Evaluating silicone breast implant rupture with photon-counting CT and volumetric silicone maps

We present a case of an 81-year-old woman who presented to the emergency department with bleeding from a right breast wound. The patient had prior imaging suggestive of bilateral silicone implant rupture and a history of low tolerance for MRI scans. Ultrasound imaging in the emergency setting showed findings in the right breast suggestive of a fistula with free silicone and hematoma. A subsequent photon-counting CT scan with custom silicone-specific segmentation allowed differentiation of silicone from hematoma, provided anatomic assessment and location of the fistula, and revealed bilateral silicone-induced lymphadenopathy.

What to Expect (and What Not) from Dual-Energy CT Imaging Now and in the Future?

Dual-energy CT (DECT) imaging has broadened the potential of CT imaging by offering multiple postprocessing datasets with a single acquisition at more than one energy level. DECT shows profound capabilities to improve diagnosis based on its superior material differentiation and its quantitative value. However, the potential of dual-energy imaging remains relatively untapped, possibly due to its intricate workflow and the intrinsic technical limitations of DECT. Knowing the clinical advantages of dual-energy imaging and recognizing its limitations and pitfalls is necessary for an appropriate clinical use. The aims of this paper are to review the physical and technical bases of DECT acquisition and analysis, to discuss the advantages and limitations of DECT in different clinical scenarios, to review the technical constraints in material labeling and quantification, and to evaluate the cutting-edge applications of DECT imaging, including artificial intelligence, qualitative and quantitative imaging biomarkers, and DECT-derived radiomics and radiogenomics.

Photon-counting CT of degenerative changes and rupture of silicone breast implants: a pilot study

BACKGROUND

Accurate assessment of breast implants is important for appropriate clinical management. We evaluated silicone properties and diagnostic accuracy for characterizing silicone implants and detecting degenerative changes including rupture in photon-counting computed tomography (PCCT).

METHODS

Over 16 months, we prospectively included patients with silicone implants and available breast magnetic resonance imaging (MRI) who received thoracic PCCT performed in prone position. Consensus reading of all available imaging studies including MRI served as reference standard. Two readers evaluated all implants in PCCT reconstructions for degenerative changes. In a subgroup of implants, mean density of silicone, adjacent muscle, and fat were measured on PCCT reconstructions. Contrast-to-noise ratios (CNRs) were calculated for implant-to-muscle and implant-to-fat.

RESULTS

Among 21 subjects, aged 60 ± 13.1 years (mean ± standard deviation) with 29 implants PCCT showed the following: high accuracy for linguine sign, intraimplant fluid (all > 0.99), peri-implant silicone (0.95), keyhole sign (0.90), and folds of the membrane (0.81); high specificity for linguine sign, intraimplant fluid, keyhole sign, folds of the membrane (all > 0.99), and peri-implant silicone (0.98); and high sensitivity for linguine sign and intraimplant fluid (all > 0.99). In a subgroup of 12 implants, the highest CNR for implant-to-muscle was observed on virtual unenhanced reconstructions (20.9) and iodine maps (22.9), for implant-to-fat on iodine maps (27.7) and monoenergetic reconstructions (31.8).

CONCLUSIONS

Our findings demonstrate that silicone breast implants exhibit distinct contrast properties at PCCT, which may provide incremental information for detection of degenerative changes and rupture of implants.

RELEVANCE STATEMENT

Thoracic photon-counting computed tomography is a promising modality for the diagnostic assessment of silicone breast implants.

KEY POINTS

• Thoracic photon-counting computed tomography demonstrates unique contrast properties of silicone breast implants. • Iodine map reconstructions reveal strong contrast-to-noise ratios for implant-to-muscle and implant-to-fat. • Thoracic photon-counting computed tomography shows high diagnostic accuracy in detecting implant degeneration and rupture.

TRIAL REGISTRATION

German Clinical Trials Register number DRKS00028997, date of registration 2022-08-08, retrospectively registered.

