Francisco; Hadlich,Marcelo Souza; Mussi,Henrique Thadeu Periard; Taets,Gunnar de Cunto; Nascimento,Emília Matos do; Pereira,Basílio de Bragança; Silva,Nels
Fonte: Sociedade Brasileira de Cardiologia - SBC Publicador: Sociedade Brasileira de Cardiologia - SBC
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2015 EN
Relevância na Pesquisa
96.18%
Background: Cardiac magnetic resonance imaging provides detailed anatomical information on infarction. However, few studies have investigated the association of these data with mortality after acute myocardial infarction. Objective: To study the association between data regarding infarct size and anatomy, as obtained from cardiac magnetic resonance imaging after acute myocardial infarction, and long-term mortality. Methods: A total of 1959 reports of “infarct size” were identified in 7119 cardiac magnetic resonance imaging studies, of which 420 had clinical and laboratory confirmation of previous myocardial infarction. The variables studied were the classic risk factors – left ventricular ejection fraction, categorized ventricular function, and location of acute myocardial infarction. Infarct size and acute myocardial infarction extent and transmurality were analyzed alone and together, using the variable named “MET-AMI”. The statistical analysis was carried out using the elastic net regularization, with the Cox model and survival trees. Results: The mean age was 62.3 ± 12 years, and 77.3% were males. During the mean follow-up of 6.4 ± 2.9 years, there were 76 deaths (18.1%). Serum creatinine...

Evaluation of the rupture of silicone breast implants by mammography, ultrasonography and magnetic resonance imaging in asymptomatic patients: correlation with surgical findings

Scaranelo,Anabel Medeiros; Marques,Américo Ferreira; Smialowski,Elizabeth Brenda; Lederman,Henriquel Manoel
Fonte: Associação Paulista de Medicina - APM Publicador: Associação Paulista de Medicina - APM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2004 EN
Relevância na Pesquisa
96.21%
CONTEXT: Different imaging methods can identify the integrity of breast implants and also the extent of possible silicone leakage. Mammography, ultrasonography and magnetic resonance imaging are often used to evaluate the integrity of breast implants, usually in patients that are symptomatic for rupture. A group of clinically asymptomatic patients was taken as a sample. These patients wanted to remove or change their breast implants for psychological or cosmetic reasons. OBJECTIVE: The purpose of this study was to compare the efficacy of mammography, sonography and magnetic resonance imaging in the detection of breast implant rupture in an asymptomatic population. TYPE OF STUDY: Prospective study. SETTING: Department of Diagnostic Imaging, Universidade de São Paulo, São Paulo, Brazil. METHODS: The participants were 44 asymptomatic patients who subsequently had implants surgically removed. Eighty-three implants were evaluated by both film-screen mammography and high-resolution sonography and 77 implants were evaluated by magnetic resonance imaging. The sensitivity and specificity of mammography, ultrasonography and magnetic resonance imaging were assessed using predetermined diagnostic criteria for implant rupture. All radiological signs were discussed and false positives and false negatives were retrospectively evaluated to identify the pitfalls in the investigations. RESULTS: The respective sensitivity and specificity of mammography were 20% and 89%; sonography...

Intracellular labeling and quantification process by magnetic resonance imaging using iron oxide magnetic nanoparticles in rat C6 glioma cell line

