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Breast Implant Classification with MR Imaging Correlation¹

¹ From the Department of Radiology, 410 Dickinson St, San Diego, CA 92103-8749 (M.S.M.) and Case Western Reserve University, Breast Imaging Center MetroHealth Medical Center, 2500 MetroHealth Dr, Cleveland, OH 44109-1998 (M.P.M.). Received July 8, 1999; revision requested December 13; revision received and accepted December 21.

	Abstract

Top Abstract LEARNING OBJECTIVES Introduction Materials and Methods Description of Implant Types Discussion Conclusions References

 
Rupture is now recognized as an important and common complication of breast implants. Magnetic resonance (MR) imaging is the most accurate method for evaluating implant integrity but requires an understanding of the numerous variations in implant construction that are encountered clinically. To assist in diagnosis, the authors provide an MR-oriented breast implant classification scheme based on data from 4,014 patients (>9,966 current or previous implants), the literature, and other primary documentation. This scheme consists of 14 implant types: 1) single-lumen silicone gel-filled, 2) single-lumen gel-saline adjustable, 3) single-lumen saline-, dextran-, or polyvinyl pyrrolodone-filled, 4) standard double-lumen, 5) reverse double-lumen, 6) reverse-adjustable double-lumen, 7) gel-gel double-lumen, 8) triple-lumen, 9) Cavon "cast gel", 10) custom, 11) solid pectus, 12) sponge (simple or compound), 13) sponge (adjustable), and 14) other. The MR imaging and mammographic appearance of many implant types is correlated with their actual appearance after explantation. A brief history of prosthetic breast augmentation and reconstruction is also provided to allow this classification method to be placed in historical perspective. Knowledge of the variety of breast implant types will help reduce misdiagnoses by providing imagers with better understanding of the expected appearances of breast implants. This classification scheme will allow stratification of data for studying incidence, prevalence, and risk factors for and causes of implant failure, as well as permitting better correlation with patient symptoms and surgical outcome.

Index Terms: Breast, MR, 00.121411, 00.121415 • Breast, prostheses, 00.4543, 00.4544 • Silicone

	LEARNING OBJECTIVES

Top Abstract LEARNING OBJECTIVES Introduction Materials and Methods Description of Implant Types Discussion Conclusions References

 
After reading this article and taking the test, the reader will:

• Be familiar with the history and terminology of breast implants.

• Know the typical MR imaging appearances of the various implant types on the basis of an understanding of their actual construction.

• Use knowledge of implant construction and appearance to avoid misdiagnosis of the many types of implants that have been used over the last 50 years.

	Introduction

Top Abstract LEARNING OBJECTIVES Introduction Materials and Methods Description of Implant Types Discussion Conclusions References

 
Breast implants have been the object of considerable attention since the U.S. Food and Drug Administration (FDA) imposed a moratorium on silicone gel implants in 1992 (1,2,3,4,5,6,7,8,9,10,11). In particular, the recently released report "Safety of Silicone Breast Implants", prepared by the Institute of Medicine of the National Academy of Sciences, concluded that while the current scientific literature does not demonstrate an association between breast implants and various diseases, local complications of implant rupture are frequent² (9). The committee noted the difficulties that occur both in imaging diagnosis as well as the conduct of epidemiologic studies of local complications because of the great diversity of implant types and styles.

This report will present a comprehensive breast implant classification scheme based on historical and magnetic resonance (MR) imaging considerations, and in doing so will illustrate the essential components from which breast implants are constructed.

Early history of augmentation
Czerny is credited with the first breast reconstruction in 1895, using a lipoma from a patient to augment her breast after removal of an adenoma (12,13,14). The record is clear that paraffin was used in the 1880s to treat tuberculosis (15); however, the contemporaneous literature from the turn of the (last) century is unclear as to when paraffin was first used for breast augmentation. Gersuny suggested in 1900 that it would be possible to do this (16), but was referenced by others many years later as having suggested or performed breast augmentation with paraffin in 1899 (17,18,19,20,21,22), and as early as "the 1880's" (unreferenced) by Clarkson and Jeffs (23). In his 1900 paper, Gersuny does report " ... a few therapeutic attempts ... years ago ...", but does not state that they were in the breast (16). Caffee (1997) reported (without references) that the first reported injections of paraffin for breast augmentation occurred in 1904 (24). The unacceptable incidence of complications due to paraffin, including embolization to the lung and brain and solidification into "paraffinomas" and "wax cancer" (15), was the reason its use was discontinued³ in Europe and the United States in the 1920s (25). Placement of glass balls and ivory for breast augmentation also have been reported (2,17,18,20,22,26,27,28).

Plastic sponges
After several years of use in other parts of the body in the late 1940s (29,30,31), plastic implants, most in the form of a sponge made from polyethylene (Polystan), nylon, polyvinyl alcohol (Ivalon), polyurethane (Surgifoam, Etheron, Scottfoam), Teflon, silicone (SILASTIC) sponge, or poly-HEMA (Hydron) were experimented with or used for breast reconstruction and augmentation (32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51). Even though others may have used sponges for breast augmentation earlier (32,40), Pangman is usually credited with first seriously investigating the use of sponges for breast augmentation starting in 1951 (52,53). Complications soon became apparent, including capsular contracture, seroma formation, fistulization, and infection (54). Ivalon sponges were shown to induce sarcoma in rodents (55,56), and to harden and shrink in patients within the first year (57). Following the introduction and rapid acceptance in late 1963 of the new "natural feel" silicone gel-filled implant from Dow Corning (58), the use of sponge implants rapidly declined, with what could be regarded as vestigial use in some custom and other implants until the early 1970s.

