Dual-energy Contrast-enhanced Mammography Research Articles

Evaluation of exposure factors of dual-energy contrast-enhanced mammography to optimize radiation dose with improved image quality.

BackgroundDual-energy contrast-enhanced mammography (DECEM) is an advanced breast imaging technique of digital mammography.PurposeTo assess the total radiation dose received from complete DECEM using different combinations of exposure parameters for low- and high-energy images.Materials and methodsA dedicated phantom with three different concentrations of iodine inserts was used. Each iodine insert was 10 mm in diameter and concentration of 1.0 mgI/cm3, 2.0 mgI/cm3, and 4.0 mgI/cm3. The phantom was exposed at varying kVp levels. Mean glandular dose (MGD) was estimated. Contrast to noise ratio (CNR) and figure of merit (FOM) of the iodine inserts were used to assess the image quality.ResultsThe optimum CNR of the recombined images was obtained by using 28 kVp + 49 kVp tube voltage combination for 50 mm thickness, 50% fibroglandular phantom only with a 26% dose increase compared to the highest voltages (32 kVp + 49 kVp) that can be used for low energy (LE) and high energy (HE) imaging. The CNR value was increased with increasing iodine concentration (R 2 > 0.99).ConclusionThe use of as low as possible tube voltage for the LE imaging of standard 50% fibroglandular–50% adipose, 50 mm thickness breast while using the highest tube voltage for HE imaging has reduced the MGD while keeping optimum image quality.

Radiomics and Artificial Intelligence Analysis with Textural Metrics Extracted by Contrast-Enhanced Mammography in the Breast Lesions Classification.

The aim of the study was to estimate the diagnostic accuracy of textural features extracted by dual-energy contrast-enhanced mammography (CEM) images, by carrying out univariate and multivariate statistical analyses including artificial intelligence approaches. In total, 80 patients with known breast lesion were enrolled in this prospective study according to regulations issued by the local Institutional Review Board. All patients underwent dual-energy CEM examination in both craniocaudally (CC) and double acquisition of mediolateral oblique (MLO) projections (early and late). The reference standard was pathology from a surgical specimen for malignant lesions and pathology from a surgical specimen or fine needle aspiration cytology, core or Tru-Cut needle biopsy, and vacuum assisted breast biopsy for benign lesions. In total, 104 samples of 80 patients were analyzed. Furthermore, 48 textural parameters were extracted by manually segmenting regions of interest. Univariate and multivariate approaches were performed: non-parametric Wilcoxon–Mann–Whitney test; receiver operating characteristic (ROC), linear classifier (LDA), decision tree (DT), k-nearest neighbors (KNN), artificial neural network (NNET), and support vector machine (SVM) were utilized. A balancing approach and feature selection methods were used. The univariate analysis showed low accuracy and area under the curve (AUC) for all considered features. Instead, in the multivariate textural analysis, the best performance considering the CC view (accuracy (ACC) = 0.75; AUC = 0.82) was reached with a DT trained with leave-one-out cross-variation (LOOCV) and balanced data (with adaptive synthetic (ADASYN) function) and a subset of three robust textural features (MAD, VARIANCE, and LRLGE). The best performance (ACC = 0.77; AUC = 0.83) considering the early-MLO view was reached with a NNET trained with LOOCV and balanced data (with ADASYN function) and a subset of ten robust features (MEAN, MAD, RANGE, IQR, VARIANCE, CORRELATION, RLV, COARSNESS, BUSYNESS, and STRENGTH). The best performance (ACC = 0.73; AUC = 0.82) considering the late-MLO view was reached with a NNET trained with LOOCV and balanced data (with ADASYN function) and a subset of eleven robust features (MODE, MEDIAN, RANGE, RLN, LRLGE, RLV, LZLGE, GLV_GLSZM, ZSV, COARSNESS, and BUSYNESS). Multivariate analyses using pattern recognition approaches, considering 144 textural features extracted from all three mammographic projections (CC, early MLO, and late MLO), optimized by adaptive synthetic sampling and feature selection operations obtained the best results (ACC = 0.87; AUC = 0.90) and showed the best performance in the discrimination of benign and malignant lesions.

