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1.
Am J Transplant ; 16(5): 1569-78, 2016 05.
Artigo em Inglês | MEDLINE | ID: mdl-26613555

RESUMO

Neoplasm history increases morbidity and mortality after solid organ transplantation and has disqualified patients from transplantation. Studies are needed to identify factors to be considered when deciding on the suitability of a patient with previous tumor for heart transplantation. A retrospective epidemiological study was conducted in heart transplant (HT) recipients (Spanish Post-Heart Transplant Tumor Registry) comparing the epidemiological data, immu-nosuppressive treatments and incidence of post-HT tumors between patients with previous malignant noncardiac tumor and with no previous tumor (NPT). The impact of previous tumor (PT) on overall survival (OS) was also assessed. A total of 4561 patients, 77 PT and 4484 NPT, were evaluated. The NPT group had a higher proportion of men than the PT group (p < 0.001). The incidence of post-HT tumors was 1.8 times greater in the PT group (95% confidence interval [CI] 1.2-2.6; p < 0.001), mainly due to the increased risk in patients with a previous hematologic tumor (rate ratio 2.3, 95% CI 1.3-4.0, p < 0.004). OS during the 10-year posttransplant period was significantly lower in the PT than the NPT group (p = 0.048) but similar when the analysis was conducted after a first post-HT tumor was diagnosed. In conclusion, a history of PT increases the incidence of post-HT tumors and should be taken into account when considering a patient for HT.


Assuntos
Cardiopatias/complicações , Transplante de Coração/efeitos adversos , Neoplasias/epidemiologia , Neoplasias/fisiopatologia , Complicações Pós-Operatórias/epidemiologia , Idoso , Feminino , Seguimentos , Cardiopatias/cirurgia , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Retrospectivos , Fatores de Risco , Espanha/epidemiologia , Fatores de Tempo
2.
Estud. psicol. (Campinas) ; 32(4): 743-753, Oct.-Dec. 2015.
Artigo em Português | LILACS | ID: lil-764135

RESUMO

Este estudo investigou a percepção de professores de Língua Portuguesa sobre fatores relacionados à criatividade em produções textuais discentes. Foram entrevistados 12 docentes do segundo ciclo do ensino fundamental (seis de escolas públicas e seis de escolas particulares). Os resultados revelaram ser a elaboração de textos pouco trabalhada pelos professores, tendo sido dada como justificativa a falta de tempo gerada pelo número elevado de alunos e carga horária extensa. Um percentual expressivo de docentes considerou pouco criativas as produções textuais discentes, embora a quase totalidade tenha se avaliado como profissionais inventivos e apontado diversas estratégias para facilitar a escrita de textos criativos em sala de aula. Indicaram, como fatores limitadores à expressão da criatividade nas produções textuais, elementos relacionados aos estudantes, professores e escola. Os resultados trazem implicações para a formação de professores de Língua Portuguesa no que diz respeito à criatividade na redação de textos em sala de aula.


This study investigated Portuguese language teachers' perceptions of factors associated with creativity in students' written production. Twelve elementary school Portuguese language teachers (six from public schools and six from private schools) were interviewed. The results revealed that written production has not been widely used in school, especially due to teachers' lack of time owing to the high number of students and number of hours of work. A considerable number of teachers considered their students' written production as not very creative although most of them considered themselves as highly creative professionals who make frequent use of several strategies to facilitate creative written production in the classroom. They indicated elements related to the students, teachers, and school as limiting factors to the expression of creativity in written production. The results show impacts on Portuguese language teachers' education and training in terms of creativity in written productions in the classroom.


Assuntos
Humanos , Criatividade , Ensino Fundamental e Médio , Docentes
3.
Estud. psicol. (Campinas) ; 32(4): 743-753, out.-dez. 2015.
Artigo em Português | Index Psicologia - Periódicos | ID: psi-64731

RESUMO

Este estudo investigou a percepção de professores de Língua Portuguesa sobre fatores relacionados à criatividade em produções textuais discentes. Foram entrevistados 12 docentes do segundo ciclo do ensino fundamental (seis de escolas públicas e seis de escolas particulares). Os resultados revelaram ser a elaboração de textos pouco trabalhada pelos professores, tendo sido dada como justificativa a falta de tempo gerada pelo número elevado de alunos e carga horária extensa. Um percentual expressivo de docentes considerou pouco criativas as produções textuais discentes, embora a quase totalidade tenha se avaliado como profissionais inventivos e apontado diversas estratégias para facilitar a escrita de textos criativos em sala de aula. Indicaram, como fatores limitadores à expressão da criatividade nas produções textuais, elementos relacionados aos estudantes, professores e escola. Os resultados trazem implicações para a formação de professores de Língua Portuguesa no que diz respeito à criatividade na redação de textos em sala de aula.(AU)