Silicone fluid and gel injections
Injections for cosmetic reasons of non-silicone fluids from about 1935, and then silicone fluid preparations sometime in or soon after 1945, are reported to have been performed in Japan (25), and were later introduced in the United States (59). The main problem encountered when a large volume of "pure" liquid silicone is injected into the breast or elsewhere is that it tends to migrate unacceptably away from the site of injection. It was reported in 1968 that "pure silicone oil is so non-reactive that it drifts in subcutaneous fat" (60). Two approaches were devised to minimize this problem: (a) addition of a fibrosing agent to the injected silicone fluid and (b) injection of the silicone in gel form. Later, to achieve a more "natural feel" than obtained with sponges, Cronin began enclosing the silicone in a bag (58,61). Most practitioners found that the Cronin implants also gave a more natural feel than direct silicone injections.

The first approach for preventing or reducing migration was instituted by Japanese and other practitioners who added fibrosing agents such as vegetable oil, fatty acids, and other materials to "pure" silicone to form what have been referred to as "adulterated" silicones (ie, the Japanese or Sakurai formula) (25,59,62). Some of these "adulterated" formulas were in use in the United States by about 1963 (59). About 18 years after this practice started, problems were reported in patients with silicone fluid injections, including formation of silicone granulomas, sometimes called "siliconomas" (63,64). This was a longer delay than was seen for the (much) earlier paraffin injections. Siliconomas are not tumors per se, but are masslike focal collections of histiocytes and foreign body giant cells surrounded by and engulfing silicone (65). Intraarterial injection of silicone fluid was shown to be fatal in dogs because of embolization (66), and the death of a patient after injection by a "travelling therapist" of silicone fluid into the breasts has been reported (67). The cause of death was determined to be severe acute bilateral pulmonary edema secondary to intravascular silicone injection (67). Many women in the United States and abroad have received such injections⁴. Some women with paraffin (79) and silicone (79,80) breast injections have undergone and continue to undergo mastectomy to remove the material.

The second approach for preventing or reducing migration was to inject or surgically place silicone in the form of a gel. As per a 1964 release from Japan Medical Plastics Center, Dr Taichiro Akiyama first formulated silicone for injection in 1948, and then later in about 1949-50 developed an injectable form of (cross-linked) silicone gel called Elicon (81,82). Koken offered Elicon for sale in 1964, marketed as "Dr. Akiyama's Natural Fat" (83,84). In the United States, breast injections of silicone gel were used on an experimental basis in patients by Frank Gerow, MD, in 1962 at Baylor University (85). Others also reported silicone gel breast injections (86,87). Freeman reported in 1974 that silicone gel was intentionally removed from an implant shell and then used for breast augmentation (88). Cavon designed and patented an implant that was used from about 1979 to 1985, consisting of cohesive silicone gel without a shell (89,90). The total number of patients in the United States with "native" silicone gel still in place in any of these categories at this time is likely to be small.

The Cronin implant
Dr Thomas Cronin placed silicone gel in a bag consisting of rubberlike silicone sheeting (elastomer), forming what is recognized as the modern silicone gel-filled implant (58). These were investigated experimentally from February 1961 until late 1963, with the first ones placed in a patient in about March 1962 by Cronin and Gerow (Baylor University) in conjunction with the Dow Corning Center for Aid to Medical Research, and produced commercially by Dow Corning starting in about October 1963 (58,91,92,93,94,95). These were considered medical devices, and hence not subject to the FDA rules and regulations of the time regarding drugs, as were silicone injections. In 1976, the FDA began regulating medical devices, at which time breast implants were "grandfathered in", with further investigation planned.

Subsequent implant development
Early silicone gel-filled implants had a thick shell (or envelope), a peripheral seam, and a backing of Dacron mesh meant to promote tissue ingrowth and fixation along the posterior surface. Seamless implants became available in about 1968, and by the early 1970s implants were available without fixation. After a period of experimentation that may have started as early as 1964 (96), silicone gel-filled breast implants fully coated with polyurethane became available in 1968 with a thick shell, a peripheral seam, and an internal Y-shaped baffle⁵ (ie, the "Natural-Y", or "Ashley", implant), and then in greater numbers in a variety of styles from about 1982 onward. Implants designed to reduce silicone fluid bleed, called "low bleed" implants, first became available in the early 1980s. Texturing of implant shells in the middle 1980s was intended to reduce capsular contracture. Although saline- (and, earlier, dextran-) filled implants never attained the popularity of the silicone gel-filled implant, they were experimentally placed or used in the early 1960s in the United States (97) and abroad (98). Recent modifications include filling the (silicone elastomer) shell of implants with triglyceride-based fillers (99) and providing fixed-volume prefilled saline implants (100).

