Siemens Mammomat Inspiration Research Articles

In situ tumor model for longitudinal in silico imaging trials

Objective. In this article, we introduce a computational model for simulating the growth of breast cancer lesions accounting for the stiffness of surrounding anatomical structures. Approach. In our model, ligaments are classified as the most rigid structures while the softer parts of the breast are occupied by fat and glandular tissues As a result of these variations in tissue elasticity, the rapidly proliferating tumor cells are met with differential resistance. It is found that these cells are likely to circumvent stiffer terrains such as ligaments, instead electing to proliferate preferentially within the more yielding confines of the breast’s soft topography. By manipulating the interstitial tumor pressure in direct proportion to the elastic constants of the tissues surrounding the tumor, this model thus creates the potential for realizing a database of unique lesion morphology sculpted by the distinctive topography of each local anatomical infrastructure. We modeled the growth of simulated lesions within volumes extracted from fatty breast models, developed by Graff et al with a resolution of 50 μm generated with the open-source and readily available Virtual Imaging Clinical Trials for Regulatory Evaluation (VICTRE) imaging pipeline. To visualize and validate the realism of the lesion models, we leveraged the imaging component of the VICTRE pipeline, which replicates the siemens mammomat inspiration mammography system in a digital format. This system was instrumental in generating digital mammogram (DM) images for each breast model containing the simulated lesions. Results. By utilizing the DM images, we were able to effectively illustrate the imaging characteristics of the lesions as they integrated with the anatomical backgrounds. Our research also involved a reader study that compared 25 simulated DM regions of interest (ROIs) with inserted lesions from our models with DM ROIs from the DDSM dataset containing real manifestations of breast cancer. In general the simulation time for the lesions was approximately 2.5 hours, but it varied depending on the lesion’s local environment. Significance. The lesion growth model will facilitate and enhance longitudinal in silico trials investigating the progression of breast cancer.

Threshold in breast compression reduction for full-field digital mammography and digital breast tomosynthesis

IntroductionBreast compression is essential in mammography to improve image quality and reduce radiation dose. However, it can cause discomfort or even pain in women which could discourage them from attending future mammography examinations. Therefore, this study aims to explore the maximum reduction in breast compression in full-field digital mammography (FFDM) and digital breast tomosynthesis (DBT) that is achievable without impacting on image quality and dose. MethodsTen compression force (CF) levels (20N–110N, with 10N intervals) were assessed on Siemens MAMMOMAT Inspiration with Nuclear Associates 18–228 phantom. Imaging was carried out in craniocaudal projection using Automatic Exposure Control at 28 kVp with a Tungsten/Rhodium anode/filter combination, and at 50° sweep angle for DBT. Using ImageJ software, image quality of the acquired mammograms and central tomosynthesis slices were examined based on mass conspicuity (MC) and microcalcification conspicuity (MicroC). Entrance skin dose (ESD) and mean glandular dose (MGD) were recorded from Digital Imaging and Communication in Medicine image header. Linear regression was performed to examine the relationship between CF with ESD, MGD, MC and MicroC. Differences in image quality and radiation dose were assessed with one-way analysis of variance and Kruskal-Wallis H test. ResultsSignificant correlations were noted between CF with ESD and MicroC for FFDM and DBT, with DBT also demonstrating associations with MGD and MC. No significant differences were observed for ESD, MGD, MC and MicroC when CF was reduced to 40N and 80N in FFDM and DBT respectively. ConclusionThis study demonstrated that CF can be reduced as low as 40N and 80N in FFDM and DBT respectively, without significant impact on image quality and radiation dose. Implications for practiceReduced mammographic compression may reduce discomfort or pain in women, which may improve attendance rate in breast screening programmes. Findings from this study will provide reference for future work examining breast compression in mammography.

Comparing eDQE and eNEQ metrics – is there an alternative approach to assessing image quality in digital mammography?