This study investigated Portuguese language teachers' perceptions of factors associated with creativity in students' written production. Twelve elementary school Portuguese language teachers (six from public schools and six from private schools) were interviewed. The results revealed that written production has not been widely used in school, especially due to teachers' lack of time owing to the high number of students and number of hours of work. A considerable number of teachers considered their students' written production as not very creative although most of them considered themselves as highly creative professionals who make frequent use of several strategies to facilitate creative written production in the classroom. They indicated elements related to the students, teachers, and school as limiting factors to the expression of creativity in written production. The results show impacts on Portuguese language teachers' education and training in terms of creativity in written productions in the classroom.(AU)


Assuntos
Humanos , Criatividade , Docentes , Ensino Fundamental e Médio
4.
Clin Transplant ; 29(9): 771-80, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26074358

RESUMO

A multicenter cross-sectional study was conducted to determine the current heart transplant (HTx) outcomes in Spain. Clinical and functional status, health-related quality of life (HRQoL), social support, and caregiver burden were analyzed in 303 adult transplant recipients (77.9% males) living with one functioning graft. Mean age at time of HTx (SD) was 56.4 (11.4) years, and the reason for transplantation in all patients was congestive heart failure. All patients had received a first heart transplant 6 (± 1), 12 (± 2), 36 (± 6), 60 (± 10), or 120 (± 20) months previously. Participants completed the Kansas City Cardiomyopathy Questionnaire (KCCQ), the EQ-5D, the Duke-UNC Functional Social Support Questionnaire, and the Zarit Caregiver Burden Scale. Reasonable HRQoL, social support, and caregiver burden levels were found at all time points, although a slight decrease in HRQoL was recorded at 120 months (p ≤ 0.033). Multivariate regression analyses showed that complications, comorbidities, and hospitalizations were associated with HRQoL (EQ-5D: 48.4% of explained variance, F4,164 = 38.46, p < 0.001; KCCQ overall summary score: 45.0%, F3,198 = 54.073, p < 0.001). Patient functional capabilities and complications affected caregiver burden (p < 0.05). In conclusion, HTx patients reported reasonable levels of HRQoL with low caregiver burden. Clinical variables related to these outcomes included functional status, complications, and number of admissions.


Assuntos
Cuidadores/psicologia , Efeitos Psicossociais da Doença , Insuficiência Cardíaca/cirurgia , Transplante de Coração/psicologia , Qualidade de Vida , Apoio Social , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos Transversais , Feminino , Insuficiência Cardíaca/psicologia , Humanos , Masculino , Pessoa de Meia-Idade , Espanha , Inquéritos e Questionários , Resultado do Tratamento , Adulto Jovem
5.
Phys Med Biol ; 60(1): 117-36, 2015 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-25479147

RESUMO

Although current PET scanners are designed and optimized to detect double coincidence events, there is a significant amount of triple coincidences in any PET acquisition. Triple coincidences may arise from causes such as: inter-detector scatter (IDS), random triple interactions (RT), or the detection of prompt gamma rays in coincidence with annihilation photons when non-pure positron-emitting radionuclides are used (ß(+)γ events). Depending on the data acquisition settings of the PET scanner, these triple events are discarded or processed as a set of double coincidences if the energy of the three detected events is within the scanner's energy window. This latter option introduces noise in the data, as at most, only one of the possible lines-of-response defined by triple interactions corresponds to the line along which the decay occurred. Several novel works have pointed out the possibility of using triple events to increase the sensitivity of PET scanners or to expand PET imaging capabilities by allowing differentiation between radiotracers labeled with non-pure and pure positron-emitting radionuclides. In this work, we extended the Monte Carlo simulator PeneloPET to assess the proportion of triple coincidences in PET acquisitions and to evaluate their possible applications. We validated the results of the simulator against experimental data acquired with a modified version of a commercial preclinical PET/CT scanner, which was enabled to acquire and process triple-coincidence events. We used as figures of merit the energy spectra for double and triple coincidences and the triples-to-doubles ratio for different energy windows and radionuclides. After validation, the simulator was used to predict the relative quantity of triple-coincidence events in two clinical scanners assuming different acquisition settings. Good agreement between simulations and preclinical experiments was found, with differences below 10% for most of the observables considered. For clinical scanners and pure positron emitters, we found that around 10% of the processed double events come from triple coincidences, increasing this ratio substantially for non-pure emitters (around 25% for (124)I and > 50% for (86)Y). For radiotracers labeled with (18)F we found that the relative quantity of IDS events in standard acquisitions is around 18% for the preclinical scanner and between 14 and 22% for the clinical scanners. For non-pure positron emitters like (124)I, we found a ß(+)γ triples-to-doubles ratio of 2.5% in the preclinical scanner and of up to 4% in the clinical scanners.


