More than 250,000 women in the United States undergo an augmentation mammoplasty annually. Two studies (1,2) have reported the incidence of implants in American women to range from 3.3 to 8.1 per 1,000. The augmented breast presents a challenge to the radiologist to image the residual parenchyma adequately and to detect any abnormalities. The presence of implants may interfere with routine mammography and therefore has the potential to delay the diagnosis of breast cancer (3,4).
Fortunately, most women in the United States who have had augmentation mammoplasty have undergone placement of implants rather than direct silicone or paraffin injection. Augmentation may be performed for cosmetic reasons: to increase the size of both breasts unilaterally for an asymmetric hypoplastic breast, or after mastectomy for reconstruction. Augmentation procedures have included direct injection of silicone or paraffin into the breast, placement of a variety of types of implants in either a subpectoral or retroglandular location, and the use of several types of autologous myocutaneous flaps for reconstruction. In this chapter, the mammographic findings associated with the augmented breast will be discussed.
Direct Injection for Augmentation
Silicone injection for breast augmentation was never approved in the United Stated by the Food and Drug Administration (FDA) (5). Many patients seen in the United States with augmentation by direct injection have had the procedure performed in Asia or Mexico (6). Because of the intense response to the foreign material, management of the patient is quite difficult. Clinically, the breasts are quite hard or lumpy, and the exclusion of a tumor by palpation is impossible (6). Parsons and Thering (6) found that mastodynia was the most common presenting symptom in 28 patients with silicone-injected breasts. Another problem that these patients face is the tendency for the silicone to migrate far outside the breasts (7). Histologically, the silicone incites areas of fat necrosis, infiltration with fibrocytes, and cystlike spaces lined by fibrous tissues (7). There may be hyaline degeneration with calcifications of the inner surface of the fibrous capsule of the siliconoma (8). The calcification may represent deposition of calcium and phosphates near necrotic tissue (8).
Mammography is markedly limited in patients who have undergone augmentation by injection, because the breasts are thick and hard and therefore difficult to compress well (Figs. 13.1 and 13.2). The injected substances and the fibrous response create a very dense appearance requiring a long exposure. Technically, by increasing the kVp to 30 or 32 or by using a tungsten target, one is sometimes able to penetrate the breasts adequately. Ultrasound shows numerous areas of dense shadowing related to the reaction to the injected substances. Because of this, sonography is usually not helpful to evaluate for malignancy.
Magnetic resonance imaging (MRI) can be very helpful to assess for tumors in a patient who has a compromised mammogram because of the density related to augmentation by injection. In a study of 16 patients who had undergone silicone injection breast augmentation and who underwent breast MRI, Cheung et al. (9) found that four of four cancers were accurately identified by using contrast enhancement techniques. In this series, the silicone granulomas were nonenhancing on MRI or were associated with a benign rimlike enhancement.
Koide and Katayama (8) found differences in the mammographic findings in breasts augmented by injection, depending on the substances used for injection. In patients who had paraffin injections, radiolucent masses were seen; 75% of these patients developed extensive small annular calcifications, and lymphadenopathy was common. In patients who received silicone injections, the mammographic nodules were of high density, and 29% of these women were found to have large, localized, eggshell calcifications in the breasts. Others (10,11) have found calcifications in patterns varying from irregular to small ringlike to eggshell shaped in patients with silicone injections.
Figure 13.1 HISTORY: A 41-year-old woman after augmentation mammoplasty with silicone injections, presenting with numerous hard masses and distortion of the contour of the breasts bilaterally.
MAMMOGRAPHY: Left MLO (A) and right MLO (B) views. Technically, the examination is limited by the extreme density of the breasts and the inability to compress them adequately. The study was performed at 32 kVp with a tungsten target and rhodium filtration to attempt to penetrate the tissue. The breasts are extremely dense, with multiple soft tissue masses bilaterally. There are also innumerable circular calcifications bilaterally that represent dystrophic and granulomatous reaction to the silicone injections. Ultrasound was not of help because of diffuse shadowing from this process.
IMPRESSION: Extensive reactive changes secondary to silicone injection for augmentation mammoplasty.
Figure 13.2 HISTORY: A 40-year-old woman after augmentation mammoplasty with silicone injections and saline implants. On clinical examination the breasts were filled with hard nodules, particularly in the upper outer quadrants.
MAMMOGRAPHY: Bilateral MLO (A) and right enlarged (2X) MLO (B) views. The breasts are very difficult to image because of the postsurgical changes. Saline implants are present bilaterally, and the valves of these prosthesis are seen (A, small arrows). There are also extremely dense nodules bilaterally (A, large arrows) that are related to the silicone injections. On the enlarged view (B), these very dense masses are seen, and some areas of fat necrosis (rimlike calcifications, secondary to the injections) are also identified (B, curved arrow).
IMPRESSION: Postoperative changes of augmentation mammoplasty with both implants and direct silicone injections. (Case courtesy of
Dr. Cherie Scheer, Richmond, VA.
Augmentation with Implants
Implants are most often placed for augmentation for cosmetic reasons, but also are frequently used for breast reconstruction after mastectomy. In patients with asymmetric breast size, a hypoplastic breast, or a chest wall deformity, an implant may be placed to achieve symmetry. Some of the types of implants used for augmentation have included saline filled, silicone gel, inflatable double lumen, and polyurethane coated (12,13). Commonly encountered silicone implants are those composed of a silicone gel contained within a silicone elastomer shell. The single lumen gel-filled implant can have a smooth or a textured shell; the textured shell was designed to reduce the incidence of capsular contraction (14). Another type of single-lumen implant that was designed to reduce capsular contraction is polyurethane covered. In this type of prosthesis, a thin layer of polyurethane foam is adherent to the gel-filled implant.