Abstract Introduction: Early detection of breast cancer requires high-quality mammographic images that have been made possible by the introduction of new technologies, such as full-field digital mammography (FFDM). In this new study, we perform extended measurements to calculate effective detective quantum efficiency (eDQE) and introduce effective noise equivalent quanta (eNEQ). Our aim was to show how these two metrics relate to the image quality of two digital mammography systems. Material and methods: Measurements were performed for a Siemens Mammomat Inspiration and a GE Senographe Pristina system. Each was equipped with an automatic exposure control (AEC) for use in a clinical setting. We used a polymethyl methacrylate (PMMA) phantom at thicknesses of 20, 30, 40 and 70 mm to cover the range of scatter conditions expected in mammography, with and without an anti-scatter grid. The Siemens system had an a-Se detector, and the GE system had an indirect-conversion detector. Measurements of Kerma were performed with Piranha Black 657 meter (RTI Electronics AB). The majority of our calculations were automated, using a modified version of our software. Results: For the two mammographic systems evaluated, we characterized physical quality parameters, such as effective modulation transfer function (eMTF), effective normalized noise power spectrum (eNNPS), eDQE and eNEQ for a wide range of exposures, phantom thicknesses, with and without an anti-scatter grid. Results are presented as a function of spatial frequency. A contrast-detail analysis was performed with a CDMAM 3.4 phantom with dedicated software (CDMAM analysis 1.5.5, NCCPM) and a set of different PMMA phantoms. Conclusions: We successfully demonstrated that the eNEQ metric can be used as a new option to evaluate image quality for images taken with and without a grid and with phantoms of different thicknesses for the Siemens and GE systems. These results were consistent with the results obtained from CDMAM.

Evaluation of in-house phantoms for mammography accreditation with various 3D printer filaments

One of the routine activities in the mammography modality is image quality testing using the American College of Radiology (ACR) accreditation phantom, approved by the Mammography Quality Standards Act (MQSA). ACR has approved the CIRS Model 015 for use in the Mammography Accreditation Program. However, because the price of this phantom can be reasonably high, not all hospitals have it. This study aims to fabricate the ACR CIRS model 015 phantom with various 3D printer filaments and compare it with the ACR phantom standard. Phantom was designed by depicting small structures similar to those found clinically to test the capabilities of quantitatively evaluated mammographic imaging systems. The designed in-house phantom consists of fibers, microcalcifications or specks, and masses to simulate tumors. Polylactic Acid (PLA) and Polyvinyl Alcohol (PVA) were used to fabricate in-house phantoms. Meanwhile, the fibers and specks were filled with nylon fiber and Al2CO3. The phantom was designed using the CATIA 3D design based on the CIRS phantom mammography accreditation model 015. The diameter of the specks was printed with the 3D printer in various sizes of 1, 0.9, 0.8, 0.7, and 0.6 mm, respectively. The fabricated phantom was irradiated three times to maintain accuracy using mammography type Siemens Mammomat Inspiration with serial number control 11238. The assessment was conducted with manual irradiation mode at a voltage of 28 kV, 100 mAs, target/filter W/Rh, and a compression rate of 50 N. The all-fabricated phantoms met the ACR standard phantom for fiber, and mass detection with the best result was achieved for the second material with six fibers, four specks, and five masses. The fabricated phantom can potentially be used for image quality control for mammography systems in determining the early detection of breast cancer.

