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2.
J Neurovirol ; 25(3): 405-409, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30610740

RESUMO

We present an immunocompetent patient with transverse myelitis (TM) during acute cytomegalovirus (CMV) infection, as evidenced by a reactive serum CMV IgM and CMV viremia. The patient had an excellent outcome after receiving only high-dose methylprednisolone. Given concerns that practitioners may have around the use of immunosuppressive therapy for this potentially infectious myelopathy, we systematically reviewed the literature to assess outcomes after administration of high-dose corticosteroids to this population. Despite severe disease at clinical nadir with inability to ambulate, immunocompetent patients with acute CMV-associated TM who received high-dose corticosteroids had good clinical outcomes 1 month to 1 year after presentation.

3.
Hum Mutat ; 39(5): 593-620, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29446198

RESUMO

The prevalence and spectrum of germline mutations in BRCA1 and BRCA2 have been reported in single populations, with the majority of reports focused on White in Europe and North America. The Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA) has assembled data on 18,435 families with BRCA1 mutations and 11,351 families with BRCA2 mutations ascertained from 69 centers in 49 countries on six continents. This study comprehensively describes the characteristics of the 1,650 unique BRCA1 and 1,731 unique BRCA2 deleterious (disease-associated) mutations identified in the CIMBA database. We observed substantial variation in mutation type and frequency by geographical region and race/ethnicity. In addition to known founder mutations, mutations of relatively high frequency were identified in specific racial/ethnic or geographic groups that may reflect founder mutations and which could be used in targeted (panel) first pass genotyping for specific populations. Knowledge of the population-specific mutational spectrum in BRCA1 and BRCA2 could inform efficient strategies for genetic testing and may justify a more broad-based oncogenetic testing in some populations.

4.
Blood Cancer J ; 6(7): e442, 2016 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-27391574

RESUMO

Clinical outcome and mutations of 96 core-binding factor acute myeloid leukemia (AML) patients 18-60 years old were examined. Complete remission (CR) after induction was 94.6%. There was no significant difference in CR, leukemia-free-survival (LFS) and overall survival (OS) between t(8;21) (N=67) and inv(16) patients (N=29). Univariate analysis showed hematopoietic stem cell transplantation at CR1 as the only clinical parameter associated with superior LFS. Next-generation sequencing based on a myeloid gene panel was performed in 72 patients. Mutations in genes involved in cell signaling were associated with inferior LFS and OS, whereas those in genes involved in DNA methylation were associated with inferior LFS. KIT activation loop (AL) mutations occurred in 25 patients, and were associated with inferior LFS (P=0.003) and OS (P=0.001). TET2 mutations occurred in 8 patients, and were associated with significantly shorter LFS (P=0.015) but not OS. Patients negative for KIT-AL and TET2 mutations (N=41) had significantly better LFS (P<0.001) and OS (P=0.012) than those positive for both or either mutation. Multivariate analysis showed that KIT-AL and TET2 mutations were associated with inferior LFS, whereas age ⩾40 years and marrow blast ⩾70% were associated with inferior OS. These observations provide new insights that may guide better treatment for this AML subtype.


Assuntos
Fatores de Ligação ao Core/genética , Fatores de Ligação ao Core/metabolismo , Proteínas de Ligação a DNA/genética , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Mutação , Proteínas Proto-Oncogênicas c-kit/metabolismo , Proteínas Proto-Oncogênicas/genética , Adolescente , Adulto , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Terapia Combinada , Metilação de DNA , Análise Mutacional de DNA , Proteínas de Ligação a DNA/metabolismo , Feminino , Transplante de Células-Tronco Hematopoéticas/métodos , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Leucemia Mieloide Aguda/mortalidade , Leucemia Mieloide Aguda/terapia , Masculino , Pessoa de Meia-Idade , Prognóstico , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-kit/genética , Transdução de Sinais , Análise de Sobrevida , Translocação Genética , Transplante Homólogo , Adulto Jovem
5.
Bioinformatics ; 31(24): 4035-7, 2015 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-26315902

RESUMO

UNLABELLED: Rapid advances of next-generation sequencing technology have led to the integration of genetic information with clinical care. Genetic basis of diseases and response to drugs provide new ways of disease diagnosis and safer drug usage. This integration reveals the urgent need for effective and accurate tools to analyze genetic variants. Due to the number and diversity of sources for annotation, automating variant analysis is a challenging task. Here, we present database.bio, a web application that combines variant annotation, prioritization and visualization so as to support insight into the individual genetic characteristics. It enhances annotation speed by preprocessing data on a supercomputer, and reduces database space via a unified database representation with compressed fields. AVAILABILITY AND IMPLEMENTATION: Freely available at https://database.bio.