Assuntos
Simulação por Computador , Raios gama , Imagens de Fantasmas , Fótons , Tomografia por Emissão de Pósitrons/métodos , Animais , Partículas beta , Humanos , Radioisótopos do Iodo , Camundongos , Método de Monte Carlo , Tomógrafos Computadorizados
6.
Phys Med Biol ; 57(22): 7493-518, 2012 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-23103969

RESUMO

Technological advances have improved the assembly process of PET detectors, resulting in quite small mechanical tolerances. However, in high-spatial-resolution systems, even submillimetric misalignments of the detectors may lead to a notable degradation of image resolution and artifacts. Therefore, the exact characterization of misalignments is critical for optimum reconstruction quality in such systems. This subject has been widely studied for CT and SPECT scanners based on cone beam geometry, but this is not the case for PET tomographs based on rotating planar detectors. The purpose of this work is to analyze misalignment effects in these systems and to propose a robust and easy-to-implement protocol for geometric characterization. The result of the proposed calibration method, which requires no more than a simple calibration phantom, can then be used to generate a correct 3D-sinogram from the acquired list mode data.


Assuntos
Artefatos , Tomografia por Emissão de Pósitrons/instrumentação , Rotação , Algoritmos , Animais , Calibragem , Processamento de Imagem Assistida por Computador , Ratos
7.
Transplant Proc ; 44(7): 2103-5, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22974924

RESUMO

This is the first official report of the Andalusian Registry of Heart Transplantation. Since 1986, two centers in the community have been authorized to perform adult heart transplantation. Until 2010, 854 adult heart transplantation procedures were performed, which constitute the basis of the present report. Clinical features and survival are analyzed. The leading reason for heart transplantation was ischemic cardiomyopathy (34%) and nonischemic dilated cardiomyopathy (34%). The mean age of the recipients was 46 ± 16 years and the mean age of the donors was 29 ± 13 years. After a median follow-up of 106 months, the mean survival was 13.4 ± 0.6 years.


Assuntos
Transplante de Coração/estatística & dados numéricos , Sistema de Registros , Adulto , Cardiomiopatia Dilatada/cirurgia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Isquemia Miocárdica/cirurgia , Espanha/epidemiologia , Análise de Sobrevida
8.
Transplant Proc ; 44(7): 2113-4, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22974927

RESUMO

Cytomegalovirus (CMV) infection remains a major complication in recipients of solid organ transplantation. Based on available evidence, most centers are committed to an aggressive strategy, especially in high-risk patients, consisting of the use of universal prophylaxis in the posttransplantation period of maximum risk (3 months). In seropositive recipients there is no ideal model for prevention, although there is more acceptance in the international community for preemptive therapy. This paper shows the results obtained after analysis of a cohort of 86 patients undergoing heart transplantation in 2005-2011 at the Virgen del Rocío University Hospital, Seville. The 86 patients followed a strategy of preemptive therapy for both high- and low-risk recipients based on the use of antivirals for a variable period of ∼3 weeks when rising antigenemia was detected, determined by polymerase chain reaction above a set threshold. The incidence of CMV disease in our cohort was 4.6%. There are no data available from randomized clinical trials to establish which of the 2 strategies is more effective and safer in these patients, although there is a little experience with preemptive therapy in high-risk patients. Given our positive results and considering the adverse effects of antiviral prophylaxis derivatives, together with the development of resistance and the economic cost, we suggest an individualized prevention strategy at each center.


