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.