Motion Artifact Reduction in Contrast-Enhanced Dual-Energy Mammography - A Multireader Study about the Effect of Nonrigid Registration as Motion Correction on Image Quality.

The technically caused delay between low-energy (LE) and high-energy (HE) acquisitions allows motion artifacts in contrast-enhanced dual-energy mammography (CEDEM). In this study the effect of motion correction by nonrigid registration on image quality of the recombined images was investigated. Retrospectively for 354 recombined CEDEM images an additional recombined image was processed from the raw data of LE and HE images using the motion correction algorithm. Five radiologists with many years of experience in breast cancer diagnostic imaging compared side-by-side one conventional processed CEDEM image with the corresponding image processed by the motion correction algorithm. Every pair of images was compared based on six criteria: General image quality (1), sharpness of skin contour (2), reduction of image artifacts (3), sharpness of lesion contour (4), contrast of lesion (5), visibility of lymph nodes (6). These criteria were rated on a Likert scale (improvement: + 1, + 2; deterioration: -1, -2). The mean ratings concerning criteria 1-5 showed a superiority of the recombined images processed by the motion correction algorithm. For example, the mean rating of general image quality was 0.86 (95 % CI: 0.78; 0.93). Only the mean rating concerning criterion 6 showed an inferiority of the recombined images processed by the motion correction algorithm (-0.29 (-0.46; -0.13)). The usage of nonrigid registration for motion correction significantly improves the general image quality and the quality of subordinate criteria on the recombined CEDEM images at the expense of somewhat reduced lymph node visibility in some cases. · The usage of motion correction in CEDEM improves the general image quality. · Motion correction might have the potential to increase diagnostic accuracy. · Alternative methods of motion artifact reduction are not yet available in clinical practice. · Sistermanns M, Kowall B, Hörnig M et al. Motion Artifact Reduction in Contrast-Enhanced Dual-Energy Mammography - A Multireader Study about the Effect of Nonrigid Registration as Motion Correction on Image Quality. Fortschr Röntgenstr 2021; 193: 1183 - 1188.

Radiomic features analysis by digital breast tomosynthesis and contrast-enhanced dual-energy mammography to detect malignant breast lesions

PurposeTo detect malignant breast lesions using radiomic morphological features from Digital Breast Tomosynthesis (DBT) and radiomic textural features from Contrast-enhanced Dual-Energy Digital Mammography (CEDM). MethodsIn a 8-month period, we enrolled 72 consecutive patients with breast lesions; their age ranging from 26 to 72 years (mean, 52.2; standard deviation 11.1). Ninety-three breast lesions subjected to CEDM and DBT in cranio caudal (CC) and mediolateral oblique (MLO) view were included: 36 histopathologically proven benign lesions and 59 histopathologically proven malignant lesions were analyzed. We considered a feature set including 23 textural features calculated on CEDM and 14 morphological features extracted by DBT. Non-parametric statistics, receiver operating characteristic with area under curve (AUC), Spearman correlation coefficient and Bonferroni correction were applied. ResultsAt univariate analysis, the area under ROC was obtained by the best textural feature, the contrast with a value of 0.78. To differentiate malignant lesions with different grading only one textural feature had significant results: median absolute deviation (MAD) (p < 0.01 at Kruskal Wallis test). As a morphological feature by DBT, at univariate analysis, the best area under ROC was obtained by angularity with a value of 0.74. Using morphological parameters there were no statistically significant differences among malignant lesions with different grading. At bivariate analysis using couple combinations of features did not increase the accuracy with respect to single feature. The cross validated decision tree considering the best textural feature (the contrast) and the best morphological feature (the angularity) showed an area under ROC of 0.90, an accuracy of 87.1%, a true positive rate of 84% and a false positive rate of 12%. Considering all texture and morphological metrics with pattern recognition approach was not obtained an increase of diagnostic accuracy. ConclusionsRadiomic textural features from CEDM and radiomic morphological features from DBT have shown a good power to differentiate malignant to benign lesions. A decision tree considering the contrast as textural parameter and the angularity as morphological metric reached the best results (87% of accuracy).

