Tc-99m pyrophosphate imaging of poloxamer-treated electroporated skeletal muscle in an in vivo rat model

Objective: This study investigates whether Tc-99m pyrophosphate (PYP) imaging provides a quantitative non-invasive assessment of the extent of electroporation injury, and of the effect of poloxamer in vivo on electroporated skeletal muscle. Methods: High-voltage electrical shock was used to produce electroporation injury in an anesthetized rat's hind limb. In each experiment, the injured limb was treated intravenously by either poloxamer-188, dextran, or saline, and subsequently imaged with Tc-99m PYP. The radiotracer's temporal behavior among the experimental groups was compared using curve fitting of time-activity curves from the dynamic image data. Results: The washout kinetics of Tc-99m PYP changed in proportion to the electric current magnitude that produced electroporation. Also, Tc-99m PYP washout from electroporated muscle differed between poloxamer-188 treatment and saline treatment. Finally, 10-kDa dextran treatment of electroporated muscle altered Tc-99m PYP washout less than poloxamer-188 treatment. Conclusions: Behavior of Tc-99m PYP in electroporated muscle appears to be an indicator of the amount of electroporation injury. Compared to saline, intravenous polaxamer-188 treatment reduced the amount of Tc-99m PYP uptake. Coupled to results showing poloxamer-188 seals ruptured cellular membranes, lessens the extent of clectroporation injury and improves cell viability, Tc-99m PYP imaging appears to be a useful in vivo monitoring tool for the extent of electroporation injury. (C) 2006 Elsevier Ltd and ISBI. All rights reserved.