Assuntos
Bases de Dados de Ácidos Nucleicos , Variação Genética , Software , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Internet , Anotação de Sequência Molecular
6.
Phys Chem Chem Phys ; 13(43): 19449-53, 2011 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-21971281

RESUMO

Ripples naturally occur in graphene sheets. First-principles calculations reveal that, by altering the pyramidalization angles of the carbon atoms, these ripples can be used to direct the chemical reactivity of graphene towards hydrogenation. A fraction of the carbon atoms of a rippled graphene, located around the crests and troughs, show significantly increased reactivity. The remaining carbon atoms have comparable reactivity to those in a flat graphene. To illustrate the increased reactivity, we show that hydrogenation becomes exothermic when the characteristic ratio between the amplitude and wavelength reaches ~0.55. This finding offers a practical chemical venue for regioselectivity control of graphene functionalization. While the rippling does not directly affect the band gap of the graphene, the rippling-induced hydrogenation does.


Assuntos
Grafite/química , Teoria Quântica , Flúor/química , Hidrogenação , Modelos Teóricos
7.
Neurology ; 75(24): 2185-9, 2010 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-21172841

RESUMO

BACKGROUND: The association between protein S deficiency (PSD) and ischemic stroke is controversial and warrants further investigation. METHODS: We conducted a genotype and MRI correlation study in a Chinese family in which hereditary PSD cosegregated with premature ischemic strokes. Six out of 11 family members inherited PSD type III in an autosomal dominant manner. RESULTS: Among all PSD members, a novel missense mutation 1063C→T in exon 10 of protein S alpha (PROS1) was identified, which encoded a substitution of arginine to cysteine at position 355 (R355C) in the first globular domain of laminin A of protein S. Wild-type PROS1 sequences were retained in non-PSD members. MRI detected deep white matter infarctions predominantly distributed in the borderzone regions. The infarct topography was homogeneous in all adult mutant carriers. By contrast, cerebral infarction was absent in nonmutant carriers. Extensive investigation in the family did not reveal any confounding stroke risk. Haplotype analysis with high-density single nucleotide polymorphism markers revealed a 6.1-Mb minimally rearranged region (rs12494685 to rs1598240) in 3q11.2, lod = 3.0. Among the 7 annotated genes in this region, PROS1 is known to be associated with thrombotic disorders. MRI screening in an additional 10 PSD families without R355C showed no cerebral infarction. CONCLUSIONS: PROS1 R355C mutation cosegregated with PSD type III and premature white matter infarctions in the index family. The findings substantiate an association between PSD and stroke. Study of the mechanism underlying this association may improve our understanding of premature cryptogenic white matter infarction.


Assuntos
Encéfalo/patologia , Infarto Cerebral/genética , Infarto Cerebral/patologia , Mutação de Sentido Incorreto , Deficiência de Proteína S/complicações , Proteína S/genética , Adolescente , Adulto , Idoso , Arginina , Encéfalo/irrigação sanguínea , Criança , Cisteína , Feminino , Predisposição Genética para Doença , Haplótipos , Hong Kong , Humanos , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Anotação de Sequência Molecular , Linhagem , Polimorfismo de Nucleotídeo Único , Fatores de Risco , Adulto Jovem
8.
Nanotechnology ; 21(44): 445701, 2010 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-20921590

RESUMO

The morphology and biaxial texture of vacuum evaporated CaF(2) films on amorphous substrates as a function of vapour incident angle, substrate temperature and film thickness were investigated by scanning electron microscopy, x-ray pole figure and reflection high energy electron diffraction surface pole figure analyses. Results show that an anomalous [220] out-of-plane texture was preferred in CaF(2) films deposited on Si substrates at < 200 °C with normal vapour incidence. With an increase of the vapour incident angle, the out-of-plane orientation changed from [220] to [111] at a substrate temperature of 100 °C. In films deposited with normal vapour incidence, the out-of-plane orientation changed from [220] at 100 °C to [111] at 400 °C. In films deposited with an oblique vapour incidence at 100 °C, the texture changed from random at small thickness (5 nm) to biaxial at larger thickness (20 nm or more). Using first principles density functional theory calculation, it was shown that [220] texture formation is a consequence of energetically favourable adsorption of CaF(2) molecules onto the CaF(2)(110) facet.