Abstract P5-01-02: Glandular dose in contrast-enhanced dual-energy mammography

Abstract INTRODUCTION Estimation of the Average Glandular Dose (AGD) absorbed by the breast during x-ray based examination is an established part of quality control procedures for breast imaging, both for standard mammography and new techniques as digital breast tomosynthesis (DBT) and contrast enhanced digital mammography (CEDM). It is however fundamental that every optimization program obtains an adequate imaging quality. In our study we evaluated the AGD absorbed by the breast, during CEDM examinations, performed with Dual Energy (DE) technique in our Department. MATERIALS AND METHODS We retrospectively evaluated 37 DE mammograms; we reported and analyzed AGD, Entrance Skin Exposure (ESE), anode/filter combinations, breast thickness, kV (kilovolt), mAs (milliAmpere per second), and compression in daN (decaNewton) values, for each mammography view obtained on high and low energy. In 10 Patients, it was possible to compare DE with a recent standard mammography performed on the same mammography unit. RESULTS AGD values for the entire DE study, in craniocaudal and mediolateral oblique views, resulted between 4.23 mGy and 13.44 mGy; based on the breast thickness (27-79 mm) and on the anod/filter combination. We found out a significantly lower AGD for small breast thicknesses and Mo/Rh and Mo/Cu combination compared to Rh/Rh and Rh/Cu. In the whole study evaluation, the AGD percentage report due to low and high energy acquisitions resulted between 76.8% and 81.6%, and between 18.4% and 23.2%, respectively. For the 10 Patients in which was possible a direct comparison with the data obtained with recent standard mammography, resulted a ratio between DE AGD and standard mammography AGD variable from 1.43 to 2.48 (mean value: 2.0), again with lower AGD values obtained with Mo/Rh - Mo/Cu combination and for small breast thicknesses. AGD ratio between low energy and standard mammography acquisition resulted between 1.23 and 3.31. DISCUSSION CEDM is proving to have all the potential to get a definite role in diagnosis and breast tumor staging, providing a direct correlation between morphologic and functional imaging. In our study we assessed the dosimetry to determine if an additional x-ray exposure will be a limit to DE use and, if that is the case, in which measure. Data in the literature on DE dosimetry are still spare and extremely heterogenous. In any case, the increase of delivered dose could be justifiable when compared to the great benefits given by this technique in breast cancer early diagnosis and staging, especially in dense breast tissue, in the follow-up of Patients with breast cancer history and in case of MRI incompatibility. Furthermore, when compared to MRI, CEDM is an easy-access, low-cost, fast and well accepted exam by the patient. CONCLUSIONS Although the risk of induced carcinogenesis associated with x-ray breast modalities is small, dosimetric aspects should be considered both for the risk evaluation and for optimization of acquisition systems; with the advance of the technologies we will be able to have a dose reduction by maintaining high quality standards. Results obtained from this preliminary study needs to be extended by a larger case study to get a complete evaluation and comprehension of the phenomenon. Citation Format: Cossu E, Castellani F, Fiaschetti V, Mariateresa M, Tiziana R, Angelo T. Glandular dose in contrast-enhanced dual-energy mammography [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-01-02.

Application of BI-RADS Descriptors in Contrast-Enhanced Dual-Energy Mammography: Comparison with MRI

Background: Contrast-enhanced (CE) magnetic resonance imaging (MRI) BI-RADS descriptors are used in the evaluation of contrast-enhanced dual-energy mammography (CEDEM) images of mass lesions and are assumed to be applicable. Patients and Methods: Patients with suspicious mass lesions on mammography (BI-RADS 4 or 5) were included. CEDEM examinations were performed using a modified prototype unit. CE-MRI was performed using a high temporal and high spatial resolution imaging protocol. 2 blinded breast radiologists evaluated all images using criteria related to contrast enhancement intensity and morphology according to the BI-RADS lexicon (5th edition) in 2 sessions. Histopathology was used as the standard of reference. Results: 11 patients with 5 benign and 6 malignant index lesions were included. Enhancement characteristics were similar in the malignant cases. Enhancement of the benign lesions was moderate on CEDEM and strong on MRI. Discrepancies in the BI-RADS descriptors did not influence the final BI-RADS score. Overall, the BI-RADS assessment was almost identical in all cases. 1 malignant lesion was rated BI-RADS 4 with CEDEM and BI-RADS 5 with MRI, and 1 benign was rated BI-RADS 2 and BI-RADS 1, respectively. Conclusion: MRI BI-RADS descriptors of contrast-enhancing lesions can be applied for the morphologic analysis of mass lesions on CEDEM.

