Laser-Raman microprobe identification of inclusions in capsules associatedwith silicone gel breast implants

Raman spectroscopy (the analysis of scattered photons after excitation with a monochromatic light source) provides a nondestructive method for identif ying organic and inorganic materials on the basis of the molecule's charact eristic spectrum of vibrational frequencies. Although the technique has bee n predominantly applied in sciences other than pathology, the recent advent of high-quality microscope optics coupled to optical Raman spectrometers ( a variation known as a Raman microprobe) rendered this technique amenable t o applications in human pathology. In the Raman microprobe, a laser beam is focused on a spot approximately 1 mu m in diameter on the surface of the s ample, e.g., tissue, and the scattered light is collected and analyzed. In this investigation, we used the Raman microprobe for the identification of foreign materials in breast implant capsular tissues. The characteristic si licone group frequencies associated with the silicon-oxygen stretch, the si licone-carbon stretch, the silicon-methyl and the methyl carbon-hydrogen st retch frequencies were used to identify polydimethylsiloxane and to define chemical differences among the various other implant-related inclusions. Al l of the inclusions were positively identified in a series of 44 capsules f rom silicone gel-filled implants: polydimethylsiloxane was found in 44 of 4 4 capsules surrounding silicone gel-filled implants; polyurethane was seen in 4 of 4 capsules around polyurethane foam-coated gel-filled implants; 4 o f 4 capsules enveloping Dacron patch gel-filled implants revealed Dacron; a nd talc was identified in 8 of these 44 capsules. Raman microspectroscopy p rovides a rapid, accurate, and sensitive method for identifying inclusions associated with silicone and other implant materials in tissue.