Imaging of Ruptured Breast Implants: Finding the Leak
Breast implant placement is a commonly performed procedure, both in reconstruction after mastectomy and in cosmetic breast augmentation.[1,2] Various types of implants are used in current practice, including single-lumen silicone and saline implants (shown). Rupture of a breast implant is a frequent and significant complication, with a reported 10-year incidence of approximately 10-14%.[3] Among the more prominent causes of implant rupture are iatrogenic damage, shell swelling, trauma, and chemical degradation of the implant shell.[4]
Imaging of Ruptured Breast Implants: Finding the Leak
Saline and silicone implant ruptures typically manifest differently. Whereas a ruptured saline implant quickly deflates and thus is easily noticed by the patient,[5] a ruptured silicone implant generally does not give rise to clinical symptoms, because the more viscous silicone may be largely contained within the fibrous capsule that forms around the implant. Signs and symptoms of implant rupture, when present, may include the following:
- Change in breast shape, size, or firmness
- Palpable abnormalities
- Breast pain
Current recommended management of implant ruptures consists of surgical removal of the ruptured implant and any free silicone with capsulectomy.
Imaging of Ruptured Breast Implants: Finding the Leak
The most common types of breast implants are single-lumen saline (left) and silicone (middle) implants. Less commonly seen types include double-lumen (inner silicone and outer saline components [right]), reverse double-lumen (inner saline and outer silicone components), triple-lumen (inner silicone, middle silicone, and outer saline components), and stacked implants.[6,7]
Imaging of Ruptured Breast Implants: Finding the Leak
A 57-year-old woman presents with a 6-month history of abnormal sensation that is noted in the lateral aspect of both breasts but predominantly in the lateral left breast. In 1991, she underwent bilateral silicone implant placement for breast augmentation. Magnetic resonance imaging (MRI) of the breasts is performed to evaluate the integrity of the silicone breast implants.
Which of the following best describes the appearance of intracapsular silicone implant rupture on MRI?
- Radial fold
- Keyhole
- Stepladder
- Snowstorm
Imaging of Ruptured Breast Implants: Finding the Leak
Answer: B. Keyhole.
The keyhole sign (white arrow) represents a collapsed portion of the implant shell, with silicone present both within the ruptured implant and external to the implant but contained within the fibrous capsule. Additional descriptors of intracapsular implant rupture on MRI include the subcapsular line sign (yellow arrow) and the teardrop sign (early stages [red arrow]).[8] A radial fold (green arrow) is an inward fold of the implant shell, which is typically in intimate contact with the fibrous capsule.[9] A radial fold can occur if the implant is squeezed or deformed, but it is not a sign of implant rupture.
Imaging of Ruptured Breast Implants: Finding the Leak
A 67-year-old asymptomatic woman with bilateral silicone implants that were placed 38 years ago presents for routine screening mammography. Bulges in the implant contour are noted on the screening mammogram. Subsequently, ultrasonography is performed for evaluation of implant rupture.
Which of the following terms is a descriptor of intracapsular implant rupture on ultrasonography?
- Snowstorm
- Linguine
- Subcapsular line
- Stepladder
Imaging of Ruptured Breast Implants: Finding the Leak
Answer: D. Stepladder.
The stepladder sign, consisting of the horizontal lines visible in the slide (green arrow), is the ultrasonographic equivalent of the subcapsular line sign and the linguine sign, which are used in MRI to describe intracapsular silicone implant rupture.[3] The horizontal lines represent the collapsed shell of the silicone implant, which is floating in the silicone located both within and external to the ruptured shell but still contained within the fibrous capsule.
Imaging of Ruptured Breast Implants: Finding the Leak
A 62-year-old woman presents for routine screening mammography. One year previously, she experienced an extracapsular silicone implant rupture that necessitated removal of the implant. She subsequently had saline breast implants placed. The image in the slide shows a hyperdense mass lateral to one of the saline implants.
Which of the following is this hyperdense mass most likely to represent?
- Silicone granuloma
- Involuting fibroadenoma
- Oil cyst
- Invasive ductal carcinoma
Imaging of Ruptured Breast Implants: Finding the Leak
Answer: A. Silicone granuloma.
The term silicone granuloma (green arrow) refers to residual free silicone in the breasts from prior extracapsular silicone implant rupture.[10] On mammography, silicone granulomas appear as hyperdense oval or round masses; they may calcify over time. On ultrasonography, free silicone may appear as an area of "dirty shadowing," which is described as a snowstorm appearance. Calcified silicone granulomas may appear hyperechoic with posterior shadowing. On MRI, silicone granulomas are hypointense or isointense with T1-weighted imaging and hyperintense with T2-weighted imaging, and they may demonstrate variable enhancement.
Imaging of Ruptured Breast Implants: Finding the Leak
A 71-year-old woman presents with a history of tightness and upward displacement of her right silicone breast implant. She underwent bilateral silicone breast implant placement 30 years previously, and the left implant was revised 10 years ago. On examination, the right breast implant is significantly displaced cranially and is larger than the left implant. Both implants demonstrate abnormal shape and contour. MRI of the breasts reveals rupture of the right silicone implant, as demonstrated by the linguine sign (shown), which describes the collapsed implant shell floating in the silicone that is both within and external to the ruptured implant but is contained within the fibrous capsule.
Which of the following is the criterion standard imaging modality for the evaluation of breast implant rupture?
- Mammography
- Ultrasonography
- MRI
- Computed tomography
Imaging of Ruptured Breast Implants: Finding the Leak
Answer: C. MRI. MRI has both a high sensitivity (72-94%) and a high specificity (85-100%) for the detection of silicone implant rupture.[8] The US Food and Drug Administration currently recommends that women with silicone breast implants undergo MRI screening for implant rupture 3 years after implantation and then every 2 years thereafter. This screening does not require the use of gadolinium-based contrast agents. Special sequences that saturate fat and water can be helpful in visualizing silicone.
Imaging of Ruptured Breast Implants: Finding the Leak
A 62-year-old woman presents with a history of breast asymmetry. She underwent bilateral silicone breast implant reconstruction 29 years previously after right mastectomy for breast cancer and prophylactic left mastectomy. Bilateral breast ultrasonography is performed for evaluation of implant rupture.
Which of the following is an ultrasonographic descriptor applied to extracapsular breast implant rupture?
- Stepladder
- Snowstorm
- Mass
- Anechoic
Imaging of Ruptured Breast Implants: Finding the Leak
Answer: B. Snowstorm.
The snowstorm sign (green arrows) describes the dirty shadowing appearance of extracapsular free silicone.[3]
Imaging of Ruptured Breast Implants: Finding the Leak
An asymptomatic 63-year-old woman with a history of silicone breast implant placement presents for routine screening mammography. The mammogram demonstrates irregular implant contour with hyperdense masses in the left breast, findings compatible with extracapsular implant rupture with free silicone.
What is the location of this patient's silicone breast implant?
- Retropectoral
- Submuscular
- Prepectoral
- Subareolar
Imaging of Ruptured Breast Implants: Finding the Leak
Answer: C. Prepectoral.
The pectoralis muscle is visualized posterior to the ruptured silicone implant, as is characteristic of prepectoral or retroglandular implant placement.[11,12,13] Implants can also be placed posterior to the pectoralis (ie, retropectorally), in which case the pectoralis muscle is seen anterior to the implant.
Advantages of prepectoral implant placement include the following:
- Easier dissection
- More predictable sizing and contouring
- Decreased risk of pectoralis injury
- Capacity for larger implant size
Disadvantages include the following:
- Possible increased risk of capsular contraction
- Increased sensory changes to the nipple
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