Objectives: Brain single-photon emission computed tomography (SPECT) has been proposed as a potentially useful modality for the metabolic assessment of various brain tumors. Material and methods: In a 10-patient prospective pilot study we evaluated whether (99m)Tc-Tetrofosmin ((99m)Tc-TF) uptake correlates with glioma proliferative activity assessed by flow cytometric analysis. (99m)Tc-TF brain SPECT was performed shortly before surgical tumor excision. Results: Eight patients were diagnosed with glioblastoma multiform and 2 with anaplastic astrocytoma. All tumors were aneuploid. We found a significant positive linear correlation between 99mTc-TF uptake and percentage of tumor cells on the S-phase of the cell cycle (r=0.92, P=0.001). Conclusion: Initial evidence suggests that 99mTc-TF could provide a non-invasive indicator of glioma proliferative activity. (C) 2009 Elsevier B.V. All rights reserved. Clin Neurol Neurosurg