High energy resolution hyperspectral X-ray imaging for low-dose contrast-enhanced digital mammography (original) (raw)
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Simulation and Phantom Studies of Contrast-Enhanced Dual Energy Mammography (CEDEM
2008
Contrast-enhanced dual energy mammography (CEDEM) has been shown effective in enhancing the visibility of breast cancer in diagnostic mammographic images. The simulation and phantom studies of CEDEM were implemented to enhance acquisition techniques of a dedicated cone-beam breast CT scanner fabricated in our laboratory. CEDEM images were computer-simulated numerically, and the results were compared and validated with physical experiments using a custom-made breast-equivalent phantom with pseudo anatomical structures. The technique factors to be optimized included low- and high-energy x-ray spectra (kVp), spectra filters and mAs (x-ray tube current × scan time in second). Signal-difference-to-noise ratio (SDNR) of the log-weighted subtracted image was computed to optimize subtraction parameters using several combinations of breast compositions and thicknesses. Both simulation and phantom studies suggest that 40 kVp (filtered with 1.5 mm Al) and 50 kVp (filtered with 1.5 mm Al and 0.3 mm Cu) were the optimal spectra with the highest SDNR on the dual energy subtracted image of a 6-cm, 50% glandular breast. Breast composition and thickness were found to have little influence on the optimized technique factors. We conclude that the simulation and phantom studies demonstrated the effectiveness of CEDEM using the prototype breast CT scanner in producing high-quality, lesion-enhanced images.
Quantification of a silver contrast agent in dual-energy breast x-ray imaging
Medical Imaging 2013: Physics of Medical Imaging, 2013
Dual-energy (DE) breast x-ray imaging involves acquiring images using a low-and high-energy x-ray spectral pair. These images are then subtracted with a weighting factor that eliminates the soft-tissue signal variation present in the breast leaving only contrast that is attributed to an exogenous imaging agent. We have previously demonstrated the potential for silver (Ag) as a contrast material for DE breast imaging. Theoretical analysis shows that silver can provide better contrast to clinically-used iodine. Here, we present the subtraction method developed to eliminate the contrast between adipose and glandular tissue; the two major component materials in the breast. The weighting factor is calculated from the attenuation coefficients of the two tissue types and varies between values of 0 and 1 for the energy combinations studied. A spectral search was performed to identify the set of clinically-feasible imaging parameters that will optimize the contrast of silver using our subtraction technique. The subtraction methodology was tested experimentally using step-phantoms and demonstrated that we are able to a) nullify the soft-tissue contrast that arises from differences in glandularity, and b) preserve an image contrast for silver that is independent of the underlying soft-tissue composition. By applying the DE subtraction proposed, a silver-based agent will outperform an iodinated contrast agent on a commercially-available CEDE breast x-ray imaging system.
SPIE Proceedings, 2016
Dual-energy contrast-enhanced digital mammography (DE CE-DM) uses an iodinated contrast agent to image the perfusion and vasculature of the breast. DE images are obtained by a weighted logarithmic subtraction of the high-energy (HE) and low-energy (LE) image pairs. We hypothesized that the optimal DE subtraction weighting factor is thicknessdependent, and developed a method for determining breast tissue composition and thickness in DE CE-DM. Phantoms were constructed using uniform blocks of 100% glandular-equivalent and 100% adipose-equivalent material. The thickness of the phantoms ranged from 3 to 8 cm, in 1 cm increments. For a given thickness, the glandular-adipose composition of the phantom was varied using different combinations of blocks. The logarithmic LE and logarithmic HE signal intensities were measured; they decrease linearly with increasing glandularity for a given thickness. The signals decrease with increasing phantom thickness and the x-ray signal decreases linearly with thickness for a given glandularity. As the thickness increases, the attenuation difference per additional glandular block decreases, indicating beam hardening. From the calibration mapping, we have demonstrated that we can predict percent glandular tissue and thickness when given two distinct signal intensities. Our results facilitate the subtraction of tissue at the boundaries of the breast, and aid in discriminating between contrast agent uptake in glandular tissue and subtraction artifacts.
Physics in medicine and biology, 2014
Contrast-enhanced (CE) dual-energy (DE) x-ray breast imaging uses a low- and high-energy x-ray spectral pair to eliminate soft-tissue signal variation and thereby increase the detectability of exogenous imaging agents. Currently, CEDE breast imaging is performed with iodinated contrast agents. These compounds are limited by several deficiencies, including rapid clearance and poor tumor targeting ability. The purpose of this work is to identify novel contrast materials whose contrast-to-noise ratio (CNR) is comparable or superior to that of iodine in the mammographic energy range. A monoenergetic DE subtraction framework was developed to calculate the DE signal intensity resulting from the logarithmic subtraction of the low- and high-energy signal intensities. A weighting factor is calculated to remove the dependence of the DE signal on the glandularity of the breast tissue. Using the DE signal intensity and weighting factor, the CNR for materials with atomic numbers (Z) ranging from...
Application of a dual energy X-ray imaging method on breast specimen
Results in Physics, 2017
The purpose of this study was to evaluate a dual energy method, developed by our group, on a breast cancer specimen. A modified radiographic X-ray tube combined with a high resolution complementary metal-oxide semiconductor (CMOS) active pixel sensor (APS) X-ray detector was used. A 40/70 kV spectral combination was filtered with 100 lm cadmium (Cd) and 1000 lm copper (Cu) for the low/highenergy combination. Dual energy images were obtained from a formalin-fixed breast cancer specimen for various entrance surface doses (ESD). Initial results showed that the DE images were directly comparable with the mammographic image and similar or even increased calcification information was identified, with mean glandular dose values at acceptable levels.
