Inclusion Criteria:

• * Male and female, 18-99 years of age and any race;
• * Have had a prior clinical SPECT MPI positive for ischemia in two myocardial segments and referred for invasive coronary angiography (ICA) or have had a prior clinical SPECT MPI negative for ischemia;

Exclusion Criteria:

• * Inability to receive and sign informed consent;
• * Percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) within 6-months prior to SPECT or in the intervening days between SPECT and PET examination;
• * Participants who have received chemotherapeutic agents within 6 months of enrollment;
• * Heart failure (left ventricular ejection fraction ≤ 35%);
• * Known non-ischemic cardiomyopathy;
• * Inability to undergo pharmacologic stress testing with regadenoson (Lexiscan). Contraindications include:
• * Symptomatic bradycardia or second to third degree atrioventricular (AV) block;
• * Pre-existing obstructive lung disease with active wheezing, i.e., COPD, asthma with active wheezing that precludes the safe administration of the pharmacological stress agent 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);
• * Women who are pregnant or breastfeeding;
• * Severe claustrophobia;
• * Weight ≥ 500 lbs (weight limit of PET/CT table)