Saline implants are composed of a silicone elastomer shell that is filled with saline. These implants usually have a fill valve that is used for inflation of the implant. Double-lumen implants typically are composed of an inner lumen of silicone gel that is encased within an outer lumen of saline. Other double-lumen implants are reversed, with saline internally and silicone in the outer lumen.
When an implant is placed into the breast, the body reacts to the prosthesis by forming a fibrous capsule around it. This fibrous capsule surrounds the implant and can thicken and contract. The capsule can also calcify, which is visible on mammography and is often associated with capsular contraction (15). The use of implants with a textured surface or polyurethane coating has been found to decrease the severity of encapsulation (14).
Goodman et al. (16) in a meta-analysis of literature evaluating implant rupture found that the estimated median life span of a silicone gel implant was 16.4 years. In the event of a rupture of a silicone implant, the intact fibrous capsule may contain the extruded silicone, so the contour of the implant both clinically and on mammography is unchanged. If the fibrous capsule also tears, the silicone can extend outside the capsule and into the surrounding breast tissue. This finding is termed an extracapsular rupture. The relationship of the implant wall to the capsule in the normal implant, in intracapsular rupture and extracapsular rupture is shown in Figure 13.3.
In the patient with a saline prosthesis, the implant is identified as saline filled because it is not of homogeneous density. The wall of the implant is more dense than the contents because the shell is a silicone elastomer that is more dense than the contained saline. Often folds and a fill valve are visible, and these are normal findings (Fig. 13.4). The density of a silicone implant is homogeneous because the wall and the contents are both silicone, and overall, the silicone implant is more dense than a saline implant (Figs. 13.5 and 13.6).
Positioning the Augmented Breast
Implants may be placed beneath the pectoralis major muscle or may be located anteriorly, in the retroglandular or prepectoral area. The imaging of a patient with implants is limited in that on routine mammography the prosthesis may obscure large areas of glandular tissue. The use of manual techniques (17) rather than phototiming is usually of help in imaging these patients.
Eklund et al. (18) have described a modified positioning technique in which the implant is displaced posteriorly and the breast tissue is pulled anteriorly as compression is applied. This technique allows for improved compression and visualization of the parenchyma (Fig. 13.7). The implant-displacement views have become a standard part of the mammographic examination for patients with implants. This technique is more easily performed on patients with a moderate amount of native tissue over the implant or in patients with subpectoral implants. The description of Eklund et al. (18) for imaging the augmented breast includes (a) standard mediolateral oblique (MLO) and craniocaudal (CC) views using normal positioning techniques and (b) modified MLO and CC views with phototiming and implant displacement. In those patients who have encapsulated implants or in whom implant displacement is not successful, a third view, the lateromedial oblique (LMO), can prove useful in imaging the upper inner and the inner lower quadrants that are obscured on the routine views. Some authors also routinely perform a 90-degree lateral (mediolateral [ML]) view with the implant displaced (19). This may include tissue that may not be visualized otherwise on the MLO or CC implant-displaced view.
Complications associated with implants include infection, hematoma formation, encapsulation, leakage or rupture, and collapse. In the immediate postoperative period following augmentation mammoplasty, infections or hematomas may occur. These are usually clinically evident, and ultrasound may be used for confirmation of a fluid collection. Treatment includes drainage and antibiotics if needed.
In the 2 to 3 weeks after an implant has been inserted, a fibrous capsule is deposited around it (12). This capsule may become fibrotic and contract, which is the most commonly associated complication with
implants (20); encapsulation may occur in as many as 10% to 40% of patients (20,21). Retromuscular implants are much less likely to develop contractures (12). On mammography, the findings of a crenulated or irregular contour of the implant may suggest capsular contraction (13) (Fig. 13.8). A very rounded contour of the implant is also seen in patients with encapsulation. Irregularity of the implant contour may be palpated as a mass (11,13,22), but the irregular contour, as opposed to a parenchymal mass, can be differentiated with mammography and ultrasound if needed.
Figure 13.3 A: Schematic of the normal anatomy related to a single-lumen silicone implant. The implant is contained by a fibrous capsule. B: Intracapsular implant rupture shows the broken wall of the implant floating in the silicone and contained by the intact fibrous capsule. C: Extracapsular rupture showing the disruption of the fibrous capsule and the extrusion of the silicone into the breast.
The capsule around the implant may become calcified. This is thought to be related to inflammation of the capsule and encapsulation. This is evident on mammography as curvilinear plaquelike calcifications (Figs. 13.9,13.10,13.11). Calcifications that are coarse and ringlike may also develop in the capsule of the implant and are indicative of an inflammatory reaction to the prosthesis (13) but not leakage of silicone. Irregularity of the contour of the implant may be caused by distortion or herniation of the prosthesis without a rupture (Figs. 13.12 and13.13). Herniation has the appearance of a smooth bulge in the implant contour.
Rupture of an implant may be manifested clinically in a variety of ways. A saline implant that ruptures typically suddenly collapses, and there is an obvious decrease in the size of the breast. On mammography, the collapsed saline implant infolds on itself like a crumpled bag and the saline is absorbed (Figs. 13.14 and 13.15). The presentation is dramatic both clinically and on mammography. The rupture of a silicone implant may be associated clinically with pain, a change in contour of the implant, or a palpable mass.
The rupture of a silicone implant in the intracapsular space may cause a subtle change in contour of the implant but no obvious change in size or shape of the breast.
Mammography is typically normal, and the rupture is identified only on three-dimensional imaging, such as ultrasound or MRI. With an extracapsular rupture, the silicone extends beyond the edge of the capsule into the surrounding parenchyma, and this complication may be diagnosed on mammography as well as on ultrasound or MRI.
