AJR:197, December 2011

Transcription

1 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

2 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

3 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

4 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

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

6 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

7 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

8 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

9 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

10 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

11 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 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

12 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

13 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

14 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

15 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

16 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

17 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

18 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

19 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

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

21 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

22 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

23 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

24 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

25 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

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

27 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

28 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

29 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

30 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

31 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

32 AJR: 197, December

33 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

34 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

35 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

36 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

37 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

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

39 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

40 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

41 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

42 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

43 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

44 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 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

45 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

46 AJR: 197, December

47 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

48 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

49 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

50 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

51 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

52 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

53 Breast implant--mri MRI is the most reliable imaging method for evaluation of silicone implant integrity, with sensitivity of % and specificity of %, 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

54 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

55 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

56 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

57 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

58 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

59 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

60 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

61 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

62 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

63 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

64 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

65 Fig 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

66 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

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

68 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

69 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

70 Fig 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

71 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

72 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

73 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

74 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

75 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

76 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

77 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

78 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

79 Fig 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

80 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

81 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

82 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

83 Fig 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

84 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

85 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

86 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

87 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

88 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

89 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

90 Autologous Fat Augmentation Autologous fat was used to fill scars initially in 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

91 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

92 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

93 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

94 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

95 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

96 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

97 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

98 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

99 Polyacrylamide Gel Injection Polyacrylamide gel has been used for augmentation in China, Eastern Europe, and South America since The gel is injected freely into the retroglandular space. Polyacrylamide gel contains % 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

100 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

101 Fig 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

102 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

103 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

104 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

105 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

106 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

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