Accurate measurements from a non-invasive test like myocardial perfusion positron emission tomography/ computed tomography (PET/CT) may decrease the need for invasive procedures such as cardiac catheterization.The investigators wish to see if the measurements from cardiac catheterization can be predicted using a non-invasive 13N-NH3 digital PET/CT scan.

Cardiac imaging using standard-of-care Nuclear Medicine techniques assess the relative radiopharmaceutical distribution from coronary arteries to cardiac tissue. This standard interpretation however, lacks the clinical utility of modern quantitative techniques that are now routinely obtained during cardiac catheterization, such as fractional flow reserve (FFR). Cardiologists routinely base critical management decisions, including the choice for revascularization, stenting, or angioplasty, on these measurements.

Non-invasive measurements of MBF (Myocardial Blood Flow), CFR (Coronary Flow Reserve) and RFR (Relative Flow Reserve) using PET/CT have been investigated, but have yet to reach clinicl use. Given the inherent gains in sensitivity and resolution, digital PET/CT, may allow for a more robust and accurate platform to obtain quantitative measurements of MBF, CFR and RFR which may greatly enhance the clinical utility of cardiac PET/CT for management of coronary artery disease.

Inclusion Criteria:

• Patient is ≥ 18 years old at the time of the scan
• Patient has known or suspected coronary artery disease
• Patient has had a recent or will be scheduled for a diagnostic coronary angiogram
• Patient provides written informed consent
• Patient is referred for myocardial perfusion scan
• Patient is capable of complying with study procedures
• Patient is able to remain still for duration of imaging procedure (approximately 60 minutes total for both PET/CT)

Exclusion Criteria:

• Patients who are pregnant or breast feeding
• Patients with contraindications to regadenoson

Stanford Cardiologists will be aware of this ongoing prospective study. Potential participants will be referred to the study by Stanford Cardiology once they are identified by a cardiologist as having intermediate or high risk for a cardiovascular event.

GE Healthcare is the monitoring entity because GE Healthcare is the Study Sponsor. The monitoring visits will be conducted by a GE Clinical Research Associate (CRA).