[1] Hosp Clin San Carlos, Dept Nucl Med, Madrid 28040, Spain
[2] Hosp Gen Univ Gregorio Maranon, Dept Nucl Med, Madrid 28007, Spain
[3] Hosp Clin San Carlos, Res Unit, Madrid 28040, Spain
[4] Stanford Univ, Sch Med, Dept Radiol, James H Clark Ctr, Stanford, CA USA
[5] Univ Calif Los Angeles, David Geffen Sch Med, Dept Mol & Med Pharmacol, Los Angeles, CA 90095 USA