Indian Journal of Radiology and Imaging Indian Journal of Radiology and Imaging

BREAST
Year
: 2016  |  Volume : 26  |  Issue : 2  |  Page : 216--225

Imaging of common breast implants and implant-related complications: A pictorial essay


Amisha T Shah, Bijal B Jankharia 
 Department of Breast Imaging, Dr. Jankharia's Imaging Centre, Mumbai, Maharashtra, India

Correspondence Address:
Dr. Amisha T Shah
27060 Cedar Road, Beachwood, Ohio - 44122
India

Abstract

The number of women undergoing breast implant procedures is increasing exponentially. It is, therefore, imperative for a radiologist to be familiar with the normal and abnormal imaging appearances of common breast implants. Diagnostic imaging studies such as mammography, ultrasonography, and magnetic resonance imaging are used to evaluate implant integrity, detect abnormalities of the implant and its surrounding capsule, and detect breast conditions unrelated to implants. Magnetic resonance imaging of silicone breast implants, with its high sensitivity and specificity for detecting implant rupture, is the most reliable modality to asses implant integrity. Whichever imaging modality is used, the overall aim of imaging breast implants is to provide the pertinent information about implant integrity, detect implant failures, and to detect breast conditions unrelated to the implants, such as cancer.



How to cite this article:
Shah AT, Jankharia BB. Imaging of common breast implants and implant-related complications: A pictorial essay.Indian J Radiol Imaging 2016;26:216-225


How to cite this URL:
Shah AT, Jankharia BB. Imaging of common breast implants and implant-related complications: A pictorial essay. Indian J Radiol Imaging [serial online] 2016 [cited 2020 Apr 5 ];26:216-225
Available from: http://www.ijri.org/text.asp?2016/26/2/216/184409


Full Text

 Introduction



There is a very high procedural demand for breast augmentation surgeries, the main indications being reconstruction after mastectomy, correction of congenital malformations, and cosmetic augmentation. With the evolution of implant devices and surgical options, the breast radiologist is faced with specific challenges such as identification of the type of implant, diagnosis of implant-related complications, as well as diagnosis and follow-up of additional breast lesions such as cancer. In this article, we illustrate the imaging appearances of commonly used breast implants and of complications encountered due to the implants. In the end, we describe the prominent role of magnetic resonance imaging (MRI) in both screening and diagnosing implant failures.

 Breast Prosthesis



Breast augmentation was first attempted in 1895, when Vincenz Czerny transplanted a lumbar lipoma to enhance a patient's breast after excision of a large fibroadenoma.[1] Since then, a wide variety of breast augmentation techniques have evolved, with saline and silicone prototypes being the most commonly performed today.

Breast implants may have a single lumen or double lumen. Most commonly encountered are single lumen implants which contain either silicone or saline as the filling [Figure 1] and [Figure 2]. Other variations such as double lumen (silicone on the inside with an outer saline component) [Figure 3], reverse double lumen (saline on the inside with an outer silicone component), and stacked implants (presence of more than one implant per breast) may also be encountered. All implants have an outer silicone membrane or shell. After placement, a thin fibrous capsule normally forms around the prosthesis as a physiological response to foreign body (encapsulation). The main surgical planes for implant placement are subglandular (in front of pectoralis major muscle) or retropectoral (behind the pectoralis major muscle) planes [Figure 4] and [Figure 5].{Figure 1}{Figure 2}{Figure 3}{Figure 4}{Figure 5}

On mammography, saline implants appear as oval masses with a dense outer silicone envelope and a less radio-opaque center. Often a valve is visible, which is used to fill the saline implant [Figure 1]. Normal membrane foldings may be seen, as also partially the glandular tissue may be seen through the implant depending on the penetration used. Silicone implants are seen as dense oval masses, so that a separate envelope or accompanying folds are not visualized on mammography [Figure 2]. The screening mammogram should include implant displaced (Eklund technique), craniocaudal (CC), and mediolateral oblique (MLO) views, in addition to the standard CC and MLO views [2] [Figure 6]. Displacing the implant allows more breast tissue to be visualized than the standard compression views.{Figure 6}

Ultrasound (USG) evaluation of breast implants includes assessing the morphology, contour, content, and peri-implant tissues and axillae. The transverse to longitudinal ratio of the implant is calculated; the smooth undulations of the envelope (radial folds), the homogeneity of the implant lumen, and signs of free silicone or silicone granulomas in the axillae or breast tissue are checked. On USG, saline and silicone implants have a similar appearance. They appear anechoic surrounded by a linear echogenic envelope [Figure 7]. Low-level echoes may be seen within the implant. Reverberation artifacts seen anteriorly and echoes produced behind the implant may be confused with loss of implant integrity by an inexperienced interpreter. The implant shell may be seen as a single echogenic line or parallel echogenic lines. The fibrous capsule is visualized as two parallel echogenic lines superficial to the implant surface [Figure 8]. Normal undulations of the envelope may be seen as wavy echogenic lines with or without minimal intervening fluid [Figure 9].{Figure 7}{Figure 8}{Figure 9}

