AJR:197, December 2011

AJR:197, December 2011 William R. Geiser, Tamara Miner Haygood Lumarie Santiago, Tanya Stephens Debra Thames, Gary J. Whitman Presented by Chia-Ying WEN 2012/3/8

Early detection of breast cancer is directly related to the radiologist s ability to detect abnormalities visible only on mammograms. Artifacts on mammograms reduce image quality and may present clinical and technical difficulties for the radiologist, mammography technologist, medical physicist, and equipment service personnel. AJR:197, December 2011 2

Mammography is the reference standard for the detection of breast cancer. A mammogram is considered to be of high quality when it possesses the requisite characteristics to optimize a radiologist s ability to identify abnormalities with high sensitivity and high specificity. Artifacts reduce the quality of mammograms and may mimic or obscure abnormalities and cause interpretation errors. Recognizing artifacts improves the quality of mammographic interpretation and prevents the characterization of artifacts as breast disease. In this article, we group examples of artifacts into the following categories: detector related, machine related, patient related, and those associated with processing and storage. AJR:197, December 2011 3

In this article, we will illustrate the appearance of artifacts in full field digital mammography, review the causes of these artifacts, and discuss methods to eliminate artifacts in digital mammography. AJR:197, December 2011 4

Detector related Machine related Patient related Processing related Storage related AJR:197, December 2011 5

Detector-related artifacts arise directly from problems with the detector. The artifacts can be single dead pixels, groups of dead pixels, dead or unread lines, or ghosting. These artifacts can obscure or mimic breast disease (Figs. 1 4). AJR:197, December 2011 6

Fig. 1 Dead detector element identified on two different views. A, Right craniocaudal image of augmented breast taken on mammography system with seleniumbased detector. Zoomed image shows dead detector element (arrow) projecting over implant. Dead detector element is surrounded by black pixels in region of implant because of image processing that tries to make calcification-like objects stand out in otherwise white background. B, Same dead detector element (arrow) viewed in right craniocaudal view. Note that dead pixels can be mistaken for calcifications. Pixel appears white because it is in dark background. Service engineer was able to map out dead pixel and return system to clinic operations. AJR:197, December 2011 7

Fig. 2 Large number of misread or dead detector elements. A, Right craniocaudal magnification view shows selenium detector as it begins to fail with large number of misread or dead detector elements. Misread or dead pixels can look like clusters of microcalcifications (circle). B, Digital detector failure with large numbers of misread or dead pixels. Misread or dead pixels (circle) can look like clusters of microcalcifications (zoomed). AJR:197, December 2011 8

C, Magnification image of American College of Radiology accreditation phantom on detector as it starts to fail. Note white band of dead pixels (arrows). Failure of detector is a result of radiation damage to selenium layer that converts x-rays to signal. Manufacturer determined that detector was failing and replaced it within couple of days. Our experience shows that newer versions of this detector are more robust and do not suffer from this type of failure as often. AJR:197, December 2011 9

Fig. 3 Readout failure. A, Left mediolateral oblique view with failure of line (arrows) to read out on detector caused by problem with readout software. B, On repeat exposure, software corrected itself and image was correctly read out. To ensure that problem would not repeat itself, new detector readout sequence file was installed. AJR:197, December 2011 10

Fig. 4 Right lateromedial image shows ghost of previous mediolateral oblique image (arrows) visible. Ghost image was caused by low detector temperature. Allowing detector to warm up properly cleared problem. Proper operating temperature for detector is 25 35 C. Detector temperature was found to be at low end of allowed temperature range. With improvements in detector technology and systems to better regulate detector temperature, this problem is becoming less common. AJR:197, December 2011 11

Machine-related artifacts are created by components in the imaging chain that are not directly related to the detector. Most of these artifacts come from dirt or dust on the compression paddle or problems associated with the x-ray tube filtration and the grid. Other machine-based artifacts can arise when the automatic exposure control system is not properly adjusted. The image may process well and have the correct contrast and gray scale, but improper technique may result in a high noise level, which may obscure small objects that need to be seen (Figs. 5 7). AJR:197, December 2011 12

Fig. 5 Artifacts resulting from dust on compression paddle. A, Right mediolateral oblique view shows high-density specks (arrows) resulting from dust on compression paddle. B, Right lateromedial view shows highdensity specks (arrows), secondary to dust on compression paddle. Dust artifacts may mimic calcifications. AJR:197, December 2011 13

Mammography Quality Standards Act requires that procedures be established for infection control that allows... cleaning and disinfecting mammography equipment after contact with blood or other potentially infectious materials. This system shall specify methods for documenting facility compliance with infection control procedures established. Thorough cleaning of all surfaces of compression paddles at least weekly will prevent these artifacts. AJR:197, December 2011 14

