Heart failure is a clinical syndrome of exercise intolerance and/or congestion. The potential roles of myocardial perfusion and metabolic abnormalities in subjects with cardiovascular risks, metabolic disease and heart failure assessed by nuclear dynamic imaging warrant further investigations. The study investigators propose that microvascular dysfunction and abnormal metabolic substrate shift precedes and triggers the onset of diastolic dysfunctions. The aims are (1) to develop and validate the noninvasive measurement of absolute myocardial blood flow (MBF) and myocardial flow reserve (MFR) by using dynamic imaging with a CZT camera, (2) to assess myocardial glucose metabolism by using 18F-FDG dynamic PET, and MBF, MFR and LV systolic and diastolic function by dynamic SPECT comprehensively in subjects at cardiovascular risks and metabolic disease, HFrEF and HFpEF, (3) to correlate with peripheral serum markers and blood mononuclear cells subsets with myocardial perfusion and metabolic abnormalities, and (4) to test the hypothesis of these imaging and blood markers in diagnosis and prognostic implications. The study investigators also assess myocardial metabolic utilization in healthy and mice model of different metabolic disorders (obesity, diabetes mellitus and hypertension) by using 18F-FDG dynamic micro PET/CT, as an in-vivo measures which could be used to better understanding the disease mechanism and evaluating therapeutic strategies.