Pentavalent technetium-99m dimercaptosuccinic acid [99m Tc-(V)DMSA] brain scintitomography--a plausible non-invasive depicter of glioblastoma proliferation and therapy response

Abstract

The biological behavior and prognosis of gliomas depend largely on cellular proliferation, resistance to chemotherapy, and metastatic potential. Proliferative propensity has significant implications on patient management but its assessment requires tissue sampling; the non-invasive estimation of brain tumor proliferation represents therefore a major goal. Pentavalent technetium-99 m dimercapto-succinic acid [99m Tc-(V)DMSA] is a tumor-seeking radiotracer displaying affinity for gliomas; its intracellular accumulation is directly linked to cell proliferation. We performed a tomographic 99m Tc-(V)DMSA brain scan in a 35-year-old male baring a recurrent glioblastoma multiforme, to depict its proliferative disposition. The patient had been diagnosed 14 months earlier and had been submitted to surgery, followed by adjuvant radiotherapy and temozolomide-based chemotherapy. On clinical suspicion of recurrence 5 months later, magnetic resonance imaging (MRI) revealed a lesion at the site of preceded surgery, which was treated by imatinib mesylate. No improvement was ascertained the following months and radiographic assessment verified tumor progression. Scintitomography revealed avid radiotracer uptake in the entirety of the lesion (the distribution of radioactivity closely conforming to the morphological tumor boundaries), an indication that the neoplasm demonstrated no substantial proliferation decline in response to imatinib. The patient deceased a few weeks later. Mounting in vivo and in vitro evidence indicates that 99m Tc-(V)DMSA is a credible non-invasive proliferation depicter, its cellular accumulation linked closely to phosphate uptake and kinase pathway activation. A potential role in patient management, prognosis estimation, and therapy response monitoring could occur for this tracer.