Fig. 6 Noise obscuring calcification. A, Left craniocaudal view with visible calcification (arrow) seen through hematoma. B, Noise on magnified left craniocaudal view obscures calcification (circle). AJR:197, December 2011 15

Noise makes image appear to have many underexposed pixels, resulting in grainy appearance. This view should be repeated at higher peak kilovoltage and with exposure compensation setting of +2. Higher exposure compensation setting will cause automated exposure control system to increase required exposure by about 30%, lowering noise in image and improving contrast Automated exposure control for this system would normally compensate for difference in required exposure for magnification view. However, with hematoma in this patient, automated exposure control system did not properly compensate, and technologist was required to intervene. AJR:197, December 2011 16

Fig. 7 Gridlines (subtle cross-hatch pattern) on left craniocaudal view were caused by grid speed parameter being set incorrectly. This caused grid to be stopped during exposure, leaving grid shadow on image (cross-hatch pattern in region of clip marker). Grid speed parameter is set by service engineer and cannot be changed by technologist. Service call was placed to have grid speed parameter set properly. AJR:197, December 2011 17

Patient-related artifacts may be caused by motion or by superimposition of objects or substances over the breast parenchyma or substances on the skin [2]. The most common patient-related artifact is patient motion. Other types of artifacts include hair, gowns, or other foreign objects laid over the breast during imaging. The technologist may not notice that the patient has placed a hand on the breast support plate or compression paddle or that there are other foreign objects in the image field (Figs. 8 14). Proper positioning and examination of the field of view prior to making the exposure can eliminate many patient-related artifacts. AJR:197, December 2011 18

Fig. 8 Blurring as a result of patient motion during diagnostic mammogram. A, Blurring on magnified right lateromedial view as a result of patient motion. Edges of clips (arrows) have shadows. Patient motion is most common reason for repeat views at our facility. Blurring was not detected by technologist before sending image to be viewed by radiologist because technologist could not see blurring on relatively low- quality monitor at acquisition station. B, Repeat magnified right mediolateral view without patient motion shows clips in focus (arrows). Higher compression and reduced exposure time eliminated patient motion and improved image quality. AJR:197, December 2011 19

Fig. 9 Tape (arrows) on right craniocaudal view. Tape artifact can cause anatomy to be obscured on image. AJR:197, December 2011 20

Fig. 10 Skin lesion mimicking calcifications. A, Left craniocaudal view of patient with yeast infection resulting in coarse flaky skin mimicking calcifications (oval). Bright circle is nipple marker. Powders, creams, and ointments may also cause such artifacts. B, Left craniocaudal view of patient 1 month later, after infection has cleared. Artifacts mimicking calcifications are no longer visible. AJR:197, December 2011 21

Fig. 11 Right mediolateral oblique view of patient with port for central line. Dark halo around high-density axillary port represents common processing artifact resulting from high degree of edge enhancement in image processing. Gray halo at periphery of image (arrows) is also processing artifact, but has no effect on image quality. AJR:197, December 2011 22

Fig. 12 Left mediolateral oblique view with eye glasses (arrow) in image field of view. Making sure that face shield is in place will prevent this type of artifact. AJR:197, December 2011 23

Fig. 13 Left mediolateral oblique view of patient with free silicone injections. Free silicone can obscure disease and lowers sensitivity of mammography. AJR:197, December 2011 24

Fig. 14 Right craniocaudal view with scar marker. Tape (arrows) holding scar marker in place is visible. This may obscure underlying disease. AJR:197, December 2011 25

Processing artifacts are caused by the inability of the processing algorithm to compensate for differences in exposure across the detector (Figs. 15 17). AJR:197, December 2011 26

Fig. 15 Right lateromedial view of radiated breast shows detector interface line (arrow) from seleniumbased detector. This artifact is caused by slight difference in calibration of two halves of detector and relatively high exposure for imaging very dense irradiated breast. AJR:197, December 2011 27

Fig. 16 Incorrect setting of skin line processing. A, Right craniocaudal view with appropriate skin line processing. B, Left craniocaudal view after segmental mastectomy and radiation therapy with incorrect skin line processing. AJR:197, December 2011 28

Fig. 17 Pixel dropout. A, Right lateromedial view of patient with clip marker placed after percutaneous biopsy. B, Right lateromedial sport compression view shows pixel dropout in center of clip marker. Pixel dropout was caused by effect of spot compression paddle on image processing algorithm. This artifact is seen frequently in spot views of highdensity objects. AJR:197, December 2011 29

Storage-related artifacts are caused when the PACS does not properly reconstruct the image for display or does not properly interpret the DICOM header information and uses improper display parameters. There can also be problems with the reconstruction of the image when it is sent to the review workstation. Failure to properly reconstruct the image at the review station can cause improper display of the image, making the image unreadable[4] (Fig. 18). AJR:197, December 2011 30

