Feature article

MRI Detecting the Rupture of Breast Implants

Beginning in the early 20th Century, surgeons started using prosthetic techniques and materials to perform breast augmentation surgery. This surgery is performed for many reasons, including cosmetic enhancement, correction of congenital malformations, or reconstruction following breast surgery, such as mastectomy. The first silicone gel-based augmentation was performed in the United States in 1962 and was quickly regulated by the US Food and Drug Administration (FDA).1 Years later, the FDA restricted the use of silicone implants to specific instances of medical necessity, and saline breast implants began to replace silicone as the common breast prosthesis.

The FDA has since approved breast implants for breast augmentation in women at least 22 years of age, and for breast reconstruction for women of any age. Since 2015, more than 3.5 million women in the United States have received breast implants. Indeed, breast augmentation is the most commonly performed cosmetic surgical procedure in the US annually.2 

The rupturing of a breast implant is recognized as a frequent and serious complication, with a reported 10-year incidence of approximately 10-14%.3

What is a Breast Implant Rupture?

A breast implant rupture is defined as a tear or hole in the outer shell of the breast implant.5 In current medical practice, the most common types of breast implants employed are single-lumen silicone and saline implants. After implantation occurs, a fibrous capsule (scar) forms around the implant shell. Implant ruptures are therefore categorized as intra-capsular or extra-capsular.

An intra-capsular rupture occurs when the shell of the implant ruptures but the fibrous capsule formed by the breast remains intact. Implant material does not freely extravasate, making it difficult to detect on a clinical exam or certain imaging modalities. When an extra-capsular rupture occurs, it can lead to a change in the implant contour and it is possible to detect the rupture on a clinical examination or mammography.4 This type of rupture results in saline or silicone gel extravasating into the surrounding tissues. It is also important to note that there cannot be an extra-capsular rupture without an intra-capsular rupture. 8

The type of implant may also influence the type of rupture, as saline and silicone implant ruptures typically manifest differently. Generally, a ruptured saline implant quickly deflates, while a ruptured silicone implant may appear asymptomatic. This is because silicone is more viscous and is more likely to be contained within the fibrous capsule that formed around the implant. 3

A ruptured silicone implant is more dangerous to a patient than a saline implant. A saline implant consists of a silicone shell filled with a saline solution, similar to the consistency of water. When a saline implant ruptures the material is absorbed by the body, causing little to no harm to the body.7

A silicone implant consists of a silicone gel solution and is a much thicker consistency than water. If silicone gel leaks outside of the capsule surrounding the implant, the silicone may travel away from the breast. The leaked silicone can cause lumps to form in the breast or surrounding tissues, making it difficult or impossible to remove the migrated silicone from the body.5

When symptoms of implant rupture are present, they include the following:

  • change in breast shape, size or firmness
  • palpable abnormalities
  • breast pain

There are many possible causes behind an implant rupture, including:

  • compression during a mammogram
  • normal aging of the implant
  • physical stresses such as trauma or intense physical pressure 5

 Studies show that clinical diagnosis of implant rupture based on physical exam findings is unreliable and will miss more than half of implant ruptures. Breast pain during an exam is a strong predictor of a rupture, but the most common predictive symptom is contour deformity (44%).2 Furthermore, most ruptures occur 10-15 years following the implant placement, with an increasing incidence over time. It is estimated that 98% of implants will be intact after 5 years, and approximately 84% will be intact after 10 years.2

 Medical Exams for Imaging Ruptured Implants

 The most common imaging modalities used in examining ruptured breast implants are mammogram, ultrasound, and magnetic resonance imaging (MRI). Factors to consider when deciding which imaging modality to use when evaluating implant integrity include:

  • clinical relevance of the information obtained
  • existent contraindication to MRI
  • availability of the imaging modality
  • the radiologists’ ability to accurately interpret the images
  • the cost of the exam.2

Many radiologists agree that mammography is not the ideal imaging exam when assessing implant integrity. Detection of implant ruptures, especially in silicone implants, are very difficult to detect on mammograms. Furthermore, detection of intra-capsular silicone ruptures are almost impossible to document with this modality.