MO-FG-CAMPUS-IeP1-02: Dose Reduction in Contrast-Enhanced Digital Mammography Using a Photon-Counting Detector

Purpose: Photon-counting detectors (PCDs) allow multi-energy X-ray imaging without additional exposures and spectral overlap. This capability results in the improvement of accuracy of material decomposition for dual-energy X-ray imaging and the reduction of radiation dose. In this study, the PCD-based contrast-enhanced dual-energy mammography (CEDM) was compared with the conventional CDEM in terms of radiation dose, image quality and accuracy of material decomposition. Methods: A dual-energy model was designed by using Beer-Lambert's law and rational inverse fitting function for decomposing materials from a polychromatic X-ray source. A cadmium zinc telluride (CZT)-based PCD, which has five energy thresholds, and iodine solutions included in a 3D half-cylindrical phantom, which composed of 50% glandular and 50% adipose tissues, were simulated by using a Monte Carlo simulation tool. The low- and high-energy images were obtained in accordance with the clinical exposure conditions for the conventional CDEM. Energy bins of 20–33 and 34–50 keV were defined from X-ray energy spectra simulated at 50 kVp with different dose levels for implementing the PCD-based CDEM. The dual-energy mammographic techniques were compared by means of absorbed dose, noise property and normalized root-mean-square error (NRMSE). Results: Comparing to the conventional CEDM, the iodine solutions were clearly decomposed for the PCD-based CEDM. Although the radiation dose for the PCD-based CDEM was lower than that for the conventional CEDM, the PCD-based CDEM improved the noise property and accuracy of decomposition images. Conclusion: This study demonstrates that the PCD-based CDEM allows the quantitative material decomposition, and reduces radiation dose in comparison with the conventional CDEM. Therefore, the PCD-based CDEM is able to provide useful information for detecting breast tumor and enhancing diagnostic accuracy in mammography.

Gold silver alloy nanoparticles (GSAN): an imaging probe for breast cancer screening with dual-energy mammography or computed tomography.

Earlier detection of breast cancer reduces mortality from this disease. As a result, the development of better screening techniques is a topic of intense interest. Contrast-enhanced dual-energy mammography (DEM) is a novel technique that has improved sensitivity for cancer detection. However, the development of contrast agents for this technique is in its infancy. We herein report gold-silver alloy nanoparticles (GSAN) that have potent DEM contrast properties and improved biocompatibility. GSAN formulations containing a range of gold : silver ratios and capped with m-PEG were synthesized and characterized using various analytical methods. DEM and computed tomography (CT) phantom imaging showed that GSAN produced robust contrast that was comparable to silver alone. Cell viability, reactive oxygen species generation and DNA damage results revealed that the formulations with 30% or higher gold content are cytocompatible to Hep G2 and J774A.1 cells. In vivo imaging was performed in mice with and without breast tumors. The results showed that GSAN produce strong DEM and CT contrast and accumulated in tumors. Furthermore, both in vivo imaging and ex vivo analysis indicated the excretion of GSAN via both urine and feces. In summary, GSAN produce strong DEM and CT contrast, and has potential for both blood pool imaging and for breast cancer screening.

Contrast-enhanced dual energy mammography with a novel anode/filter combination and artifact reduction: a feasibility study.

