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Coronary Microvascular Dysfunction: Clinical Considerations and Noninvasive Diagnosis.
Schindler, TH, Dilsizian, V
JACC. Cardiovascular imaging. 2020;(1 Pt 1):140-155
Abstract
Chest pain in patients without obstructive coronary artery disease has been realized as a frequent problem encountered in clinical practice. Invasive flow investigations have suggested that up to two-thirds of patients with nonobstructive coronary atherosclerosis may have microvascular dysfunction (MVD). Positron emission tomography myocardial perfusion imaging in conjunction with tracer-kinetic modeling enables the concurrent quantification of myocardial blood flow (MBF) in milliliters per minute per gram of tissue. This allows the assessment of hyperemic MBFs and myocardial flow reserve for the noninvasive identification and characterization of MVD as an important functional substrate for angina symptoms amenable to intensified and individualized medical intervention with nitrates, calcium-channel blockers, statins, angiotensin-converting enzyme inhibitors, and/or angiotensin II type 1 receptor blockers. Recent investigations suggest that cardiac magnetic resonance and computed tomography may also be suitable for the noninvasive detection of MVD. Whether intensified and individualized treatment related improvement or even normalization of hyperemic MBF and/or myocardial flow reserve may lead to a persistent reduction in angina symptoms and/or improved cardiovascular outcome as compared to standard care, deserves further testing in large-scale randomized clinical trials.
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2.
Assessment of Left Ventricular Myocardial Diseases with Cardiac Computed Tomography.
Ko, SM, Kim, TH, Chun, EJ, Kim, JY, Hwang, SH
Korean journal of radiology. 2019;(3):333-351
Abstract
Rapid advances in cardiac computed tomography (CT) have enabled the characterization of left ventricular (LV) myocardial diseases based on LV anatomical morphology, function, density, and enhancement pattern. Global LV function and regional wall motion can be evaluated using multi-phasic cine CT images. CT myocardial perfusion imaging facilitates the identification of hemodynamically significant coronary artery disease. CT delayed-enhancement imaging is used to detect myocardial scar in myocardial infarction and to measure the extracellular volume fraction in non-ischemic cardiomyopathy. Multi-energy cardiac CT allows the mapping of iodine distribution in the myocardium. This review summarizes the current techniques of cardiac CT for LV myocardial assessment, highlights the key findings in various myocardial diseases, and presents future applications to complement echocardiography and cardiovascular magnetic resonance.
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3.
Clinical imaging in dementia with Lewy bodies.
Surendranathan, A, O'Brien, JT
Evidence-based mental health. 2018;(2):61-65
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Abstract
Dementia with Lewy bodies (DLB) is a common neurodegenerative dementia in older people; however, the clinical features, particularly cognitive fluctuations and rapid eye movement sleep disorder, are often hard to elicit, leading to difficulty in making the diagnosis clinically. Here we examine the literature for the evidence behind imaging modalities that could assist in making the diagnosis. Dopamine transporter (DAT) imaging remains the best modality for differentiation from dementia of Alzheimer's type with high sensitivity and specificity reported based on pathological diagnoses. 123Iodine-metaiodobenzylguanidine myocardial scintigraphy (MIBG) however is rapidly becoming an alternative imaging modality for the diagnosis of DLB, though studies assessing its accuracy with postmortem verification are still awaited. However, there are suggestions that MIBG may be better in the differentiation of vascular parkinsonism from DLB than DAT scans but may have lower sensitivity for detecting DLB compared with the 80% sensitivity seen in DAT imaging. Structural MRI scans have long been used for the diagnosis of dementia; however, their utility in DLB is limited to revealing the presence of coexisting Alzheimer's disease. Fluorodeoxyglucose (FDG) PET is an alternative biomarker that can also differentiate Alzheimer's disease and DLB but lacks the evidence base of both DAT and MIBG scans.
