Pinhole imaging of 131I-metaiodobenzylguanidine (131I-MIBG) in an animal model of neuroblastoma.

ABSTRACT

PURPOSE: To evaluate (131)I-MIBG scintigraphic localization of xenotransplanted and spontaneously arising neuroblastomas in murine models of high-risk neuroblastoma. METHODS: Neuroblastoma xenografts were created by inoculation of human neuroblastoma cell suspensions into the subcutaneous flanks of athymic nude mice. In addition, spontaneous paraspinal neuroblastomas were detected by direct palpation in MYCN transgenic mice. After measured tumor volumes exceeded 200 mm(3), each mouse received an intraperitoneal injection of 18 muCi/g (131)I-metaiodobenzylguanidine ((131)I-MIBG). Pinhole scintigraphy was performed to evaluate the MIBG biodistribution and to attempt to visualize the tumors. Each mouse was imaged on a gamma camera equipped with a 3-mm pinhole on one head and an HEGP collimator on the other. RESULTS: Images demonstrated absorption of radiolabeled MIBG and visualization of tumors. Analysis of the images allowed for quantification of relative MIBG uptake and for determination of linear and area measurements of the tumors. CONCLUSION: High-energy pinhole imaging effectively demonstrates uptake of radiolabeled MIBG by human neuroblastoma tumors in murine laboratory models. This technique allows for in vivo assessment of tumor burden. In the future, we plan to use this method to evaluate sensitivity for detecting metastatic spread as well as investigating the therapeutic efficacy of high-dose (131)I-MIBG in combination with radiosensitizing agents.