Breast implant classification
Initially there was only one style in one size, which was the 1962 Dow Corning experimental single-lumen silicone gel-filled implant⁶. Later, many types, styles, and sizes of implants were introduced by Dow Corning and other manufacturers. We are aware of no current complete published catalogue of breast implants. In 1973, Braley gave a brief history of breast implants (93). In that same year, Snyder also listed styles and sizes of implants available at that time (101). In 1976 and 1978, Gerow updated that information (102,103), as did Baker in 1979 (104). In 1982, Elbaz and Ohana illustrated and described a number of implants that had since become available (105). The description, MR imaging appearance, and mammographic appearance of several implant types have been described (1,2,106), but the issue of classification was not addressed.

We have previously described 14 breast implant types (3,4,5,107), the most common of which is still the single-lumen silicone gel-filled type. For most implant types and styles, there have been variations over the years in shell thickness, method and location of patching, shell marking, type and "thickness" of silicone gel, shape and size, and method of fixation or orientation.

To date we have noted over 240 breast implant styles from American manufacturers alone⁷ (108). The actual number of styles is far larger because many implants of a single style from a single manufacturer evolved through many variants over the years. Also, the "custom" implant type alone is diverse.

Summary
Implant rupture has been recognized as an important, if not the most important, complication of breast implants (9). In this report, we will describe and illustrate the various types of implants, with special attention to correlating the MR imaging appearance of implants with their actual construction and appearance. Special emphasis is given to describing the essential features of each implant type. This will allow a better understanding of breast implants by radiologists and aid in implant imaging. Misinterpretation resulting from unfamiliarity with the variety of implant types may be avoided. This also will permit stratification of research data by implant type and allow investigation of the incidence and causes of rupture, local breast symptoms, systemic symptoms, and outcomes of surgery.

	Materials and Methods

Top Abstract LEARNING OBJECTIVES Introduction Materials and Methods Description of Implant Types Discussion Conclusions References

 
The authors have compiled a breast implant catalogue listing manufacturer, implant type, style, size, and other detailed information⁷ (108). The material contained there forms part of the basis for this report. Our sources of information have included the following:

1. Medical records of 4,014 patients (more than 9,966 current or previous breast implants), 1,377 of whom underwent 1,524 breast MR scans at the University of California San Diego over the last 8 years⁸.
   
2. Direct visual examination of 4,821 implants from that population, 499 of which were observed at time of removal during 258 explantation operations attended by one of us (M.S.M.).
   
3. Documents produced in the MDL 926 Class Action Breast Implant Litigation, referenced here by the "Bates" numbers. As noted in the Institute of Medicine Study on the Safety of Silicone Breast Implants, this type of information can "identify directions for inquiry, useful literature, and data" that can assist in inquiries of this sort (9). These documents are in the public domain and can be obtained by contacting Tina J. Crowe, the Document Depository Librarian, at the National MDL 926 Document Depository, 105-D Potter Stewart U.S. Courthouse, 100 East Fifth Street, Cincinnati, OH 45202; telephone: (513) 684-6688; fax: (513) 684-5853; e-mail: tjcrowe{at}fuse.net.
   
4. Formal meetings and later correspondence with representatives of Dow Corning Corporation concerning their breast implant products.
   
5. Informal feedback from representatives of several other breast implant manufacturers, including Bioplasty, Cox-Uphoff International (CUI), Inamed, McGhan, Mentor, Progress Mankind Technology (PMT), Collagen, PIP, and Surgitek, with regard to their products.
   
6. Published accounts of breast implants.
   

The MR images shown in this report were obtained with a 1.5-T imager (4.8x software) (GE Medical Systems, Milwaukee, Wis) with dedicated bilateral breast surface coil (Medical Advances, Milwaukee, Wis, and GE Medical Systems). Typically, the field of view was 15 or 20 cm, matrix size was 256 x 256, section thickness was 3 or 4 mm, and a T2-weighted water-suppressed fast spin-echo (FSE) technique was used (repetition time, > 3,000 msec; echo time, 208 or 304 msec; echo train length, eight or 16; bandwidth, 16 kHz) (3). These same types of high-resolution T2-weighted water- (and silicone-) suppressed surface-coil images are also obtainable with other MR imagers, although the names of the sequences may be different. Institutional Review Board approval was obtained to review medical records. Informed consent was obtained for those cases in which MR images were obtained as part of a research protocol.

	Description of Implant Types

Top Abstract LEARNING OBJECTIVES Introduction Materials and Methods Description of Implant Types Discussion Conclusions References

 
The proposed breast implant classification scheme is given in Table 1. This scheme is based on implant construction and MR imaging appearance. Saline-filled, dextran-filled, and PVP-filled implants are in the same implant type because they have the same MR imaging appearance. The numbers and percentages of each of the types of implant that our patients at UCSD have or have had are also given in Table 1. A summary of implant valve types (Figs 1–26) is given in Table 2. A summary of fixation and orientation devices (Figs 27–45), implant texturing (Figs 46–47), and reinforcement disks (Figs 48–49) is given in Table 3. A summary of polyurethane-coated implants (Figs 51–56) is given in Table 4.

