New Heart Imaging Techniques to Evaluate Possible Heart Disease

* INCLUSION CRITERIA: 1. Subjects with or without history of cardiovascular diseases and with various degrees of cardiovascular risk factor. Subjects with known or suspected atherosclerotic disease based on clinical findings or documented by angiography (conventional, CTA or MRA), or Doppler ultrasound. And, healthy volunteers and subjects with known or suspected diseases affecting the thoracic organs, abdominal organs, and other organs affected by metabolic diseases such as body fat and muscles. Subjects at risk for atherosclerosis including: smoking, obesity, hyperlipidemia, low levels of high density lipoproteins (\<50 mg/dl for women and \<40 mg/dl for men), hypertension, family history (early onset atherosclerosis \<55 year old in male and \< 65 year old in female who is first degree relative), and diabetes mellitus or metabolic syndrome. 2. Subject must be willing to participate in the protocol. 3. Subject age greater than 18 years old. 4. Subject must be able to provide informed consent. 5. Subject must be clinically stable and be able to come to the Clinical Center to participate in the study. EXCLUSION CRITERIA: 1. Subjects with contraindication to MRI scanning. These contraindications include but are not limited to the following devices or conditions: 1. Implanted cardiac pacemaker or defibrillator 2. Cochlear Implants 3. Ocular foreign body (e.g. metal shavings) 4. Embedded shrapnel fragments 5. Central nervous system aneurysm clips 6. Implanted neural stimulator 7. Medical infusion pumps 8. Any implanted device that is incompatible with MRI. 2. Unsatisfactory performance status as judged by the referring physician such that the subject could not tolerate an MRI scan. Examples of medical conditions that would not be accepted would include unstable angina and dyspnea at rest. 3. Subjects requiring sedation for MRI studies. 4. Subjects with a condition precluding entry into the scanner (e.g. morbid obesity, claustrophobia, etc.). 5. Pregnant or lactating women. 6. Subjects with severe back-pain or motion disorders who will be unable to tolerate supine positioning within the MRI scanner and hold still for the duration of the examination. 7. Subjects who are unable to undergo a CTA within 2 months of the MRA part of this study, or are unable to undergo or be scheduled for a cardiac catheterization within 2 months of the MRA. EXCLUSION CRITERIA - FOR GADOLINIUM BASED MRI STUDIES ONLY: 1. History of allergic reaction to gadolinium contrast agents despite the use of premeditation with an anti-histaminic and cortisone. 2. eGFR \< 60 ml/min/1.73m\^2 EXCLUSION CRITERIA - FOR CORONARY CTA: 1. Contraindication to the use of CTA contrast agents: 1. Creatinine value \> 1.4 mg/dl 2. History of multiple myeloma 3. Use of metformin-containing products less than 24 hrs prior to contrast administration 4. History of allergic reaction to CTA contrast agents despite the use of pre- medication with an anti-histaminic and cortisone. 2. Subjects with contraindication precluding the use of beta blockers necessary to perform the coronary CTA. These include: 1. Asthma 2. Active bronchospasm 3. Moderate or severe COPD 4. 2nd or 3rd degree AV block 5. Decompensated cardiac failure 6. Allergy to beta blockers 7. Systolic blood pressure \< 100 mm Hg 8. Pregnancy or nursing EXCLUSION CRITERIA - FOR NITROGLYCERIN USE: Subjects reporting a history of the following conditions will be excluded: 1. Severe aortic stenosis 2. Hypertrophic cardiomyopathy 3. Inferior myocardial infarction with right ventricular involvement 4. Cardiac tamponade 5. Constrictive pericarditis 6. Severe hypotension (systolic BP \<90 mmHg) 7. Uncorrected hypovolemia 8. Raised intracranial pressure 9. Glaucoma 10. Severe anemia 11. Concomitant use of phosphodiesterase-5 inhibitors (sildenafil-Viagra, tadalifil-Cialis, verdenafil-Levitra) 12. History of hypersensitivity to nitroglycerin