Fig. 18 Reconstruction artifact caused incorrect storage of frequency coefficients for image. Image could not be recovered from PACS. It is important that technologist check images sent to PACS after completion of each study. This artifact would only be seen with PACS vendors that use wavelet coeffi cients to store images. AJR:197, December 2011 31

AJR: 197, December 2011 32

Challenges in Mammography: Part 2, Multimodality Review of Breast Augmentation Imaging Findings and Complications AJR:197, December 2011 Shambhavi Venkataraman Neely Hines Priscilla J. Slanetz

OBJECTIVE. Breast augmentation is common throughout the world; however, there is variation in materials and surgical techniques. This review illustrates the mammographic, sonographic, and MRI characteristics of the different types of breast augmentation, including silicone, saline, polyacrylamide gel, and autologous fat augmentation. AJR: 197, December 2011 34

Be sure to hold both a Natrelle silicone gel (left) and saline implant (right) in your hands before making your choice. There is a measurable difference in the feel you achieve with each of these choices. AJR: 197, December 2011 35

Introduction Breast augmentation is a common cosmetic procedure, and many women who have undergone augmentation present for mammographic screening. Although silicone and saline implants are the most common form of augmentation seen on imaging, there is tremendous variation in surgical techniques and materials throughout the United States and the world. Therefore, less common forms of augmentation, such as free silicone injection, polyacrylamide gel, and autologous fat augmentation, may also be seen when evaluating women in a screening or diagnostic setting. Familiarity with all forms of augmentation is important to maximize cancer detection and manage complications related to augmentation procedures. AJR: 197, December 2011 36

Introduction In this article, we will review the imaging appearance of the various types of augmentation that may be seen in a typical breast imaging practice and present some of the more common complications that may be encountered. The imaging findings of complications such as implant rupture, free silicone, and fat necrosis in association with augmentation will be illustrated. AJR: 197, December 2011 37

All forms of augmentation Silicone Saline Polyacrylamide gel (PAAG) Autologous fat augmentation Free silicone injection AJR: 197, December 2011 38

OUTLINE Breast implant Implant Complications (1) Periimplant Fluid Collection (2) Capsular Contraction (3) Rupture (4) Gel Bleed Free Silicone Injection Autologous Fat Augmentation Polyacrylamide Gel Injection Summary AJR: 197, December 2011 39

Breast implant Placement of an implant is the most common form of augmentation around the world. Implants are typically composed of an envelope which contains the implant filling Implants most commonly contain either silicone or saline and are single lumen. Other variations, such as double lumen (i.e., silicone on the inside with an outer saline component), reverse double lumen (i.e., saline on the inside with an outer silicone component), and stacked implants, may also be encountered. AJR: 197, December 2011 40

Breast implant Double lumen--- silicone on the inside with an outer saline component Reverse double lumen--- saline on the inside with an outer silicone component AJR: 197, December 2011 41

Breast implant Implants can be placed anterior (subglandular) or posterior (subpectoral) to the pectoralis major muscle (Figs. 1A and 1B). Once placed into the body, a thick fibrous capsule forms around the implant, which may be visualized as a band of soft-tissue density with or without calcification surrounding the implant. AJR: 197, December 2011 42

Fig. 1 Subpectoral and subglandular silicone, saline, and double-lumen breast implants in different patients. A, In left mediolateral oblique B, In left MLO view of subpectoral (MLO) view of extremely dense saline implant, pectoralis muscle subglandular silicone implant, (arrow) is seen anterior to implant. pectoralis muscle (arrow) is seen Saline implant is less dense than diving posterior to dense oval silicone implant implant. AJR: 197, December 2011 43

Breast implant Silicone implants consisting of a silicone or polyurethane envelope filled with silicone gel came into use in 1963 and were used as a common form of augmentation until 1992 when they were banned by the U.S. Food and Drug Administration because of a possible association with connective tissue diseases. Further investigation into the safety of silicone gel by the Institute of Medicine began in 1998, leading to a reversal of the ban in 2005. Saline implants were first used in 1962 but came into favor in 1992 after the ban of using silicone for augmentation. They are composed of a silicone envelope with a valve and are inflated with saline. AJR: 197, December 2011 44

Breast implant--mammography The screening mammogram should include implantdisplaced (Eklund technique) craniocaudal (CC) and mediolateral oblique(mlo) views in addition to the standard CC and MLO views. On mammography, silicone implants appear as dense oval masses in either a subglandular or subpectoral position(fig. 1A). Because of the density of the silicone, a discernable envelope and its accompanying folds are not visualized mammography (Table 1). AJR: 197, December 2011 45

