Cardiac SPECT is a non-invasive tomographic nuclear medicine technique which allows to perform a myocardial perfusion imaging (MPI). During this procedure, a specifically designed radiotracer is administered to a patient and it concentrates in the heart tissues. The 3D distribution of the radiopharmaceutical activity inside the heart is reconstructed by collecting enough 2D projection images around the patient. This technique is a powerful tool for coronary artery disease (CAD) diagnosis. Comparing two sets of images, one acquired after a stress test and another in a rest state, a SPECT MPI study highlights possible perfusion defects, which may result in a myocardial ischemia or a myocardial infarction.