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Effects of Caffeine on Myocardial Blood Flow: A Systematic Review.
van Dijk, R, Ties, D, Kuijpers, D, van der Harst, P, Oudkerk, M
Nutrients. 2018;(8)
Abstract
Caffeine is one of the most widely consumed stimulants worldwide. It is a well-recognized antagonist of adenosine and a potential cause of false-negative functional measurements during vasodilator myocardial perfusion. The aim of this systematic review is to summarize the evidence regarding the effects of caffeine intake on functional measurements of myocardial perfusion in patients with suspected coronary artery disease. Pubmed, Web of Science, and Embase were searched using a predefined electronic search strategy. Participants-healthy subjects or patients with known or suspected CAD. Comparisons-recent caffeine intake versus no caffeine intake. Outcomes-measurements of functional myocardial perfusion. Study design-observational. Fourteen studies were deemed eligible for this systematic review. There was a wide range of variability in study design with varying imaging modalities, vasodilator agents, serum concentrations of caffeine, and primary outcome measurements. The available data indicate a significant influence of recent caffeine intake on cardiac perfusion measurements during adenosine and dipyridamole induced hyperemia. These effects have the potential to affect the clinical decision making by re-classification to different risk-categories.
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Research Progress on 18F-Labeled Agents for Imaging of Myocardial Perfusion with Positron Emission Tomography.
Mou, T, Zhang, X
Molecules (Basel, Switzerland). 2017;(4)
Abstract
Coronary artery disease (CAD) is the leading cause of death in the world. Myocardial perfusion imaging (MPI) plays a significant role in non-invasive diagnosis and prognosis of CAD. However, neither single-photon emission computed tomography nor positron emission tomography clinical MPI agents can absolutely satisfy the demands of clinical practice. In the past decades, tremendous developments happened in the field of 18F-labeled MPI tracers. This review summarizes the current state of 18F-labeled MPI tracers, basic research data of those tracers, and the future direction of MPI tracer research.
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Topics of nuclear medicine research in Europe.
Inubushi, M, Kaneta, T, Ishimori, T, Imabayashi, E, Okizaki, A, Oku, N
Annals of nuclear medicine. 2017;(8):571-574
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Abstract
Last year in the European Journal of Nuclear Medicine and Molecular Imaging, we introduced some recent nuclear medicine research conducted in Japan. This was favorably received by European readers in the main. This year we wish to focus on the Annals of Nuclear Medicine on some of the fine nuclear medicine research work executed in Europe recently. In the current review article, we take up five topics: prostate-specific membrane antigen imaging, recent advances in radionuclide therapy, [18F]fluorodeoxyglucose positron-emission tomography (PET) for dementia, quantitative PET assessment of myocardial perfusion, and iodine-124 (124I). Just at the most recent annual meeting of the European Association of Nuclear Medicine 2016, Kyoto was selected as the host city for the 2022 Congress of the World Federation of Nuclear Medicine and Biology. We hope that our continuous efforts to strengthen scientific cooperation between Europe and Japan will bring many European friends and a great success to the Kyoto meeting.
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CACS and the Frequency of Stress-Induced Myocardial Ischemia During MPI: A Meta-Analysis.