Figure 13.4 HISTORY: A 49-year-old woman who is status post–right mastectomy and reconstruction with augmentation on the left.
MAMMOGRAPHY: Left MLO (A) and CC (B) views show a subpectoral saline implant. This can be identified as saline filled, because the valve is evident and the inner aspect of the wall is seen. Implant-displaced MLO (C) and CC (D) views show normal parenchyma.
IMPRESSION: Normal saline subpectoral implant.
Figure 13.5 HISTORY: Routine mammogram on a patient with a history of breast augmentation.
MAMMOGRAPHY: Bilateral MLO (A) and CC (B) views show normal-appearing subpectoral silicone implants. On the implant-displaced MLO (C) and CC (D) views, the implants have been moved posteriorly out of the field of view, and the anterior breast tissue and anterior edge of the pectoralis major muscle are well compressed and in the field of view.
IMPRESSION: Images demonstrating proper positioning of normal subpectoral silicone implants.
Figure 13.6 HISTORY: A 45-year-old patient with a history of implants, for routine mammography.
MAMMOGRAPHY: Right MLO (A) and CC (B) views show a normal double-lumen implant. In this case, the inner lumen is silicone and is very dense, and the outer lumen is saline and is less dense.
IMPRESSION: Normal double-lumen implant.
Palpable irregularity may also be associated with rupture of the implant with silicone extravasation. Mammography can identify the dense globules of silicone that may be calcified outside the contour of the implant, indicating rupture (12) (Figs. 13.16,13.17,13.18,13.19,13.20). The leaking silicone not only can form calcified nodules but also can present as intraductal casts of silicone (23) (Fig. 13.21). Silicone that is free in the breast is sometimes cleared by lymphatics and drains into the intramammary or axillary nodal chain. Nodes containing dense silicone may be seen on mammography and sometimes on ultrasound (Fig. 13.22). In patients with saline implants that were placed after a prior rupture of a silicone implant, residual free silicone that was not removed at surgery may be manifested clinically, mammographically, and on ultrasound (Figs. 13.23,13.24,13.25,13.26).
Role of Ultrasound
Sonography is most helpful for the evaluation of possible implant rupture, and ultrasound is best performed by using a linear array transducer. Scanning both superficially and deep is necessary to evaluate the entire implant and the
peri-implant space; this may require a lower power for the deeper area of the implant and a 5- to 7-MHz transducer (24). Scanning of the soft tissues and the axilla is also important to assess for signs of extracapsular rupture and free silicone.
Figure 13.7 HISTORY: Routine mammogram on a woman with a history of breast implants.
MAMMOGRAPHY: Bilateral MLO (A) and CC (B) views show normal prepectoral saline implants. The valves and some folds are evident bilaterally. On the implant-displaced MLO (C) and CC (D) views, only a sliver of the anterior edge of the implants is seen, and the anterior breast tissue is well compressed and well visualized.
IMPRESSION: Normal prepectoral saline implants; normal mammogram demonstrated on routine and implant-displaced views.
Figure 13.8 HISTORY: A 45-year-old gravida 2, para 2, abortus 1 woman after bilateral augmentation mammoplasty, with a smooth nodule in the left breast.
MAMMOGRAPHY: Left MLO (A), exaggerated CC medial (B), and CC (C) views. There is a prepectoral silicone implant in a breast that is heterogeneously dense. There is irregularity of the contour of the implant, particularly medially (C, arrow), and this irregularity corresponds to the palpable finding for which the patient was referred. Such irregularity may indicate encapsulation of the implant.
IMPRESSION: Irregularity of the left implant; possible encapsulation.
Figure 13.9 HISTORY: Patient with a history of augmentation, for routine mammography.
MAMMOGRAPHY: Left (A) and right (B) MLO views show that the patient has prepectoral saline implants. The capsule surrounding the implant in each breast is heavily calcified.
IMPRESSION: Calcified implants.
The normal appearance of implants depends on the type of prosthesis. Saline and silicone single-lumen implants have a similar appearance: an anechoic oval structure that has a prominent anterior reverberation artifact. Anterior to this component is an echogenic line that represents the wall of the implant and the fibrous capsule. The port of the saline implant is often visible on ultrasound as an echogenic focus. Double-lumen implants and particularly expander implants are more complicated on ultrasound. In particular, the inner lumen may appear as echogenic line within the lumen and may simulate an intracapsular rupture.
With an intracapsular rupture, the wall of the implant is broken and is floating in the lake of silicone contained by the fibrous capsule that formed around the prosthesis. Because of this, the mammogram is normal. On ultrasound, the broken segments of implant wall are identified as a stairstep pattern within the silicone. Diffuse internal factors are also sometimes identified on sonography (Figs. 13.27 and13.28). Mammography is limited in its ability to detect intracapsular ruptures (25,26). Ultrasound has a
reported sensitivity for implant rupture of 70% and a specificity of 92% (27).
Figure 13.10 HISTORY: A 67-year-old woman with a history of breast implants.
MAMMOGRAPHY: Left MLO (A) and right MLO (B) views show rounded, calcified saline implants bilaterally. On the enlarged left MLO view (C), the dense calcification in the fibrous capsule around the implant is noted.
IMPRESSION: Calcified implant capsules.
Figure 13.11 HISTORY: A 56-year-old woman with a history of implants, for screening mammography.
MAMMOGRAPHY: Left MLO (A) and CC (B) views show a silicone prepectoral implant. Slight irregularity of the contour is noted. The periphery of the implant is calcified, consistent with capsular calcification.
