Enhanced uptake of [C-11]TPMP in canine brain tumor: A PET study

In vitro studies have demonstrated the membrane potential dependent enhance d uptake of phosphonium salts, including [H-3]triphenylmethylphosphonium (T PMP), into mitochondria of carcinoma and glioma-derived tumor cells, sugges ting the potential use of phosphonium salts as tracers for tumor imaging. T his study characterizes the in vivo uptake of [C-11]TPMP in canine brain gl ioma using PET. Methods: Dynamic paired PET studies of [C-11]TPMP followed by [Ga-68]ethylenediaminetetraacetic acid (EDTA) were performed 4 d before and 9 d after tumor cell inoculation. Graphical analysis was used to evalua te [C-11]TPMP retention in tumor tissue. Distribution of tracer uptake was compared with tumor histological sections. Results: [C-11]TPMP exhibited en hanced uptake and prolonged retention in tumor cells. Patlak plot was linea r over the 20- to 95-min postinjection period (r = 0.97 +/- 0.1). [Ga-68]ED TA exhibited a gradual washout from the tumor tissue. The tumor-to-normal b rain uptake ratio at 55 to 95 min postinjection was 47.5 for [C-11]TPMP and 8.1 for [Ga-68]EDTA. Qualitative comparison with histological sections ind icated that [C-11]TPMP enhanced uptake was restricted to the tumor area. Co nclusion: The enhanced uptake and prolonged retention in tumor suggest [C-1 1]TPMP as a promising means for imaging of gliomas in dogs. The need for st udies in humans is indicated.