Assuntos
Infecções por Citomegalovirus/prevenção & controle , Transplante de Coração , Estudos de Coortes , Infecções por Citomegalovirus/epidemiologia , Humanos , Incidência , Fatores de Risco
9.
Transplant Proc ; 43(7): 2699-706, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21911149

RESUMO

Chronic renal failure (CRF) due to calcineurin inhibitor (CNI) nephrotoxicity is a frequent complication among heart transplant (HT) recipients. Small studies have suggested that the introduction of mycophenolate mofetil (MMF) can help to reduce CNI doses thereby to maintaining or improving renal function. We conducted a 4-year, prospective, multicenter study in 89 maintenance HT recipients at 5.6 ± 2.7 years postgrafting who displayed CRF (serum creatinine > 1.4 mg/dL) and were undergoing treatment with cyclosporine and prednisone ± azathioprine. We introduced MMF and reduced cyclosporine to level below 100 ng/mL. Creatinine clearance (CrCl), acute rejection episodes, and survival were through retrospectively compared with a contemporary cohort of HT recipients who were not treated with MMF (control group; n = 38). After conversion to MMF, a rapid increase was observed in the CrCl, which was maintained over the follow-up: namely, CrCl at month 6 and at 4 years were 51.0 ± 15.6 and 54.1 ± 15.6 mL/min versus 41.9 ± 11.1 mL/min at baseline (P < .0001). No renal function changes were observed among the control group. Acute rejection rates were 5.6% and 2.6% in the MMF versus control groups (P = NS) with 4-year survivals >85%. In conclusion, the introduction of MMF allowed a safe reduction of cyclosporine and significantly improved renal function after 4 years.


Assuntos
Ciclosporina/administração & dosagem , Transplante de Coração , Imunossupressores/administração & dosagem , Falência Renal Crônica/fisiopatologia , Ácido Micofenólico/análogos & derivados , Relação Dose-Resposta a Droga , Feminino , Rejeição de Enxerto , Humanos , Masculino , Pessoa de Meia-Idade , Ácido Micofenólico/administração & dosagem , Estudos Prospectivos , Espanha , Taxa de Sobrevida
10.
Transpl Infect Dis ; 13(2): 136-44, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21040280

RESUMO

BACKGROUND: The objectives of this epidemiological, prospective study were to describe the characteristics of cytomegalovirus (CMV) infection in heart transplant (HT) recipients and to identify the variables that may influence the development of CMV viremia and CMV disease in these patients. METHODS: HT recipients ≥18 years of age (n=199) were included in the study. Variables studied included CMV serostatus, immunosuppressive treatment, and administration of anti-CMV prophylaxis. RESULTS: The mean age of the population was 52 years, and 84% were males. Immunosuppressive regimens were administered as induction therapy to 92.5% of patients; 88.5% of patients received calcineurin inhibitors as maintenance therapy. Anti-CMV treatment was given to 59% of 199 patients as prophylaxis (70%), preemptive therapy (10%), or to treat CMV infection (20%). Overall, 43% of patients had at least 1 positive viremia test. No patient with a high-risk serostatus (donor+/recipient-) receiving prophylaxis developed CMV syndrome, and only 2.5% of 199 patients developed CMV invasive disease. Multivariate analysis showed that having a positive donor CMV serostatus was associated with an increased risk of developing CMV viremia (P<0.012), while use of mammalian target of rapamycin (mTOR) inhibitors was associated with a decreased risk (P=0.005). CONCLUSIONS: In a population of HT recipients, the CMV infection rate was similar to that seen in previous studies, but the progression to overt CMV disease was very low. Having a CMV-positive donor was identified as an independent risk factor for developing CMV viremia, while the use of mTOR inhibitors was protective against viremia.


Assuntos
Infecções por Citomegalovirus/etiologia , Transplante de Coração/efeitos adversos , Adulto , Infecções por Citomegalovirus/epidemiologia , Feminino , Humanos , Imunossupressores , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Estudos Prospectivos , Fatores de Risco , Espanha/epidemiologia
11.
Phys Med Biol ; 55(15): 4291-308, 2010 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-20647602

