Whole body autoradiography by positron emitting radionuclides

The technique of freezing whole body autoradiography using positron emitting nuclides has been developed in the present study. Because of rapid decay of positron emitters, a frozen section to contact with a X-ray film must be prepared within a few hours. All the procedures to obtain autoradiograms of rats using 18F-2-deoxy-2-fluoro-D-glucose (18F-FDG) or 11C-glucose-fructose mixture (11C-glucose) were described in detail. In the present technique, exposure must be performed at -200C to keep a section frozen. Density of X-ray films after exposure at 200C or -200C was examined using various radioactive sections. The reduction of the density exposured at -200C was observed. But the density exposured at -200C was proportional to the radioactivity. Freezing whole body autoradiography of rats bearing subcutaneous AH109A tumors was performed using 18F-FDG (half life of 109.7 min) and 11C-glucose (half life of 20 min). Density of tumors and other organs on the autoradiogram was comparable with tissue distribution studies of 18F-FDG and 11C-glucose. Freezing whole body autoradiography can be feasible for the analysis of tissue distribution on positron emitting radiopharmaceuticals. (author)