9.
Sci Total Environ ; 408(4): 865-72, 2010 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-19919875

RESUMO

The use of methanol in combination with diesel fuel is an effective measure to reduce particulate matter (PM) and nitrogen oxides (NOx) emissions from in-use diesel vehicles. In this study, a diesel/methanol compound combustion (DMCC) scheme was proposed and a 4-cylinder naturally-aspirated direct-injection diesel engine modified to operate on the proposed combustion scheme. The effect of DMCC and diesel oxidation catalyst (DOC) on the regulated emissions of total hydrocarbons (THC), carbon monoxide (CO), NOx and PM was investigated based on the Japanese 13 Mode test cycle. Certain unregulated emissions, including methane, ethyne, ethene, 1,3-butadiene, BTX (benzene, toluene, xylene), unburned methanol and formaldehyde were also evaluated based on the same test cycle. In addition, the soluble organic fraction (SOF) in the particulate and the particulate number concentration and size distribution were investigated at certain selected modes of operation. The results show that the DMCC scheme can effectively reduce NOx, particulate mass and number concentrations, ethyne, ethene and 1,3-butadiene emissions but significantly increase the emissions of THC, CO, NO(2), BTX, unburned methanol, formaldehyde, and the proportion of SOF in the particles. After the DOC, the emission of THC, CO, NO(2), as well as the unregulated gaseous emissions, can be significantly reduced when the exhaust gas temperature is sufficiently high while the particulate mass concentration is further reduced due to oxidation of the SOF.


Assuntos
Poluentes Atmosféricos/análise , Gasolina/análise , Metanol , Emissões de Veículos/análise , Catálise , Monitoramento Ambiental , Oxirredução , Material Particulado/análise , Emissões de Veículos/legislação & jurisprudência , Resíduos/análise
10.
Phys Rev Lett ; 102(17): 176101, 2009 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-19518799

RESUMO

We propose an efficient scheme to simulate noncontact atomic force microscopy images by using first-principles self-consistent potential from the sample as input without explicit modeling of the atomic force microscopy tip. Our method is applied to various types of semiconductor surfaces including Si(111)-(7x7), TiO2(110)-(1x1), Ag/Si(111)-(sqrt[3]xsqrt[3])R30 degrees, and Ge/Si(105)-(1x2) surfaces. We obtain good agreement with experimental results and previous theoretical studies, and our method can aid in identifying different structural models for surface reconstruction.

11.
Sci Total Environ ; 407(15): 4497-505, 2009 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-19446309

RESUMO

This study is aimed to investigate the combined application of fumigation methanol and a diesel oxidation catalyst for reducing emissions of an in-use diesel engine. Experiments were performed on a 4-cylinder naturally-aspirated direct-injection diesel engine operating at a constant speed of 1800 rev/min for five engine loads. The experimental results show that at low engine loads, the brake thermal efficiency decreases with increase in fumigation methanol; but at high loads, it slightly increases with increase in fumigation methanol. The fumigation method results in a significant increase in hydrocarbon (HC), carbon monoxide (CO), and nitrogen dioxide (NO(2)) emissions, but decrease in nitrogen oxides (NO(x)), smoke opacity and the particulate mass concentration. For the submicron particles, the total number of particles decreases. In all cases, there is little change in geometrical mean diameter of the particles. After catalytic conversion, the HC, CO, NO(2), particulate mass and particulate number concentrations were significantly reduced at medium to high engine loads; while the geometrical mean diameter of the particles becomes larger. Thus, the combined use of fumigation methanol and diesel oxidation catalyst leads to a reduction of HC, CO, NO(x), particulate mass and particulate number concentrations at medium to high engine loads.