To demonstrate the feasibility of contrast-enhanced dual-energy mammography (CEDEM) using titanium (Ti) filtering at 49 kVp for high-energy images and a novel artefact reducing image-subtraction post-processing algorithm. Fifteen patients with suspicious findings (ACR BI-RADS 4 and 5) detected with digital mammography (MG) that required biopsy were included. CEDEM examinations were performed on a modified prototype machine. Acquired HE and low-energy raw data images were registered non-rigidly to compensate for possible subtle tissue motion. Subtracted CEDEM images were generated via weighted subtraction, using a fully automatic, locally adjusted tissue thickness-dependent subtraction factor to avoid over-subtraction at the breast border. Two observers evaluated the MG and CEDEM images according to ACR BI-RADS in two reading sessions. Results were correlated with histopathology. Seven patients with benign and eight with malignant findings were included. All malignant lesions showed a strong contrast enhancement. BI-RADS assessment was altered in 66.6% through the addition of CEDEM, resulting in increased overall accuracy. With CEDEM, additional lesions were depicted and false-positive rate was reduced compared to MG. CEDEM using Ti filtering with 49 kVp for HE exposures is feasible in a clinical setting. The proposed image-processing algorithm has the potential to reduce artefacts and improve CEDEM images. • CEDEM with a titanium filter is feasible in a clinical setting. • Breast thickness-dependent image subtraction has the potential to improve CEDEM images. • The proposed image-processing algorithm reduces artefacts.

Dual-energy contrast-enhanced spectral mammography (CESM).

Dual-energy contrast-enhanced mammography is one of the latest developments in breast care. Imaging with contrast agents in breast cancer was already known from previous magnetic resonance imaging and computed tomography studies. However, high costs, limited availability-or high radiation dose-led to the development of contrast-enhanced spectral mammography (CESM). We reviewed the current literature, present our experience, discuss the advantages and drawbacks of CESM and look at the future of this innovative technique.

Dual-energy contrast-enhanced mammography

The degree of vascularization in breast lesions is related to their malignancy. For this reason, functional diagnostic imaging techniques have become important in recent years. Dual-energy contrast-enhanced mammography is a new, apparently promising technique in breast cancer that provides information about the degree of vascularization of the lesion in addition to the morphological information provided by conventional mammography. This article describes the state of the art for dual-energy contrast-enhanced mammography. Based on 15 months’ clinical experience, we illustrate this review with clinical cases that allow us to discuss the advantages and limitations of this technique.

Mamografía con realce de contraste mediante técnica de energía dual

The degree of vascularization in breast lesions is related to their malignancy. For this reason, functional diagnostic imaging techniques have become important in recent years. Dual-energy contrast-enhanced mammography is a new, apparently promising technique in breast cancer that provides information about the degree of vascularization of the lesion in addition to the morphological information provided by conventional mammography. This article describes the state of the art for dual-energy contrast-enhanced mammography. Based on 15 months’ clinical experience, we illustrate this review with clinical cases that allow us to discuss the advantages and limitations of this technique.

Contrast-enhanced dual-energy mammography: a promising new imaging tool in breast cancer detection.

Contrast-enhanced dual-energy mammography (CEDM) is a promising new breast imaging tool for breast cancer detection. In CEDM, an iodine-based contrast agent is intravenously administered and subsequently, dual-energy mammography is performed. This results in a set of images containing both a regular mammogram and an image that contains contrast enhancement information. Preliminary studies have indicated that CEDM is superior to conventional mammography and might even match the diagnostic performance of breast MRI. In this review, the imaging technique, protocol and patient handling of CEDM is presented. Furthermore, an overview of current results on CEDM and potential future indications are outlined.

Dual-energy contrast-enhanced digital mammography in routine clinical practice in 2013

To date, analysis of the vascularisation of breast lesions mainly relies on MR imaging. However, the accessibility of MRI is sometimes limited and has led to the development of new means of imaging, such as dual-energy contrast-enhanced mammography, which provides data on the vascularisation of the breast along with the usual morphological information. The purpose of this paper is to present this new imaging technique as well as the recent references, illustrated by clinical reports derived from our everyday practice to focus on the advantages and disadvantages of this new breast exploration. Dual-energy contrast-enhanced mammography is a recent, seemingly promising technique, in the management of breast cancer. The main advantages consist of its easy installation, the good tolerance and the comfort in the interpretation of difficult to read mammograms. However, the indications and the role of dual-energy contrast-enhanced mammography still have to be determined within the diagnostic strategy of breast tumours. New studies are expected, especially to compare dual-energy contrast-enhanced mammography with breast MRI.

