There are three FDA-approved imaging agents for use in the diagnosis and monitoring Alzheimer's disease (AD), which started off with the 2012 approval for Eli Lilly's Amyvid (florbetapir F 18 injection). But reimbursement for positron emission tomography (PET) amyloid beta imaging has remained limited, due in large part to a 2013 decision from the Centers for Medicare & Medicaid Services (CMS).