Assuntos
Poluentes Ambientais/análise , Metanol/química , Material Particulado/análise , Emissões de Veículos/análise , Catálise , Poluentes Ambientais/química , Oxirredução , Tamanho da Partícula , Material Particulado/química , Fumaça/análise
12.
J Phys Condens Matter ; 21(6): 064207, 2009 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-21715910

RESUMO

Solving the electronic structure problem for nanoscale systems remains a computationally challenging problem. The numerous degrees of freedom, both electronic and nuclear, make the problem impossible to solve without some effective approximations. Here we illustrate some advances in algorithm developments to solve the Kohn-Sham eigenvalue problem, i.e. we solve the electronic structure problem within density functional theory using pseudopotentials expressed in real space. Our algorithms are based on a nonlinear Chebyshev filtered subspace iteration method, which avoids computing explicit eigenvectors except at the first self-consistent-field iteration. Our method may be viewed as an approach to solve the original nonlinear Kohn-Sham equation by a nonlinear subspace iteration technique, without emphasizing the intermediate linearized Kohn-Sham eigenvalue problems. Replacing the standard iterative diagonalization at each self-consistent-field iteration by a Chebyshev subspace filtering step results in a significant speed-up, often an order of magnitude or more, over methods based on standard diagonalization. We illustrate this method by predicting the electronic and vibrational states for silicon nanocrystals.

13.
J Chem Phys ; 129(14): 144109, 2008 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-19045136

RESUMO

We present a real space pseudopotential method for calculating the electronic structure of one-dimensional periodic systems such as nanowires. As an application of this method, we examine H-passivated Si nanowires. The band structure and heat of formation of the Si nanowires are presented and compared to plane wave methods. Our method is able to offer the same accuracy as the traditional plane wave methods but offers a number of computational advantages such as faster convergence for heteropolar nanowires.

14.
Nano Lett ; 8(2): 596-600, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18154366

RESUMO

We studied the electronic properties of phosphorus-doped silicon nanocrystals using the real-space first-principles pseudopotential method. We simulated nanocrystals with a diameter of up to 6 nm and made a direct comparison with experimental measurement for the first time for these systems. Our calculated size dependence of hyperfine splitting was in excellent agreement with experimental data. We also found a critical nanocrystal size below which we predicted that the dopant will be ejected to the surface.


Assuntos
Cristalização/métodos , Modelos Químicos , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Nanotecnologia/métodos , Fósforo/química , Silício/química , Simulação por Computador , Condutividade Elétrica , Substâncias Macromoleculares/química , Teste de Materiais , Modelos Moleculares , Conformação Molecular , Tamanho da Partícula , Semicondutores , Propriedades de Superfície
15.
Sci Total Environ ; 389(1): 115-24, 2008 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-17920660

RESUMO

Experiments were conducted on a 4-cylinder direct-injection diesel engine with fumigation methanol injected into the air intake of each cylinder. The fumigation methanol was injected to top up 10%, 20% and 30% of the power output under different engine operating conditions. The effects of fumigation methanol on engine performance, gaseous emissions and particulate emission were investigated. The experimental results show that there is a decrease in the brake thermal efficiency when fumigation methanol is applied, except at the highest load of 0.67 MPa. At low loads, the brake thermal efficiency decreases with increase in fumigation methanol; but at high loads, it increases with increase in fumigation methanol. The fumigation method results in a significant increase in hydrocarbon (HC), carbon monoxide (CO), and nitrogen dioxide (NO(2)) emissions. The concentration of nitrogen oxides (NOx) is significantly reduced except at close to full load condition. There is also a reduction in the smoke opacity and the particulate matter (PM) mass concentration. For the submicron particles, the total number of particles decreases at low and medium loads but increases at high loads. In all cases, there is a shift of the particles towards smaller geometrical mean diameter, especially at high loads. The increase in nano-sized particles and the increase in NO(2) emission could have serious impact on human health.