IMPRESSION: Capsular calcification of a silicone implant.
Figure 13.12 HISTORY: A 58-year-old woman with a history of implants with a palpable mass in the left breast at 4 o'clock.
MAMMOGRAPHY: Bilateral MLO views (A) show distorted calcified silicone prostheses in both breasts. On the implant displaced MLO views (B), the capsular calcification is evident, and the herniation and distortion of the right implant is present superiorly. The palpable mass is not seen on mammography. Ultrasound of the palpable region (C) shows a small simple cyst. Ultrasound of the implants shows dense shadowing related to extracapsular leakage of silicone in both axillary tail regions.
IMPRESSION: Simple cyst left breast, bilateral herniated, calcified implants with extracapsular free silicone.
Figure 13.13 HISTORY: Patient who presents with a change in the shape of the left implant and a palpable mass.
MAMMOGRAPHY: Left CC views (A) show a distorted double-lumen implant. The palpable mass corresponded to the focal bulging in the subareolar region of the implant. On ultrasound (B), irregularity of the contour of the implant is noted that suggests rupture. The implants were removed and replaced with saline prostheses.
IMPRESSION: Possible rupture of the double-lumen implant.
SURGICAL FINDINGS: Volvulus of the implant with the posterior margin and fill valve rotated anteriorly. No rupture was found.
NOTE: Ultrasound of a double-lumen implant is difficult to interpret because of the presence of the bands within the outer lumen that are caused by the inner lumen.
Figure 13.14 HISTORY: A 60-year-old woman who reports pain in the left axilla and who has a history of breast implants.
MAMMOGRAPHY: Bilateral MLO (A) and CC (B) views with the implants in place show a normal right saline implant with several folds. On the left, the implant has collapsed, with a typical appearance of a saline implant rupture.
IMPRESSION: Ruptured left saline implant.
Figure 13.15 HISTORY: Patient with implants who reports decrease in size of the left breast.
MAMMOGRAPHY: Bilateral MLO (A) and CC (B) views show a normal prepectoral saline implant in the right breast. The left saline implant has collapsed in a typical form.
IMPRESSION: Collapsed left prepectoral saline implant.
Figure 13.16 HISTORY: A 43-year-old woman who reports firmness in the right breast.
MAMMOGRAPHY: Right MLO (A) and CC (B) views show a subpectoral silicone implant. On the MLO view (A), there is deformity of the shape of the implant, with apparent extension of silicone into the axillary region (arrow). This finding is very suspicious for rupture of the implant. Extracapsular rupture was confirmed on ultrasound.
IMPRESSION: Extracapsular leak of silicone implant.
Figure 13.17 HISTORY: A 58-year-old woman with a history of congenital deformity of the sternum and right anterior chest wall who had implant placement.
MAMMOGRAPHY: Left MLO (A) and CC (B) views show the prepectoral silicone implant to be calcified and slightly distorted. There is a small focus of silicone beyond the lumen of the implant laterally on the left CC view (B, arrow) consistent with extracapsular rupture. On the right MLO (C) and CC (D) views, the deformity of the chest wall is seen. The anterior ribs are visible, yet no pectoralis major muscle is seen.
IMPRESSION: Implant placement for congenital deformity of the chest wall with an extracapsular rupture on the left.
Figure 13.18 HISTORY: A 48-year-old woman with history of breast implants.
MAMMOGRAPHY: Bilateral MLO (A) and CC (B) views show prepectoral silicone implants. Calcification of the capsules is seen best on implant displaced MLO views (C). A coned image (D) of the superior margin of the right implant shows a contour irregularity with high-density streaks (arrows) outside the implant, consistent with rupture.
IMPRESSION: Right extracapsular implant rupture.
Figure 13.19 HISTORY: A 63-year-old patient with a history of implants.
MAMMOGRAPHY: Right CC view (A) shows that the patient has a prepectoral silicone implant. Capsular calcification (arrow) is present around the implant. There is a very-high-density irregular band surrounding the anterior margin of the implant, suggestive of extracapsular rupture. On ultrasound (B), a snowstorm appearance of dense shadowing related to this free silicone is seen, consistent with extracapsular rupture.
IMPRESSION: Left capsular calcifications surrounding implant with extracapsular rupture.
Figure 13.20 HISTORY: A 49-year-old woman with a history of ruptured implants that were replaced, now presenting with a palpable right breast mass.
MAMMOGRAPHY: Right MLO (A) and CC (B) views show the saline implant to be intact. There is hyperdense nodularity (arrows)surrounding the implant, including in the region of palpable concern. On the spot implant-displaced magnification CC view (C), the palpable mass is noted to correspond to the droplets of residual silicone from the prior rupture.
IMPRESSION: Free silicone from prior rupture corresponding to palpable mass.
Figure 13.21 HISTORY: A 44-year-old woman after bilateral augmentation mammoplasties who presents with a firm nodule in the inferior aspect of the right breast.
MAMMOGRAPHY: Right MLO view (A) and right MLO (B) and implant-displaced MLO (C) views 1 year later. On the initial study, a prepectoral silicone implant is present. There are globules of free silicone beneath and above the implant in the surrounding parenchyma (A, arrows). This silicone was leaking from a rupture in the implant and was removed at the same time as a replacement of the implant. On the subsequent mammogram (B and C), the silicone globules have been removed. There is, however, a dense cast of the ductal system (C, arrows) consistent with silicone in the lactiferous ducts.
IMPRESSION: Rupture of implant treated surgically, with the development of silicone casts of lactiferous ducts. (Case courtesy of
Dr. Cherie Scheer, Richmond, VA.