Apart from its high spatial and soft tissue resolution and lack of ionizing radiation, the ability of MRI to suppress or emphasize the signal from water, fat, or silicone makes it the most ideal modality for evaluating breast implants.[3] A dedicated breast coil should be used to obtain high-resolution images. Saline implants follow fluid signal on all sequences. However, MRI is not used for assessing the integrity of saline implants because a ruptured saline implant is a clinical diagnosis presenting as an acute reduction in breast size.[4] Silicone appears hypointense on T1-weighted image and hyperintense on T2-weighted image. The envelope and capsule have low signal on all sequences. MRI often shows low signal intensity radial folds extending to the periphery of the implant. Radial folds and periprosthetic fluid are considered normal findings and should not be mistaken for rupture [5] [Figure 10].{Figure 10}

[Table 1] summarizes the imaging features of saline and silicone breast implants.{Table 1}

Implants placed for congenital abnormalities such as Poland syndrome may have an asymmetric appearance and should not be confused with malpositioning [Figure 11].{Figure 11}

 Implant Complications



Early post-surgical complications are infection and hematoma. Delayed complications include capsular contracture, implant rupture, and gel bleed. In 2006, the Food and Drug Administration (FDA) recommended that women with silicone gel breast implants receive MRI screening 3 years after they receive a new implant and every 2 years after that.[6] However, the cost of these screening examinations over the lifetime is very high.

Infection

Infection is a significant complication related to breast implants. After breast esthetic surgery, up to 2.9% of patients develop a surgical site infection with an even higher rate of 1–53% noted after breast reconstruction surgery.[7] The majority of the cases occur in the early postoperative period presenting with breast pain, swelling, and erythema. USG may reveal an abscess visualized as irregular hypoechoic fluid collection with internal debris. MRI findings suggestive of implant infection include skin thickening, edema, and capsular enhancement. Peri-implant complex fluid collections may also be seen.

Hematoma

Breast implant surgery can be complicated by hematoma formation with a majority of cases occurring in the early postoperative period or it could be post-traumatic. On mammography, well-defined hyperdense or heterogeneous density masses may be seen. USG, computed tomography (CT), and MRI can be used to demonstrate the hematoma.

Capsular contracture

Capsular contracture is the most common delayed complication noted in patients with smooth-walled silicone prosthesis. It is the abnormal constriction of the fibrous capsule that surrounds the breast implant resulting in hardening and deformity of the implant. Predominantly a clinical diagnosis, it presents with a distorted, tough and sometimes painful breast. On mammography, the implant may appear spherical rather than oval in shape with transverse diameter measuring less than two times the anteroposterior diameter of the implant [8] [Figure 12]. It may develop unusual areas of bulging, irregularity, or tenting. On USG and MRI, loss of the normal triangular configuration of the implants may be seen with an increased anteroposterior diameter of the implant [Figure 13] and [Figure 14]. Thickening of the echogenic fibrous capsule and increase in the number of radial folds [Figure 15] and [Figure 16] may be noted. Peri-implant calcifications may be seen [Figure 17].{Figure 12}{Figure 13}{Figure 14}{Figure 15}{Figure 16}{Figure 17}

Implant rupture

Rupture is one of the main complications of breast implants. The incidence of breast implant rupture increases with implant age with most implant ruptures occurring 10–15 years after placement.[8] Saline implant ruptures are easily diagnosed clinically as the implant significantly decreases in size with extrusion of fluid [Figure 18]. Silicone implant ruptures can be difficult to identify. Breast pain on physical examination of implants is a strong predictor of rupture, but absence of pain does not exclude rupture. The rupture is classified into two categories depending on the location of the silicone with respect to the fibrous capsule [Table 2].{Figure 18}{Table 2}

Intracapsular rupture

This is the most common type (77–89%).[9] The integrity of the implant is breached, but the fibrous capsule is intact; so the leaked silicone is confined within the fibrous capsule. Mammography does not confidently detect intracapsular rupture. A contour bulge may indicate intracapsular rupture; however, the differential diagnosis includes implant herniation. On USG, horizontally stacked echogenic lines traversing through the implant interior at various levels, termed the “stepladder sign” is seen [Figure 19]. Low-level echoes in the central portion of the prosthesis may be observed, but they can also be seen in intact silicone breast implants; therefore, they should be interpreted with caution. Isoechoic silicone may be found between the fibrous capsule and the implant surface, indicative of minimal prosthetic collapse; however, these findings should be confirmed with MRI [Figure 20]. The most reliable sign on MRI for intracapsular rupture is the presence of multiple curvilinear low signal intensity lines within the T2 bright silicone, called the “linguine sign” [Figure 21]. The curvilinear lines represent collapsed implant membrane floating within the silicone gel.[10] Signs of minimally collapsed intracapsular rupture include the “tear drop sign,” the “key hole or noose sign,” and the “subcapsular line sign.” The tear drop sign represents focal silicone invagination between the inner shell and the fibrous capsule, with the margins of the collapsing shell in contact with one another. The key hole or noose sign represents focal invagination of silicone, with the margins of the collapsing shell not in contact with one another [Figure 22]. Subcapsular line sign represents a thin layer of silicone between the shell and the fibrous capsule [Figure 23].{Figure 19}{Figure 20}{Figure 21}{Figure 22}{Figure 23}

