Abstract
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Objectives Canine transmissible venereal tumor (cTVT) to approximate human dimensions has been studied in lungs using CT (Ahrar K, et al. 2003.). In this study, cTVT is placed in canine lungs and prostates to allow evaluation of locoregional retention of a paramagnetic radiopharmaceutical Ga-68 GIMA (Wong FC et al, 2004).
Methods Under an approved animal protocol, 6 male Beagle dogs (20-30 Kg) received injection of cTVT into the left and right lungs under CT guidance. cTVT was also injected into the left and right prostate lobes in 4 dogs by open surgery. Intratumoral injection of Ga-68 GIMA was under MR guidance. Intratumoral retention was monitored by PET for Ga-68 and by MRI for iron. Tumoral metabolism before and after injection was monitored by F-18 FDG PET within 2 weeks and correlated with necropsy findings.
Results All lung cTVT were identified by baseline F-18 FDG PET with SUV= 2.2-6.5. Prostate cTVT’s showed SUV=2.1-4.3. After injection in lungs, Ga-68 GIMA loculation was seen on Ga-68 PET with max SUV of 1600-4000 and up to 5 days on MRI. Lung cTVT retained GIMA longer than prostate cTVT did. Followup SUV of FDG rose to lesser extent (1.0 vs 1.8) for tumors treated with GIMA.
Conclusions Metabolic imaging using FDG-PET is able to visualize cTVT activities and may correlate with growth or response to treatment in this preliminary study. Lung cTVT may serve as a tumor model for metabolic imaging. Further studies are also warranted to investigate retention of radioactive iron macroaggregates as potential locoregional therapeutic radiopharmaceuticals.
Research Support US DOD BCRP DAMD17-03-1-0455 (PI: F. Wong)
- © 2009 by Society of Nuclear Medicine