Migration and biodegradation of free silicone from silicone gel-filled implants after long-term implantation

In vivo¹H NMR chemical shift imaging (CSI), ¹H NMR localized spectroscopy (STEAM) and multinuclear NMR spectroscopy ²⁹sl, ¹³C, ¹H) were used to characterize the aging process of silicone gel-filled implants in a rat model after long-term implantation. Although no significant changes could be observed in the implants or surrounding tissue by in vivo ¹H chemical shift imaging, in vivo ¹H localized spectroscopy of the livers from the longer term population revealed the presence of silicone. Ex vivo ²⁹Sl spectroscopy of the liver, spleen, and the capsule formed around the 9 and 12 month implants clearly demonstrated and confirmed for the first time that a significant amount of free silicone migrates from silicone gel-filled implants. Also, these results show that silicones are not metabolically inert, and their biodegradation in tissue and within the implant can be monitored after 9 and 12 months by changes in the ²⁹Sl chemical shifts seen in corresponding ex vivo spectra. The NMR findings are supported by those obtained by atomic absorption spectroscopy. Silicone aging changes not only the chemical composition of the gel, but also its proton T₂ relaxation times, which increase with long implantation times. The three dimensional structure of the gel disintegrates (i.e., polymer chain rupture), increasing the molecular mobility of the polymer and, consequently, its protons T₂ values. The relaxation data we obtained reflect this in vivo degradation, especially in the case of implant rupture. Additionally, small concentrations of fat in the silicone gel were found within the implants. The presence of these lipophilic substances also might increase the T₂ values (plasticizer effect). These findings may assist in evaluating the implant integrity and disease symptoms related to their presence in humans.     

Clonorchiasis: sonographic findings in 59 proved cases

Clonorchiasis is a parasitic disease of the bile ducts that occurs in endemic areas after ingestion of the raw flesh of freshwater fish. We analyzed the sonographic findings in 59 patients with clonorchiasis, suspected prospectively from sonographic findings and proved subsequently by demonstration of eggs in their stools. Diffuse dilatation of the small intrahepatic bile ducts with no or minimal dilatation of the large intra- and extrahepatic ducts was observed in all cases. The extrahepatic ducts were patent throughout in all except one case. This characteristic finding reflects diffuse intrahepatic bile duct obstruction and resultant proximal dilatation caused by an adult worm or aggregates of worms, as worms reside diffusely in the medium and small intrahepatic bile ducts. Cholangitis and multifocal periductal fibrosis with proximal dilatation may play an additional role. Increased echogenicity of the intrahepatic bile duct wall was present in 39 cases (66%), reflecting cholangitis and periductal fibrosis. In 17 cases (29%), floating or dependent, discrete, nonshadowing, intraluminal, echogenic foci caused by adult worms in the bile were demonstrated in the gallbladder. These echogenic foci were distinguished from stones because they were fusiform, weak in echogenicity, and floated with a change in position. Clonorchiasis should be considered when sonography discloses the characteristic pattern of bile duct dilatation with increased wall echogenicity and nonshadowing, discrete, echogenic foci in the gallbladder lumen.     

Oriental cholangiohepatitis: sonographic findings in 48 cases

Oriental cholangiohepatitis is characterized by recurrent attacks of abdominal pain, fever, chill, and jaundice and grossly dilated extrahepatic and intrahepatic ducts containing soft, pigmented stone and pus. Sonograms were studied in 48 patients in whom the diagnosis was later proved during surgery (n = 34) or on the basis of clinical and laboratory findings and endoscopic retrograde cholangiography (n = 14). The sonographic findings included intrahepatic and/or extrahepatic bile duct stones (n = 47); moderate to severe dilatation of the extrahepatic ducts with relatively mild or no dilatation of intrahepatic bile ducts (n = 41); localized dilatation of the lobar or segmental bile ducts, especially the left hepatic lobe (n = 16); and gallstones (n = 22). Our experience suggests that the preoperative diagnosis of oriental cholangiohepatitis can be strongly suggested by sonographic findings.     

