1. Molecular
Imaging Center, National Institute of Radiological Science, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
2. Medical
Faculty, Trakia University, 11 Armejska Str., Stara Zagora 6000, Bulgaria
3. Institute of Biophysics & Biomedical Engineering, Bulgarian Academy of Sciences, 21 Acad. G. Bonchev Str., Sofia 1114, Bulgaria