RESUMO
Non-invasive cardiac imaging is pivotal in the diagnosis and prognosis of patients with stable CAD. Nuclear SPECT, PET, stress echocardiography and more recently cardiac magnetic resonance imaging have been utilized with excellent diagnostic accuracy. However, along with their inherent individual limitations, most modalities detect ischemia but lack the ability to define coronary anatomy or evaluate for subclinical atherosclerosis. A modality that not only accurately diagnoses obstructive CAD and also facilitates early identification of non-obstructive CAD may be of interest because it may allow for earlier aggressive risk factor modification and primary prevention. Cardiac computerized tomographic angiography (CCTA) has the potential to accurately detect or exclude luminal stenosis, as well as identify and quantify subclinical atherosclerosis in the absence if luminal narrowing. However CCTA, being a relatively a new modality, has less supporting evidence when compared to more mature modalities such as SPECT. Therefore, the question that begs to be addressed is whether CCTA can be utilized as a first line test in establishing the diagnosis and prognosis of CAD.
Assuntos
Doença da Artéria Coronariana/diagnóstico por imagem , Doença da Artéria Coronariana/diagnóstico , Tomografia Computadorizada de Emissão de Fóton Único/métodos , Tomografia Computadorizada por Raios X/métodos , Angiografia Coronária/métodos , Ponte de Artéria Coronária , Vasos Coronários/patologia , Análise Custo-Benefício , Humanos , Prognóstico , Reprodutibilidade dos Testes , Fatores de Risco , Sensibilidade e EspecificidadeRESUMO
Nuclear imaging, predominantly with single-photon emission tomography, has established and demonstrated value for the assessment of cardiovascular disease (CVD). Formerly, the clinical application of positron emission tomography (PET) was precluded by methodological complexity, high operating costs and lack of widespread availability. However, as PET and radiotracer development technologies have improved and continue to do so, PET is expected to become a mainstay diagnostic cardiovascular imaging modality. Not only is PET imaging of great importance for routine clinical decision-making and diagnosing CVD, it is also gaining prominence in fundamental and translational research models. The scope of this review is to summarize the state-of-the-art advances in PET imaging methodology, clinical utility and potential future application.
Assuntos
Doenças Cardiovasculares/diagnóstico por imagem , Coração/diagnóstico por imagem , Tomografia por Emissão de Pósitrons/métodos , Doenças Cardiovasculares/fisiopatologia , Coração/fisiopatologia , Humanos , Tomografia por Emissão de Pósitrons/tendências , RadiografiaRESUMO
Prodigious efforts and landmark discoveries have led toward significant advances in our understanding of atherosclerosis. Despite significant efforts, atherosclerosis continues globally to be a leading cause of mortality and reduced quality of life. With surges in the prevalence of obesity and diabetes, atherosclerosis is expected to have an even more pronounced impact upon the global burden of disease. It is imperative to develop strategies for the early detection of disease. Positron emission tomography (PET) imaging utilizing [(18)F]fluorodeoxyglucose (FDG) may provide a non-invasive means of characterizing inflammatory activity within atherosclerotic plaque, thus serving as a surrogate biomarker for detecting vulnerable plaque. The aim of this review is to explore the rationale for performing FDG imaging, provide an overview into the mechanism of action, and summarize findings from the early application of FDG PET imaging in the clinical setting to evaluate vascular disease. Alternative imaging biomarkers and approaches are briefly discussed.
Assuntos
Aterosclerose/diagnóstico por imagem , Fluordesoxiglucose F18 , Imagem Multimodal/métodos , Tomografia por Emissão de Pósitrons , Compostos Radiofarmacêuticos , Tomografia Computadorizada por Raios X , Aterosclerose/diagnóstico , Humanos , Inflamação/diagnóstico por imagem , Placa Aterosclerótica/diagnóstico por imagem , Valor Preditivo dos Testes , Sensibilidade e EspecificidadeRESUMO
PURPOSE: To compare T2-weighted cardiovascular magnetic resonance (CMR) imaging with AASPIR (asymmetric adiabatic spectral inversion recovery) and STIR (short T1 inversion recovery) for myocardial signal intensity, image quality, and fat suppression. MATERIALS AND METHODS: Forty consecutive patients (47 ± 16 years old) referred by cardiologists for CMR-based myocardial tissue characterization were scanned with both STIR and AASPIR T2-weighted imaging approaches. Signal intensity of left ventricular myocardium was normalized to a region of interest generating a signal-to-noise ratio (SNR). In six patients with regional edema on STIR the contrast-to-noise ratio (CNR) was assessed. Two independent observers used a scoring system to evaluate image quality and artifact suppression. Six healthy volunteers (three males, 32 ± 7 years) were recruited to compare fat suppression between AASPIR and STIR. RESULTS: SNR of AASPIR was greater than STIR for basal (128 ± 44 vs. 83 ± 40, P < 0.001), mid- (144 ± 65 vs. 96 ± 39, P < 0.01), and apical (145 ± 59 vs. 105 ± 35, P < 0.05) myocardium. Improved image quality and greater suppression of artifacts was demonstrated with AASPIR. In patients with regional edema, CNR increased by 49% with AASPIR, while SNR of pericardial fat did not differ (44 ± 39 vs. 33 ± 30, P > 0.05). CONCLUSION: Our findings support the implementation of an AASPIR-based approach for T2-weighted imaging due to improved pericardial fat suppression, image quality, and artifact suppression with greater CNR and SNR.