Assessment of the uterine dose in digital mammography and digital breast tomosynthesis

IntroductionDigital Mammography (DM-2D) and more recently Digital Breast Tomosynthesis (DBT), are two of the most effective imaging modalities for breast cancer detection, often used in screening programmes. It may happen that exams using these two imaging modalities are inadvertently performed to pregnant women. The objective of this study is to assess the dose in the uterus due to DM-2D and DBT exams, according to two main irradiation scenarios: in the 1st scenario the exposure parameters were pre-selected directly by the imaging system, while in the 2nd scenario, the maximum exposure parameters were chosen. MethodsThe mammography equipment used was a Siemens Mammomat Inspiration. A physical anthropomorphic phantom, PMMA plates (simulating a breast thickness of 6 cm) and thermoluminescent dosimeters (TLDs) were used to measure entrance air kerma values on the phantom's breast and abdomen in order to successively estimate the mean glandular dose (MGD) and the dose in the uterus. For the two irradiation scenarios chosen, two-breast imaging modalities were selected: 1) DBT in Cranio-Caudal (CC) view (with 28 kV and 160 mAs as exposure parameters), 2) DBT and DM in Medio Lateral-Oblique (MLO) and CC views (with 34 kV and 250 mAs as exposure parameters). ResultsIn the 1st scenario, the TLD measurements did not detect significant dose values in the abdomen whereas the MGD estimated using the D.R. Dance model was in close agreement with data available in the literature. In the 2nd scenario, there was no significant difference in MGD estimation between the different views, whereas the air kerma values in the abdomen (in DBT mode, CC and MLO) were 0.049 mGy and 0.004 mGy respectively. In CC DM-2D mode the abdomen air kerma value was 0.026 mGy, with no significant detected value in MLO view. ConclusionsFor the dose in the uterus, the obtained values seem to indicate that DM-2D and DBT examinations inadvertently performed during pregnancy do not pose a significant radiological risk, even considering the case of overexposure in both breasts. Implications for practiceThe accurate knowledge of the doses in DM-2D and DBT will contribute to raise the awareness among medical practitioners involved in breast imaging empowering them to provide accurate information about dose levels in the uterus, improving their radiation risk communication skills and consequently helping to reduce the anxiety of pregnant women undergoing this type of examinations.

Determination of DQE as a quantitative assessment of detectors in digital mammography: Measurements and calculation in practice

Abstract Introduction: Advances in digital detector technology and methods of image presentation in digital mammography now offer the possibility of implementing mathematical assessment methods to quantitative image analysis. The aim of this work was to develop new software to simplify the application of the existing international standard for DQE in digital mammography and show in detail how it can be applied, using a Siemens Mammomat Inspiration as a model. Material and methods: Consistent with the IEC standard a 2 mm Al filter at the tube exit and images in DICOM format as raw data, without applying any additional post-processing were used. Measurements were performed for W/Rh anode/filter combination and different tube voltage values (26 ÷ 34 kV) without any anti-scatter grid. To verify new software doses ranging from 20-600 µGy were used in measurements. Exposure (air kerma) was measured using a calibrated radiation meter (Piranha Black 457, RTI Electronics AB, Sweden). MTF was determined, using an edge test device constructed specifically for this work. Results: It has been demonstrated that with the new software the DQE can be measured with the accuracy required by the international standard IEC 62220-1-2. DQE has been presented as a function of spatial frequency for W/Rh anode/filter combination and different tube voltage. Conclusions: New software was used successfully to analyze image quality parameters for the Siemens Mammomat Inspiration detector. This was done on the basis of an internationally accepted methodology. In the next step, mammographs with different detector types can be compared.

Normalized glandular dose coefficients for digital breast tomosynthesis systems with a homogeneous breast model

