Comparison of automated and manual protocols for magnetic resonance imaging assessment of liver iron concentration.

OBJECTIVE: To compare automated and manual magnetic resonance imaging protocols for estimating liver iron concentrations at 1.5 T. MATERIALS AND METHODS: Magnetic resonance imaging examination of the liver was performed in 53 patients with clinically suspected hepatic iron overload and in 21 control subjects. Liver iron concentrations were then estimated by two examiners who were blinded to the groups. The examiners employed automated T2* and T1 mapping, as well as manual T2* and signal-intensity-ratio method. We analyzed accuracy by using ROC curves. Interobserver and intraobserver agreement were analyzed by calculating two-way intraclass correlation coefficients. RESULTS: The area under the ROC curve (to discriminate between patients and controls) was 0.912 for automated T2* mapping, 0.934 for the signal-intensity-ratio method, 0.908 for manual T2*, and 0.80 for T1 mapping, the last method differing significantly from the other three. The level of interobserver and intraobserver agreement was good (intraclass correlation coefficient, 0.938-0.998; p < 0.05). Correlations involving T1 mapping, although still significant, were lower. CONCLUSION: At 1.5 T, T2* mapping is a rapid tool that shows promise for the diagnosis of liver iron overload, whereas T1 mapping shows less accuracy. The performance of T1 mapping is poorer than is that of T2* methods.

OBJETIVO: Comparar protocolos automatizados e manuais de ressonância magnética para estimar a concentração hepática de ferro em 1,5 T. MATERIAIS E MÉTODOS: Foi realizada ressonância magnética hepática em 53 pacientes com suspeita de sobrecarga de ferro hepática e 21 controles, seguida da estimativa cega da concentração hepática de ferro por dois examinadores usando mapas automáticos T2* e T1, assim como o manual T2* e o método signal-intensity-ratio. O desempenho foi medido usando curvas ROC e a correlação interobservador e intraobservador usando o coeficiente de correlação intraclasse bidirecional. RESULTADOS: O desempenho da curva ROC separando pacientes e controles mostrou áreas sob a curva de 0,912 para o mapa automático T2*, 0,934 para o método signal-intensity-ratio, 0,908 para manual T2* e 0,80 para mapa T1 (este difere significativamente dos outros três métodos). Houve boa correlação interobservador e intraobservador (coeficiente de correlação intraclasse entre 0,938 e 0,998; p < 0,05). Correlações envolvendo o mapa T1, embora ainda significativas, foram menores. CONCLUSÃO: Em 1,5 T, o mapa T2* representa uma nova ferramenta rápida e promissora para avaliar o diagnóstico de sobrecarga de ferro hepática, enquanto o mapa T1 mostrou menor precisão. O desempenho do mapa T1 foi menor que o dos métodos T2*.

Comparison of automated and manual protocols for magnetic resonance imaging assessment of liver iron concentration / Comparação de protocolos automatizados e manuais de ressonância magnética para avaliação da concentração hepática de ferro

Abstract Objective: To compare automated and manual magnetic resonance imaging protocols for estimating liver iron concentrations at 1.5 T. Materials and Methods: Magnetic resonance imaging examination of the liver was performed in 53 patients with clinically suspected hepatic iron overload and in 21 control subjects. Liver iron concentrations were then estimated by two examiners who were blinded to the groups. The examiners employed automated T2* and T1 mapping, as well as manual T2* and signal-intensity-ratio method. We analyzed accuracy by using ROC curves. Interobserver and intraobserver agreement were analyzed by calculating two-way intraclass correlation coefficients. Results: The area under the ROC curve (to discriminate between patients and controls) was 0.912 for automated T2* mapping, 0.934 for the signal-intensity-ratio method, 0.908 for manual T2*, and 0.80 for T1 mapping, the last method differing significantly from the other three. The level of interobserver and intraobserver agreement was good (intraclass correlation coefficient, 0.938-0.998; p < 0.05). Correlations involving T1 mapping, although still significant, were lower. Conclusion: At 1.5 T, T2* mapping is a rapid tool that shows promise for the diagnosis of liver iron overload, whereas T1 mapping shows less accuracy. The performance of T1 mapping is poorer than is that of T2* methods.