Mamani,Javier Bustamante; Pavon,Lorena Favaro; Miyaki,Liza Aya Mabuchi; Sibov,Tatiana Tais; Rossan,Fabiana; Silveira,Paulo Henrique; Cárdenas,Walter Humberto Zavala; Amaro Junior,Edson; Gamarra,Lionel Fernel
Fonte: Instituto Israelita de Ensino e Pesquisa Albert Einstein Publicador: Instituto Israelita de Ensino e Pesquisa Albert Einstein
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2012 EN
Relevância na Pesquisa
96.13%
OBJECTIVE: To assess intracellular labeling and quantification by magnetic resonance imaging using iron oxide magnetic nanoparticles coated with biocompatible materials in rat C6 glioma cells in vitro. These methods will provide direction for future trials of tumor induction in vivo as well as possible magnetic hyperthermia applications. METHODS: Aminosilane, dextran, polyvinyl alcohol, and starch-coated magnetic nanoparticles were used in the qualitative assessment of C6 cell labeling via light microscopy. The influence of the transfection agent poly-L-lysine on cellular uptake was examined. The quantification process was performed by relaxometry analysis in T1 and T2weighted phantom images. RESULTS: Light microscopy revealed that the aminosilane-coated magnetic nanoparticles alone or complexed with poly-L-lysine showed higher cellular uptake than did the uncoated magnetic particles. The relaxivities of the aminosilane-coated magnetic nanoparticles with a hydrodynamic diameter of 50nm to a 3-T field were r1=(6.1±0.3)×10-5 ms-1mL/µg, r2=(5.3±0.1)× 10-4 ms-1mL/µg, with a ratio of r2 / r1 ≅ 9. The iron uptake in the cells was calculated by analyzing the relaxation rates (R1 and R2) using a mathematical relationship. CONCLUSIONS: C6 glioma cells have a high uptake efficiency for aminosilane-coated magnetic nanoparticles complexed with the transfection agent poly-L-lysine. The large ratio r2 / r1 ≅ 9 indicates that these magnetic nanoparticles are ideal for quantification by magnetic resonance imaging with T2-weighted imaging techniques.

Clinically low-risk prostate cancer: evaluation with transrectal doppler ultrasound and functional magnetic resonance imaging

Novis,Maria Inês; Baroni,Ronaldo Hueb; Cerri,Luciana Mendes de Oliveira; Mattedi,Romulo Loss; Buchpiguel,Carlos Alberto
Fonte: Faculdade de Medicina / USP Publicador: Faculdade de Medicina / USP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 EN
Relevância na Pesquisa
96.23%
OBJECTIVES: To evaluate transrectal ultrasound, amplitude Doppler ultrasound, conventional T2-weighted magnetic resonance imaging, spectroscopy and dynamic contrast-enhanced magnetic resonance imaging in localizing and locally staging low-risk prostate cancer. INTRODUCTION: Prostate cancer has been diagnosed at earlier stages and the most accepted classification for low-risk prostate cancer is based on clinical stage T1c or T2a, Gleason score <6, and prostate-specific antigen (PSA) <10 ng/ml. METHODS: From 2005 to 2006, magnetic resonance imaging was performed in 42 patients, and transrectal ultrasound in 26 of these patients. Seven patients were excluded from the study. Mean patient age was 64.94 years and mean serum PSA was 6.05 ng/ml. The examinations were analyzed for tumor identification and location in prostate sextants, detection of extracapsular extension, and seminal vesicle invasion, using surgical pathology findings as the gold standard. RESULTS: Sixteen patients (45.7%) had pathologically proven organ-confined disease, 11 (31.4%) had positive surgical margin, 8 (28.9%) had extracapsular extension, and 3 (8.6%) presented with extracapsular extension and seminal vesicle invasion. Sensitivity, specificity, positive predictive value (PPV)...

Silicon Nanoparticles as Hyperpolarized Magnetic Resonance Imaging Agents

Aptekar, Jacob W.; Cassidy, Maja Clare; Johnson, Alexander C.; Barton, Robert A.; Lee, Menyoung; Ogier, Alexander C.; Vo, Chinh; Anahtar, Melis Nuray; Yin, Ren; Bhatia, Sangeeta; Ramanathan, Chandrasekhar; Cory, David G.; Hill, Alison Lynn; Mair, Ross W.;
Fonte: American Chemical Society Publicador: American Chemical Society
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
96.14%
Magnetic resonance imaging of hyperpolarized nuclei provides high image contrast with little or no background signal. To date, in vivo applications of prehyperpolarized materials have been limited by relatively short nuclear spin relaxation times. Here, we investigate silicon nanoparticles as a new type of hyperpolarized magnetic resonance imaging agent. Nuclear spin relaxation times for a variety of Si nanoparticles are found to be remarkably long, ranging from many minutes to hours at room temperature, allowing hyperpolarized nanoparticles to be transported, administered, and imaged on practical time scales. Additionally, we demonstrate that Si nanoparticles can be surface functionalized using techniques common to other biologically targeted nanoparticle systems. These results suggest that Si nanoparticles can be used as a targetable, hyperpolarized magnetic resonance imaging agent with a large range of potential applications.; Physics; Other Research Unit