View larger version (151K): [in this window] [in a new window] [Download PPT slide]   Figure 1. Ligation valve. Style 1400 Heyer-Schulte Tabari saline-filled implant (placed 1972) with a ligation valve seen here pulled out of the pocket in which it can be buried (photographed upside down). A narrow strip of Dacron mesh-reinforced elastomer is present around the entire circumference of the implant inside the implant shell. Two crescent-shaped strips (arrows) of Dacron felt fixation material are present on the posterior superior part of the implant, with some ingrown tissue still attached (143,144).

View larger version (97K): [in this window] [in a new window] [Download PPT slide]   Figure 2. Tube valve. Roger Klein saline-filled implant (placed 1974), originally designed by Dr H. G. Arion (98), imported into the United States by Roger Klein. (New York, NY) from Simaplast (Paris, France) as the Arion implant, and later manufactured by Roger Klein as the Mammatech implant (123,124). These implants had a circumferential seam and a tube protruding from the implant that could be stoppered, inverted into the implant, or both. The valve could be at the side (thin arrow), on the anterior surface, or on the posterior surface of the implant. A large round shell patch is shown here on the posterior surface of the implant (thick arrow). This type of valve has a characteristic appearance at mammography (Fig 3) and probably also on MR images.

View larger version (128K): [in this window] [in a new window] [Download PPT slide]   Figure 3. Tube valve. Xeromammogram of the Roger Klein saline-filled implant shown in Figure 2, showing the plug valve inverted into the implant and the large round back patch.

View larger version (100K): [in this window] [in a new window] [Download PPT slide]   Figure 4. Plug valve. One early Surgitek implant, known as the Dahl implant, was inflated with silicone at time of placement (115). Shown here is the "plug valve" of such an implant placed in about April 1975, stoppered with a white plug. The inner edge of the hole in the shell is just discernible. Free gel is present on the implant surface. This type of valve should have a characteristic and identifiable cylindric appearance on MR images.

View larger version (110K): [in this window] [in a new window] [Download PPT slide]   Figure 5. Plug valve. Shown here is an early Koken implant, which we understand also was known as the Akiyama implant13 , with a plug valve (82). The plug (arrow) is removable, rivet-shaped (or mushroom-shaped), and placed directly into the implant shell hole. The Dacron mesh used to provide fixation for this implant, remnants of which are seen here, has a rather coarse rectangular weave pattern. It is our understanding that this implant was placed in 1980. This type of valve may have a characteristic appearance on MR images.

View larger version (126K): [in this window] [in a new window] [Download PPT slide]   Figure 6. Seal-Seal inflatable (SSI) valve. Xeromammogram of an early Surgitek saline-filled implant (placed 1974). Both the SSI valve (thin arrow) and the implant back patch (thick arrow), on the posterior surface of the implant, are evident.

View larger version (138K): [in this window] [in a new window] [Download PPT slide]   Figure 7. Seal-Seal inflatable (SSI) valve. Surgitek Georgiade contoured standard double-lumen implant (placed 1978), showing the Dacron mesh-reinforced SSI valve (arrow), containing a fairly thick silicone gel, mounted on the inner surface of the back patch on the outer posterior shell. This type of valve also can be found mounted directly on the internal surface of the outer shell of other Surgitek standard double-lumen implants, and is the same type of valve that was used in some Surgitek saline-filled and gel-saline implants in the 1970s and early 1980s. This type of valve has a characteristic appearance on MR images (Fig 8).

View larger version (128K): [in this window] [in a new window] [Download PPT slide]   Figure 8. Seal-Seal inflatable (SSI) valve. Sagittal T2-weighted fast spin-echo water-suppressed MR image showing the SSI valve in a round (ruptured) Surgitek Munna standard double-lumen implant (placed 1982). The signal from the silicone in the SSI valve (long arrow) is not as bright as the signal from the silicone gel in the inner (and outer) lumen most likely for two reasons: It is more highly crosslinked, and it is likely that there is suppressed waterlike fluid intermixed with the silicone gel. The presence of silicone outside the (outer shell) SSI valve (short arrow) is a definitive sign that the implant is ruptured. This type of fill-port is shown in Figure 7 on a different style of Surgitek standard double-lumen implant.

View larger version (107K): [in this window] [in a new window] [Download PPT slide]   Figure 9. Leaflet valve. Posterior surface of a Surgitek 22000 series round standard double-lumen implant (placed 1983), with the characteristic small white 3-mm dot (thin arrow) with a slit, proximally marking one end of the fill channel. The rectangular leaflet valve, measuring about 10 x 60 mm, is seen here extending to the left (thick arrow). Rarely seen MR images capturing the appearance of this type of leaflet valve are shown in Figures 10 and 11.

View larger version (78K): [in this window] [in a new window] [Download PPT slide]   Figure 10. Leaflet valve. T2-weighted fast spin-echo silicone-suppressed MR image (original magnification, x5) of the distal part of the leaflet valve of a Surgitek standard double-lumen implant such as that shown in Figure 9, showing the characteristic appearance of the leaflet valve in cross section. (This cross section is what would be seen at about the location of the thick arrow in Figure 9). In this image the inner-lumen silicone gel is dark and the outer-lumen saline surrounding the leaflet valve is bright. Another more distal (en face) MR cross section through this same type of valve is shown in Figure 11.