AJR: 197, December 2011 46

Breast implant--mammography Mammographically, saline implants are seen as oval masses either anterior or posterior to the pectoralis muscle with a dense peripheral envelope and a valve with a more lucent center. Folds in the implant envelope, the valve, glandular tissue, and vasculature can all be seen through the implant given the appropriate mammographic technique (Figs. 1B and 1C and Table 1). AJR: 197, December 2011 47

C, Left MLO view of subglandular saline implant shows visible folds as curvilinear densities superimposed on implant (arrowhead). Valve (oval) is seen anteriorly in profile. D, Left MLO view of subpectoral double-lumen silicone and saline implant shows that implant is composed of extremely dense inner siliconefilled envelope surrounded by less dense saline-filled envelope. AJR: 197, December 2011 48

Breast implant--mammography Double-lumen implants are less commonly used and are produced with many variations. Combination silicone and saline double-lumen implants may be seen with an inner silicone gel-filled envelope surrounded by an outer adjustable saline-filled envelope or an inner adjustable saline-filled envelope surrounded by an outer silicone envelope (Fig. 1D). Double-lumen implants consisting of a silicone-filled envelope within a silicone-filled envelope may also be seen (Table 1). AJR: 197, December 2011 49

Breast implant--ulatrasound On ultrasound, both saline and silicone implants appear internally anechoic with triangular shape, surrounded by a linear echogenic envelope. The envelope is variable in appearance, consisting of a single echogenic line or parallel echogenic lines. The fibrous capsule may also be visualized sonographically as two parallel echogenic lines superficial to the implant surface (Figs. 2A and 2B and Table 1). If calcification of the fibrous capsule is present, echogenic foci with posterior shadowing may be seen within the fibrous capsule. AJR: 197, December 2011 50

Fig. 2 Gray-scale ultrasound images of silicone and saline breast implants in different patients. A, In gray-scale image, silicone implant is seen as anechoic luid posterior to breast tissue. Envelope (arrows) is seen as two undulating parallel echogenic lines. AJR: 197, December 2011 B, In gray-scale image, saline implant is seen as anechoic luid posterior to breast tissue. Envelope is seen as two parallel echogenic lines. Inlation valve (arrows) is seen as two areas of disruption of lines. 51

Breast implant--ultrasound Undulations and folds in the envelope are seen as waves and extension of the envelope into the substance of the implant without intervening fluid. Glandular tissue and fat are seen superficial to the implant and fibrous capsule. The valve of saline implants may be seen as a focal disruption or separation in the parallel lines of the capsule. The second chamber of a double lumen implant can be visualized and should not be confused for a rupture AJR: 197, December 2011 52

Breast implant--mri MRI is the most reliable imaging method for evaluation of silicone implant integrity, with sensitivity of 74 100% and specificity of 63 100%, depending on the technique. In contrast, MRI does not have a role in evaluating saline implant integrity because a ruptured saline implant presents clinically as an acute reduction in breast size, especially compared with the unaffected side. AJR: 197, December 2011 53

Breast implant--mri Despite this fact, when MRI is performed to evaluate the breast tissue, all types of breast augmentation may be encountered. Silicone gel within an implant is homogeneously high signal intensity on T2-weighted images and low signal intensity on T1-weighted images surrounded by a low signal envelope and fibrous capsule on all sequences (Figs. 3A and 3B). Silicone-sensitive inversion recovery sequences or a modified 3-point Dixon technique are also used to detect high-signal silicone in the evaluation of implant rupture. AJR: 197, December 2011 54

Fig. 3 MRI scans of patients with silicone (A and B) and saline implants (C and D). A, Woman with silicone implants. Axial fat-suppressed silicone-sensitive inversion recovery image shows bilateral hyperintense breast implants. Fold (arrowhead) is seen as low-signal projection originating from envelope in lateral aspect of left implant. B, Axial fat-suppressed contrastenhanced T1-weighted image shows intermediate-to-low-signal bilateral silicone implants. Folds (arrowheads) are seen as low-signal lines extending into implant from envelope. AJR: 197, December 2011 55

Breast implant--mri Saline implants follow fluid signal on all sequences, high signal intensity on T2-weighted images, and low signal intensity on T1-weighted images (Figs. 3C and 3D). The envelope and fibrous capsule are low signal on all sequences, as is the valve, which is seen as a low-signal mural nodule on all sequences. Folds in the envelope are seen as low-signal linear and curvilinear lines extending from the envelope into the silicone gel or saline. Folds are frequently seen in both saline and silicone implants and should not be mistaken for rupture (Fig. 3B and Table 1). AJR: 197, December 2011 56

