PGP and cancer: 99mTc-Sestamibi was the first radiopharmaceutical recognized as a useful probe for cancer early detection and functional Pgp imaging transport[9], followed by other 99mTc complexes, namely 99mTc-tetrofosmin[10], 99mTc-furifosmin[11], and 99mTc-areneisonitrile[12], and, more recently, mixed-ligand 99mTc-dithiocarbamate complexes[13] and a 99mTc-labeled triphenylphosphonium cation[14].