Resumo Objetivo: Comparar protocolos automatizados e manuais de ressonância magnética para estimar a concentração hepática de ferro em 1,5 T. Materiais e Métodos: Foi realizada ressonância magnética hepática em 53 pacientes com suspeita de sobrecarga de ferro hepática e 21 controles, seguida da estimativa cega da concentração hepática de ferro por dois examinadores usando mapas automáticos T2* e T1, assim como o manual T2* e o método signal-intensity-ratio. O desempenho foi medido usando curvas ROC e a correlação interobservador e intraobservador usando o coeficiente de correlação intraclasse bidirecional. Resultados: O desempenho da curva ROC separando pacientes e controles mostrou áreas sob a curva de 0,912 para o mapa automático T2*, 0,934 para o método signal-intensity-ratio, 0,908 para manual T2* e 0,80 para mapa T1 (este difere significativamente dos outros três métodos). Houve boa correlação interobservador e intraobservador (coeficiente de correlação intraclasse entre 0,938 e 0,998; p < 0,05). Correlações envolvendo o mapa T1, embora ainda significativas, foram menores. Conclusão: Em 1,5 T, o mapa T2* representa uma nova ferramenta rápida e promissora para avaliar o diagnóstico de sobrecarga de ferro hepática, enquanto o mapa T1 mostrou menor precisão. O desempenho do mapa T1 foi menor que o dos métodos T2*.

Characterization of CD4+CD28null T cells in patients with coronary artery disease and individuals with risk factors for atherosclerosis.

Risk factors for atherosclerosis may contribute to chronic low-grade inflammation. A highly cytotoxic and inflammatory CD4(+) cell subset (CD4(+)CD28(null) cells) has been associated with inflammatory diseases, including acute coronary syndromes (ACS). The aim of this study was to quantify and characterize CD4(+)CD28(null) cells in individuals with risk factors for atherosclerosis and patients with coronary artery disease (CAD). In order to achieve this goal, peripheral blood mononuclear cells (PBMCs) from individuals with risk factors for atherosclerosis and patients with CAD were analyzed using flow cytometry to detect cytotoxic molecules and evaluate the expression of homing receptors and inflammatory cytokines in CD4(+) cell subsets. The cells were evaluated ex vivo and after stimulation in culture. We found no differences in the proportions of CD4(+)CD28(null) cells among the groups. Compared with the CD4(+)CD28(+) population, the ex vivo CD4(+)CD28(null) subset from all groups expressed higher levels of granzymes A and B, perforin, granulysin and interferon-γ (IFN-γ). Individuals with risk factors and patients with ACS showed the highest levels of cytotoxic molecules. After stimulation, tumor necrosis factor-α (TNF-α) expression in the CD4(+)CD28(null) subset from these groups increased more than in the other groups. Stimulation with LPS decreased the expression of cytotoxic molecules by CD4(+)CD28(null) cells in all groups. In conclusion, our results show that risk factors for atherosclerosis may alter the CD4(+)CD28(null) cells phenotype, increasing their cytotoxic potential. Our findings also suggest that CD4(+)CD28(null) cells may participate in the early phases of atherosclerosis.

Radiação ionizante em imagem cardiovascular e risco de neoplasias / Ionozing radiation in cardiovascular imaging and the risk of neoplasia

O uso de exames de imagem com radiação ionizante vem crescendo de forma substancial na cardiologia nos últimos anos, tendo sido multiplicado em até seis vezes o número total de exames realizados atualmente, em comparação com 1980. Os riscos de câncer associados a esse aumento ainda são incertos, mas a preocupação com o fato gerou diversas publicações e estudos que se intensificaram nos últimos três anos. A radiação por exames cardiológicos pode ser medida de diversas formas, porém nenhuma delas diretamente em órgãos humanos. Assim, todas as estimativas de radiação são baseadas em modelos teóricos, que tentam possibilitar extrapolações entre os diversos métodos, diferentes formas de exposição e efeitos sobre cada tecido. Esses efeitos biológicos são particularmente foco de atenção, uma vez que a relação entre carcinogêne e radiação foi bastante documentada a partir dos efeitos de acidentes ou guerras prévias. Porém, o uso desses modelos para se estabelecer o risco real de desenvolvimento de neoplasias a partir da exposição a radiação em exames radiológicos ainda é bastante controverso. Nas situações de baixas doses, em especial, o uso de modelos lineares pode superestimar esses riscos, embora, conservadoramente, se saiba que não existem níveis mínimos considerados totalmente seguros no que tange a essa exposição. Diante desses fatos, o cardiologista clínico deve sempre pesar a relação risco-benefício desses exames, considerando o risco atribuível de surgimento de casos de câncer induzido pelo exame e o benefício que o procedimento trará para a pergunta clínica em questão.