Effekte der Hochfrequenzabsorption bei der Magnetresonanztomografie; The effects of high frequency absorption during Magnetic Resonance Imaging

Berger, Alexander
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
Relevância na Pesquisa
96.14%
Die technische Weiterentwicklung der Magnetresonanztomografie und das sich erweiternde Indikationsgebiet insbesondere der interventionellen MRT erfordern weitergehende Untersuchungen über mögliche Wechselwirkungen der elektromagnetischen Felder mit dem Patienten und ggf. vorhandenen Instrumenten und Implantaten. Die größte Gefahrenquelle geht dabei von der Wärmewirkung in oder in der Umgebung elektrisch leitfähiger Strukturen durch das elektromagnetische Hochfrequenzfeld aus. Das Ziel dieser Arbeit war es, die verschiedenen Mechanismen der Wärmeentstehung während der Magnetresonanztomografie systematisch mittels Infrarotthermografie zu untersuchen. Es wurden dazu drei MRT-Scanner unterschiedlicher Grundmagnetfeldstärken verwendet. Das elektromagnetische Hochfrequenzfeld kann Gewebe sowohl direkt als auch indirekt durch eine zusätzliche Anwesenheit von metallischen Leitern erwärmen. Zur Messung der direkten Erwärmung erfolgten zunächst in vitro Untersuchungen an verschiedenen Flüssigkeiten unterschiedlicher elektrischer Leitfähigkeiten. Hierbei fand sich ein deutlicher Zusammenhang zwischen der elektrischen Leitfähigkeit und der Energieabsorption. Der Bezug zur klinischen Anwendung wurde durch eine Studie an MR-tomographisch untersuchten Personen hergestellt...

Silsesquioxanes and Silica Nanoparticles as Platforms for Fluorine and Gadolinium Based Contrast Agents for Magnetic Resonance Imaging; Silsesquioxane und Silika-Nanopartikel als Grundlagen für Fluor- und Gadolinium-basierte Kontrastmittel für die Magnetresonanz-Bildgebung

Kocak, Filiz
Fonte: Universität Tübingen Publicador: Universität Tübingen
Tipo: Dissertação
EN
Relevância na Pesquisa
96.16%
Magnetic resonance imaging (MRI) is an important diagnostic tool for the imaging of soft tissues. The non-invasive technique of MRI allows for the detection of tumors, infections and injuries at an early stage. New opportunities for medical diagnosis and magnetic resonance (MR) imaging techniques are offered with the use of hybrid nanomaterials. The functionalization of a nano-sized material, e.g. with paramagnetic Gd(III) chelate complexes for 1H imaging or with 19F containing molecules for 19F imaging leads to a high concentration of contrast agents, which can be obtained at low volumes. In the first part of the work T8-silsesquioxanes were functionalized with polyorganofluorinated groups (PFG). By different synthetic pathways highly symmetrical polyorganofluorinated POSS cubes (PF-POSS) which generate a sharp singlet in the 19F spectrum were obtained. The properties of the PF-POSS cubes in dependency of their PFG structures, the resulting solubility and their hydrolysis stability were investigated. Additionally, in vitro measurements as well as post mortem experiments were performed for chosen examples. In the second part of this work the size dependent properties of spherical and monodisperse silica nanoparticles (SNPs) with diameters of about 15...

Prostate Cancer: The Role of Multiparametric Magnetic Resonance Imaging; Cancro da Próstata: O Papel da Ressonância Magnética Multiparamétrica