Afferent loop syndrome: sonographic findings in seven cases

We studied the sonographic findings in seven patients in whom afferent loop obstruction was first detected by sonography. All seven subsequently were proved at surgery to have afferent loop syndrome. The causes of the obstruction included internal hernia (n = 3), cancer recurrence (n = 2), marginal ulcer (n = 1), and development of cancer at the anastomosis site (n = 1). In all cases, the dilated afferent loop was seen on sonography as a tubular structure in the upper abdomen crossing transversely over the midline. The distal end of the afferent loop could be traced toward the anastomosis. The probable cause of the syndrome was predicted on the basis of sonography in two of three patients with cancer at the anastomosis. Our experience suggests that afferent loop syndrome can be diagnosed sonographically on the basis of the detection, location, and shape of the dilated afferent loop.     

Ruptured breast implant: computed tomographic and mammographic findings

We report the computed tomographic and mammographic findings in a patient with a ruptured breast implant. The diagnosis was made by recognition of alteration in prosthesis contour, collapse of the prosthesis envelope, and the presence of free silicone in the breast and axillary region.     

MR imaging of extracapsular silicone from breast implants: diagnostic pitfalls.

OBJECTIVE: We sought to identify pitfalls in recognition of extracapsular silicone on MR imaging. MATERIALS AND METHODS: Three experienced observers reviewed MR images from 359 women with current (n = 320), prior (n = 15), or both current and prior (n = 24) silicone gel implants. Axial and sagittal fast spin-echo T2-weighted images with water suppression, axial inversion-recovery T2-weighted images with water suppression, and axial T2-weighted images with silicone suppression were obtained in a dedicated phased array breast coil on a 1.5-T magnet. Images were reviewed again when only one observer saw extracapsular silicone, and reasons for disagreement were recorded. RESULTS: Rupture was identified in 265 women (77%) with current silicone implants and 378 (55%) of 687 implants. Observers agreed in describing extracapsular silicone in 85 (12%) of 687 breasts with current silicone gel implants, of which 81 (95%) showed definite evidence of rupture on MR imaging. One observer reported extracapsular silicone in another 79 breasts. Confusion over contour deformity due to weakening versus breach of the capsule accounted for 33 (42%) of 79 disagreements. Another 20 (25%) of the 79 disagreements were attributed to poor conspicuity of extracapsular silicone on fast spin-echo T2-weighted images combined with intermittent observer failure to review inversion-recovery images. Subtlety of findings (n = 17, 22%) and technical issues (n = 9, 11%) with failed water suppression of pleural effusion or cysts and ghosting artifacts accounted for remaining disagreements. CONCLUSION: Extracapsular rupture is usually manifest as local spread of silicone in the breast and is not well-depicted on fast spin-echo T2-weighted images. Water-suppressed inversion-recovery T2-weighted images are often needed to identify extracapsular silicone. Distinction of the bulge in the fibrous capsule from herniation through the capsule remains problematic.     

Phantom evaluation of imaging modalities for silicone breast implants.

RATIONALE AND OBJECTIVES. Recent concern regarding possible adverse effects from silicone breast implants has increased the role of radiologists in assessing augmented breasts. The authors compare the commonly available imaging modalities in evaluating the intact silicone implant as well as free silicone in the adjacent tissue. METHODS. A contrast resolution phantom and breast of veal phantom were tested. Fat was used as a reference material. The phantoms were imaged with xeromammography, film-screen mammography, ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI). Proton MRI spectroscopy also was performed on fat, silicone, water, and water/gelatin samples. The consensus of two radiologists determined whether free silicone was present. RESULTS. CT and MRI provided the best images of the implant and the free silicone. Several features of MRI were useful: spin-density scans and the fast low-angle shot (FLASH) and fast imaging with steady-state precision (FISP) techniques provided excellent resolution, a consistent chemical shift artifact appeared around the silicone, and frequency selective pre-saturation techniques resulted in marked suppression of the silicone. CONCLUSION. Additional testing in a more realistic setting, breast coil design, and improvement of various MRI techniques, particularly the frequency selective pre-saturation techniques, all appear promising in evaluating breast implants, the presence of free silicone, and the adjacent tissues.     