Assuntos
Poluentes Atmosféricos/análise , Metanol/química , Veículos Automotores , Material Particulado/análise , Emissões de Veículos/análise , Dióxido de Carbono/análise , Monóxido de Carbono/análise , Hidrocarbonetos/análise , Óxidos de Nitrogênio/análise , Óxidos de Nitrogênio/química , Oxigênio/análise , Tamanho da Partícula
16.
Phys Rev Lett ; 96(22): 226102, 2006 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-16803324

RESUMO

An intriguing growth morphology of Pb islands on a Si(111) surface is observed in our STM experiments: the growth of a Pb layer on Pb islands with unstable heights starts from the periphery and moves towards the center, while the nucleation of the next layer on stable Pb islands starts away from the periphery. Using first-principles total energy calculations, we have studied the diffusion barriers of Pb adatoms on a freestanding Pb(111) film as a function of film thickness. The diffusion barriers are found to be very low (<60 meV), and a bi-layer oscillation due to the quantum size effect (QSE) is observed, with a lower barrier on the odd-layered, relatively unstable Pb films. The diffusion barrier difference between the odd- and even-layered film is as large as 40 meV. The observed unusual growth can be attributed to this big difference in the diffusion barriers due to QSE.

17.
Huan Jing Ke Xue ; 27(12): 2382-5, 2006 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-17304827

RESUMO

The fine particle size distribution characteristics obtained from a diesel taxi, a diesel light bus, a gasoline private car and a liquefied petroleum gas (LPG) fuelled taxi were carried out on a chassis dynamometer system. The measurements were performed at different driving modes, i.e. , with low and high idling and from 10 kmxh(-1) to 70 kmxh(-1), 4 cruise operations using the instrument SMPS for collecting particles of 0.015-0.7microm diameter in range. It was found that different fuelled vehicles and different driving modes characterize considerable differences in size number and mass concentration distributions. Diesel vehicles contribute much more nuclei and accumulation mode particles of 30 - 150 nm, while LPG and gasoline fuelled vehicles exhaust much more nuclei mode particles of 15-30 nm. Overall, diesel-fuelled vehicles exhaust much more particles number and mass than gasoline and LPG fuelled vehicles; In the present study, diesel vehicles exhaust the ranges of total SMPS particle number, mass concentration with (0.3-3.6) x 10(8) number x cm(-3), 0.03 - 0.6 microg cm(- 3) respectively, and gasoline and LPG fuelled vehicles exhaust 2.3 x 10(4) - 1.2 x 10(7) number x cm(-3), 8 x 10(-5)-0.1 microgxcm(-3); 8.2 x 10(3)8.8 x 10(6) number x cm(-3), 1.7 x 10(-5) -0.09 microg x cm(-3), respectively; For all types of vehicles, the particle number and mass concentrations are small at low-idle and low-speed-driving modes, and are large at high-idle and high-speed-driving modes. They generally increase with the vehicle speed increasing from 10 to 70 kmx h(-1).


Assuntos
Poluentes Atmosféricos/análise , Veículos Automotores , Material Particulado/análise , Emissões de Veículos/análise , Poluentes Atmosféricos/química , Tamanho da Partícula , Material Particulado/química
18.
J Clin Pathol ; 58(6): 640-4, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15917418

RESUMO

BACKGROUND: Malignant melanoma arising from different body compartments may be associated with differing aetiological factors and clinical behaviour, and may manifest diverse molecular genetic profiles. Although many studies have focused on cutaneous melanoma, little is known of mucosal and other types of melanoma. In particular, malignant melanoma of soft parts is different from other melanomas in many respects, yet manifests a common melanocytic differentiation. Mutation of BRAF is now known to be common in cutaneous melanomas, and raises possible new therapeutic options of anti-RAF treatment for these patients. Few data are available for non-cutaneous melanomas. AIMS: To study the incidence of BRAF and NRAS mutations in melanomas arising in diverse internal organs. METHODS: Fifty one melanomas from various internal organs were investigated for BRAF and NRAS mutation by direct DNA sequencing. RESULTS: BRAF and NRAS mutations were found in two and five mucosal melanomas arising from the aerodigestive and female genital tracts (n = 36). Their occurrence is mutually exclusive, giving a combined mutation incidence rate of 19.4% in mucosal melanomas. Both BRAF and NRAS mutations were absent in malignant melanoma of soft parts (n = 7). BRAF mutation was also absent in uveal melanoma (n = 6), but was seen in two of five cutaneous melanomas. The incidence of BRAF or combined BRAF/NRAS mutations in all non-cutaneous groups was significantly lower than published rates for cutaneous melanomas. CONCLUSION: Each melanoma subtype may have a unique oncogenetic pathway of tumour development, and only a small fraction of non-cutaneous melanomas may benefit from anti-RAF treatment.