C, Woman with bilateral saline implants. Axial fat-suppressed inversion recovery image shows uniformly high-signalintensity implants. Valve (oval) is seen as low-signal mural nodule at anterolateral aspect of right implant. Small fold (arrowhead) is seen at medial margin of right implant. AJR: 197, December 2011 D, Axial fat-suppressed contrastenhanced T1-weighted image of same patient in C shows uniformly low-signal implants. Valve (circle) is again seen as low-signal mural nodule. 57

Implant Complications In addition to postoperative complications of breast augmentation, such as seroma, hematoma, and infection, delayed complications such as implant rupture, gel bleed, and capsular contraction may occur. AJR: 197, December 2011 58

Implant Complications -- Periimplant Fluid Collection Fluid collections surrounding silicone and saline implants are common.the implant capsule generates a foreign body reaction and chronic inflammation, resulting in fluid collection. On ultrasound imaging, the fluid can be complex with multiple internal echoes or simple and anechoic (Figs. 4A and 4B). AJR: 197, December 2011 59

Fig. 4 Gray-scale ultrasound images (A and B) and MR images (C and D) of implants in two different patients. B, Gray-scale image of saline A, In gray-scale image, saline implant implant in same patient in A is seen as anechoic luid posterior to seen as anechoic luid posterior breast tissue. Envelope is seen to breast tissue. Envelope is partially as curvilinear echogenic line. seen partially as curvilinear Fluid collection (star) is seen external echogenic line. Anechoic simple to capsule containing multiple internal luid collection (star) is seen echoes. external to capsule. AJR: 197, December 2011 60

Implant Complications -- Periimplant Fluid Collection The fluid collection surrounding an intact implant capsule is also well seen on MRI, presenting with homogeneous increased T2 signal surrounding an intact implant (Figs. 4C and 4D). The presence of fluid surrounding an implant is a nonspecific finding and does not necessarily warrant intervention. AJR: 197, December 2011 61

C, Woman with intact silicone implant. Axial fat-suppressed unenhanced wateronly image shows homogeneously highsignal luid surrounding implant. D, Axial fat-suppressed fluidsensitive inversion recovery image from same patient in C shows intact silicone implant and T2 high-signal fluid surrounding implant capsule. AJR: 197, December 2011 62

Implant Complications -- Capsular Contraction Capsular contraction is the most common implant complication and is more commonly seen with silicone implants as a result of foreign body reaction, possibly incited by small droplets of silicone that traverse the envelope. The fibrous capsule around the implant contracts, resulting in hardening and deformity of the implant, which leads to alteration in breast shape and discomfort. Capsular contraction is a clinical diagnosis and often is not appreciated on imaging. AJR: 197, December 2011 63

Implant Complications -- Capsular Contraction Mammographically, the implant may appear spherical rather than elliptical in shape, or it may develop unusual areas of bulging (Fig. 5). Capsular contracture may not always have findings sonographically or on MRI; however, thickening of the echogenic fibrous capsule with an increased number of radial folds and an increased anteriorposterior diameter may be seen. If it is symptomatic, treatment consists of capsulectomy or capsulotomy (multiple longitudinal slices in the capsule) AJR: 197, December 2011 64

Fig. 5 40-year-old woman presenting with hardening of left breast implant shows capsular contraction in this mediolateral oblique view. Affected implant is spherical with deformity of superior aspect of implant. AJR: 197, December 2011 65

Implant Complications -- Rupture Rupture is the most common reason for removal of a breast implant, although there is no known medical risk of having a ruptured implant. When a saline implant ruptures, the body resorbs the saline, leaving a collapsed envelope and capsule. The capsule may not completely collapse if it is coarsely calcified. AJR: 197, December 2011 66

Implant Complications -- Rupture For silicone breast implants, there are two types of rupture: (1) Intra-capsular (2) Extra-capsular AJR: 197, December 2011 67

Implant Complications -- Rupture : Intra-capsular Intracapsular rupture: is defined as rupture of the polyurethane envelope with silicone contained within the surrounding fibrous capsule. On mammography: This type of rupture may not be detectable mammographically, because the density of the silicone prevents visualization of the implant envelope. The shape of the implant is generally maintained; however, the implant may appear expanded compared with the contralateral implant. AJR: 197, December 2011 68

Implant Complications -- Rupture : Intra-capsular On ultrasound: the presence of horizontally stacked echogenic lines corresponding to the displaced envelope within the anechoic silicone gel, or the stepladder sign, may be seen, which is in contrast to the normal vertical extensions of radial folds (Fig. 6A). The silicone gel between the fibrous capsule and the collapsed envelope may be slightly increased in echogenicity, although this is a less reliable sign. AJR: 197, December 2011 69

Fig. 6 52-year-old woman with intracapsular silicone implant rupture presenting for evaluation of implant integrity A, Gray-scale transverse image of left breast shows partially collapsed envelope (arrows) as parallel echogenic lines within substance of implant. AJR: 197, December 2011 70

