IN-VIVO LOCALIZED PROTON NMR-SPECTROSCOPY OF SILICONE

H-1 NMR localized spectroscopy (STEAM) can assess unambiguously the pr esence of free chemically unchanged silicone in animal tissue after in jection of silicone oil. Although the signal-to-noise ratio obtained i n H-1 imaging is sufficient to detect the distribution of relatively l arge amounts of silicone in vivo, the specificity of silicone detectio n can be improved by using H-1 localized spectroscopy techniques. The sensitivity of the STEAM experiments is sufficient to detect silicone at a concentration of 0.5% in a voxel of 27 MM3. Preliminary results f rom rats with silicone gel-filled implants show no detectable amounts of silicone in sites such as lymph nodes, the liver or the spleen, 3 o r 6 months after implantation.