F-18 Rhodamine 6G PET Imaging for Myocardial Blood Flow

Inclusion Criteria: * Male and female, 21-75 years of age and any race. * Capable of giving written informed consent. * "Healthy adult volunteer subject" is someone who is volunteering to undergo imaging procedures and based on screening procedures has no known significant health problems. * Stable patients with known or suspected coronary artery disease that are scheduled to have or have undergone a clinically indicated conventional rest/stress SPECT MPI and no intervention between SPECT and PET. * Female subjects must not be pregnant or lactating. Exclusion Criteria: * Has any condition that, in the opinion of the Sponsor-Investigator or designee could increase risk to the subject, limit the subject's ability to tolerate the research procedures, or interfere with collection of the data. * Have abnormal findings on any screening/baseline procedure, e.g. physical examination, laboratory tests, electrocardiogram that suggest the subject might have a condition that could, in the opinion of the Sponsor-Investigator, affect the subject's response to the radiopharmaceutical or related research procedures. * Is deemed likely to be unable to perform all research procedures for any reason, (e.g., subjects unable to lie still or inability to tolerate up to 60 minutes in a supine position with arms up during the PET imaging procedures due to chronic back/shoulder pain or arthritis as assessed by physical examination and medical history). * Has a history of hypersensitivity to Fluorine-18 or other radiopharmaceutical or any of its excipients. * Have contraindications to cardiovascular PET/CT imaging such as claustrophobia. * Have high blood pressure (\>200/110) * Have Epilepsy * Have major kidney or liver problems * Have current or past history of major medical illness * Currently using recreational drugs * Body weight of \> 300 lbs. (weight limit of the PET/CT table) * Stable Cardiac Disease: Rest/Stress Group only: * Cardiac patients who suffer an intervening clinical event such as worsening angina pectoris or myocardial infarction or whom undergo a myocardial revascularization procedure or have myocardial ischemia at rest. * Sinus node disease (e.g. SA block) or symptomatic bradycardia, second or third degree atrioventricular (AV) block. * Pre-existing obstructive lung disease (e.g. asthma) that precludes the safe administration of the pharmacological stressor according to the approved label. * Uncontrolled and severe hypertension (e.g. systolic blood pressure \>200 mmHg, diastolic blood pressure \>110 mmHg). * Baseline hypotension (e.g. systolic blood pressure \< 90 mmHg, diastolic blood pressure \<50 mmHg). * Seizures * The use of caffeine, nicotine or over the counter cold medicines within 12 hours prior to stress imaging day with regadenoson. * The theophylline-based medications or dipyridamole within 48 hours prior to each imaging day.