Implant Complications -- Rupture : Intra-capsular On MRI: In reality, the most sensitive and specific imaging test for intracapsular rupture is MRI. The ruptured envelope is seen as multiple lowsignal curvilinear lines within the highsignal silicone gel on T2-weighted and silicone-sensitive sequences, often referred to as the linguine sign (Fig. 6B). AJR: 197, December 2011 71

B, Axial T2-weighted image shows low-signal collapsed envelope within high-signal-intensity silicone ( linguine sign ) in left breast. Highsignal silicone is within expected margins of implants. Right breast implant is intact. AJR: 197, December 2011 72

Implant Complications -- Rupture : Intra-capsular On MRI: More subtle areas of focal separation of the envelope from the fibrous capsule forming teardrop-shaped involutions of the envelope or subcapsular lines with intervening silicone are early signs of intracapsular rupture (sometimes referred to as the teardrop or keyhole sign). Silicone signal is not seen to extend beyond the low-signal fibrous capsule. AJR: 197, December 2011 73

Implant Complications -- Rupture : Extra-capsular Extracapsular rupture : may be diagnosed mammographically, sonographically, or on MRI. Free silicone is seen as dense lobulated masses outside the implant margins (Fig. 7A). Extremely dense axillary lymph nodes may be present because silicone gel is cleared by the lymphatics of the breast. Less-specific mammographic signs of extracapsular rupture include implant asymmetry or irregularity of the implant contour. AJR: 197, December 2011 74

Fig. 7 Two patients with ruptured silicone implants A, 36-year-old woman with silicone implant who complained of palpable lump in right upper outer quadrant. Mediolateral oblique view shows three round dense masses of free silicone (arrows) in superior right breast corresponding to palpable area of concern. Presence of extracapsular silicone is diagnostic of extracapsular rupture. B, Gray-scale image of same patient in A shows echogenic round mass (star) with dirty shadowing (triangle) supericial to implant, corresponding to free silicone seen mammographically. AJR: 197, December 2011 75

Implant Complications -- Rupture : Extra-capsular Sonographic evaluation may reveal masses with a well-defined echogenic anterior surface and dirty shadowing (snowstorm sign). Hypoechoic or anechoic masses with or without posterior shadowing may also be seen (Fig. 7B). If silicone is present within lymph nodes, the node may become echogenic and have dirty shadowing. AJR: 197, December 2011 76

Implant Complications -- Rupture : Extra-capsular Rupture of saline implants is evident clinically and with all forms of imaging because the extruded saline is resorbed by the lymphatics, leading to complete collapse of the implant. This leak can be acute or gradual over a few days or months, resulting in decrease in size or change of shape of the implant. Clinical breast examination to evaluate difference in size of shape of the implant is sufficient to make the diagnosis. AJR: 197, December 2011 77

Implant Complications -- Rupture : Extra-capsular On Mammography: The collapsed envelope is seen folded posterior to the breast tissue (Fig. 8A). On Sonography: Multiple stacked echogenic linear and curvilinear parallel lines may be seen posterior to the breast tissue sonographically (Fig. 8B). AJR: 197, December 2011 78

Fig. 8 38-year-old woman with history of trauma and delated saline implant on clinical examination complaining of pain following saline implant rupture. A, Left mediolateral oblique view shows collapsed folded implant envelope (arrow) posterior to pectoralis muscle. B, Transverse gray-scale image of left breast shows stacked echogenic lines (arrows) corresponding to collapsed envelope of delated implant. There is no residual saline present. AJR: 197, December 2011 79

Implant Complications -- Rupture : Extra-capsular On MRI: The collapsed envelope appears as multiple stacked curvilinear low-signal bands. MRI is useful for the evaluation of mammographically occult extracapsular rupture and can evaluate the extent of free silicone. The contour of the implant may be irregular, with globular masses or linear collections of high-signal-intensity free silicone separate from the implant in the breast tissue or within the axilla on T2-weighted and silicone-selective sequences (Fig. 7C). There is no enhancement with gadolinium administration, unless there is active inflammation related to the formation of silicone granulomas. AJR: 197, December 2011 80

7C, Woman with palpable mass and history of ruptured silicone implant replaced with saline implant. Sagittal fatsuppressed silicone-sensitive inversion recovery image shows multiple lobulated high-signal masses of residual silicone (arrows) are seen supericial to new implant and deep to pectoralis muscle. AJR: 197, December 2011 81

Implant Complications Gel Bleed Transudation of microscopic silicone gel across an intact envelope into the surrounding tissue and lymphatics is referred to as a gel bleed. This may result in a thickened fibrous capsule and capsular contraction. Additionally, silicone may be visualized in axillary lymph nodes mammographically, sonographically, and on MRI (Fig. 9). AJR: 197, December 2011 82