View larger version (94K): [in this window] [in a new window] [Download PPT slide]   Figure 11. Leaflet valve. T2-weighted fast spin-echo silicone-suppressed MR image (original magnification, x5) of the distal part of the same type of leaflet valve shown in Figures 9 and 10, showing its characteristic squared-off appearance en face. In this image the inner-lumen silicone gel is dark and the outer-lumen saline surrounding the leaflet valve is bright.

View larger version (92K): [in this window] [in a new window] [Download PPT slide]   Figure 12. Leaflet valve. Posterior surface of a Dow Corning 380 series standard double-lumen implant (placed 1985), showing the most common configuration for the leaflet valve for this series (thick arrow). Just barely visible on this implant itself (but not in this photograph) were the markings "SILASTIC II 300 cc" on the round inner-lumen back patch (thin arrow). The xeromammographic appearance of this implant is shown in Figure 13, and the characteristic MR imaging appearance of this type of leaflet valve is shown in Figure 14.

View larger version (108K): [in this window] [in a new window] [Download PPT slide]   Figure 13. Leaflet valve. The appearance of the distal part of the leaflet valve for the Dow Corning 380 series standard double-lumen implant shown in Figure 12 is demonstrated on this xeromammogram (arrow). The characteristic xeromammographic appearance of saline present in the outer lumen of the standard double-lumen implant is also shown here (a). The characteristic appearance of this type of leaflet valve on MR images is shown in Figure 14.

View larger version (118K): [in this window] [in a new window] [Download PPT slide]   Figure 14. Leaflet valve. T2-weighted silicone-suppressed MR image of the distal part of the leaflet valve in a Dow Corning 380 series standard double-lumen implant, showing the en face MR imaging appearance of the type of leaflet valve illustrated in Figures 12 and 13.

View larger version (101K): [in this window] [in a new window] [Download PPT slide]   Figure 15. Leaflet valve. Surgitek reverse-adjustable double-lumen implant (placed 1985). Beveled back patch outside implant shell is shown here (thick arrow) with two gel fill points (short arrows), one for each silicone gel-filled lumen. Toward the center of the back patch is the 3-mm white dot and slit (long arrow) marking the entry point to the short Quin-Seal leaflet valve leading to the inner lumen. (The slit is not discernible on this photograph.) The MR imaging appearance of this implant is illustrated in Figures 58 and 59.

View larger version (80K): [in this window] [in a new window] [Download PPT slide]   Figure 16. Double leaflet valve. Mentor Becker 25/75 reverse double-lumen implant with a double leaflet valve, one for the inner and one for the outer shell (placed 1986). The fill tube has been withdrawn from this implant, and so both leaflet valves have curled (arrows), giving a "window-shade" appearance. This type of curled window shade appearance can be seen on some MR images. This type of implant also was manufactured with one curled (inner) and one flat (outer) leaflet valve.

View larger version (101K): [in this window] [in a new window] [Download PPT slide]   Figure 17. Retention valve. Heyer-Schulte Style 1200 saline-filled breast implant with a retention valve (placed 1976). The valve has a round narrow proximal part (short arrow) and a flat distal part (thick arrow), and is attached to the implant shell through a round patch (long arrow). The cross-sectional MR imaging appearance of this type of valve is shown in Figures 18 and 19.

View larger version (81K): [in this window] [in a new window] [Download PPT slide]   Figure 18. Retention valve. T2-weighted fast spin-echo silicone-suppressed MR image of Heyer-Schulte Style 1200 (or 1300) saline-filled breast implant with a retention valve, showing a cross section through the proximal round neck of the valve (short arrow). A peripheral fold is also seen (long arrow). A photograph of a valve of this type is shown in Figure 17, and the MR imaging appearance of the distal flat part of this valve is shown in Figure 19.

View larger version (76K): [in this window] [in a new window] [Download PPT slide]   Figure 19. Retention valve. T2-weighted fast spin-echo silicone-suppressed MR image of Heyer-Schulte Style 1200 (or 1300) saline-filled breast implant with a retention valve, showing a cross section through the distal flat part of the valve (short arrow). The peripheral fold is also seen (long arrow). A photograph of a valve of this type is shown in Figure 17, and the MR imaging appearance of the proximal round part of this valve is shown in Figure 18.

View larger version (100K): [in this window] [in a new window] [Download PPT slide]   Figure 20. Retention valve. Heyer-Schulte Style 7000 Hartley-type standard double-lumen breast implant (late version with slit in shell patch, placed 1982), showing the retention valve (a) on the posterior shell adjacent to the central back patch (b). The valve is attached to the shell through an elastomer disk (c). The opening to the valve (d) is placed just under the slit in that disk. The MR imaging appearance of this type of implant is shown in Figure 21.

View larger version (90K): [in this window] [in a new window] [Download PPT slide]   Figure 21. Retention valve. Axial T2-weighted silicone-suppressed MR image of Heyer-Schulte standard double-lumen implant with a retention valve (placed 1983). This MR image illustrates the slightly curled (thickened) edges of the distal flat part of the valve (arrow). A photograph of this type of implant is shown in Figure 20.