Mammographic and sonographic findings in the breast and axillary tail following a COVID-19 vaccine

Axillary lymphadenopathy on breast imaging after recent coronavirus disease 2019 (COVID-19) vaccination has been reported in the literature as immunization has become more widespread. While muscle edema at the injection site has been observed on MRI secondary to an immune response, ipsilateral breast imaging observations of edema have not been reported to be seen with the COVID-19 vaccinations to date. Mammographic findings such as trabecular and skin thickening, along with increased echogenicity on ultrasound, can be seen with edema secondary to capillary leak or poor lymphatic drainage, and should be considered as a possible etiology for the observed breast edema following a recent COVID-19 vaccine. Inflammatory changes observed in the breast and axillary tail post vaccination described in this case series are transient, but clinically relevant for patients who experience swelling following injection. Similar to evaluations for suspected mastitis, a short interval imaging follow up to confirm resolution may be appropriate for patients with ipsilateral vaccination histories, and could potentially reduce the number of false positive examinations in this clinical scenario. However, inflammatory breast cancer can mimic inflammation and infection, therefore close follow up to resolution is critical as to not miss cancer.     

Infection in utero: US findings in 19 cases.

The results of antenatal sonographic studies of 19 fetuses with congenital infections were retrospectively reviewed by the authors. Recognizing the significance of these antenatal sonographic findings is important because in utero infections can have devastating effects on the developing fetus. An infectious viral agent was isolated in laboratory tests at birth in 11 patients, and the effects of a viral agent were proved clinically in eight. Antenatal sonography demonstrated abnormalities in 18 fetuses: Multiple organ systems were affected in 47%; intracranial abnormalities, cardiac abnormalities, and parenchymal calcifications occurred in 42%, 37%, and 32%, respectively; large placentas were seen in 32%; and the volume of amniotic fluid was decreased in 37% and increased in 37%. Sixty-three percent of fetuses were either aborted or died at birth; the 37% that lived were all developmentally impaired. On the basis of these sonographic, laboratory, and clinical findings, the authors conclude that when multiple organ system abnormalities are found at antenatal ultrasound, the presence of an in utero infection should be considered. The parents should be informed that there is a poor prognosis for any fetus demonstrating such abnormalities.     

29Si imaging of silicone breast implants and intraocular silicone oil

Silicon-29 (²⁹Si) imaging was investigated as a potential imaging modality for monitoring silicone prostheses in humans. The ²⁹Si relaxation times of several silicone gels were measured and found to average T₁ = 21.2 ± 1.5 s and T₂ = 207 ± 40 ms, with no significant difference between virgin and explanted gels. A single-shot half-Fourier rapid acquisition with relaxation enhancement (RARE) and a refocused gradientecho sequence were used for acquiring ²⁹Si images with 5 × 5 mm² resolution and no slice selection. Three volunteers with silicone-gel-filled breast implants and one subject with an intraocular silicone oil injection were thus examined in a total acquisition time of 10–15 min per image. On all ²⁹Si images, the shape of the silicone object was well depicted. Although at present, conventional proton images are superior in resolution and signal-to-noise ratio, ²⁹Si imaging has the advantage of optimal specificity, since only the silicone itself is visible.     

Paget's disease of the breast: clinical, mammographic, sonographic and pathologic findings in 52 cases

PURPOSE: To determine and quantitate radiologic characteristics of Paget's disease of the breast and to report clinical and pathologic findings. MATERIALS AND METHODS: A retrospective review of records of 2872 women who received a diagnosis of breast carcinoma between January 1988 and January 2006 revealed 52 histologically proved Paget's disease of the breast. Analysis included history, findings at physical examination, mammography and sonography (US) and histologic type of Paget's disease. RESULTS: At physical examination, palpable mass (n=33, 63%), nipple erythema-eczema-ulceration (n=17, 33%) and blood-stained nipple discharge (n=5, 10%) were noted. Among 17 patients who had clinically evident Paget's disease, the mammographic findings were isolated microcalcifications in 3 (18%), mass associated with microcalcifications in 5 (29%), mass in 2 (12%) and negative in 7 (41%) patients. In the 35 patients with clinically inevident Paget's disease, these mammographic findings were 43% (n=15), 34% (n=12), 20% (n=7) and 3% (n=1), respectively. US depicted 43 masses in 35 patients, all of which were lobulated or irregularly contoured, mostly (n=41, 95%) without posterior acoustic shadowing. The cancer was clinically occult in 10% (n=5), mammographically occult in 15% (n=8) and radiologically occult in 13% (n=7) of the 52 patients. Histologically, the tumor was multifocal and/or multicentric in 11 (21%) patients. CONCLUSION: The clinical features of Paget's disease are characteristic and should alert the clinician to the likelihood of an underlying carcinoma, which should be evaluated radiologically. However, as Paget's disease is primarily a clinical diagnosis and mammograms may be negative, screening programs without clinical examination may result with delay in diagnosis. As a result, both clinical and imaging findings are complementary and should be correlated to confirm or exclude a diagnosis of Paget's disease.     

