Multimodality functional imaging of spontaneous canine tumors using 64Cu-ATSM and 18FDG PET/CT and dynamic contrast enhanced perfusion CT

Purpose: To compare the distribution and uptake of the hypoxia tracer Cu-64-diacetyl-bis(N-4-methylthiosemicarbazone) (Cu-64-ATSM) PET/CT, FDG PET/CT and dynamic contrast enhanced perfusion CT (DCE-pCT) in spontaneous canine tumors. In addition Cu-64-ATSM distribution over time was evaluated. Methods and materials: Nine spontaneous cancer-bearing dogs were prospectively enrolled. FDG (1 h pi.) and Cu-64-ATSM (3 and 24 h pi.) PET/CT were performed over three consecutive days. DCE-pCT was performed on day 2. Tumor uptake of FDG and Cu-64-ATSM was assessed semi-quantitatively and the distribution of FDG, Cu-64-ATSM and CT perfusion parameters correlated. Results: Cu-64-ATSM distribution on scans performed 24 h apart displayed moderate to strong correlation; however, temporal changes were observed. The spatial distribution pattern of Cu-64-ATSM between scans was moderately to strongly positively correlated to FDG, whereas the correlation of CT perfusion parameters to FDG and to Cu-64-ATSM yielded more varying results. Conclusions: Cu-64-ATSM uptake was positively correlated to FDG. Cu-64-ATSM was found to be relatively stable between PET scans performed at different time points, important temporal changes were however observed in hypo-perfused regions. These findings potentially indicate that prolonged uptake periods for Cu-64-ATSM imaging may be needed. Although a moderate to strong correlation between Cu-64-ATSM and FDG PET/CT is observed, the two tracers provide different biological information with an overlapping spatial distribution. (c) 2011 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 102 (2012) 424-428