View larger version (107K): [in this window] [in a new window] [Download PPT slide]   Figure 22. Diaphragm valve. Style 1600 Heyer-Schulte saline-filled implant (placed 1982), showing the anterior diaphragm valve (thin arrow) with a strap (thick arrow) and attached central plug, bonded to the implant shell on both sides. The MR imaging appearance of this type of valve is shown in Figure 24. Earlier saline-filled implants from this manufacturer had a larger so-called Jenny valve, named after Dr Henry Jenny, who was the first to design saline implants, in 1968, with a diaphragm valve14 . Those earlier implants had a plug attached to the shell with a strap on only one side.

View larger version (71K): [in this window] [in a new window] [Download PPT slide]   Figure 23. Back patch of Heyer-Schulte Style 1600 implant. Same Heyer-Schulte implant as shown in Figure 22, showing the posteriorly placed back patch and annulus inside the implant shell, with an "M" on the overlap portion of the shell and the back patch (arrow). The back patch on saline-filled implants such as this are necessary to close the shell hole remaining after the shell is formed on a mandrel. These patches can sometimes be seen at mammography, and also on MR images (Fig 24).

View larger version (81K): [in this window] [in a new window] [Download PPT slide]   Figure 24. Diaphragm valve. Axial T2-weighted fast spin-echo silicone-suppressed MR image of a Style 1600 Heyer-Schulte saline-filled implant (placed 1983) showing the diaphragm valve and back patch. The usually anterior-facing diaphragm valve is posterior here (thin arrow), and the usually posterior-facing back patch is seen anteriorly (thick arrow). (This implant position is occasionally seen and does not have any clinical or cosmetic significance.) Photographs of the type of diaphragm valve and back patch used on this kind of implant are shown in Figures 22 and 23.

View larger version (72K): [in this window] [in a new window] [Download PPT slide]   Figure 25. Internal tube valve. Sagittal T2-weighted fast spin-echo water-suppressed MR image of a Mentor Becker Siltex (textured) reverse double-lumen implant (placed 1991), with bright(er) outer-lumen silicone gel (a) and dark inner-lumen saline (b), showing portions of the posterior valve assembly (arrow). These were available in a 50/50 or a 25/75 gel-to-saline ratio. The appearance of this implant with silicone-suppression MR imaging is shown in Figure 26.

View larger version (81K): [in this window] [in a new window] [Download PPT slide]   Figure 26. Internal tube valve. Sagittal T2-weighted fast spin-echo silicone-suppressed MR image (same section as in Fig 25) of a Mentor Becker Siltex (textured) reverse double-lumen implant, with dark outer-lumen silicone gel (a) and bright inner-lumen saline (b). Bright intracapsular waterlike fluid is seen surrounding the implant (c), a common finding for implants with a textured surface.

View larger version (106K): [in this window] [in a new window] [Download PPT slide]   Figure 27. Four-quadrant fixation patches. Dow Corning 830 series implant showing the four-quadrant fixation patch design (placed 1965). The outer layer of loose Dacron mesh has been cut from each of the Dacron mesh-reinforced elastomer fixation patches. Seen here are the cut sutures that originally joined those two layers (thin arrow). Those sutures compartmentalize the fixation patches, producing a characteristic "zebra-stripe" appearance on MR images (Fig 28). The posterior surface of the implant is shown here, photographed from the side. Most early versions of the 830 series implants, such as this one, have a non-everted peripheral seam (thick arrow); later versions have an everted peripheral seam.

View larger version (104K): [in this window] [in a new window] [Download PPT slide]   Figure 28. Four-quadrant fixation patches. Sagittal T2-weighted fast spin-echo water-suppressed MR image of a Dow Corning 830 series implant (single-lumen silicone gel-filled, placed 1965) (Fig 27), showing its characteristic four-quadrant Dacron mesh-backed fixation patches. On water-suppressed MR images this type of fixation patch has a "zebra-stripe" appearance (thick arrows). This implant is in a state of uncollapsed rupture, as evidenced by the "keyhole" (short arrows) and "pull-away" (long arrow) appearances peripherally (4), confirmed at surgery.

View larger version (127K): [in this window] [in a new window] [Download PPT slide]   Figure 29. Dow Corning 530 series fixation patches. Posterior surface of a contoured Dow Corning 530 FP series implant (placed 1970, not ruptured) showing the dumbbell-shaped inferior Dacron mesh fixation patch and three additional fixation disks bonded directly to the implant shell. Each patch consists of a layer of loose Dacron mesh, which is sewn to a layer of Dacron mesh-reinforced elastomer. The outer mesh layer has been cut away from this implant and is not shown here. Portions of it with ingrown tissue are shown in Figure 30. The dumbell-shaped patch overlies two shell holes separated by a slit (not shown here). This was the first "seamless" style of Dow Corning implant. The fixation patches can often be seen on MR images, depending on the imaging protocol used (Fig 31).

View larger version (127K): [in this window] [in a new window] [Download PPT slide]   Figure 30. Dow Corning 530 series fixation patches. Shown here are portions of the outer Dacron mesh layer that were dissected from the fixation patches at the time of explantation, for the Dow Corning 530 FP series implant (placed 1970) shown in Figure 29. Tissue has grown directly into the Dacron mesh layer of these fixation patches. The fixation patches can often be seen on MR images, depending on the imaging protocol used (Fig 31).