Figure 13.22 HISTORY: A 79-year-old woman with saline implants and a history of prior silicone implants that were removed.
MAMMOGRAPHY: Bilateral MLO implant-displaced views (A) show a small high-density mass (arrow) in the axillary tail of the left breast. On spot magnification (B), the mass is very high density and is consistent with a focus of free silicone from prior rupture. A spot-magnification view of the right axilla (C) at a palpable lump shows a silicone-laden lymph node as well.
IMPRESSION: Bilateral free silicone from prior implant rupture.
Sonographic features of extracapsular rupture include disruption of the echogenic line surrounding the implant, “silicone cysts,” echogenic foci around the implant, and the snowstorm appearance of shadowing (Figs. 13.29 and 13.30). This noisy shadow is created by the tissue reaction to the free silicone. Ultrasound misdiagnoses of rupture have been caused by intrinsic changes in polyurethane implants, the structure of double-lumen implants, and extracapsular silicone from a prior rupture (28).
Role of Magnetic Resonance Imaging
MRI is an excellent method to evaluate silicone implants for rupture, particularly if mammography and ultrasound
are negative or equivocal, and there is concern about leakage. Typical sequences are fast-spin echo (FSE) with T2 weighting in axial and sagittal planes, T1-weighted images with silicone suppression, and FSE T2-weighted images with water suppression (24). Radial folds are a common finding and represent infolding of the elastomer shell; radial folds connect to at least one surface of the implant.
Figure 13.23 HISTORY: A 52-year-old woman with a history of prior silicone implants, replaced with saline implants.
MAMMOGRAPHY: Left (A) and right (B) MLO views show normal-appearing prepectoral saline implants. Benign eggshell calcifications are present in the right breast. On the left, multiple droplets of free silicone are seen (arrows) in the axillary tail. On the enlarged MLO image (C), the free silicone in the tissue is seen, as well as some silicone-laden lymph nodes in the axilla.
IMPRESSION: Normal saline implants, free silicone in the left breast and axillary nodes from prior rupture.
Figure 13.24 HISTORY: A 58-year-old woman for routine mammography. She has a history of silicone implant removal and replacement with saline implants.
MAMMOGRAPHY: Left MLO (A) and CC (B) views show a normal-appearing saline implant. A valve is present, as well as some normal folds. In the medial aspect of the breast, overlapping the implant in part, are two lobular high-density masses (arrows). These extend beyond the implant on the CC view (B) and are typical of residual silicone from the prior rupture.
IMPRESSION: Normal saline implant, residual silicone from prior rupture.
Figure 13.25 HISTORY: A 45-year-old woman with implants who reports a new palpable mass in the left breast medially. She had prior silicone implants that were replaced.
MAMMOGRAPHY: Left CC view (A) and left ML spot view (B) over the palpable mass show a very-high-density region around the edge of the implant. This finding is typical of free silicone from the prior implant rupture that was not removed completely. Often, there is a foreign body reaction and granuloma formation around the silicone that may be clinically evident as a palpable mass.
IMPRESSION: Free silicone from prior rupture creating a palpable mass.
Figure 13.26 HISTORY: A 62-year-old woman with a history of silicone implant rupture and replacement with saline implants.
MAMMOGRAPHY: Left (A) and right (B) MLO views show bilateral, normal-appearing, prepectoral saline implants. There is residual free silicone present in the left axillary tail (arrow), as evidenced by a very-high-density region adjacent to the implant capsule. Normal folds are noted in the implants. Ultrasound (C, D) of the left implant shows echogenic shadowing diffusely consistent with free silicone. There is also a small hypoechoic mass that represents a “silicone cyst.”
IMPRESSION: Normal saline implants, residual free silicone from extracapsular rupture of prior left implant.
Figure 13.27 HISTORY: A 48-year-old woman who reported some change in contour of her right breast implant.
MAMMOGRAPHY: Bilateral MLO views (A) show subpectoral silicone implants. The right implant is situated slightly higher than the left, and it has some bulging of its superior border. Ultrasound of the right (B) and left (C) implants showed similar findings. The normal anechoic implant is not present. Instead, multiple bands traverse the implant lumen in a stairstep pattern. These findings are consistent with intracapsular rupture of the implant, and the bands represent the broken segments of the implant wall contained within the collection of silicone. The fibrous capsule contains the silicone, so it maintains a relatively normal shape.
IMPRESSION: Intracapsular silicone implant ruptures bilaterally.
NOTE: The implants were removed, and bilateral intracapsular rupture was confirmed at surgery.
Figure 13.28 HISTORY: A 43-year-old patient with a history of silicone implants.
MAMMOGRAPHY: Bilateral MLO views (A) show prepectoral silicone implants to be present. There is distortion in the shape of the left implant. Ultrasound of the right (B) and left (C) implants shows internal echoes within the silicone with a stairstep pattern, consistent with intracapsular rupture.
IMPRESSION: Bilateral intracapsular rupture.
NOTE: The stairstep structures represent broken implant wall, floating in the silicone, which is contained within the fibrous capsule that formed around the implant.
Figure 13.29 HISTORY: A 42-year-old woman after bilateral augmentation mammoplasty, presenting with bilateral palpable nodularity at the inferior aspects of the implants.
MAMMOGRAPHY: Bilateral MLO views (A), CC views (B), coned-down MLO view (C), and ultrasound (D and E). Bilateral, retroglandular silicone-filled implants are present. There is some deformity of the contour of both implants, which may be associated with encapsulation. There are multiple areas (arrows) of high-density nodularity near the border of the implants, both inferiorly and superiorly. On the enlargement (C), these nodules contain densities that appear to be calcific. Ultrasound (D) in the region of the palpable nodularity showed disruption of the border of the implant and a hyperechoic region (arrow) with vague irregularity in the capsule at the point of disruption. This contrasts with other areas (E) where the capsule is intact and the overlying parenchyma is normal.