Lopes Dias, João; Departamento de Radiologia. Hospital de São José. Centro Hospitalar Lisboa Central. Lisboa. Portugal.; Magalhães Pina, João; Departamento de Urologia. Hospital de São José. Centro Hospitalar Lisboa Central. Lisboa. Portugal.; Joã
Fonte: Ordem dos Médicos Publicador: Ordem dos Médicos
Tipo: info:eu-repo/semantics/article; review; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em 29/05/2015 ENG
Relevância na Pesquisa
96.22%
Multiparametric Magnetic Resonance Imaging has been increasingly used for detection, localization and staging of prostate cancer over the last years. It combines high-resolution T2 Weighted-Imaging and at least two functional techniques, which include Dynamic Contrast–Enhanced Magnetic Resonance Imaging, Diffusion-Weighted Imaging, and Magnetic Resonance Imaging Spectroscopy. Although the combined use of a pelvic phased-array and an Endorectal Coil is considered the state-of-the-art for Magnetic Resonance Imaging evaluation of prostate cancer, Endorectal Coil is only absolute mandatory for Magnetic Resonance Imaging Spectroscopy at 1.5 T. Sensitivity and specificity levels in cancer detection and localization have been improving with functional technique implementation, compared to T2 Weighted-Imaging alone. It has been particularly useful to evaluate patients with abnormal PSA and negative biopsy. Moreover, the information added by the functional techniques may correlate to cancer aggressiveness and therefore be useful to select patients for focal radiotherapy, prostate sparing surgery, focal ablative therapy and active surveillance. However, more studies are needed to compare the functional techniques and understand the advantages and disadvantages of each one. This article reviews the basic principles of prostatic mp-Magnetic Resonance Imaging...

Cardiac flow analysis using magnetic resonance imaging.

Wong, Kelvin Kian Loong
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2009
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96.15%
Many types of cardiac abnormality have an implication on blood flow. However, most present-day diagnostic modalities analyse myocardial structures and not the cardiac flow within to detect heart defects in vivo. Currently, various imaging modalities, such as echocardiography, single photon emission computed tomography (SPECT), positron emission tomography (PET), X-ray computed tomography (CT), and cardiac magnetic resonance imaging (CMRI) provide a non-invasive approach for scanning humans with heart abnormalities, and are utilised in the management of cardiac patients. There is a need to develop a visualisation system for analysing flow of blood within the human heart. Motional properties of blood can be measured against normal controls and patients with cardiac abnormalities in order to discover underlying cause of these flow phenomena. This can potentially extend medical knowledge of the defects and their hemodynamic behaviour. We characterise motion patterns of blood in the human heart and analyse the flow properties, by means of tracking, using a series of time dependent magnetic resonance images. An indication of flow vortices can be provided by numerical computation of vorticity values within the defined region of blood flow. The global estimation of parametric motion flow fields over the whole image provides useful information on the presence of vortices within the heart chamber that can be used to assess cardiac functions. In this study...

Cardiovascular assessment of patients with Ullrich-Turner's Syndrome on Doppler echocardiography and magnetic resonance imaging

Castro,Ana Valéria Barros de; Okoshi,Katashi; Ribeiro,Sérgio Marrone; Barbosa,Maurício Fregonesi; Mattos,Patricia Ferreira; Pagliare,Luciana; Bueno,Nancy Figueiredo; Rodrigueiro,Débora Aparecida; Haddad,Adriana Lúcia Mendes
Fonte: Sociedade Brasileira de Cardiologia - SBC Publicador: Sociedade Brasileira de Cardiologia - SBC
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2002 EN
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OBJECTIVE: To assess the cardiovascular features of Ullrich-Turner's syndrome using echocardiography and magnetic resonance imaging, and to correlate them with the phenotype and karyotype of the patients. The diagnostic concordance between the 2 methods was also assessed. METHODS: Fifteen patients with the syndrome were assessed by echocardiography and magnetic resonance imaging (cardiac chambers, valves, and aorta). Their ages ranged from 10 to 28 (mean of 16.7) years. The karyotype was analyzed in 11 or 25 metaphases of peripheral blood lymphocytes, or both. RESULTS: The most common phenotypic changes were short stature and spontaneous absence of puberal development (100%); 1 patient had a cardiac murmur. The karyotypes detected were as follows: 45,X (n=7), mosaics (n=5), and deletions (n=3). No echocardiographic changes were observed. In regard to magnetic resonance imaging, coarctation and dilation of the aorta were found in 1 patient, and isolated dilation of the aorta was found in 4 patients. CONCLUSION: The frequencies of coarctation and dilation of the aorta detected on magnetic resonance imaging were similar to those reported in the literature (5.5% to 20%, and 6.3% to 29%, respectively). This confirmed the adjuvant role of magnetic resonance imaging to Doppler echocardiography for diagnosing cardiovascular alterations in patients with Ullrich-Turner's syndrome.