This work aims at calculating and releasing tabulated values of dose conversion coefficients, DgNDBT, for mean glandular dose (MGD) estimates in digital breast tomosynthesis (DBT). The DgNDBT coefficients are proposed as unique conversion coefficients for MGD estimates, in place of dose conversion coefficients in mammography (DgNDM or c, g, s triad as proposed in worldwide quality assurance protocols) used together with the T correction factor. DgNDBT is the MGD per unit incident air kerma measured at the breast surface for a 0° projection and the entire tube load used for the scan. The dataset of polyenergetic DgNDBT coefficients was derived via a Monte Carlo software based on the Geant4 toolkit. Dose coefficients were calculated for a grid of values of breast characteristics (breast thickness in the range 20–90 mm and glandular fraction by mass of 1%, 25%, 50%, 75%, 100%) and the simulated geometries, scan protocols, irradiation geometries and typical spectral qualities replicated those of six commercial DBT systems (GE SenoClaire, Hologic Selenia Dimensions, GE Senographe Pristina, Fujifilm Amulet Innovality, Siemens Mammomat Inspiration and IMS Giotto Class). For given breast characteristics, target/filter combination, tube voltage and half value layer (HVL), two spectra with two HVL values have been simulated in order to permit MGD estimates from experimental HVL values via mathematical interpolation from tabulated values. The adopted breast model assumes homogenous composition of glandular and adipose tissues; it includes a 1.45 mm thick skin envelope in place of the 4–5 mm envelope commonly adopted in dosimetry protocols. The simulation code was validated versus AAPM Task group 195 Monte Carlo reference data sets (absolute differences not higher than 1.1%) and by comparison to relative dosimetry measurements with radiochromic film in a PMMA test object (differences within the maximum experimental uncertainty of 11%). The calculated coefficients show maximum relative deviations of −17.6% and +6.1% from those provided by the DBT dose coefficients adopted in the EUREF protocol and of 1.5%, on average, from data in the AAPM TG223 report. A spreadsheet is provided for interpolating the tabulated DgNDBT coefficients for arbitrary values of HVL, compressed breast thickness and glandular fraction, in the corresponding investigated ranges, for each DBT unit modeled in this work.

A phantom study comparing technical image quality of five breast tomosynthesis systems

BackgroundDigital breast tomosynthesis (DBT) is a three-dimensional breast imaging method. DBT vendors employ various approaches in both image acquisition and data processing, which may affect image quality and radiation exposure to patients. ObjectiveThis study aimed to evaluate the performance of five DBT systems: Fujifilm Amulet Innovality (using both a standard mode and high-resolution mode), GE Senographe Essential, Hologic Selenia Dimensions, Planmed Clarity 3D, and Siemens Mammomat Inspiration. Materials and methodsThe performance of each device and imaging technique was evaluated and compared by phantom measurements performed with four quality assurance phantoms. Technical image quality assessments consisted of measuring artefact extent, in-plane resolution, relative noise power spectrum, and geometric accuracy. ResultsArtefact spreading varied remarkably between the devices, and the full width at half maximum values of artefact spread functions varied from 3.5 mm to 10.7 mm. Noticeable in-plane resolution anisotropy, determined using modulation transfer function (MTF) analysis, was typically observed between tube travel direction and chest wall-nipple direction. The MTF50 varied from 1.1 mm−1 to 1.6 mm−1 and from 1.5 mm−1 to 4.1 mm−1 in the tube travel and chest wall-nipple directions, respectively. Moreover, distinctly different noise power spectra were observed between the systems. The geometric accuracy in every system was within 0.5%. ConclusionTechnical image quality assessments with image quality phantoms revealed remarkable differences in artefact spread, in-plane resolution, and noise properties between the DBT systems and imaging methods.

Channelized Hotelling observer assessing microcalcification detectability on 2D mammography: a first application to study the impact of tube voltage

This work was aimed to assess the detectability of microcalcifications as a function of tube voltage in 2D mammography using an in-house developed Channelized Hotelling Observer (CHO). The images of a 3D structured phantom, containing acrylic beads of different diameters in water and inserted signals (microcalcifications, spiculated and non-spiculated mass models) were assessed. Images had been acquired on a Siemens Mammomat Inspiration system at 5 different tube voltage levels (28-32 kVp) under AEC setting. The detectability of microcalcifications was analyzed in terms of percentage correctly detected signals (PC) as well as diameter threshold (dtr), using the CHO and human observers. Two Laguerre-Gauss and 8 Gabor channels were included in the two-layers CHO. The model and human observer results were retrieved from a 4-alternative forced choice (4-AFC) study. At 28 kVp and 32 kVp, the diameter thresholds dtr of microcalcifications together with their 95% confidence intervals (CI95) were 0.114 [0.110-0.118] mm and 0.119 [0.116-0.122] mm for the CHO, and 0.110 [0.093-0.127] mm and 0.123 [0.111-0.134] mm for the human observers. The Pearson correlation (r) between the PC values of model and human observer was more than 0.934. The in-house developed CHO and the human observer scores correlated very well for the application on 2D digital mammography acquired with different tube voltages. The overlapping range of CI95 of the dtr for the tested kVp shows that the tube voltage setting does not significantly affect the detectability of microcalcifications neither by the CHO nor by the human observers.