In fact, the mammographic evaluation of the implant-augmented breast is more tedious than those without implants because there are more images to review, the associated tissue distortion, postsurgical changes, and difficulty evaluating the tissues on the lateral and deep margins of the implant.2

Ultrasound is the most appropriate test for screening and follow-up of women with implant-based breast reconstruction. However, according to a report by Dr. Mario Reitjens et. al of the European Institute of Oncology in Milan, MRI is the imaging tool that should be used to make a definitive diagnosis of an implant rupture.6

This study compared the accuracy of MRI versus ultrasound in detecting ruptured implants. It included 102 women who had received silicone gel implants for breast reconstruction after mastectomy for breast cancer. A median of five years later the women were undergoing repeat surgery to replace the implant for cosmetic reasons. The patients were asymptomatic and had no signs of implant rupture. Before the surgery all of the patients were scanned with both ultrasound and MRI. Once in surgery, 28% of women were found to have an implant rupture.6

This study concluded that MRI was 94% more accurate in detecting ruptured implants, compared to 72% accuracy for ultrasound. MRI also had a lower “false-negative” rate of 5% compared to ultrasound’s 9%.6

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 MRI Technique for Imaging the Implant-augmented Breast

 MRI is considered the gold standard when evaluating the integrity of the both saline and silicone implant shells, because of its high spatial resolution and excellent contrast between the implants and adjacent soft tissues. MR imaging of the breast should be performed on a high-field strength magnet, of at least 1.5 Tesla, as the higher magnet strengths have the ability to better emphasize or reduce signal intensity from silicone, water or fat.

STIR silicone-selective sequences demonstrate hyperintense silicone with water suppression and silicone-saturated images give hyperintense water signal with silicone suppressed. In addition, Turbo spin-echo T2-weighted images are useful when evaluating silicone implants for ruptures. Intravenous gadolinium-based contrast agents are not necessary when evaluating solely the integrity of the breast implant. 2

MRI’s ability to suppress or enhance silicone, as well as suppress signal intensity of water and fat allows this modality to provide the highest sensitivity and specificity for implant rupture compared to all other modalities. MRI’s sensitivity and specificity for rupture is between 80-90% and 90-97% respectfully. Furthermore, an MRI can be performed without the addition of harmful ionizing radiation. 

Conclusion

 The FDA recommends follow up MRI scanning biannually starting after the third year of implant placement.2 However, the positive predictive value of this imaging modality in an asymptomatic patient is likely not cost effective. Mammography and ultrasound are useful tools for evaluating the condition of implant-augmented breasts until abnormalities or ambiguous findings occur. If implant integrity is in question, MRI is the most accurate and valuable imaging modality for documenting a rupture and examining the extent of the issue. As medical imaging technology continues to improve the ability to detect early signs of implant rupture may be possible and may result in different implant rupture detection rates.

 

 

References: 

1. Hallett, Richard L. et al. "Imaging in Breast Implant Rupture." Medscape. 22 February 2017. Web. 13 August 2018. <https://emedicine.medscape.com/article/345877-overview>.

2. Wiedenhoerfer, James F., et al. "MR imaging of breast implants: Useful information for the interpreting radiologist." Applied Radiology. 2015. Web. 13 August 2018. <https://www.appliedradiology.com/articles/mr-imaging-of-breast-implants-useful-information-for-the-interpreting-radiologist>.

3. Cho, Michael W. "Imaging of Ruptured Breast Implants: Finding the Leak." Medscape. 19 October 2017. Web. 13 August 2018. <https://reference.medscape.com/slideshow/ruptured-breast-implants-6009136#17>.

4. Knipe, Henry and Wang, Morlie L., et al. "Breast Implant Rupture." Radiopaedia. Web. 13 August 2018. <https://radiopaedia.org/articles/breast-implant-rupture>.

5. "Risks of Breast Implants" U.S Food and Drug Administration. Web. 13 August 2018. <https://www.fda.gov/medicaldevices/productsandmedicalprocedures/implantsandprosthetics/breastimplants/ucm064106.htm>.

6. "MRI is Most Accurate Test for Detecting Ruptured Silicone Breast Implants". American Society of Plastic Surgeons. 30 June 2014. Web. 13 August 2018. <https://www.plasticsurgery.org/news/press-releases/mri-is-most-accurate-test-for-detecting-ruptured-silicone-breast-implants>.

7. "Signs of Silicone and Saline Breast Implant Rupture". Mark Dueber. Web. 27 August 2018. <https://www.drdeuber.com/signs-of-silicone-and-saline-breast-implant-rupture/>.

8. Shikhman, Rachel, Moufarrege, Richard. "Breast, Implants, Rupture."  NCBI. 5 November 2017. Web. 27 August 2018. <https://www.ncbi.nlm.nih.gov/books/NBK459308/>.