RESUMO

We present a new high-performance and low-cost approach for implementing radiation detection acquisition systems. The basic elements used are charge-integrating ADCs and a set of components encapsulated in an HDL (hardware definition language) library which makes it possible to implement several acquisition tasks such as time pickoff and coincidence detection using a new and simple trigger technique that we name WMLET (width-modulated leading-edge timing). As proof of concept, a 32-channel hybrid PET/SPECT acquisition system based on these elements was developed and tested. This demonstrator consists of a master module responsible for the generation and distribution of trigger signals, 2 x 16-channel ADC cards (12-bit resolution) for data digitization and a 32-bit digital I/O PCI card for handling data transmission to a personal computer. System characteristics such as linearity, maximum transmission rates or timing resolution in coincidence mode were evaluated with test and real detector signals. Imaging capabilities of the prototype were also evaluated using different detector configurations. The performance tests showed that this implementation is able to handle data rates in excess of 600k events s(-1) when acquiring simultaneously 32 channels (96-byte events). ADC channel linearity is >98.5% in energy quantification. Time resolution in PET mode for the tested configurations ranges from 3.64 ns FWHM to 7.88 ns FWHM when signals from LYSO-based detectors are used. The measured energy resolution matched the expected values for the detectors evaluated and single elements of crystal matrices can be neatly separated in the acquired flood histograms.


Assuntos
Equipamentos e Provisões Elétricas , Raios gama , Processamento de Imagem Assistida por Computador/instrumentação , Tomografia , Modelos Lineares , Tomografia por Emissão de Pósitrons , Reprodutibilidade dos Testes , Tomografia Computadorizada de Emissão de Fóton Único
12.
Transplant Proc ; 41(9): 3835-7, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19917397

RESUMO

BACKGROUND: Chronic renal failure is a common complication of heart transplantation. Sirolimus (SRL) is an immunosuppressive drug that, unlike calcineurin inhibitors (CNIs), is not associated with nephrotoxicity. METHODS: We collected efficacy and safety data from a Spanish registry of heart transplant recipients who were switched from a CNI to SRL due to renal failure. Patients were included if the serum creatinine level before switching was >1.5 mg/dL and/or the estimated creatinine clearance level was below 50 mL/min. RESULTS: Ninety-seven patients started SRL due to renal impairment. When SRL was started, CNIs were progressively tapered and in some cases withdrawn. Mean baseline creatinine level was 2.5 mg/dL and mean creatinine clearance level was 39 mL/min. Only 1 episode of acute rejection was observed in a patient receiving SRL plus cyclosporine (CsA) but the eventual allograft function remained stable. Compared with baseline, a significant improvement in renal function was observed at 6 months among patients who stopped CNIs before the third month after SRL was started, although not among those who continued taking CNIs. Upon multivariate analysis, no predictors of response were observed. SRL was withdrawn in 18% of patients due to adverse events. CONCLUSIONS: Switching to SRL was safe in heart allograft recipients, improving renal function among those previously receiving a CNI. Renal function improves if CNIs are withdrawn soon after starting SRL.


Assuntos
Transplante de Coração/imunologia , Insuficiência Renal/complicações , Sirolimo/uso terapêutico , Adulto , Inibidores de Calcineurina , Creatinina/sangue , Creatinina/metabolismo , Relação Dose-Resposta a Droga , Transplante de Coração/efeitos adversos , Humanos , Imunossupressores/administração & dosagem , Imunossupressores/uso terapêutico , Sistema de Registros , Estudos Retrospectivos , Segurança , Sirolimo/administração & dosagem , Espanha
13.
Transplant Proc ; 41(6): 2244-6, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19715887

RESUMO

OBJECTIVE: Steroid withdrawal (SW) from maintenance therapy in heart transplant patients is still a controversial subject. We designed a questionnaire to ascertain the attitudes and procedures of a number of Spanish heart transplant units (16) regarding the use/withdrawal of steroids as part of the immunosuppressive maintenance therapy. MATERIALS AND METHODS: We sent an 11-item questionnaire to the clinical director in charge of each unit. The questionnaire was completed and returned by 14 units. RESULTS: In 21.5% of the centers SW was performed in all patients, while 78.5% of the centers only performed SW in selected patients. In 57% of units SW was performed at 12 months posttransplantation and between 6 and 12 months in the rest. Fewer than 20% of patients were steroid-free in 46% of units while in 23% of units this proportion was >50%. In 11 units, the minimum prednisone dose administered was

Assuntos
Corticosteroides/uso terapêutico , Transplante de Coração/imunologia , Imunossupressores/uso terapêutico , Corticosteroides/administração & dosagem , Esquema de Medicação , Inquéritos Epidemiológicos , Transplante de Coração/mortalidade , Transplante de Coração/patologia , Transplante de Coração/estatística & dados numéricos , Humanos , Estudos Multicêntricos como Assunto , Complicações Pós-Operatórias/classificação , Complicações Pós-Operatórias/epidemiologia , Sistema de Registros , Fatores de Risco , Espanha , Inquéritos e Questionários , Taxa de Sobrevida , Transplante Homólogo/patologia
14.
Phys Med Biol ; 54(18): 5427-41, 2009 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-19700817