Staging of breast cancer in the breast and regional lymph nodes using contrast-enhanced photon-counting detector CT: accuracy and potential impact on patient management

OBJECTIVES

To describe the feasibility and evaluate the performance of multiphasic photon-counting detector (PCD) CT for detecting breast cancer and nodal metastases with correlative dynamic breast MRI and digital mammography as the reference standard.

METHODS

Adult females with biopsy-proven breast cancer undergoing staging breast MRI were prospectively recruited to undergo a multiphasic PCD-CT using a 3-phase protocol: a non-contrast ultra-high-resolution (UHR) scan and 2 intravenous contrast-enhanced scans with 50 and 180 s delay. Three breast radiologists compared CT characteristics of the index malignancy, regional lymphadenopathy, and extramammary findings to MRI.

RESULTS

Thirteen patients underwent both an MRI and PCD-CT (mean age: 53 years, range: 36-75 years). Eleven of thirteen cases demonstrated suspicious mass or non-mass enhancement on PCD-CT when compared to MRI. All cases with metastatic lymphadenopathy (3/3 cases) demonstrated early avid enhancement similar to the index malignancy. All cases with multifocal or multicentric disease on MRI were also identified on PCD-CT (3/3 cases), including a 4 mm suspicious satellite lesion. Four of five patients with residual suspicious post-biopsy calcifications on mammograms were detected on the UHR PCD-CT scan. Owing to increased field-of-view at PCD-CT, a 5 mm thoracic vertebral metastasis was identified at PCD-CT and not with the breast MRI.

CONCLUSIONS

A 3-phase PCD-CT scan protocol shows initial promising results in characterizing breast cancer and regional lymphadenopathy similar to MRI and detects microcalcifications in 80% of cases.

ADVANCES IN KNOWLEDGE

UHR and spectral capabilities of PCD-CT may allow for comprehensive characterization of breast cancer and may represent an alternative to breast MRI in select cases.

On the Safety of Implanted Breast Prostheses in Accidental Impacts

The employment of breast silicone implants, both in aesthetic and reconstructive medicine, is widespread thanks to their recognized biocompatibility and durability. Some critical situations, for example, in the case of accidental impacts, may induce concerns by potential patients about their use. Dynamic tests reproducing frontal impacts at speeds up to 90 km/h, with anthropomorphic dummies carrying 330 cc prostheses and wearing safety belts, were conducted. Tests showed a significant probability of internal gel loss following implant damage at the highest speed. Moreover, considering that prostheses may remain implanted for many years, the effects of accelerated aging at 37 °C, 60 °C, 75 °C and 90 °C in physiological solution were also investigated. Tensile tests of the shell material and compressive tests of the full prosthesis showed evidence of variation in the prostheses' mechanical characteristics after aging, which affects their stiffness, deformability and strength. These results stress the importance of medical investigations for possible damages of the implanted prostheses in the case of an accident.

Magnetic Resonance Imaging Surveillance Study of Silicone Implant-based Breast Reconstruction: A Retrospective Observational Study

This study aimed to evaluate the results of magnetic resonance imaging (MRI) surveillance of implant-based breast reconstruction in patients with breast cancer.

Methods

This retrospective observational study analyzed patients who underwent implant-based breast reconstruction and MRI surveillance by a single surgeon from March 2011 to December 2018, in a single center. All patients were informed about the recommendation of the Food and Drug Administration for MRI surveillance, and they choose to undergo MRI 3 years after surgery.

Results

The compliance rate for MRI surveillance was 56.5% (169/299). MRI surveillance was performed at a mean of 45.8 (4.04 years) ± 11.5 months after surgery. One patient (0.6%) showed an abnormal finding of an intracapsular rupture of the silicone implant.

Conclusions

MRI surveillance for implant rupture in implant-based breast reconstruction showed a low incidence of silent implant rupture (0.6%), whereas the compliance of MRI was relatively high (56.5%). These results raise questions about whether taking an MRI in 3-4 years is suitable for imaging surveillance of breast silicone implants. Screening recommendations should be more evidence-based, and more studies are needed to prevent unnecessary screening and patient burden.

