Assessment of tissue viability in frostbite by 99Tcm-HDP scintigraphy: an experimental study in New Zealand white rabbits.

Since the appearance of superficial tissue is often an unreliable indicator of deep tissue viability in cases of frostbite, radionuclide scintigraphy with 99Tcm-disodium oxidronate (HDP) was used to assess changes in tissue viability after experimental freezing and thawing of the rabbit ear. One shaved ear, left or right, of each of eight New Zealand white rabbits was frozen with a glass bottle (diameter of bottom 2 cm) filled with liquid nitrogen (-180 degrees C) for 5 min under Ketalar-Rompun anesthesia, the other ear serving as a control. Radionuclide scintigraphy was performed by giving a bolus intravenous injection of 130-170 MBq (3.5-4.5 mCi) 99Tcm-HDP. Radionuclide imaging was used to follow the development of the demarcation line. Scintigraphy was performed 2 h after frostbite and then after 24 h, 48 h, 1 week and 3 weeks. The frostbitten area seemed macroscopically to be warm and swollen immediately after the induction of frostbite. Scintigraphy showed the frostbitten area to be much warmer than the surrounding tissue for the first week and it was not until after that the first cold spots appeared in the middle of the frostbitten area. The necrotic and vital tissue could easily be distinguished after 3 weeks.