Evaluating noise reduction techniques while considering anatomical noise in dual‐energy contrast‐enhanced mammography

The authors describe modifications to previously developed cascaded systems analysis to include the anatomical noise in evaluation of dual-energy noise reduction techniques. Previous models have ignored the anatomical noise in theoretical analysis of noise reduction techniques. The inclusion of anatomical noise leads to more accurate estimation of potential noise reduction improvements and optimization. The model is applied to dual-energy contrast-enhanced mammography. The effect of linear noise reduction filters on the anatomical noise is taken into account using cascaded systems analysis. The noise model is included in the ideal observer detectability for performance evaluation of the noise reduction techniques. Dual-energy image noise with and without including the effect of anatomical noise in noise reduction technique analysis is reported. The theoretical model is compared with clinical images from a previous dual-energy contrast enhanced mammography clinical study and good agreement is observed. The results suggest that the inclusion of anatomical noise in the evaluation and comparison of noise reduction techniques is highly warranted for more accurate analysis. This work establishes a useful extension to dual-energy cascaded systems analysis for maximizing image quality using noise reduction techniques. The extension includes the effect of linear image filtering, such as that used for noise reduction, on anatomical noise. The results suggest that the inclusion of anatomical noise in the evaluation of noise reduction techniques can lead to more accurate optimization, noise, and performance estimations.

Development and production of a prototype iodine contrast phantom for CEDEM

Phantoms containing iodine details with clinically relevant iodine concentrations are required to systematically study dose requirements, for quality assurance and optimizing exposure parameters and protocols for contrast enhanced dual energy mammography (CEDEM) applications. Most such phantoms use liquid iodine solutions, challenging the user with air inclusions, evaporation or the necessity for changing the iodine concentration through refilling. A prototype phantom with an array of sintered solid iodine-containing platelets with iodine area weights of 0, 0.25, 0.5, 1, 1.5 and 2 mg cm−2 is described. Disks containing various iodine concentrations were produced using polymer sintering of Iopamidol embedded into a polystyrene/graphite matrix. Iopamidol-containing platelets with a diameter of 0.5 cm and thickness of 550 µm forming an array with gradually increasing iodine area weight, were embedded in PMMA to allow statistical analysis of contrast and contrast-to-noise ratio (CNR). The homogeneity of the plates was tested and images of the phantom were acquired to assess the iodine area density progression and to evaluate phantom accuracy. The phantom was imaged on a mammography system applying low and high energy spectra as used for CEDEM. The disks show good homogeneity. Uncertainties in absolute iodine area weight were estimated ±5%. The iodine CNR showed a linear correlation with R2 > 0.99. Polymer powder sintering works well for producing stable iodine contrast phantoms without the necessity to handle liquid iodine solutions. Thus, it is a promising approach to construct phantoms not only for CEDEM but also angiography or other contrast enhanced methods with iodine details for quality control or research purposes and optimization.

Including the effect of motion artifacts in noise and performance analysis of dual-energy contrast-enhanced mammography

In contrast-enhanced mammography (CEM), the dual-energy dual-exposure technique, which can leverage existing conventional mammography infrastructure, relies on acquiring the low- and high-energy images using two separate exposures. The finite time between image acquisition leads to motion artifacts in the combined image. Motion artifacts can lead to greater anatomical noise in the combined image due to increased mismatch of the background tissue in the images to be combined, however the impact has not yet been quantified. In this study we investigate a method to include motion artifacts in the dual-energy noise and performance analysis. The motion artifacts are included via an extended cascaded systems model. To validate the model, noise power spectra of a previous dual-energy clinical study are compared to that of the model. The ideal observer detectability is used to quantify the effect of motion artifacts on tumor detectability. It was found that the detectability can be significantly degraded when motion is present (e.g., detectability of 2.5 mm radius tumor decreased by approximately a factor of 2 for translation motion on the order of 1000 μm). The method presented may be used for a more comprehensive theoretical noise and performance analysis and fairer theoretical performance comparison between dual-exposure techniques, where motion artifacts are present, and single-exposure techniques, where low- and high-energy images are acquired simultaneously and motion artifacts are absent.