IMPRESSION: Bilateral leakage of silicone implants.
Figure 13.30 HISTORY: A 61-year-old woman with a history of implants, who presents for routine follow-up.
MAMMOGRAPHY: Left MLO view (A) shows a prepectoral silicone implant with a deformity along the superior aspect. Extending into the axilla are multiple high-density nodules and strands consistent with free silicone (arrows). On ultrasound (B) of the axillary region, the typical features of free silicone are seen: disruption of the wall of the implant, hyperechogenicity superficial to the implant with very prominent shadowing, and the snowstorm appearance related to the free silicone.
IMPRESSION: Ruptured silicone implant with extracapsular free silicone.
A rupture of the silicone implant into the intracapsular space is identified on MRI as the so-called linguine sign (29,30). This is the fragmented elastomer shell that is floating in the silicone and contained within the fibrous capsule (Figs. 13.31 and 13.32). Extrusion of the silicone beyond the capsule is depicted on MRI in the case of extracapsular rupture. In patients with a double-lumen implant that has failed internally, there may be admixing of the saline and silicone components without rupture of the outer lumen.
In a meta-analysis of articles that examined the diagnostic accuracy of various imaging techniques for implant rupture, Goodman et al. (16) found that the sensitivities and specificities for rupture were as follows: mammography, 28.4% and 92.9%; ultrasound, 59.0% and 76.8%; MRI,
78.1% and 80.0%. In a study of 81 patients with 160 implants that were removed and who had preoperative MRI and ultrasound, Weizer et al. (28) found an additive benefit by using the two modalities. Twenty percent of the implants were ruptured. The sensitivity and specificity of ultrasound were found to be 47% and 83%, respectively. For MRI, the sensitivity and specificity were 46% and 88%, respectively. Other authors have found that the sensitivity of MRI for implant rupture was 76% and the specificity was 97% (29).
Figure 13.31 Sagittal T2 weighted MRI image of a patient with silicone implants. Within the fibrous capsule that surrounds the implant and within the pool of silicone is a circumlinear structure (arrow) that is the broken implant wall. There is no evidence for extracapsular extension of silicone.
IMPRESSION: Intracapsular rupture (the “linguine sign”) (Case courtesy of
Dr. Patricia Abbitt, Gainesville, Fl
Figure 13.32 Axial T2 weighted image (TR 5500, TE 81.7) in a patient with silicone implants shows signs of intracapsular rupture and focal extracapsular rupture.
Within the silicone is a linear structure that is coiled in the anterior aspect, consistent with the broken implant wall (the “linguine sign”)(black arrow). Posteriorly, is a small focus of silicone (white arrow) behind the fibrous capsule. This represents an extracapsular rupture as well.
IMPRESSION: Ruptured silicone implant (Case courtesy of
Dr. Neeti Goel, Harrisburg, Pa
Other Implant Complications
Gel bleed is a term that is used to describe the microscopic diffusion of silicone gel through the elastomer shell that is an intact semipermeable structure. This may be evident on ultrasound as echogenic lines separate from the fibrous capsule. On MRI, the elastomer shell appears folded with silicone gel on both sides of the fold (24) when gel bleed has occurred.
Peri-implant fluid collections may occur as a result of several causes, including infections, ruptured saline components, malignancy, and inflammation. In patients with polyurethane-covered silicone gel implants, peri-implant fluid collections are very common and have been described in 48% of patients (31). The fragmentation of the polyurethane in vivo creates a foreign-body reaction with chronic inflammation (24). Very large fluid collections surrounding an intact implant that has been in place for years should raise the concern for malignancy. Lymphoma may present in this manner and is diagnosed on cytologic examination of the aspirate of the effusion.
Various authors have described a group of symptoms and disorders that are known as silicone-related disease. These include various connective tissue disorders, such as rheumatoid arthritis, Sjögren syndrome, scleroderma, systemic lupus erythematosus, and fibromyalgia (32,33,34,35). Others have not proven any significant relationship of implants with these disorders (29,36,37,38,39). As a result of these concerns, in 1992 the FDA decided to limit the use of breast implants to clinical trials only (40). Subsequently, the use of silicone implants for breast reconstruction was once again approved.
Parenchymal abnormalities can be demonstrated with imaging, but it is important to maximize information obtained by tailoring the examination to the patient. Both benign and malignant lesions may be demonstrated in the augmented breast (Figs. 13.33,13.34,13.35,13.36,13.37,13.38). Masses may be less readily detected than microcalcifications (13) on mammography, but ultrasound may be of help in the evaluation of dense parenchyma over the prostheses and of palpable masses (41).
The diagnosis of breast cancer may be delayed in women who have undergone breast augmentation (3,4,42,43). The use of implant-displacement views is important to optimize visualization of the parenchyma, yet in most patients, areas of breast parenchyma may still be obscured by the implants. Brinton et al. (44) found that women with breast augmentation and breast cancer had later stage disease than women without augmentation. Skinner et al. (3) found that mammography was less sensitive in women with augmentation than in women without implants (66.3% versus 94.6%). In a prospective study of women identified through seven mammography registries, Miglioretti et al. (42) found that breast augmentation decreased the sensitivity of screening mammography among asymptomatic women, but the prognostic characteristics of tumors were not affected by augmentation. The location of the implant may affect visibility of breast tissue and also potentially the cancer detection rate. Silverstein et al. (45) found that 39% to 49% of breast tissue is obscured by prepectoral implants, but only 9% to 28% of the tissue is concealed by subpectoral prostheses.