The use of cardiac imaging tests with ionizing radiation has increased substantially in the last years, with a 6 fold increase in the total number of tests performed when compared to the early 1980s. Cancer risk attributable to this increase in radiation exposure is yet uncertain but this concern has resulted in many publications and studies which have significantly increased in the last years. Radiation by imaging tests may be measured in different ways but none of them directly assess its effects in human organs. Therefore, all radiation exposure figures estimates are based on theoretical models that intend to enable extrapolations of the different methods, forms of exposure and effects on each tissue. The biological effects of radiation are a special focus of attentionsince the relationship between carcinogenesis and radiation has been well documented based on exposures in accidents and previous wars. However, the use of these models to establish the actual risk of developing neoplasias from radiation derived from cardiac imaging is still controversial. In low doses, the use of linear models may overestimate these risks, although, it is known that there is no minimum threshold for radiation to be considered absolutely safe. In face of these facts, the clinical cardiologist should always consider the risk-benefit ratio of these tests, considering the risk of cancer due to exposure and the benefits the procedure will provide.

Ressonância magnética cardiovascular na doença arterial coronária / Role of cardiovascular magnetic resonance in coronary artery disease

A ressonância magnética cardiovascular avançou de forma bastante rápida na última década, sobretudo na avaliação da doença arterial coronaria. Com o advento de técnicas de imagem cada vez mais rápidas e com maior resolução espacial, hoje é possível à ressonância avaliar diversos componentes da doença arterial coronária em um único exame de curta duração. Destacam-se nesta avaliação a possibilidade de estudar a perfusão miocárdica para detecção da relevância funcional de estenoses coronárias, a avaliação de contratilidade em repouso e no repouso e no estresse farmacológico com dobutamina, e a presença ou ausência de viabilidade miocárdica. Além de integrar todos esses elementos diagnósticos em um único exame com alta sensibilidade e especificidade, a ressonância magnética cardiovascular ainda fornece dados prognósticos de curto e longo prazos, tornando o método um dos mais completos para a prática clínica da avaliação da doença arterial coronária.

Arritmias cardíacas: principais apresentações clínicas e mecanismos fisiopatológicos / Cardic arrythmias: clinical presentation and physiopathologic mechanisms

Ultimamente o conhecimento sobre arritmias cardíacas tornou-se algo extremamente necessário a todo médico generalista. É relativamente comum encontrarmos, em todas as especialidades médicas, indivíduos com algum tipo de distúrbio do ritmo cardíaco...

The knowledge about cardiac arrythmias has become something extremely necessary to all physicians. It is common found people with some kind of cardiac rhythm disturb in all medical specialities. Diagnostic and therapeutic decisions should be quickly done due to the high incidence and potential damage...

Platelet and leukocyte adhesion and activation in unstable angina and post-PTCA.

BACKGROUND: Unstable atherosclerotic plaques activate blood cells which may adhere to the coronary endothelium causing vessel occlusion. However, it is unknown if different clinical syndromes associated with plaque rupture induce similar blood cell activation and adhesion to the endothelium. METHODS: We studied changes in adhesion molecule expression of platelets (GPIIb/IIIa), neutrophils--CD18, CD11b and L-selectin--and monocytes (CD14) after interaction with active lesions of patients with stable angina subjected to PTCA and patients with unstable angina (UA). Generation of superoxide (SO) radicals from PMNs and PMN sequestration in the coronary circulation were also assessed. Blood samples were collected from the aorta (Ao) and coronary sinus (CS) before and 15 min after PTCA (n=13) and within the first 48 h of UA (n=12). RESULTS: PTCA induced a marked up-regulation of CD18, CD11b, CD14 and GPIIb/IIIa with L-selectin shedding and reduced SO formation, whereas only minor L-selectin down-regulation and decreased SO production indicated activation in UA. However, a significant decrease in neutrophil count in the CS compared to the Ao was only observed in UA. CONCLUSIONS: The magnitude of cellular activation depends on the underlying clinical setting and just partially contributes to cell adhesion to the endothelium which might be modulated by different extent of vascular occlusion and shear forces.