(Radiology. 2000;216:838-839.)
© RSNA, 2000
Linguine Sign1
Amjad Safvi, MS, MD
1 From the Department of Radiology, Northwestern Memorial Hospital, Chicago, Ill. Received March 3, 1998; revision requested April 29; final revision received April 26, 1999; accepted August 30. Address correspondence to the author, 296 Hawkeye Court, Iowa City, IA 52242.
Index terms: Breast, MR, 00.121411 • Breast, prostheses, 00.4543, 00.91 • Signs in Imaging • Silicone, 00.4543
 |
APPEARANCE
|
|---|
The linguine sign is seen at magnetic resonance (MR) imaging of silicone breast implants by using T2-weighted spin-echo or fast spin-echo methods with or without water suppression. The breast implant contains multiple curvilinear low-signal-intensity lines within the high-signal-intensity silicone gel. The lines are usually scattered diffusely and appear as long strands of decreased signal intensity curved on top of each other.
|
EXPLANATION
|
|---|
The linguine sign indicates intracapsular rupture of the silicone breast implant (1). The breast implant is made of a Silastic elastomeric shell containing silicone. The elastomeric shell breaks, which releases the silicone inside. A fibrous capsule (scar tissue) forms around the breast implant after it is placed into the breast. The fibrous capsule usually contains the silicone as the shell collapses. The serpentine lines represent layers of collapsed elastomeric shell floating in the silicone gel within the fibrous capsule.
The Silastic elastomeric shell appears as low-signal-intensity lines, and the silicone gel appears as high signal intensity on T2-weighted images. Medical-grade silicone is composed of dimethyl siloxane, a silicon molecule with two methyl groups linked to each other by oxygen molecules in a polymer chain. The MR signal intensity is derived from the protons of the methyl groups. The Silastic elastomeric shell is also composed of the same polymer but has increased cross-linkage of the methyl groups, which results in an elastic solid. This linked polymer produces a lower MR imaging signal intensity than the unlinked silicone gel polymer (2).
|
DISCUSSION
|
|---|
There are several types of breast implants. Most are single-lumen silicone prostheses containing silicone gel within an outer elastomeric silicone shell. Implants can also contain saline or be made of a combination of saline and silicone in different encapsulated shells. The surface can be smooth or textured; the latter is thought to decrease the formation of capsular contractures, which is a fairly common complication. Gel "bleeding" indicates microscopic leakage of silicone through the shell. There almost always is some degree of leakage of silicone gel from the implant. In intracapsular implant rupture, the fibrous capsule contains the silicone. In extracapsular rupture, the silicone breaks free from the ruptured fibrous capsule and the ruptured implant and leaks into the breast parenchyma.
The linguine sign (Figure) indicates intracapsular rupture of the breast implant. This MR imaging sign is the most sensitive among all the signs of intracapsular rupture from other imaging modalities, with a sensitivity of 96% and a specificity of 94% (3). The wavy lines on MR images represent the collapsed shell floating in the silicone. Although the linguine sign is fairly easy to detect, the signs of early intracapsular rupture (4) (tear drop sign, keyhole sign, subcapsular line sign) were more common than the linguine sign in a study of 86 breast implants (5).
View larger version (98K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1. Sagittal T2-weighted short-T1 inversion-recovery MR image (3,000/60 [repetition time msec/echo time msec]) obtained with fat suppression shows intracapsular rupture of a silicone breast implant, as demonstrated by the linguine sign (arrow).
|
|
The Silastic elastomeric shell by design is not wrapped tautly around the silicone gel. There is room left for the implant to be molded and be pliable. There is a small amount of natural infolding of the implant shell seen on MR images obtained in women with intact, normal implants. This may produce curvilinear lines similar to the linguine sign. Lines longer than 3 cm seen on multiple consecutive images indicate a ruptured implant (5). There usually is some undulation of these lines, which indicates a free-floating elastomeric shell. Intracapsular rupture of breast implants can be easily and confidently detected with the presence of the linguine sign.
|
FOOTNOTES
|
|---|
A trainee (resident or fellow) wishing to submit a manuscript for Signs in Imaging should first write to the Editor for approval of the sign to be prepared, to avoid duplicate preparation of the same sign.
|
REFERENCES
|
|---|
-
Gorczyca D, Sinha S, Ahn C, et al. Silicone breast implants in vivo: MR Imaging. Radiology 1992; 185:407-410.[Abstract/Free Full Text]
-
Gorczyca D. MR imaging of breast implants. Magn Reson Imaging Clin N Am 1994; 2:659-672.[Medline]
-
Samuels JB, Rohrich R, Weatherall P, et al. Radiographic diagnosis of breast implant rupture: current status and comparison of techniques. Plast Reconstr Surg 1995; 96:865-877.[Medline]
-
Soo MS, Kornguth P, Walsh R, et al. Complex radial folds versus subtle signs of intracapsular rupture of breast implants: MR findings with surgical correlation. AJR Am J Roentgenol 1996; 166:1421-1427.[Abstract/Free Full Text]
-
Soo MS, Kornguth PJ, Walsh R, et al. Intracapsular implant rupture: MR finding of incomplete shell collapse. J Magn Reson Imaging 1997; 7:724-730.[Medline]
This article has been cited by other articles:
|
|
|
|
 
C. J. Roche, D. P. O'Keeffe, W. K. Lee, V. A. Duddalwar, W. C. Torreggiani, and J. M. Curtis
Selections from the Buffet of Food Signs in Radiology
RadioGraphics,
November 1, 2002;
22(6):
1369 - 1384.
[Abstract]
[Full Text]
[PDF]
|
|
|
TOP
APPEARANCE
EXPLANATION
