Patients with suspected or known coronary artery disease who are scheduled for clinically indicated SPECT myocardial perfusion imaging (MPI) and will receive invasive coronary angiogram are recruited to receive SPECT MBF study.

Patients with suspected or known coronary artery disease who are scheduled for clinically indicated SPECT myocardial perfusion imaging (MPI) and likely will further receive invasive coronary angiogram will be recruited for a SPECT MBF study. The MBF study will be performed as an adjunct to MPI utilizing the same rest and stress injections of 99mTc-Sestamibi (MIBI) tracer, and the same infusion of dipyridamole, adenosine or adenosine triphosphate for stressing. The MBF study will be completed in single or two days depending on the imaging protocol of MPI for a site. This is an observational study with no interventions to the clinical routine whatsoever. Three models of SPECT (GE NM530c) and SPECT/CT (Siemens Symbia-T16 and -T2) cameras are included to acquire rest/stress dynamic SPECT and MPI data. A CT scan will be acquired for the purpose of attenuation correction. All dynamic images will be reconstructed with physical corrections, including attenuation, scatter, resolution recovery and noise reduction, and processed to quantify MBF with the same kinetic modeling. The imaging processing of MBF study will be conducted with a SPECT MBF dedicated software (MyoFlowQ) in a central lab. MPI images will be collected and independently read by three consensus readers. The angiographic result will be independently reviewed by an interventional cardiologist. Diagnostic performance of SPECT MBF and perfusion will be compared utilizing angiographic result as the reference standard.

Inclusion Criteria:

• Age 18 ~ 79 years old
• Any CAD risk factor
• CAD related symptoms
• Intermediate to high probability of CAD
• Suspected or known CAD on a stable medication regime
• Able and willing to comply with the study procedures
• Written informed consent

Exclusion Criteria:

• History or risk of severe bradycardia
• History of myocardial infarction, dilated cardiomyopathy, hypertrophic cardiomyopathy, valve issue or congenital heart disease
• Wheezing asthma or COPD
• Known second- or third-degree AV block
• Known hypersensitivity to dipyridamole or adenosine
• Breastfeeding or pregnancy
• Claustrophobia or inability to lie still in a supine position
• Unwillingness or inability to provide informed consent

The study population will be adult male and female patients who have suspected or known CAD are agreed to receive MBF measurements when their MPI scan will be performed clinically.