Bavishi, C, Argulian, E, Chatterjee, S, Rozanski, A
JACC. Cardiovascular imaging. 2016;(5):580-9
Abstract
OBJECTIVES This study sought to systematically assess the relationship between the magnitude of coronary artery calcium (CAC) and presence of myocardial ischemia. BACKGROUND The likelihood of myocardial ischemia rises with increasing CAC score. However, the likelihood of ischemia according to different CAC abnormality cutoffs has not been systematically evaluated. METHODS A comprehensive systematic search was undertaken to identify all relevant studies that compared CAC with myocardial perfusion imaging and reported ischemia rates by CAC categories. The following thresholds of CAC scores were analyzed and correlated with rates of ischemia: scores of 0, 1 to 100, 101 to 399, and ≥400. RESULTS Overall, 20 studies reported frequencies of stress-induced myocardial ischemia by various CAC categories. Six studies (n = 2,123 patients) reported ischemia rates for all 4 CAC categories. A stepwise increase in the frequency of ischemia according to CAC abnormality was noted. The frequency of ischemia was low among patients with zero or very low CAC score. However, among the patients with CAC scores ≥400, the reported frequencies of ischemia varied widely among studies. Notably, most studies involved small sample sizes; only 5 of 20 studies included >500 patients and very few studies examined clinical parameters that may potentially modify the relationship between CAC score and ischemia. CONCLUSIONS Our meta-analysis indicates the presence of a quantitative relationship between the magnitude of CAC abnormality and the likelihood of inducible myocardial ischemia. Zero to low CAC scores were infrequently associated with ischemia, but there was a wide variance in the frequency of ischemia among patients with intermediate to high CAC scores. Thus, there is a need for prospective study involving larger patient samples to better define the clinical factors that influence the relationship between CAC scores and inducible myocardial ischemia.
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Relationship between Calcium Score and Myocardial Scintigraphy in the Diagnosis of Coronary Disease.
Siqueira, FP, Mesquita, CT, Santos, AA, Nacif, MS
Arquivos brasileiros de cardiologia. 2016;(4):365-374
Abstract
Half the patients with coronary artery disease present with sudden death - or acute infarction as first symptom, making early diagnosis pivotal. Myocardial perfusion scintigraphy is frequently used in the assessment of these patients, but it does not detect the disease without flow restriction, exposes the patient to high levels of radiation and is costly. On the other hand, with less radiological exposure, calcium score is directly correlated to the presence and extension of coronary atherosclerosis, and also to the risk of cardiovascular events. Even though calcium score is a tried-and-true method for stratification of asymptomatic patients, its use is still reduced in this context, since current guidelines are contradictory to its use on symptomatic diseases. The aim of this review is to identify, on patients under investigation for coronary artery disease, the main evidence of the use of calcium score associated with functional evaluation and scintigraphy.
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Advances in parametric mapping with CMR imaging.
Salerno, M, Kramer, CM
JACC. Cardiovascular imaging. 2013;(7):806-22
Abstract
Cardiac magnetic resonance imaging (CMR) is well established and considered the gold standard for assessing myocardial volumes and function, and for quantifying myocardial fibrosis in both ischemic and nonischemic heart disease. Recent developments in CMR imaging techniques are enabling clinically-feasible rapid parametric mapping of myocardial perfusion and magnetic relaxation properties (T1, T2, and T2* relaxation times) that are further expanding the range of unique tissue parameters that can be assessed using CMR. To generate a parametric map of perfusion or relaxation times, multiple images of the same region of the myocardium are acquired with different sensitivity to the parameter of interest, and the signal intensities of these images are fit to a model which describes the underlying physiology or relaxation parameters. The parametric map is an image of the fitted perfusion parameters or relaxation times. Parametric mapping requires acquisition of multiple images typically within a breath-hold and thus requires specialized rapid acquisition techniques. Quantitative perfusion imaging techniques can more accurately determine the extent of myocardial ischemia in coronary artery disease and provide the opportunity to evaluate microvascular disease with CMR. T1 mapping techniques performed both with and without contrast are enabling quantification of diffuse myocardial fibrosis and myocardial infiltration. Myocardial edema and inflammation can be evaluated using T2 mapping techniques. T2* mapping provides an assessment of myocardial iron-overload and myocardial hemorrhage. There is a growing body of evidence for the clinical utility of quantitative assessment of perfusion and relaxation times, although current techniques still have some important limitations. This article will review the current imaging technologies for parametric mapping, emerging applications, current limitations, and potential of CMR parametric mapping of the myocardium. The specific focus will be the assessment and quantification of myocardial perfusion and magnetic relaxation times.