Assuntos
Genes ras/genética , Melanoma/genética , Mutação , Proteínas de Neoplasias/genética , Proteínas Proto-Oncogênicas B-raf/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Análise Mutacional de DNA , DNA de Neoplasias/genética , Neoplasias do Sistema Digestório/genética , Feminino , Neoplasias dos Genitais Femininos/genética , Humanos , Pessoa de Meia-Idade , Neoplasias Cutâneas/genética , Neoplasias Uveais/genética
19.
Acta Paediatr ; 92(8): 965-9, 2003 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12948074

RESUMO

AIM: Knowledge of the spectrum and frequencies of pediatric emergencies presenting to an emergency department (ED) of individual developing countries is vital in optimizing the quality of care delivered locally. METHODS: A prospective 6 wk review of all pediatric (< 18 y) attendees to an urban ED was done, with patient age, presenting complaints, diagnoses, time of arrival and disposition recorded. RESULTS: Complete data were available on 1172 patients, with an age range of 4 d to 18 y (mean +/- SD 6.9 +/- 5.6 y); 43% were aged < or = 4 y. The main presenting complaints were injuries (26.9%), fever (24%) and breathing difficulties (16.6%). The most common diagnosis was minor trauma (24.2%), with soft-tissue injuries predominating (80.6%). The other diagnoses were asthma (12.6%), upper respiratory infections (12.1%), other infections (12.1%) and gastroenteritis (11.8%). Equal proportions of patients were seen throughout the day. 25% of patients were admitted. Young age (< 1 y); presence of past medical history, general practitioner referrals, diagnosis of bronchiolitis and pneumonia were significantly associated with risk of admission. CONCLUSION: A wide spectrum of paediatric illnesses was seen in the ED, with an overrepresentation of young children. This supports the decision to have either a separate pediatric ED or paediatric residents on the staff. The training curricula should emphasize the management of pediatric trauma, infections and asthma. Alternatively, developing guidelines for the five most common presenting complaints would account for 82% of all attendees and could be directed towards all staff on the ED.


Assuntos
Países em Desenvolvimento , Serviço Hospitalar de Emergência/estatística & dados numéricos , Pediatria , Adolescente , Fatores Etários , Criança , Pré-Escolar , Humanos , Lactente , Malásia , Estudos Prospectivos
20.
Comput Med Imaging Graph ; 26(1): 19-23, 2002 Jan-Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11734370

RESUMO

The aim of this study was to investigate the signal characteristics of the abscess wall and tumor wall on diffusion-weighted and perfusion-weighted images and thus to evaluate the feasibility of using combined MR diffusion and perfusion imaging to differentiate pyogenic cerebral abscess from infected brain tumor. The tumor wall of various types of cystic or necrotic brain tumor was significantly hyperintense relative to that of cerebral abscess wall on both diffusion-weighted images and regional cerebral blood volume maps. Sixteen patients who had cerebral masses with large cystic or necrotic cavities were imaged to generate diffusion-weighted images and regional cerebral blood volume maps using single-shot echoplanar imaging (EPI) pulse sequences. Apart from qualitative analysis, apparent diffusion coefficients (ADC) as well as regional cerebral blood volume (rCBV) ratios were calculated from the abscess wall and peripheral tumor wall and comparison was made by using Student's t-test. The tumor wall of various types of cystic or necrotic brain tumor had significantly lower ADCs relative to those of the abscess wall (P<0.005) and thus appeared relatively hyperintense on diffusion-weighted images. The mean rCBV ratio relative to normal white matter (2.90+/-0.62) of the peripheral tumor wall of various types of cystic or necrotic brain tumor were significantly larger than the mean rCBV ratio (0.45+/-0.11) of the pyogenic cerebral abscess wall (P<0.001) by Student's t-test. It is concluded that the combined MR diffusion and perfusion imaging might be capable of differentiating an infected brain tumor from a pyogenic cerebral abscess.


Assuntos
Adenocarcinoma/diagnóstico , Abscesso Encefálico/diagnóstico , Neoplasias Encefálicas/diagnóstico , Imagem por Ressonância Magnética/métodos , Adenocarcinoma/patologia , Adenocarcinoma/secundário , Encéfalo/irrigação sanguínea , Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/secundário , Diagnóstico Diferencial , Difusão , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Perfusão , Fluxo Sanguíneo Regional
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