RESUMO

This work reports on the development and performance evaluation of the VrPET/CT, a new multimodality scanner with coplanar geometry for in vivo rodent imaging. The scanner design is based on a partial-ring PET system and a small-animal CT assembled on a rotatory gantry without axial displacement between the geometric centers of both fields of view (FOV). We report on the PET system performance based on the NEMA NU-4 protocol; the performance characteristics of the CT component are not included herein. The accuracy of inter-modality alignment and the imaging capability of the whole system are also evaluated on phantom and animal studies. Tangential spatial resolution of PET images ranged between 1.56 mm at the center of the FOV and 2.46 at a radial offset of 3.5 cm. The radial resolution varies from 1.48 mm to 1.88 mm, and the axial resolution from 2.34 mm to 3.38 mm for the same positions. The energy resolution was 16.5% on average for the entire system. The absolute coincidence sensitivity is 2.2% for a 100-700 keV energy window with a 3.8 ns coincident window. The scatter fraction values for the same settings were 11.45% for a mouse-sized phantom and 23.26% for a rat-sized phantom. The peak noise equivalent count rates were also evaluated for those phantoms obtaining 70.8 kcps at 0.66 MBq/cc and 31.5 kcps at 0.11 MBq/cc, respectively. The accuracy of inter-modality alignment is below half the PET resolution, and the image quality of biological specimens agrees with measured performance parameters. The assessment presented in this study shows that the VrPET/CT system is a good performance small-animal imager, while the cost derived from a partial ring detection system is substantially reduced as compared with a full-ring PET tomograph.


Assuntos
Tomografia por Emissão de Pósitrons/instrumentação , Tomografia por Emissão de Pósitrons/veterinária , Técnica de Subtração/instrumentação , Técnica de Subtração/veterinária , Tomografia Computadorizada por Raios X/instrumentação , Tomografia Computadorizada por Raios X/veterinária , Animais , Desenho de Equipamento , Análise de Falha de Equipamento , Camundongos , Imagens de Fantasmas , Ratos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Integração de Sistemas
15.
Med Phys ; 36(5): 1663-71, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19544783

RESUMO

Low-pass filtering of sinograms in the radial direction is the most common practice to limit noise amplification in filtered back projection (FBP) reconstruction of positron emission tomography studies. Other filtering strategies have been proposed to prevent the loss in resolution due to low-pass radial filters, although results have been diverse. Using the well-known properties of the Fourier transform of a sinogram, the authors defined a binary mask that matches the expected shape of the support region in the Fourier domain of the sinogram ("bow tie"). This mask was smoothed by a convolution with a ten-point Gaussian kernel which not only avoids ringing but also introduces a pre-emphasis at low frequencies. A new filtering scheme for FBP is proposed, comprising this smoothed bow-tie filter combined with a standard radial filter and an axial filter. The authors compared the performance of the bow-tie filtering scheme with that of other previously reported methods: Standard radial filtering, angular filtering, and stackgram-domain filtering. All the quantitative data in the comparisons refer to a baseline reconstruction using a ramp filter only. When using the smallest size of the Gaussian kernel in the stackgram domain, the authors achieved a noise reduction of 33% at the cost of degrading radial and tangential resolutions (14.5% and 16%, respectively, for cubic interpolation). To reduce the noise by 30%, the angular filter produced a larger degradation of contrast (3%) and tangential resolution (46% at 10 mm from the center of the field of view) and showed noticeable artifacts in the form of circular blurring dependent on the distance to the center of the field of view. For a similar noise reduction (33%), the proposed bow-tie filtering scheme yielded optimum results in resolution (gain in radial resolution of 10%) and contrast (1% increase) when compared with any of the other filters alone. Experiments with rodent images showed noticeable image quality enhancement when using the proposed bow-tie filtering scheme.