Assuntos
Edema/diagnóstico , Edema/patologia , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Miocárdio/patologia , Pericárdio/patologia , Tecido Adiposo/patologia , Adulto , Idoso , Estudos de Coortes , Diagnóstico por Imagem/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Modelos CardiovascularesRESUMO
BACKGROUND: [18F]-fluorodeoxyglucose (18FDG) uptake imaged with positron emission tomography (PET) and computed tomography (CT) may serve as a biomarker of plaque inflammation. This study evaluated the relationship between carotid plaque 18FDG uptake and a) intraplaque expression of macrophage and macrophage-like cellular CD68 immunohistology; b) intraplaque inflammatory burden using leukocyte-sensitive CD45 immunohistology; c) symptomatic patient presentation; d) time from last cerebrovascular event. METHODS: 54 patients scheduled for carotid endarterectomy underwent 18FDG PET/CT imaging. Maximum 18FDG uptake (SUVmax) and tissue-to-blood ratio (TBRmax) was measured for carotid plaques. Quantitative immunohistological analysis of macrophage-like cell expression (CD68) and leukocyte content (CD45) was performed. RESULTS: 18FDG uptake was related to CD68 macrophage expression (TBRmax: râ¯=â¯0.51, pâ¯<â¯0.001), and total-plaque leukocyte CD45 expression (TBRmax: râ¯=â¯0.632, pâ¯=â¯0.009, pâ¯<â¯0.001). 18FDG TBRmax uptake in carotid plaque associated with patient symptoms was greater than asymptomatic plaque (3.58⯱â¯1.01 vs. 3.13⯱â¯1.10, pâ¯=â¯0.008). 18FDG uptake differed between an acuity threshold of <90â¯days and >90â¯days (SUVmax:3.15⯱â¯0.87 vs. 2.52⯱â¯0.45, pâ¯=â¯0.015). CONCLUSIONS: In this CAIN cohort, 18FDG uptake imaged with PET/CT serves a surrogate marker of intraplaque inflammatory macrophage, macrophage-like cell and leukocyte burden. 18FDG uptake is greater in plaque associated with patient symptoms and those with recent cerebrovascular events. Future studies are needed to relate 18FDG uptake and disease progression.
Assuntos
Estenose das Carótidas/diagnóstico por imagem , Estenose das Carótidas/metabolismo , Fluordesoxiglucose F18/metabolismo , Placa Aterosclerótica/diagnóstico por imagem , Placa Aterosclerótica/metabolismo , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Idoso , Estenose das Carótidas/cirurgia , Estudos de Coortes , Endarterectomia das Carótidas/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Placa Aterosclerótica/cirurgia , Estudos ProspectivosRESUMO
Cardiac PET has evolved over the past 30 years to gain wider acceptance as a valuable modality for a variety of cardiac conditions. Wider availability of scanners as well as changes in reimbursement policies in more recent years has further increased its use. Moreover, with the emergence of novel radionuclides as well as further advances in scanner technology, the use of cardiac PET can be expected to increase further in both clinical practice and the research arena. PET has demonstrated superior diagnostic accuracy for the diagnosis of coronary artery disease in comparison with single-photon emission tomography while it provides robust prognostic value. The addition of absolute flow quantification increases sensitivity for 3-vessel disease as well as providing incremental functional and prognostic information. Metabolic imaging using (18)F-fluorodeoxyglucose can be used to guide revascularization in the setting of heart failure and also to detect active inflammation in conditions such as cardiac sarcoidosis and within atherosclerotic plaque, improving our understanding of the processes that underlie these conditions. However, although the pace of new developments is rapid, there remains a gap in evidence for many of these advances and further studies are required.
Assuntos
Coração/diagnóstico por imagem , Miocárdio/metabolismo , Tomografia por Emissão de Pósitrons/métodos , Doença da Artéria Coronariana/diagnóstico por imagem , Doença da Artéria Coronariana/metabolismo , Humanos , Sarcoidose/diagnóstico por imagem , Sarcoidose/metabolismo , Tomografia Computadorizada de Emissão de Fóton ÚnicoRESUMO
INTRODUCTION: With more intensive medical therapy, the risk of stroke in patients with asymptomatic carotid stenosis (ACS) is now below the risk of carotid endarterectomy or stenting (intervention); â¼ 90% of patients would be better with only medical therapy. It is important, therefore, to have methods to identify the â¼ 10% of patients who stand to benefit from intervention. AREAS COVERED: We review the evidence that the risk of asymptomatic stenosis is now below the risk of intervention, and evidence for several approaches to identifying high-risk ACS: transcranial Doppler embolus detection, echolucency and neovascularity on ultrasound, ulceration on three-dimensional ultrasound, plaque composition on magnetic resonance imaging (MRI), plaque inflammation on positron emission tomography and assessment of cerebral blood flow reserve. EXPERT OPINION: Carotid endarterectomy or stenting should be performed only in patients with ACS if they have microemboli on transcranial Doppler, three or more ulcers detected on three-dimensional ultrasound or other features of unstable plaque such as plaque echolucency on ultrasound, intraplaque hemorrhage detected on MRI, inflamed plaques detected on PET/CT or reduced cerebral blood flow reserve. Most patients with ACS (â¼ 90%) would be better off with intensive medical therapy than with intervention.