Br-m-bromobenzylguanidine (Br-MBBG) for in vivo imaging of neuroendcrine-tumor with PET

Watanabe, Shigeki; Hanaoka, Hirofumi*; Liang, J. X.; Iida, Yasuhiko*; Watanabe, Satoshi; Endo, Keigo*; Ishioka, Noriko

I-m-Iodobenzylgunanidine (I-MIBG), functional analogue of norepinephrine, has been employed for the therapy of neuroendcrine tumors which express norepinephrine transporter (NET). I-MIBG scintigraphy has been also used for diagnosis of the neuroendcrine tumors. However, MIBG scintigraphy has been not enough for diagnosis of neuroendcrine tumors due to poor sensitivity and resolution. Positron emission tomography (PET) is superior to spatial resolution and quantitative capability. To improve diagnostic ability of NET positive neuroendcrine tumor, positron emitter Br labeled m-bromobenzylguanidine (Br-MBBG) was synthesized. Br was synthesized successfully with 50% of labeling efficiency, and the compound had great stability in vitro. In biodistribution studies using neuroendcrine tumor xenografted nude mice, Br-MBBG showed highest accumulation to the tumor, which is relative high compared to that of MIBG. These results indicate that Br-MBBG is useful for in vivo imaging of neuroendcrine tumors with PET.