Calcified pilomatrixoma of the breast: mammographic and sonographic findings

The authors report the ultrasonographic and mammographic features of a case of pilomatrixoma of the breast, a rare benign neoplasm originating from the hair matrix.     

乳腺叶状瘤的影像诊断

目的 总结分析乳腺叶状瘤X线钼靶照片和超声检查的影像学特征。方法 搜集1991年1月至2003年5月经手术、病理证实的25例乳腺叶状瘤，其中13例行X线钼靶摄片，17例行超声检查，回顾性分析其临床特点及影像学征象。结果 25例乳腺叶状瘤中病理诊断Ⅰ级者17例，Ⅱ级7例，Ⅲ级1例。13例行乳腺X线钼靶检查患者病灶表现为圆形(7例)或浅分叶状(6例)密度高于邻近腺体的肿块，边界清楚(8例)或部分不清(5例)，所有病例均未发现钙化及邻近皮肤增厚、乳头回缩、周围乳腺结构扭曲等恶性征象。行乳腺超声检查的17例患者，病灶表现为低回声者16例，边界规整者16例，出现囊变者10例，11例出现后方回声增强。结论 乳腺叶状瘤的影像学表现有一定的特点，但这些表现为非特征性，与纤维腺瘤等边界清楚的实性病灶的鉴别有一定的困难，对可疑病灶行切除活检非常必要。     

Mondor's disease of the breast: sonographic and mammographic findings

OBJECTIVE: The purpose of this study was to evaluate the mammographic and sonographic findings in patients with Mondor's disease of the breast. CONCLUSION: The combination of a sonographic finding of a superficial vessel-with or without an intraluminal thrombus and without flow on Doppler imaging-and a mammographic finding of a tubular density is the typical sign of Mondor's disease of the breast. Women present with a palpable cordlike structure, which is often painful, especially in the acute phase of thrombophlebitis. An understanding of such an entity and knowledge of the imaging findings will help breast imagers avoid the pitfall of mistaking this finding for a dilated duct.     

Dual-energy CT for the evaluation of silicone breast implants

Objective

The evaluation of breast implants for rupture is currently the domain of ultrasound and MRI, while mammography is of very limited diagnostic value. Recently, specific visualisation of silicone has become feasible using dual-energy CT. Our objective was to evaluate whether it is feasible to identify silicone in breast implants by dual-energy CT and to reliably diagnose or rule out ruptures.

Methods

Seven silicone breast implant specimens were examined on dual-source CT at 100- and 140-kV tube potential with a 0.8-mm tin filter (collimation 128 × 0.6 mm, current–time products 165 and 140 mAsref with modulation, rotation time 0.28 s, pitch 0.55). Two patients scheduled for implant removal or replacement were examined with identical parameters.

Results

The silicone of the implant specimens showed a strong dual-energy signal. In one patient, both implants were intact, while a rupture was identified in the other patient. Ultrasound, MRI, surgical findings and histology confirmed the dual-energy CT diagnosis.

Conclusion

Dual-energy CT may serve as an alternative technique for speedy evaluation of silicone breast implants. Specific clinical studies are required to determine the diagnostic accuracy and define indications for this technique.

Key Points

? Dual-energy CT makes it possible to visualise silicone in breast implants. ? Silicone provides a strong photoelectric effect that can be detected. ? Initial experience suggests that implant ruptures can be identified or ruled out.