Is It All about Surface Topography? An Intra-Individual Clinical Outcome Analysis of Two Different Implant Surfaces in Breast Reconstruction

The most common long-term complication of silicone breast implants (SMI) remains capsular fibrosis. The etiology of this exaggerated implant encapsulation is multifactorial but primarily induced by the host response towards the foreign material silicone. Identified risk factors include specific implant topographies. Of note, breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) has only been observed in response to textured surface implants. We hypothesize that reduction of SMI surface roughness causes less host response and, hence, better cosmetic outcomes with fewer complications for the patient. A total of 7 patients received the routinely used CPX^®4 breast expander (~60 µM Ra) and the novel SmoothSilk^® (~4 µM Ra), fixed prepectoral with a titanized mesh pocket and randomized to the left or right breast after bilateral prophylactic NSME (nipple-sparing mastectomy). We aimed to compare the postoperative outcome regarding capsule thickness, seroma formation, rippling, implant dislocation as well as comfortability and practicability. Our analysis shows that surface roughness is an influential parameter in controlling fibrotic implant encapsulation. Compared intra-individually for the first time in patients, our data confirm an improved biocompatibility with minor capsule formation around SmoothSilk^® implants with an average shell roughness of 4 µM and in addition an amplification of host response by titanized implant pockets.

Dual-energy CT: Technical considerations and clinical applications

Although dual-energy CT was initially described by Hounsfield in 1973, it remains underused in clinical practice. It is therefore important to emphasize the clinical benefits and limitations of this technique. Iodine mapping makes it possible to quantify the uptake of iodine, which is very important in characterizing tumors, lung perfusion, pulmonary nodules, and the tumor response to new treatments. Dual-energy CT also makes it possible to obtain virtual single-energy images and virtual images without iodinated contrast or without calcium, as well as to separate materials such as uric acid or fat and to elaborate hepatic iron overload maps. In this article, we review some of the clinical benefits and technical limitations to improve understanding of dual-energy CT and expand its use in clinical practice.

A Rare Cause of Respiratory Insufficiency in a 30-Year-Old Transgender Woman

CASE PRESENTATION

A 30-year-old transgender woman who was HIV positive presented to the ED with progressive severe dyspnea and hemoptysis that started 1 day earlier. The patient was undergoing antiretroviral therapy with emtricitabine-rilpivirine-tenofovir with good compliance and feminizing hormone therapy with cyproterone acetate. She was otherwise healthy and was not taking any other medications.

Dual-energy CT quantitative parameters for evaluating Immunohistochemical biomarkers of invasive breast cancer

Background

Estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) and Ki67 are the most useful immunohistochemical biomarkers of invasive breast cancer. The purpose of this study is to investigate the possibility of quantitative parameters derived from dual-energy CT (DECT) to discriminate immunohistochemical biomarkers of invasive breast cancer.

Methods

This prospective study enrolled 120 patients with invasive breast cancer who underwent preoperative contrast-enhanced DECT for staging purposes from June 2019 to January 2020. DECT quantitative parameters, including normalized iodine concentration (NIC), the slope of the spectral Hounsfield unit curve (λ_Hu), and the normalized effective atomic number (nZ_eff), were obtained from reconstructed images. DECT quantitative parameters were compared with the expression status, and the correlations with the value of immunohistochemical biomarkers were evaluated. Inter-observer reproducibility analysis was performed to assess the measurement reproducibility of quantitative parameters. The diagnostic performance of the quantitative parameters was analyzed by receiver operating characteristic curve.

Results

The ER-negative group tended to display higher venous phase NIC and nZ_eff compared with the ER-positive group (individually, p = 0.003, 0.011; area under the curve [AUC] of 0.65, 0.60). The PR-negative group demonstrated higher arterial and venous phase NIC compared with the PR-positive group (individually, p = 0.022, 0.005; AUC of 0.63, 0.65). NIC was correlated negatively with the value of ER and PR expression (r = − 0.175 ~ − 0.265, p = 0.002 ~ 0.042). The HER2-positive group tended to display higher venous phase nZ_eff than the HER2-negative group (p = 0.022; AUC of 0.59). The Ki67 high-proliferation group demonstrated higher arterial phase, venous phase NIC and nZ_eff than the Ki67 low-proliferation group (p < 0.001 ~ 0.005; AUC of 0.67 ~ 0.75). Both the NIC and nZ_eff were correlated positively with the value of Ki67 (r = 0.240 ~ 0.490, p < 0.001 ~ 0.014).

