Migration and accumulation of silicone in the liver of women with silicone gel-filled breast implants.

Magn Reson Med. 1995 Jan;33(1):8-17.Links

Migration and accumulation of silicone in the liver of women with silicone gel-filled breast implants.

Pfleiderer B, Garrido L.

NMR Center, Department of Radiology, Massachusetts General Hospital, Charlestown 02129.

1H NMR localized spectroscopy (STEAM), combined with echocardiography (ECG), respiratory gating, and water and fat suppression, was used to quantify silicone concentrations in the liver of women with silicone gel-filled breast implants. Localized spectroscopy was performed on 15 patients with silicone gel-filled breast prostheses and on eight volunteers with no implants. The 1H spectra in the liver of patients showed silicone resonances from 0.3 to -0.8 ppm, attributable to protons in the methyl groups of silicone. The presence of silicone in the liver could first be detected 3-4 years after breast prostheses implantation. No correlation between silicone concentrations and implantation times was observed. However, our results indicated that silicone concentrations may reflect implant integrity: detectable silicone concentrations in the liver appeared to be higher when the implants were ruptured than when the implants appeared intact. Moreover, new resonances in the range of -2.6 to -4 ppm were observed in most patients after long-term implantation. As these species increase with implantation time, the new resonances may reflect chemically changed silicone (paramagnetically shifted silicon complexes bound to iron) accumulated over time. The sensitivity of 1H NMR localized spectroscopy is sufficient to detect silicon concentrations as low as 0.20 mM. Results from one patient whose implants had been removed 14 months prior to the NMR examination showed no detectable silicone in the liver, indicating that it may have been excreted via bile or degraded to silica and high coordinated silicon complexes. Quantitative 1H localized spectroscopy of the liver in women with silicone gel-filled breast implants may provide valuable information concerning silicone accumulation and degradation in vivo, as well as about the kinetics of its elimination from the body after implant removal.

Magn Reson Med. 1993 Nov;30(5):534-43.

Comment in: Magn Reson Med. 1996 Sep;36(3):498-501.

Migration and biodegradation of free silicone from silicone gel-filled implants after long-term implantation.

Pfleiderer B, Ackerman JL, Garrido L.

Department of Radiology, NMR Center, Massachusetts General Hospital, Charlestown 02129.

In vivo 1H NMR chemical shift imaging (CSI), 1H NMR localized spectroscopy (STEAM) and multinuclear NMR spectroscopy (29Si, 13C, 1H) were used to characterize the aging process of silicone gel-filled implants in a rat model after long-term implantation. Although no significant changes could be observed in the implants or surrounding tissue by in vivo 1H chemical shift imaging, in vivo 1H localized spectroscopy of the livers from the longer term population revealed the presence of silicone. Ex vivo 29Si spectroscopy of the liver, spleen, and the capsule formed around the 9 and 12 month implants clearly demonstrated and confirmed for the first time that a significant amount of free silicone migrates from silicone gel-filled implants. Also, these results show that silicones are not metabolically inert, and their biodegradation in tissue and within the implant can be monitored after 9 and 12 months by changes in the 29Si chemical shifts seen in corresponding ex vivo spectra. The NMR findings are supported by those obtained by atomic absorption spectroscopy. Silicone aging changes not only the chemical composition of the gel, but also its proton T2 relaxation times, which increase with long implantation times. The three dimensional structure of the gel disintegrates (i.e., polymer chain rupture), increasing the molecular mobility of the polymer and, consequently, its protons T2 values. The relaxation data we obtained reflect this in vivo degradation, especially in the case of implant rupture. Additionally, small concentrations of fat in the silicone gel were found within the implants. The presence of these lipophilic substances also might increase the T2 values (plasticizer effect). These findings may assist in evaluating the implant integrity and disease symptoms related to their presence in humans.

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