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Linguine (Free-Floating Loose Thread) Sign

WithMichael E. Mulligan

Imaging of the breast containing a silicone implant, used for augmentation mammoplasty or reconstruction after a mastectomy, was difficult before the invention of clinical magnetic resonance imaging (MRI). In the 1990s ‘medical and public concern about the potential dangers of silicone leakage … made it imperative to find a sensitive and specific diagnostic imaging modality for patients with silicone breast implants.’ 1 David Gorczyca (University of California, Los Angeles) and his colleagues’ evaluated various magnetic resonance pulse sequences in 143 patients to determine a reliable method for differentiating between silicone and normal breast tissue and to identify ruptures or leaks. One sign of an intracapsular rupture they described as the linguine sign or ‘free-floating loose thread’ sign. ‘Pieces of free-floating silicone shell within the gel indicate an intracapsular rupture. We described this finding as the linguine sign or ‘free-floating loose thread’ sign.’ 1 This indicates that there are free-floating pieces of the silicone shell within the silicone gel (Figure 1). This sign of intracapsular rupture should not be confused with normal radial folds that are present at the implant margin. Intracapsular rupture. A 51 -year-old woman presented with a 3-year history of severe chest and breast pain. Axial fast SE T2–weighted (4000/170, shoulder coil) image of the right breast obtained with water suppression demonstrates multiple curvilinear low-signal-intensity lines (arrows) within the high-signal-intensity silicone gel. These lines (linguine sign) represent the collapsed implant shell floating within the silicone gel.’ Reprinted from Gorczyca et <italic>al.</italic> Silicone breast implants <italic>in vivo. Radiology., 1</italic>992, 185, 407–10, with permission of the RSNA