The Explant Site
After a breast implant is removed, the fibrous capsule may remain in the breast. Particularly, if the capsule's wall is thick or calcified, it will not collapse as a thin-walled capsule often does. Instead, a seroma may form within the fibrous capsule and may be evident on mammography as a mass.
The findings after explanation have been described previously (46,47,48). The capsule is visible in the position and orientation in which the implant was located. An oval mass parallel to the pectoralis muscle and located in the posterior third of the breast is commonly seen. The margins may be circumscribed or indistinct, and the mass may simulate cancer (Figs. 13.39,13.40,13.41,13.42,13.43,13.44). Residual silicone droplets may be evident within or adjacent to the seroma. The seroma may be so large and dense that it has the appearance of a saline implant on mammography. Calcification of the residual fibrous capsule may be present.
After mastectomy, an immediate or a delayed breast reconstruction may be performed. This is accomplished either by placement of an implant or by recreating a breast mound by moving an autologous myocutaneous flap. A skin-sparing mastectomy is often performed if
possible when reconstruction is planned to facilitate the cosmetic procedure. Most often the mastectomy site or the reconstructed breast is not imaged. However, occasionally, especially if there is a clinical question about a recurrence that is not on the skin, mammography may be performed.
Figure 13.33 HISTORY: A 50-year-old woman with a history of breast implants.
MAMMOGRAPHY: Bilateral MLO (A) and CC (B) views show subpectoral silicone implants bilaterally. On the left MLO view, there is extension of the silicone density into the axilla, consistent with implant rupture. Also noted are small bilateral circumscribed masses(arrows) that were found to be cystic on ultrasound.
IMPRESSION: Left extracapsular implant rupture.
Figure 13.34 HISTORY: A 38-year-old woman with bilateral breast implants and a palpable nodule in the left axillary tail.
MAMMOGRAPHY: Left MLO view (A), coned-down MLO view (B), and ultrasound (C). A retroglandular implant and a moderate amount of overlying glandular tissue are present. There is a well-circumscribed lobulated nodule (arrow) in the upper outer quadrant of the left breast (A and B). Ultrasound (C) demonstrates the nodule to be a cyst (arrow), and this corresponded to the palpable nodule.
IMPRESSION: Simple cyst anterior to the retroglandular implant.
Figure 13.35 HISTORY: A 46-year-old woman with a history of implants who now presents with two new left palpable masses.
MAMMOGRAPHY: Bilateral CC views (A) show normal-appearing saline implants. The palpable masses were not evident on mammography. On ultrasound, the left 12 o'clock mass (B) is hypoechoic, oval, and smoothly marginated, suggestive of a fibroadenoma. The left 5 o'clock mass (C) is more vertically oriented and is hypoechoic and lobulated. A small simple cyst was seen at 6 o'clock (D).
IMPRESSION: Normal implants; two solid masses corresponding to palpable lesions, possible fibroadenomas; recommend biopsy.
HISTOPATHOLOGY: Fibrosis at 12 o'clock, fibroadenoma at 5 o'clock.
Figure 13.36 HISTORY: Routine mammogram on a postmenopausal patient with prepectoral implants.
MAMMOGRAPHY: Left MLO (A) and CC (B) implant-displaced views show heterogeneously dense tissue. A small, isodense indistinct mass (arrows) is present in the upper outer quadrant. On the spot-identification CC magnification view (C), the indistinct borders of the mass are evident.
IMPRESSION: Suspicious mass anterior to the implant.
HISTOPATHOLOGY: Invasive ductal carcinoma, negative axillary nodes.
Figure 13.37 HISTORY: A 50-year-old woman with a history of implants and a new small palpable mass in the left breast at 2 o'clock.
MAMMOGRAPHY: Bilateral MLO (A) and CC (B) views show prepectoral silicone implants. A BB marks the palpable area in the left breast. The area is not visible on the implant-displaced MLO view (C). On the spot CC, implant-displaced views (D), a focal asymmetry is present at the BB. Ultrasound (E) of the palpable lump shows a hypoechoic irregular mass, suspicious for malignancy.
IMPRESSION: Solid mass, suspicious for carcinoma.
HISTOPATHOLOGY: Infiltrating ductal carcinoma, low nuclear grade.
With implant placement for reconstruction, an expander is first positioned following the mastectomy. The expander is then gradually inflated to allow the skin to adapt and stretch. Ultimately, the expander is replaced with a permanent implant, and the nipple-areolar complex is reformed.
Figure 13.38 HISTORY: A 40-year-old gravida 6, para 2 woman with bilateral breast implants, for screening.
MAMMOGRAPHY: Left MLO (A), CC (B), enlarged (2X) CC (C), and specimen (D) views. A subpectoral implant is present, and heterogeneously dense glandular tissue overlies the prosthesis. In the left upper-outer quadrant (A–C), there is a focal area of increased density associated with fine, granular microcalcifications (arrows). The area was considered suspicious for malignancy and was localized under mammographic guidance by placement of a skin marker rather than a needle over the lesion. The specimen film (D) confirms the removal of the suspicious area.
IMPRESSION: Irregular density with microcalcifications anterior to the implant, moderately suspicious for carcinoma.
HISTOPATHOLOGY: Infiltrating ductal carcinoma.
Figure 13.39 HISTORY: Postmenopausal patient with a history of silicone implant removal who also presents with left breast pain.
MAMMOGRAPHY: Bilateral MLO (A) and CC (B) views show the breasts to be heterogeneously dense. There are oval indistinct masses in both breasts having a relatively symmetrical appearance. The left mass (arrow) is slightly larger than the right. The densities are oriented along the plane of the chest wall and are most consistent with explant sites. Because of the symptoms on the left, the density was excised.
