In Vivo localized proton NMR spectroscopy of silicone

1 H NMR localized spectroscopy (STEAM) can assess unambiguously the presence of free chemically unchanged silicone in animal tissue after injection of silicone oil. Although the signal—to—noise ratio obtained in 1 H imaging is sufficient to detect the distribution of relatively large amounts of silicone in vivo , the specificity of silicone detection can be improved by using 1 H 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 mm 3 . Preliminary results from rats with silicone gel—filled implants show no detectable amounts of silicone in sites such as lymph nodes, the liver or the spleen, 3 or 6 months after implantation.