Bromocriptine enhances the uptake of ^99mTc-MIBI in patients with hepatocellular carcinoma

^99m Tc-methoxyisobutyl isonitrile (MIBI) is a suitable transport substrate for the multidrug resistance gene product P-glycoprotein (P-gp) and widely used for tumor imaging. Bromocriptine has been shown to inhibit the ATPase activity and the function of P-gp. We hypothesized that bromocriptine could promote the accumulation of MIBI by inhibiting P-gp activities, a feature that can be taken advantage of for enhancing ^99m Tc-MIBI imaging. In the current study, we sought to investigate whether bromocriptine enhanced the uptake of ^99m Tc-MIBI in hepatocellular carcinoma patients. Sixty primary hepatocellular carcinoma patients received ^99m Tc-MIBI single photon emission computer tomgraphy (SPECT) prior to surgery. ^99m Tc-MIBI SPECT was performed 15 and 120 min after injection of 20 mCi ^99m Tc-MIBI, and early uptake, delayed uptake (L/Nd), and washout rate (L/Nwr) of ^99m Tc-MIBI were obtained. In addition, a second ^99m Tc-MIBI SPECT was performed according to the same method 48 h after bromocriptine administration. We found that, prior to bromocriptine administration, significant MIBI uptake in tumor lesions was noted in only 10 (16.7%, 10/60) patients with hepatocellular carcinoma. No significant MIBI uptake was observed in the tumor lesions of the remaining 50 (83.3%, 50/60) hepatocellular carcinoma patients. Following bromocriptine administration, all the patients without apparent MIBI uptake demonstrated significant MIBI uptake on ^99m Tc-MIBI SPECT (P < 0.05). Our findings indicate that bromocriptine enhances the uptake of ^99m Tc-MIBI in patients with hepatocellular carcinoma.