and exhibited enhanced target-to-nontarget ratio. A set of five porphyrin derivatives
(7–12) was labeled with
68 Ga for PET imaging in tumor-bearing rats and exhibited
clear tumor visualization [48].
7
N
N
N
N
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
68 Ga
Cl
N
HN
N
NH
N
N
N
N
HO
68 Ga
ax
OH
HOOC
COOH
8
N
N
N
N
68 Ga
H 3 CO 2 C
CO 2 CH 3
11
N
N
N
N
O
O
Ga
6
N
N
N
N
68 Ga
9
L
L
ax
HOOC
COOH
N
N
N
N
68 Ga
H 3 CO 2 C
CO 2 CH 3
H 3 CO 2 C H 3 C
12
N
N
N
N
68 Ga
10
Lax
Ph
Ph
Ph
Ph
3.3.4 Technetium-99m
Technetium-99m complexes are extensively used in nuclear medicine in the
diagnosis of many cancers and non-cancer diseases because
99m Tc radionuclide has
favorable nuclear properties (140 keV, c emitters; t 1/2 = 6:01 h), low cost and
ready availability [49, 50].
99m Tc-labeled simple porphin and hematoporphyrin
were employed for in vivo biodistribution studies [51, 52]. Later, various modified
99m Tc labeled porphyrins were developed. On injecting
99m Tc labeled
3 Porphyrin and Phthalocyanine Radiolabeling
61