Assuntos
Algoritmos , Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador/métodos , Tomografia por Emissão de Pósitrons/métodos , Animais , Camundongos , Imagens de Fantasmas , Tomografia por Emissão de Pósitrons/instrumentação , Ratos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
16.
Am J Transplant ; 8(5): 1031-9, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18416739

RESUMO

The Spanish Post-Heart-Transplant Tumour Registry comprises data on neoplasia following heart transplantation (HT) for all Spanish HT patients (1984-2003). This retrospective analysis of 3393 patients investigated the incidence and prognosis of neoplasia, and the influence of antiviral prophylaxis. About 50% of post-HT neoplasias were cutaneous, and 10% lymphomas. The cumulative incidence of skin cancers and other nonlymphoma cancers increased with age at HT and with time post-HT (from respectively 5.2 and 8.9 per 1000 person-years in the first year to 14.8 and 12.6 after 10 years), and was greater among men than women. None of these trends held for lymphomas. Induction therapy other than with IL2R-blockers generally increased the risk of neoplasia except when acyclovir was administered prophylactically during the first 3 months post-HT; prophylactic acyclovir halved the risk of lymphoma, regardless of other therapies. Institution of MMF during the first 3 months post-HT reduced the incidence of skin cancer independently of the effects of sex, age group, pre-HT smoking, use of tacrolimus in the first 3 months, induction treatment and antiviral treatment. Five-year survival rates after first tumor diagnosis were 74% for skin cancer, 20% for lymphoma and 32% for other tumors.


Assuntos
Transplante de Coração/efeitos adversos , Neoplasias/epidemiologia , Complicações Pós-Operatórias/epidemiologia , Adolescente , Adulto , Seguimentos , Humanos , Incidência , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores de Risco , Espanha , Fatores de Tempo
17.
Int J Gynaecol Obstet ; 100(1): 60-4, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17900583

RESUMO

OBJECTIVE: To test a new noninvasive ultrasound method for diagnosing fetal anemia in red blood cell isoimmunized pregnancies. METHODS: A diagnostic accuracy study was carried out to determine the cutoff point of an ultrasound measurement, the cardiofemoral index (CFI), calculated using the biventricular outer dimension (BVOD) and femur length to diagnosis severe anemia. The CFI measurement was performed before each of the 336 cordocenteses on 131 fetuses. Diagnosis test analysis and receiver-operating characteristics (ROC) curves were used and the area under the curve (AUC) was calculated to compare the overall accuracy of the CFI for anemia diagnosis, between fetuses with or without previous intrauterine transfusions (IUT). RESULTS: At first cordocentesis (n=131) the AUC was 0.75 (95% CI, 0.66-0.84). For cases where fetuses had undergone 1 previous transfusion (n=88) the AUC was 0.76 (95% CI, 0.64-0.88) and at the time of the third cordocentesis for IUT (n=53) it was 0.73 (95% CI, 0.59-0.86). For a 0.59 CFI threshold to diagnosis fetuses with hemoglobin deficit above 5 g/dL, sensitivity values were 87.2%, 88.0%, and 94.1% respectively for fetuses without IUT, with 1 IUT, and with 2 IUTs. Likelihood ratios for positive (LR+) and negative (LR-) test results were 1.98, 2.05, 1.69 and 0.23, 0.21, 0.13 respectively. CONCLUSION: The cardiofemoral index may be an effective noninvasive marker of severe fetal anemia in high-risk fetuses, with accuracy similar for fetuses either with or without previous transfusions.


Assuntos
Anemia Hemolítica/diagnóstico por imagem , Eritroblastose Fetal/diagnóstico por imagem , Fêmur/anatomia & histologia , Ventrículos do Coração/anatomia & histologia , Isoimunização Rh , Ultrassonografia Pré-Natal , Adulto , Anemia Hemolítica/sangue , Biomarcadores , Transfusão de Sangue Intrauterina , Pesos e Medidas Corporais/métodos , Cordocentese , Estudos Transversais , Feminino , Fêmur/diagnóstico por imagem , Ventrículos do Coração/diagnóstico por imagem , Humanos , Gravidez , Curva ROC , Isoimunização Rh/sangue , Isoimunização Rh/diagnóstico por imagem , Sensibilidade e Especificidade
18.
Transplant Proc ; 38(8): 2522-3, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17097987