Optimization of contrast-enhanced spectral mammography depending on clinical indication
Journal of medical imaging, 2014
The objective is to optimize low-energy (LE) and high-energy (HE) exposure parameters of contrastenhanced spectral mammography (CESM) examinations in four different clinical applications for which different levels of average glandular dose (AGD) and ratios between LE and total doses are required. The optimization was performed on a Senographe DS with a SenoBright® upgrade. Simulations were performed to find the optima by maximizing the contrast-to-noise ratio (CNR) on the recombined CESM image using different targeted doses and LE image quality. The linearity between iodine concentration and CNR as well as the minimal detectable iodine concentration was assessed. The image quality of the LE image was assessed on the CDMAM contrastdetail phantom. Experiments confirmed the optima found on simulation. The CNR was higher for each clinical indication than for SenoBright®, including the screening indication for which the total AGD was 22% lower. Minimal iodine concentrations detectable in the case of a 3-mm-diameter round tumor were 12.5% lower than those obtained for the same dose in the clinical routine. LE image quality satisfied EUREF acceptable limits for threshold contrast. This newly optimized set of acquisition parameters allows increased contrast detectability compared to parameters currently used without a significant loss in LE image quality.
Design and use of computational models for contrast-enhanced spectral mammography
Scripta scientifica medica, 2022
INTRODUCTION: Contrast-enhanced spectral mammography (CESM) is a new technique for cancer investigations. The application of this technique to screen the breast would result in contrast improvement of the different breast lesions. This can be effectively ensured by the use of phantoms. Computational phantoms are one of the ways to investigate the characteristics of the received image and thus to evaluate the whole technique. AIM: The aim of this study is to validate and analyse the design of three different computational phantoms for CESM. MATERIALS AND METHODS: An in-house software tool was used to create three computational phantoms, consisting of iodinated inserts for the simulation of the CESM procedure. The inserts in the phantoms, modelled from Omnipaque, have a radius of 8-10 mm and varying height. The three phantoms are made of polymethyl methacrylate (PMMA), with different shape and composition. One of the phantoms is characterised by a heterogeneous background. For each phantom two x-ray radiographs were generated, one at x-ray energy of 20keV and one at 34 keV. The images were processed to obtain a recombined iodine image, which shows the iodine contrast agent and suppresses the surrounding background tissue. RESULTS: Simulated spectral images demonstrated a great improvement of the image quality compared to low-energy images of the phantoms. The simulations with the inhomogeneous model revealed that the heterogeneous background has been successively depressed while improving the visibility of the iodine inserts. CONCLUSION: The heterogeneous breast phantom might be used as a reference tool for information about the needed iodine concentration which needs to be inserted during the procedure to obtain significant enhancement in the suspicious area.
Acta radiologica (Stockholm, Sweden : 1987), 2017
Background Dual-energy (DE) contrast-enhanced digital mammography (DE-CEDM) provides additional information on tumor angiogenesis. Purpose To investigate the susceptibility of reconstructing color-coded iodine concentration maps on the basis of quantitative calibrations of the iodine concentration and contrast-to-noise ratio (CNR) in DE-CEDM applications. Material and Methods A custom-made phantom filled with iodine concentrations in the range of 0.1-10 mg/cm2 was used in calibrations. All DE images were acquired using the GE Senographe Essential system. From DE subtraction images, the image contrast and CNR were obtained, and the quantitative relationship between these two metrics and the iodine concentration at each phantom thickness was investigated. The quantitative CNR calibration curves were applied to reconstruct color-coded iodine maps on a pixel-by-pixel basis. Results Both the mean contrast and mean CNR increased linearly with the iodine concentration. The iodine concentra...
Dual-energy contrast-enhanced digital breast tomosynthesis - a feasibility study
British Journal of Radiology, 2010
The purpose of this study is to assess the feasibility of dual-energy subtraction as a technique for contrast-enhanced digital breast tomosynthesis (CE-DBT). CE-DBT is a novel modality for imaging breast lesion morphology and vascularity, and a temporal subtraction CE-DBT technique has been previously described. As CE-DBT evolves, exploration of alternate image acquisition techniques will contribute to its optimization.
Radiology and Medical Diagnostic Imaging, 2021
Purpose: To assess the iodine enhancement intensity of breast lesions in low energy (LE) images obtained in contrast-enhanced spectral mammography (CESM) with different tissue compositions. Materials and Methods: A 50 mm dedicated phantom with different lesion insert and iodine insert were used to assess the enhancement intensity quantitatively. The target slab of the phantom consists of three lesions + iodine inserts together and 100% adipose equivalent,100% glandular equivalent inserts alone to mimic the adipose and glandular lesion without contrast-enhancement. Each iodine inserts having a concentration of 0.5 mgI/cm3, 1.0 mgI/cm3, 2.0 mgI/cm3. The phantom was exposed under semiautomated function at 28 kV, 30 kV, and 32 kV with Mo/Rh target/filter combination. Iodine intensity was estimated for three types of lesions at three breast equivalent compositions. Results: Lesions with fatty tissue had high intensity while lesions with glandular tissues had the minimum intensity. Among ...