View larger version (98K): [in this window] [in a new window] [Download PPT slide]   Figure 31. Dow Corning 530 series fixation patches. Axial T2-weighted fast spin-echo water-suppressed MR image of the Dow Corning 530 FP series implant (placed 1970) shown in Figures 29 and 30, with the "dumbbell plus 3 round disk" pattern of fixation patches, showing no evidence of rupture. This image shows a cross section through the upper part of the "dumbbell." The fixation patches (arrows) can appear solid, as shown here, or can have the zebra-stripe appearance seen in Figure 28.

View larger version (134K): [in this window] [in a new window] [Download PPT slide]   Figure 32a. Dow Corning 900 series fixation patches. In about 1973, a new pattern of fixation disks was introduced by Dow Corning in which the outer Dacron mesh layer was embedded into the elastomer disk in a pleated fashion rather than sewn into it. These implants had two, three, or four such round fixation disks bonded to their posterior surface, one of which was over the shell hole, usually with a separate back patch (thick arrow) and reinforcement disk (not shown here) inside the shell hole (see Figs 48 and 49). Shown here is an example of this method of fixation on a catalogue no. 965 Dow Corning implant with four fixation disks, placed in 1975. The mandrel marking "5" is faintly seen centrally (thin arrow) in a (close-up view shown in b), about 4 mm in height, indicating the implant size.

View larger version (128K): [in this window] [in a new window] [Download PPT slide]   Figure 32b. Dow Corning 900 series fixation patches. In about 1973, a new pattern of fixation disks was introduced by Dow Corning in which the outer Dacron mesh layer was embedded into the elastomer disk in a pleated fashion rather than sewn into it. These implants had two, three, or four such round fixation disks bonded to their posterior surface, one of which was over the shell hole, usually with a separate back patch (thick arrow) and reinforcement disk (not shown here) inside the shell hole (see Figs 48 and 49). Shown here is an example of this method of fixation on a catalogue no. 965 Dow Corning implant with four fixation disks, placed in 1975. The mandrel marking "5" is faintly seen centrally (thin arrow) in a (close-up view shown in b), about 4 mm in height, indicating the implant size.

View larger version (98K): [in this window] [in a new window] [Download PPT slide]   Figure 33. Dow Corning 580 series fixation patches. Axial T2-weighted fast spin-echo water-suppressed MR image of the same type but an earlier style of implant than is shown in Figure 32. The four round fixation disks on this implant are thinner than the older four-quadrant patches, and so the "zebra" pattern is rarely if ever seen. This Dow Corning implant, placed in 1973, was intact, confirmed at surgery. The appearance of silicone outside the implant shell posteriorly on this MR image (arrow) is probably due to the presence of a small amount of silicone fluid (not gel) between the layers of one of the fixation disks. This was one our false-positive findings.

View larger version (124K): [in this window] [in a new window] [Download PPT slide]   Figure 34. Fenestration-style fixation patch. Some of the early McGhan and McGhan/3M nonround implants, such as this standard double-lumen implant placed in 1980, had an octagonal-shaped fenestration-style fixation device (a) attached to the back patch (b). It consisted of a thin sheet of silicone elastomer with numerous small holes into which tissue was meant to grow. This was called the "silicone fixation option" by the manufacturer(s). Also shown is a Dacron mesh-reinforced elastomer "keyhole"- (or "paddle"-) shaped suture tag (c), such as was used on some McGhan and McGhan/3M implants (Fig 42), a second shell patch (d) for the leaflet valve, and the leaflet fill valve itself (e). These fenestration-style fixation patches will rarely, if ever, be discernible on MR images.

View larger version (129K): [in this window] [in a new window] [Download PPT slide]   Figure 35. Fenestration-style fixation patches. Early Heyer-Schulte Style 2000 single-lumen silicone gel-filled implant, placed in 1972, with "double hemicircle" fenestration-style fixation patches (a and b) overlying a large oval Dacron mesh-reinforced back patch (c). Tissue (d) was meant to grow through the holes into the fixation patches, thereby affixing the implant to the surrounding tissues. Also shown is a Dacron mesh full-loop suture tag inferiorly (e) (see Fig 38).

View larger version (111K): [in this window] [in a new window] [Download PPT slide]   Figure 36. Fenestration-style fixation patch. Heyer-Schulte single-lumen silicone gel-filled implant (placed 1984) with a "butterfly"-shaped fenestration-style fixation patch (a) overlying a "spiral" (multiple concentric circles) back patch (b) on which is marked "200" (c, the implant size in cubic centimeters). Tissue was meant to grow through the holes in the fixation patch, thereby affixing the implant to the surrounding tissues. This style of fenestration patch will rarely if ever be discernible on MR images.

View larger version (120K): [in this window] [in a new window] [Download PPT slide]   Figure 37. Fenestration-style fixation patch. Cox-Uphoff International (CUI) single-lumen silicone gel-filled implant with a round fenestration-style fixation patch (a) overlying the superior portion of the posterior shell. Tissue was meant to grow through the holes in the fixation patch, thereby affixing the implant to the surrounding tissues. Also present is a back patch outside the implant shell (b) with a central gel fill point (c), and a small elastomer disk (d) holding a Dacron mesh suture tag (e) on the inferior implant shell.

