To evaluate estrogen receptor (ER) expression level in human breast cancer model using
18
F-fluoroestradiol (
18
F-FES) microPET/CT.
Methods:
ER
+
human
breast cancer cell lines (ZR-75-1 and MCF-7) and ER- control (MDA-MB-231) were used to construct BALB/c nude mouse model. There were ten mice in each ER
+
group. The estrogen pellets were implanted 3 d prior to tumor cell inoculation and removed 3 d before administration of
18
F-FES. The mice were implanted with ZR-75-1 and MCF-7. There were 5 mice in ER- group. MDA-MB-231 cells were inoculated into thoracic mammary fat pad.
18
F-FES PET/CT was performed until the tumor length reached 5 mm. %ID/g
max
was used to quantitate ER expression. ER expression was also detected by immunohistochemistry.
Results:
The tumor formation rates for ZR-75-1
MCF-7 and MDAMB- 231 were 100% (10/10)
70% (7/10) and 100% (5/5)
respectively. There was no statistical difference in the volume among three groups (
P
0.05). %ID/g
max
values were 6.61.0
3.30.5 and 1.10.1
respectively. Significant differences were observed when ZR-75-1 was compared to MCF-7 (
P
0.05) and MDA-MB-231 (
P
0.001). There was significant difference between MCF- 7 and MDA-MB-231 (
P
0.05). The ratios of tumor to muscle (T/M) were 4.20.3
2.60.2 and 1.10.1
respectively. There were significant differences among three groups (
P
0.001). A significantly positive correlation was found between the resultsof 18F-FES imaging and immunohistochemistry (%ID/g
max
:
r
2
=0.65
P
0.001; T/M:
r
2
=0.87
P
0.001).
Conclusion:
%ID/g
max
from
18
F-FES PET/CT imaging is able to evaluate ER expression reliably.
1
8F-FES PET/CT can be used as a noninvasive and dynamic method in vivo.