EVALUATION OF CU-PTSM AS A TRACER OF TUMOR PERFUSION - COMPARISON WITH LABELED MICROSPHERES IN SPONTANEOUS CANINE NEOPLASMS

4Copper-62-labeled Cu-PTSM is a promising generator-produced PE?: trac er for myocardial, cerebral and renal perfusion. To evaluate whether [ Cu-62]Cu-PTSM could also serve as a blood flow tracer in PET studies o f tumor tissue, the tumor uptake of [Cu-67]Cu-PTSM was examined in dog s with spontaneously-occurring soft-tissue neoplasms. Copper-67-labele d Cu-PTSM was administered intravenously to four anesthetized dogs, fo llowed c. 5 min later by a left ventricular injection of Sr-85-labeled microspheres (15 mu m) to provide an independent measure of tumor per fusion. Forty-seven tumors (average weight = 2.5 +/- 3.7 g) were obtai ned and sectioned into 80 samples. The correlation of Cu-67-PTSM uptak e with regional renal perfusion was also examined in data from 395 tis sue samples ranging in flow from 0.02 to 9.39 mt min(-1) g(-1). Rates of tumor perfusion assessed with Sr-85-labeled microspheres ranged fro m 0.011 to 3.0 mt min(-1) g(-1). No correlation was found between tumo r size and the rate of tumor perfusion. However, an excellent linear c orrelation exists between tumor perfusion calculated from [Cu-67]Cu-PT SM data and tumor perfusion measured with Sr-85-microspheres (r = 0.94 for 80 samples), suggesting that [Cu-67]Cu-PTSM may be useful as a ra diopharmaceutical for PET studies of tumor perfusion.