View larger version (95K): [in this window] [in a new window] [Download PPT slide]   Figure 38. Full-loop suture tag. Full-loop Dacron fine-mesh suture tag (a) on a Heyer-Schulte implant placed in 1975, bonded to the underlying spiral patch (b) with a small overlying round elastomer disk (c). This style of suture tag was used by Heyer-Schulte until about 1978. Note the indentation into the shell by the suture tag (d). Such indentations may potentially be sites of shell failure (ie, rupture). Although suture tags such as these may rarely be visualized on MR images, their MR imaging appearance is neither manufacturer nor style specific.

View larger version (80K): [in this window] [in a new window] [Download PPT slide]   Figure 39. Partial-loop suture tag. Side view of a ruptured Surgitek (MEC) 10140 single-lumen teardrop-shaped silicone gel-filled implant with an attached 4-mm-wide Dacron coarse-mesh partial-loop suture tag (a) inserted between the implant back patch and the shell (placed 1976). This type of suture tag formed a partial loop, as shown here, and could be sewn to surrounding tissue, providing a degree of fixation to surrounding tissue. Free silicone gel is seen on the implant surface extending to the suture tag (b). A top view of this same suture tag is shown in Figure 40. Although suture tags such as these may rarely be visualized on MR images, their MR imaging appearance is neither manufacturer nor style specific.

View larger version (110K): [in this window] [in a new window] [Download PPT slide]   Figure 40. Partial-loop suture tag. Top view of the same suture tag (a) shown in Figure 39, showing edge of overlying back patch (b).

View larger version (127K): [in this window] [in a new window] [Download PPT slide]   Figure 41. Dacron mesh-reinforced round-tip elastomer suture tag. Dacron mesh-reinforced round-tip elastomer suture tag (a) on a Style 6000 Heyer-Schulte single-lumen silicone gel-filled implant (placed 1982). Just the edge of the "spiral" (multiple concentric circles) back patch is seen here (b). This style of suture tag was used by Heyer-Schulte from about 1978 to 1984 and by Mentor after that. Although suture tags such as these may rarely be visualized on MR images, their MR imaging appearance is neither manufacturer nor style specific.

View larger version (88K): [in this window] [in a new window] [Download PPT slide]   Figure 42. Keyhole-shaped Dacron mesh-reinforced suture tag. Dacron mesh-reinforced keyhole- (or paddle-) shaped elastomer suture tag (a) on a Style 82 McGhan single-lumen silicone gel-filled implant (placed 1977). This style of suture tag was used by McGhan and McGhan/3M on some of their nonround implants. The suture tag is bonded just outside the implant shell patch (b), under a small elastomer disk (c), with the gel-fill point just on top of that (d). Note the tendency of the distal part of the tag to assume a curved shape, which may have contributed to the indentation in the implant shell under the tag (not shown here). Although suture tags such as these may rarely be visualized on MR images, their MR imaging appearance is neither manufacturer nor style specific.

View larger version (143K): [in this window] [in a new window] [Download PPT slide]   Figure 43. Elastomer orientation bar and disk. An inferior horizontal orientation bar (a) and superior round disk (b) are placed directly external to the back patch (c) and shell of this specially ordered variation of a McGhan/3M Style 81 implant (1981, Tampa, Fla). The implant patch is set inside the shell and has a "hammertone" appearance (ie, an irregular fine-scale roughening). A small raised gel fill point is seen inferior to the bar on the inferior edge of the patch (d). The shell was marked "265" in a "filled" numeral typeface inferior to the back patch and facing away from the patch (not shown here), in a configuration sometimes used by this manufacturer. A horizontal bar and external disk also were used on some specially ordered Heyer-Schulte (1975-76) and Surgitek (1984-86) implants from Tampa, Florida. These orientation features will rarely if ever be discernible on MR images.

View larger version (131K): [in this window] [in a new window] [Download PPT slide]   Figure 44. Orientation bar on implant shell. Dow Corning 930 series implant (placed about 1979) with a vertical 40-mm bar (unlabeled arrows) on the posterior inferior implant shell next to the back patch, meant to assist the surgeon in aligning the implant properly at time of placement. Note also the Dacron mesh-reinforced elastomer reinforcement disk (a) seen here internal to the Dacron mesh-reinforced elastomer back patch (b) (see Figs 48 and 49). The orientation bar will rarely if ever be discernible on MR images; however, with adequate resolution and experience, the MR imaging appearance of the internal Dacron mesh-reinforced elastomer disk can be specific for some Dow Corning implants from this period.

View larger version (99K): [in this window] [in a new window] [Download PPT slide]   Figure 45. Orientation dot on implant shell. A white orientation dot (a) is seen here attached directly to the implant shell of this Cox-Uphoff International (CUI) implant (placed 1977), adjacent to its back patch (b). The inner projection of the white dot is disklike with squared edges, about 8-9 mm in diameter, and its projection outside the implant shell is domelike. The raised gel-fill point (c) is seen centrally on the back patch. These dome-shaped white orientation dots were sometimes placed centrally on the back patch. They may sometimes be seen on MR images and, given adequate resolution and experience, may be distinguishable from the internal reinforcement disks used on Dow Corning implants from about the same period or earlier.