RESUMO

INTRODUCTION: Severe pulmonary hypertension with no response to vasodilators on an acute hemodynamic study is a contraindication to cardiac transplantation. The development of oral pulmonary vasodilators improves the prognosis in these patients. We present the case of a patient whose admission to the waiting list for cardiac transplantation was possible after 6 months of combination therapy with Sildenafil and Bosentan. CASE REPORT: The patient was a 50-year-old man with severe dilated alcohol-induced cardiomyopathy. A pretransplantation study, including a right hemodynamic analysis, revealed irreversible pulmonary hypertension, with 59 mm Hg mean pulmonary artery pressure and 6.4 Wood IU pulmonary vascular resistance, with no response to acute vasodilators with nitric oxide or prostacyclin. Initially, heart transplantation was not possible and the patient started treatment with oral Sildenafil. After 6 months there was no improvement in echocardiographic or hemodynamic parameters, and combination therapy with Bosentan was started. With the combination therapy, the patient progressively improved clinically and hemodynamically, the pressures becoming normal at the sixth month, at which time he was included on the waiting list for a heart transplantation. Eight months later he received a graft with a good posttransplantation course, no right ventricular failure in the acute phase, and absence of pulmonary hypertension on echocardiogrphic and invasive studies. CONCLUSION: Combinations of an oral pulmonary vasodilator with diverse action mechanisms may represent an alternative for patients with irreversible pulmonary hypertension who do not respond to monotherapy.


Assuntos
Anti-Hipertensivos/uso terapêutico , Transplante de Coração , Hipertensão Pulmonar/tratamento farmacológico , Piperazinas/uso terapêutico , Sulfonamidas/uso terapêutico , Bosentana , Quimioterapia Combinada , Humanos , Masculino , Pessoa de Meia-Idade , Purinas , Citrato de Sildenafila , Sulfonas , Resultado do Tratamento , Vasodilatadores/uso terapêutico , Listas de Espera
19.
Transplant Proc ; 38(8): 2531-3, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17097991

RESUMO

INTRODUCTION: Emergency heart transplantation remains an important controversy due to the shortage of donors and the previously demonstrated results inferior to other patients. These recipients display a worse clinical status and their donors are more often considered suboptimal. Nevertheless, it is the only therapeutic option for patients with advanced cardiomyopathy and acute decompensation with no response to other therapies. We compared results among the emergency indication with those of elective transplants. METHODS: We analyzed the 213 patients who underwent cardiac transplantation in our center up to December 2004 to compare emergency with elective heart transplantations for preoperative and surgical variables as well as outcomes. RESULTS: A higher percentage of emergency patients were New York Heart Association class IV, displayed renal dysfunction, and were women. Regarding donors, a higher percentage were over 40 years of age. No differences were observed in the early and first-year mortality or morbidity rates, although we noted a greater 5-year mortality rate among emergency cases. CONCLUSIONS: In our center emergency heart transplantation was associated with only slightly worse results compared with elective transplantations. Both donors and recipients should be carefully selected to improve results.


Assuntos
Emergências , Transplante de Coração/métodos , Adulto , Peso Corporal , Feminino , Transplante de Coração/mortalidade , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Estudos Retrospectivos , Análise de Sobrevida , Doadores de Tecidos/estatística & dados numéricos , Resultado do Tratamento
20.
Transplant Proc ; 38(8): 2544-6, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17097996

RESUMO

INTRODUCTION: Using previous immunosuppressive regimens the considerable number of rejections of heart transplantations required routine surveillance myocardial biopsies, particularly during the early months. More effective immunosuppressive regimens would probably allow routine biopsies to be reduced. Our objectives were to assess the incidence of and the time to rejection with a new immunosuppressive protocol, considering the possibility of reducing the number of routine biopsies. MATERIALS AND METHODS: We undertook a retrospective study of patients who had undergone heart transplantation from January 2002 to August 2005 and who received induction therapy with Daclizumab (two doses) and maintenance therapy with tacrolimus + mycophenolate + low doses of steroids. RESULTS: Among 42 patients, 13 (31%) showed myocardial rejection in the first 3 months. All episodes were grade 3A and none had hemodynamic consequences. After 3 months, three patients (7.1%) experienced 3A rejection and 1 (2.4%), grade 4 acute rejection after ceasing medical treatment. Each episode of rejection was predictable, either owing to reduction in immunosuppression therapy or to a previous history of rejection. CONCLUSIONS: The majority of rejection episodes occur in the first 3 months posttransplantation. After that time, the incidence of rejection is less and clinically predictable. Therefore, surveillance biopsies should be limited to the first 3 months, and performed later either in symptomatic patients (with a history of previous rejection) or in those whose immunosuppressive therapy needs to be reduced.


Assuntos
Biópsia/estatística & dados numéricos , Transplante de Coração/patologia , Imunossupressores/uso terapêutico , Feminino , Rejeição de Enxerto/epidemiologia , Transplante de Coração/imunologia , Transplante de Coração/mortalidade , Humanos , Masculino , Estudos Retrospectivos , Análise de Sobrevida
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