Extracapsular rupture

Extracapsular rupture is defined as rupture of both the implant shell and the fibrous capsule with macroscopic silicone leakage that extends beyond the fibrous capsule into the surrounding tissues. On mammography, extracapsular rupture is seen as radiodense silicone extending away from the implant shell into the breast parenchyma along the pectoralis muscle or within the axillary lymph nodes [Figure 24]. On USG, large conglomerates of extracapsular silicone are seen as hyperechoic or anechoic masses, almost indistinguishable from cysts. More frequently, free silicone appears as an echogenic nodule with well-defined anterior margin and posterior dirty acoustic shadowing, termed as “snowstorm sign” [Figure 25]. On MRI, extracapsular free silicone is visualized as discrete foci of isointense to low signal intensity on T1 fat-suppressed images and of high signal intensity on water-suppressed T2-weighted images [Figure 26]. Silicone granulomas may have similar enhancement to breast carcinoma and sometimes require biopsy.{Figure 24}{Figure 25}{Figure 26}

Mammography has limited value for assessing intracapsular rupture, but it is useful for detecting extracapsular rupture especially when the silicone has migrated away from the implant shell. The sensitivity of mammography in detecting implant ruptures varies between 25–30% and 68%.[11] USG has a better sensitivity than mammography in detecting implant ruptures. One limitation is the evaluation of posterior wall of breast implants and the tissue posterior to the implant. USG has a sensitivity of 50–77% and a specificity of 55–84% in detecting implant rupture.[11] Also, the silicone granulomas following an extracapsular rupture may hinder the evaluation of a new implant. MRI is the imaging test with the highest sensitivity and specificity to review the integrity of breast implants. It has a reported sensitivity of 72–94% and specificity of 85–100% in detecting implant rupture.[11] MRI has evolved to be most accurate tool in detecting free silicone, its relationship to surrounding structures, and in evaluating implant ruptures.[12]

Gel bleed

Gel bleed is the normal transudation of microscopic amounts of silicone through an intact breast prosthesis membrane into the surrounding tissues and lymphatics.[12] Gel bleed is difficult to identify on USG and MRI unless it is extensive.

[Table 3] provides a checklist of MRI findings in implant complications.{Table 3}

 Concurrent Breast Conditions



The remaining breast is a potential site for disease, benign or malignant. Cysts, fibroadenomas, cancer, all can occur. Cysts are a very common finding in the breast parenchyma with or without implants. Fibroadenomas have the same imaging appearance as in women without implants. Breast implants are not associated with an increased risk of breast carcinoma [13] [Figure 27]. There is no difference in survival rates in women with breast cancer and implants compared to those without implants. A few published cases have been reported about the associations between anaplastic large cell lymphoma (ALCL) and breast implants (both silicone and saline); however, more data is required to confirm its linkage with breast implants.[14] The presence of the implant may impair the ability of mammography or USG for cancer detection. A correlation between physical examination and mammography findings should be first done. Any palpable abnormality can then be subjected to a USG or contrast-enhanced MRI. Suspicious findings should be further evaluated with biopsy.{Figure 27}

 Role of Preoperative Mri-Based Breast Volumetry for Immediate Breast Reconstruction



Restoring volumetric symmetry is one of the main objectives of breast esthetic and reconstructive surgery. Various methods for preoperative breast volume estimation have been described previously in the literature, including anthropometry, USG, mammography, CT, liquid volume displacement technique, thermoplastic methods, MRI, and three-dimensional breast surface imaging.[15] MRI-based breast volumetry is a simple and convenient solution to assessing breast volume and composition of breast tissue for initial operative planning and post-surgical follow-up and calculating the implant size in patients with missing documentation of a previously implanted device. Breast MRI has been shown to have the highest correlation with the actual breast volume.[16] The entire augmented breast with the elliptical implant in situ is traced onto axial slices. The breasts with the implant inside are traced on a bilateral axial slice and the borders of the implant are outlined. After marking all slices, a software program is used to determine the implant volume as well as the volume of the entire breast.

 Conclusion



Since the number of breast implant procedures is increasing and an increasing number of patients present for assessing implant integrity, a radiologist should be familiar with the spectrum of appearances of the complications. The imaging appearances of the common breast implants and their complications are varied. MRI is the modality of choice for evaluation of silicone breast implant integrity. In symptomatic patients, after an initial evaluation with mammography and USG, non-contrast MRI is recommended to rule out the diagnosis of rupture. Dynamic contrast-enhanced MRI is indicated in patients with breast reconstruction surgeries after mastectomy for breast cancer or in breast implant patients with suspicious masses. MRI is not recommended as a screening modality for implant rupture in asymptomatic women with breast implants.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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