 There are no approved in vivo markers of amyloid load in humans. Several compounds with affinity for binding amyloid in vivo are under investigation. All of these compounds use radioactive chemical tags for positron emission tomography PET imaging. Attempts at finding non-radioactive amyloid tracers are underway, but still poorly developed. The most promising compound is 11C-PIB. Pittsburgh Compound-B has statistically significant increased retention in AD cortical areas, relative to controls P0.05. Price, 2005 To our knowledge, 11C-PIB imaging has not been compared against frontotemporal dementia FTD controls. 