Fig. 9 50-year-old woman with bilateral subglandular silicone implants presenting for annual examination found to have gel bleed from right implant. A, Mediolateral oblique view shows mammographically intact subglandular silicone implant with dense lymph nodes in axilla. AJR: 197, December 2011 83

Free Silicone Injection Free silicone injection was commonly used for augmentation in the 1950s and 1960s in the United States but was discontinued because of safety concerns and ineffectiveness. Free silicone injection is no longer performed in the United States because it was banned by the U.S. Food and Drug Administration in 1992, but it may be seen in older patients and immigrants, particularly those from South America and Asia. AJR: 197, December 2011 84

Free Silicone Injection Complications are common and include: (1) inflammation with formation of silicone granulomas (2) fibrosis (3) lymphadenopathy. Silicone granulomas are palpable as diffuse nodularity and hard lumps, making clinical breast examination difficult. AJR: 197, December 2011 85

Free Silicone Injection On mammography: free silicone appears as multiple extremely dense lobulated masses throughout the breast with or without peripheral calcifications (Figs. 10A and 10B). These masses can distort the breast parenchyma and obscure visualization of a small breast cancer. Extremely dense lymph nodes may also be present. AJR: 197, December 2011 86

Fig. 10 Two different women with history of free silicone injection presenting with multiple palpable masses. A, Craniocaudal view shows multiple round and lobulated extremely dense masses of free silicone obscuring breast parenchyma. B, Woman with breast biopsy marker over palpable area. Craniocaudal view shows extremely dense masses (arrows). AJR: 197, December 2011 87

Free Silicone Injection Sonographic and MRI findings are similar: To those of extracapsular rupture; however, findings are scattered throughout the breasts without the presence of an envelope or fibrous capsule (Figs. 10C 10E). MRI, especially with fat and water suppression technique or 3-point Dixon technique, provides optimal visualization of free silicone and permits differentiation of free silicone from a breast neoplasm AJR: 197, December 2011 88

C, Ultrasound of palpable area in same patient in B shows multiple lobulated anechoic masses. This is different appearance from free silicone shown in Figure 7. D, T1-weighted fat-saturated sagittal MR image of same patient in B and C shows low-density welldeined ovoid masses (arrow), corresponding to masses seen on mammogram. AJR: 197, December 2011 E, T2-weighted non fatsaturated sagittal MR image of same patient in B D shows highsignal well-deined masses (arrow) of free silicone. 89

Autologous Fat Augmentation Autologous fat was used to fill scars initially in 1893. The technique was first used for breast reconstruction in 1895, but became popular in the 1980s. After liposuction at the donor site, the fat is treated with insulin and injected into the breast with or without imaging guidance. The fat can obscure native breast tissue and can also induce inflammatory changes that decrease mammographic detection of small breast cancers. AJR: 197, December 2011 90

Autologous Fat Augmentation Mammographic findings: (1) Scattered microcalcifications (2) Single or multiple radiolucent masses with or without peripheral eggshell calcification, spiculated masses (Figs. 11A and 11B). (3) Fat necrosis is a frequent complication of autologous fat augmentation resulting from nonvascularization of the injected fat. AJR: 197, December 2011 91

Fig. 11 Two patients with history of fat augmentation. A and B, 45-year-old woman from Bolivia with history of autologous fat augmentation presenting with bilateral palpable masses. Bilateral mediolateral oblique views show single round mass with lucent center and peripheral calciication as a result of fat necrosis in each breast. AJR: 197, December 2011 92

Autologous Fat Augmentation The extent and stage of fat necrosis defines the mammographic appearance. A radiolucent mass is seen in early fat necrosis with little or no fibrosis. More extensive fibrosis can present as a spiculated mass with calcifications. The calcifications can be confused with intraductal carcinoma and necessitate careful follow-up with imaging or biopsy. AJR: 197, December 2011 93

Autologous Fat Augmentation Sonographic findings: sonographic are variable, ranging from simple or complicated cysts with low level internal echoes to cysts with an echogenic anterior margin and associated posterior shadowing resulting from calcification or a hypoechoic solid mass. In most cases, the fat is injected in the retromammary layer and the nodules from fat injection are seen predominantly in this layer, whereas most breast cancers are located in the mammary tissues. AJR: 197, December 2011 94

Autologous Fat Augmentation In most cases, autologous fat can be distinguished from breast cancer according to the location, absence of blood flow, cystic nature, and presence of eggshell calcification.onset of fat necrosis alters the ultrasound appearance of autologous fat. Fat necrosis can be seen as an oval to irregular mass, with ill-defined margins and posterior acoustic shadowing often mimicking the appearance of breast cancer. At times, biopsy may be indicated to exclude a malignancy. AJR: 197, December 2011 95