WE‐D‐304A‐06: The Characterization of Iodinated‐Contrast Kinetics Using a Dynamic Breast Phantom

Purpose: To demonstrate the effectiveness of contrast‐enhanced dual energy mammography (CEDEM) in characterizing the contrast kinetic curve. Method and Materials: The acquisition of CEDEM was performed using a dedicated cone‐beam breast CT scanner in our laboratory, with the system operating in stationary imaging mode. CEDEM images were acquired with a filter combination of 0.2 mm Cu and 0.2 mm Sn at the same kVp. Previous studies in our group have shown that 55 kVp is the optimal technique factor to acquire high‐quality CEDEM images when imaging a 6‐cm, anatomical‐complex breast phantom. As an addition to the static breast phantom, a tumor perfusion chamber was designed and fabricated to simulate the contrast kinetics of breast tumors. The chamber is composed of a “leaky” vessel (soaker hose) and the tumor interstitial space (foam). The contrast kinetics was controlled by two peristaltic pumps, the “leakiness” of the soaker hose, and the permeability of the foam. When imaged experimentally, the tumor perfusion chamber was fixed in the middle of the static breast phantom. A sequence of CEDEM images were acquired with an initial bolus injection of 100 ml Visipaque®. The contrast kinetics was determined by evaluating the signal‐to‐noise ratio of each dual‐energy subtracted image as a function of time. Results: The CEDEM image sequence of the dynamic breast phantom was acquired at 55 kVp. The contrast kinetic curve was found to follow closely that of human subjects. The influence of the phantom parameters on the kinetic curve will be presented. The contrast kinetic curve modeling benign and malignant tumors using this phantom will be presented. Conclusion: The contrast kinetic curve was evaluated using a dynamic breast phantom. CEDEM was found to be effective in characterizing the contrast kinetic curve around breast tumors.

WE-E-L100J-06: Simulation Studies On Contrast Enhanced Dual Energy Mammography

Purpose: Technique optimization for contrast-enhanced dual energy mammography in a breast CT scanner. Method and Materials: Using kVp accuracy and HVL measurements physically performed on the x-ray source of a dedicated cone beam breast CT system, a mathematical spectral model was calibrated to have the same spectral and output properties as the physical system. Mathematical breast phantoms were fabricated by generating random sized and randomly placed glandular spheres on an adipose background to approximate the anatomical noise of the breast. The simulated imaging geometry matched that of the breast CT system. Quantum noise was simulated using Poisson model and a validated random number generator. Contrast-enhanced dual energy mammography was optimized for parameters including kVp, x-ray spectral filtration, and mAs distribution between high and low energy images. Mean glandular dose to the breast was calculated using dose coefficients generated from previously published Monte Carlo simulations. A figure of merit of the contrast-to-noise ratio at constant mean glandular dose was chosen for the optimization task to maximize image quality at minimal radiation dose levels. Optimization was carried out over a range of breast diameters, breast compositions, and iodine concentrations. Results: Spectra study suggested the optimal kVp to be between 120kV and 140kV for the high energy image, and between 50kV and 60kV for the low energy image, for the studied ranges of breast diameters and compositions. Added copper filtration up to 1mm for the high kVp spectra continued to improve CNR at set dose levels. Iodine as diluted as 0.05% of the 350mg/mL standard solution could be detected with a 2.5mGy total dose. Optimized mAs distribution suggested a higher dose proportion for the low kVp image than for the high kVp image. Conclusion: An optimized contrast-enhanced dual energy mammography can efficiently suppress anatomical noise and significantly improve contrast detection.

Contrast-enhanced dual-energy mammography using a scanned multislit system: evaluation of a differential beam filtering technique

This paper describes a method for single-exposure, contrast-enhanced dual-energy imaging of tumors utilizing a scanned multislit system for digital mammography. This photon-counting system employs an array of silicon strip detectors mounted in an edge-on geometry. The line detectors and pre- and post-collimator slits are carefully aligned, and the multislit setup allows differential filtering of the x-ray beam in the pre-collimator slits. A high-energy image is constructed from those lines where the filter material has been chosen to harden the x-ray beam and the low-energy image from the lines with a filter producing softer beams. Both images are obtained in the same scan, eliminating the need to change tube voltages and anode materials and minimizing the risk of motion artifacts. The method is illustrated on a purpose-built phantom, and logarithmic subtraction of the images produces images essentially free of anatomical clutter with the contrast-enhanced targets clearly visible.