| abstract |
A compound is described which has affinity with amyloid, shows sufficiently rapid clearance from normal tissue and has reduced toxicity such as mutagenicity. A low toxic diagnostic agent for Alzheimer's disease containing this compound is further described. The compound is represented by formula (1) or a salt thereof, wherein A1, A2, A3 and A4 are independently a carbon or nitrogen atom and where R is a radioactive halogen substituent; m is an integer 0 to 4; and n is an integer 0 or 1, provided that at least one of A1, A2, A3 and A4 is a carbon atom, and R3 binds to a carbon atom represented by A1, A2, A3 or A4. |