Conclusions

NIC and nZ_eff derived from DECT could be used to discriminate expression status and may associate with the value of immunohistochemical biomarkers of invasive breast cancer.

Diagnostic value of a spiral breast computed tomography system equipped with photon counting detector technology in patients with implants: An observational study of our initial experiences

To evaluate the value of a breast computed tomography (CT) (B-CT) in assessing breast density, pathologies and implant integrity in women with breast implants.This retrospective study was approved by the local ethics committee. B-CT images of 21 women with implants (silicone/saline; 20 bilateral, 1 unilateral) who underwent opportunistic screening or diagnostic bilateral B-CT were included. Breast density, implant integrity, extensive capsular fibrosis, soft tissue lesions and micro-/macrocalcifications were rated. In 18 of the 21 women, an additional ultrasound and in two patients breast magnetic resonance imaging was available for comparison. The average dose was calculated for each breast using verified Monte Carlo simulations on 3D image data sets.Breast density was nearly completely fatty (ACR a) in two patients, scattered fibroglandular (ACR b) in five, heterogeneously dense (ACR c) in ten and very dense (ACR d) in four women. In three women showed a unilateral positive Linguine sign indicative of an inner capsule rupture. Extensive capsular fibrosis was found in three women. In three women, soft tissue lesions were depicted, which revealed to be cysts (n = 2) and lymph nodes (n = 1) on subsequent sonography. Diffuse, non-clustered microcalcifications were found in nine women. Eleven women showed cutaneous or intramammary macrocalcifications. Average dose was 6.45 mGy (range 5.81-7.28 mGy).In women with implants, B-CT presents a promising modality for evaluating breast density, implant integrity, extensive capsular fibrosis, soft tissue lesions and micro-/macrocalcifications without the need of breast compression utilizing a lower dose compared to doses reported for conventional four-view mammography.

Unique Characteristics of Intravitreal Silicone Oil on Dual-Energy Computed Tomography

Silicone oil is used as an intravitreal injection to treat retinal detachment. This material can spread into the subarachnoid space, where it may be mistaken for acute hemorrhage on single-energy computed tomography. This report describes the appearance of intravitreal silicone oil on dual-energy computed tomography, emphasizing unique virtual monoenergetic imaging characteristics that allow for confident differentiation of silicone oil from hemorrhage as well as from other potential single-energy mimics, such as calcium and iodine.

Extra-abdominal dual-energy CT applications: a comprehensive overview

Unlike conventional computed tomography, dual-energy computed tomography is a relatively novel technique that exploits ionizing radiations at different energy levels. The separate radiation sets can be achieved through different technologies, such as dual source, dual layers or rapid switching voltage. Body tissue molecules vary for their specific atomic numbers and electron density, and the interaction with different sets of radiations results in different attenuations, allowing to their final distinction. In particular, iodine recognition and quantification have led to important information about intravenous contrast medium delivery within the body. Over the years, useful post-processing algorithms have also been validated for improving tissue characterization. For instance, contrast resolution improvement and metal artifact reduction can be obtained through virtual monoenergetic images, dose reduction by virtual non-contrast reconstructions and iodine distribution highlighting through iodine overlay maps. Beyond the evaluation of the abdominal organs, dual-energy computed tomography has also been successfully employed in other anatomical districts. Although lung perfusion is one of the most investigated, this evaluation has been extended to narrowly fields of application, such as musculoskeletal, head and neck, vascular and cardiac. The potential pool of information provided by dual-energy technology is already wide and not completely explored, yet. Therefore, its performance continues to raise increasing interest from both radiologists and clinicians.