The primary objective of this study is to proof the concept of EP 1645 as a diagnostic tool for carotid artery atherosclerosis and plaque instability and to assess the safety and tolerability of this diagnostic agent, a monoclonal antibody fragment (Fab') conjugated with the diagnostic radionuclide 99mTc. Safety and tolerability will be determined by adverse events (AEs) observed and reported upon administration of the product and the absorbed dose of radiation.