IMPRESSION: Fibrous capsules from explant sites.
HISTOPATHOLOGY: Left breast: Fibrous capsule, scar.
Figure 13.40 HISTORY: A 66-year-old woman with a history of silicone implants that were removed, who now presents for screening mammography.
MAMMOGRAPHY: Right MLO (A) and exaggerated CC lateral (B) views show the breast to be fatty replaced. Located posteriorly and parallel to the pectoralis major muscle is an ovoid low-density structure (arrows). This is better visualized on the enlarged MLO image (C).
IMPRESSION: Explant site from prior silicone implant removal.
NOTE: These findings are typical of the explant site, which typically is oriented along the plane of the pectoralis major muscle in the position in which the implant was located.
Figure 13.41 HISTORY: A 59-year-old woman with history of implant removal.
MAMMOGRAPHY: Bilateral MLO (A) and CC (B) views show scattered densities bilaterally. Deep in both breasts at the chest wall, marked by wires at the explant sites, are vague indistinct densities (arrows) oriented along the pectoralis major muscles. This finding represents the residual fibrous capsule at the explant site.
IMPRESSION: Explant sites bilaterally.
Figure 13.42 HISTORY: A 48-year-old woman with a history of implant rupture and replacement with saline implants.
MAMMOGRAPHY: Bilateral MLO (A) and CC (B) views show that the saline implants have a normal appearance. On the CC views (B), a thin bandlike density surrounds the anterior edge of each of the implants (arrows). This finding is consistent with the explant site from the prior implants. Three years later, after the saline implants also were removed, typical changes after implant removal are noted. On the bilateral MLO (C) and CC (D) views, postsurgical changes are seen. There is an oval density parallel to the pectoralis muscle seen on the right (arrow) more prominently than on the left, consistent with the residual fibrous capsule after explantation. Coarse eggshell calcifications are also noted.
IMPRESSION: Postexplantation findings.
Figure 13.43 HISTORY: A 43-year-old woman for screening, with a history of removal of silicone implants.
MAMMOGRAPHY: Bilateral MLO (A) and CC (B) views show very dense parenchyma. On the right, there are multiple high-density round and lobular circumscribed masses at the 12 o'clock position. On enlarged CC image (C), these are oriented in part around a somewhat circumscribed lucency where the implant had resided. The findings represent residual silicone at the explant site.
IMPRESSION: Explant site with free silicone.
Figure 13.44 HISTORY: 53 year-old patient with history of right breast cancer treated with mastectomy and TRAM flap reconstruction.
MAMMOGRAPHY: Bilateral MLO (A), and CC (B) views show marked asymmetry in the appearance of the breasts. The left breast has a normal appearance, and it is composed of scattered fibroglandular elements. The right breast is fatty, without any ductal tissue and has mild skin thickening. The shape of the right breast is slightly flatter and wider than the left, all of which are typical features of a myocutaneous flap reconstruction.
IMPRESSION: Normal TRAM flap breast reconstruction.
When a reconstruction is performed using a myocutaneous flap, the graft is derived from the transverse rectus abdominis muscle (TRAM), the gluteus maximus, or the latissimus dorsi. The flap is turned to create the breast mound, and the blood supply is maintained through a pedicle. In the case of reconstruction from the gluteus maximus, a free flap is raised and moved, with microsurgical technique used to maintain perfusion. One complication of a myocutaneous flap is fat necrosis, which may occur if the blood supply is compromised. Fat necrosis presents as a palpable mass that is firm or hard.
Like the patient who has had a breast reconstruction with an implant, the reconstructed breast is not usually imaged. If mammography is performed, the striking finding is the marked asymmetry in the appearance of the breasts and the complete lack of any density that appears to be ductal or glandular on the reconstructed side. Autologous flaps are primarily fatty on mammography, with minimal density related to the muscle component that is visualized on the MLO view, anterior to the pectoralis major muscle (49). Fat necrosis may occur and has a similar appearance to fat necrosis in the breast itself. Fat necrosis has been reported to occur in 10% to 26% of TRAM flaps (50,51). The flap often compresses somewhat differently from the native breast, and the shape is slightly wider and thicker superiorly than the native breast. The skin over the flap is often slightly thicker than the normal breast as well. Occasionally, the patient may have a combined reconstruction that includes both a myocutaneous flap and an implant (Fig. 13.45).
The findings related to recurrent carcinoma at the mastectomy site are discussed in Chapter 12. Of concern for recurrence of cancer are the presence of findings that are suspicious otherwise: irregular or spiculated masses or suspicious microcalcifications. Imaging of the mastectomy site or the reconstructed breast is not routinely performed to search for recurrence. Often recurrence is manifested as a nodule in the skin or as erythema. If there is a palpable mass, mammography may be performed before biopsy to assess for fat necrosis versus a suspicious mass indicative of recurrent carcinoma.
Figure 13.45 HISTORY: 49 year-old woman with a history of right breast cancer treated with mastectomy and subsequent reconstruction with both a TRAM flap and a small silicone implant.
MAMMOGRAPHY: Bilateral MLO (A), and CC (B) views show a marked difference in the appearance of the breasts. The left breast is composed of scattered fibroglandular tissue. The reconstructed right breast is completely fatty, with no ductal tissue, consistent with a mastectomy site and reconstruction with a myocutaneous flap. The contour of the right breast is somewhat flatter and wider than the left. A small silicone implant also was placed medially as part of the reconstruction procedure to improve the overall symmetry.
IMPRESSION: Normal reconstructed right breast with a TRAM flap and a silicone implant.