Autologous Fat Augmentation MRI findings: The MRI appearance also depends on the stage of fat necrosis, amount of fibrosis, and degree of inflammatory change in the breast tissue. The calcifications on mammography are not usually seen on MRI but may occasionally be seen as focal signal voids (Fig. 11C). Fibrosis is seen as focal architectural distortion or as a spiculated mass. Fat necrosis can show enhancement on MRI, with more intense enhancement observed in the early stages of fat necrosis (Fig. 11D). Other complications of the procedure have been reported, including edema, hematoma, infection, granuloma formation, cyst formation, fibrosis, and fat resorption. AJR: 197, December 2011 96

C, Woman with history of free fat injection for augmentation. T1-weighted fatsuppressed unenhanced sagittal image shows focal area of calciication from fat necrosis (arrow) is seen as signal void. D, T1-weighted fat-suppressed contrast-enhanced sagittal image of same patient in C shows multiple foci of irregular enhancement with central signal void (arrows) in areas of fat necrosis. AJR: 197, December 2011 97

Autologous Fat Augmentation Treatment options for patients presenting with symptoms after autologous fat injection include pain management or surgical excision of the transplanted fat. Diagnostic or therapeutic needle aspiration is not recommended because of spillage of oil cyst contents, inciting additional foreign body and granulomatous reaction. AJR: 197, December 2011 98

Polyacrylamide Gel Injection Polyacrylamide gel has been used for augmentation in China, Eastern Europe, and South America since 1997. The gel is injected freely into the retroglandular space. Polyacrylamide gel contains 95 97.5% water and shows density similar to that of saline implants on mammography. The gel is seen most commonly as a single round, oval, or lobulated mass posterior to the glandular tissue but may present as multiple masses if multiple sites are injected. AJR: 197, December 2011 99

Polyacrylamide Gel Injection The gel cannot be distinguished from native breast tissue on palpation, and implantdisplaced views are not helpful in the imaging evaluation. The gel may be difficult to visualize mammographically because it often can be the same x-ray attenuation as dense fibroglandular tissue (Fig. 12A). AJR: 197, December 2011 100

Fig. 12 43-year-old woman with polyacrylamide gel augmentation A, Craniocaudal view shows isodense mass (star) in medial aspect of breast. B, Gray-scale image shows implant as well-deined luid collection with multiple internal echoes. AJR: 197, December 2011 101

Polyacrylamide Gel Injection Sonographic evaluation most commonly shows a circumscribed lobulated anechoic fluid collection in the retroglandular space, although it may be complex or complicated in appearance. The gel implant can contain variable internal echoes and a thin echogenic wall (Fig. 12B). AJR: 197, December 2011 102

Polyacrylamide Gel Injection Because of its high water content, polyacrylamide gel is similar to water on MRI and has low-tointermediate signal intensity on T1-weighted sequences and high signal intensity on T2-weighted sequences (Figs.12C and 12D). The gel has similar signal intensity to glandular tissue on T1-weighted non fat-saturated sequences. The implant is best seen separately from both subcutaneous and retroglandular fat and from glandular tissue on T2- weighted non fat-saturated sequence. Foci of low signal intensity can be seen on T2-weighted images and are thought to represent air or debris within the gel. A thin rim of delayed enhancement may be seen (Fig. 12E). AJR: 197, December 2011 103

C, T1-weighted fat-suppressed sagittal image shows low-signal-intensity implant (arrows) in retroglandular space. D, T2-weighted fat-suppressed sagittal image shows high-signal-intensity implant (arrows) with multiple foci of low signal within. These foci of low signal are analogous to echogenic foci seen within implant on ultrasound. E, T1-weighted fat-suppressed sagittal image obtained after gadolinium enhancement shows thin rim of enhancement surrounding implant with relative nonenhancement of gel. AJR: 197, December 2011 104

Polyacrylamide Gel Injection Common complications seen with gel injection are unsatisfactory breast shape, breast pain, breast lumps, inflammation, and gel migration. The extent and distribution of gel inside the breast to evaluate cosmesis and the presence of gel migration are best seen on T2-weighted images. It is important to include the entire gel implant in the breast coil. Parts of the breast with the gel imaged outside the coil can mimic gel migration. A dynamic contrast-enhanced T1-weighted fat saturated sequence is used to evaluate inflammatory change and mass lesions. AJR: 197, December 2011 105

Summary There is vast variation in breast augmentation materials and techniques. The radiologist must be familiar with both common and uncommon types of augmentation as well as their complications because they will be encountered in both screening and diagnostic populations. Although saline and silicone implants are by far the most commonly encountered, an awareness of the imaging appearances of free silicone injection, autologous fat augmentation, and polyacrylamide gel injection on mammography, ultrasound, and MRI is essential to provide optimal care. AJR: 197, December 2011 106