Evaluation of62Cu labeled diacetyl-bis(N4-methylthiosemicarbazone) as a hypoxic tissue tracer in patients with lung cancer

62Cu labeled diacetyl-bis(N4-methylthiosemicarbazone) (62Cu-ATSM) has been proposed as a generator-produced, positron-emitting tracer for hypoxic tissue imaging. From basic studies, the retention mechanism of62Cu-ATSM is considered to be closely related to cytosolic/microsomal bioreduction, a possible system for hypoxic bioreductive drug activation. In order to evaluate the characteristics of62Cu-ATSM, PET studies were performed in 4 normal subjects and 6 patients with lung cancer.62Cu-ATSM cleared rapidly from the blood with little lung uptake (0.43±0.09, uptake ratio; divided by the arterial input function) in normal subjects. Intense tumor uptake of62Cu-ATSM was observed in all patients with lung cancer (3.00±1.50). A negative correlation was observed between blood flow and flow-normalized62Cu-ATSM uptake in three of four patients. In contrast,62Cu-ATSM uptake was not related to that of18F-fluorodeoxyglucose. The negative correlation between blood flow and flow normalized62Cu-ATSM uptake suggests an enhancement of retention of62Cu-ATSM by low flow.62Cu-ATSM is a promising PET tracer for tumor imaging, which might bring new information for chemotherapeutic treatment as well as radiotherapy of hypoxic tumors.