274. Multi hospital experiences of Radiation Dose Index Monitoring (RDMI) in mammography

Purpose Aim of this work was to use the dose index information from 5 mammography units within USL Toscana Centro, Firenze-Empoli area, analysing and comparing the compression force data and the AGD trend with the thickness of the compressed breast. Methods The RDMI data from Siemens Mammomat Inspiration mammography units were analysed by exploiting the information gathered in a local LOG file that records all the exposure parameters of each single shot. Data in the file are extracted in a spreadsheet tool. All the devices have the same kV-breast thickness compensation curve and work in AEC mode with a W/Rh combination. For the analysis, we focused on data for the year 2015–2016 covering about 40,000 patients for a total of over 169,200 projections. Data are filtered eliminating quality test and manual exposures, breast implants and surgical pieces. Results The average compression force values, for the year 2015, are similar in the first 4 unit. For the Unit 5, it’s found that the breast is significantly less compressed. After a training session on the correct use of the compression paddle, data for year 2016 were analysed. Since then, there are comparable forces with other devices. Nevertheless, for all mammography, there is a very large compression range, with maximum points greater than 200 N and values at the lower limit of 20 N. For the analysis of AGD vs thickness, all devices fall within the EUREF limit values (see Table). Conclusions Data collection has allowed to investigate and compare retrospectively all exams executed in the year 2015 −2016, evaluate anomalies not highlighted with quality assurance tests and take corrective actions to improve performance. Download : Download high-res image (128KB) Download : Download full-size image

277. A software toolset for quality control in digital mammography and DBT

Purpose The aim is to introduce a software toolset compliant with European protocols for quality control of physical and technical aspects of mammography screening (2DFFDM) and Digital Breast Tomosynthesis (DBT) Systems. Methods The toolset is developed as a suite of plugins of the well-known free software ImageJ. The mammographic systems under study are Hologic Selenia Value+ and Siemens Mammomat Inspiration PRIME and the ARTINIS EU DBT Test Set is used to perform QC sessions. IQWorks and OBJ_IQ softwares are used to investigate the consistence for NPS and MTF values while the plugins for analysis of the remaining parameters are directly derived from EUREF guidelines. Results The toolset allows full analysis of the parameters specified in european protocols, especially AEC steps and short term reproducibility, AEC long term reproducibility by SNR referred to 2D ROI and 3D voxel, SDNR, local dense area, image receptor response function, noise, image receptor homogeneity and stability based on 2D ROI and 3D voxel calculation, detector elements failure through text files analysis for visualization and comparison of bad pixel map, uncorrected defective detector elements, inter plate sensitivity variations, AGD from DICOM headers, MTF with edge and wire techniques, NPS from 2DFFDM images, NPS for full 3DDBT slices as well as by extraction. The toolset also evaluates distortions and tilt of the reconstructed 3DDBT planes. The sorting and renaming of a set of dicom images based on their acquisition time or slice position and the evaluation of homogeneity in every DBT focal plane (PV, variance, SNR variations) are also achievable. Conclusions The aim is to introduce a software toolset compliant with European protocols for quality control of physical and technical aspects of mammography screening (2DFFDM) and Digital Breast Tomosynthesis (DBT) Systems. The toolset is developed as a suite of plugins of the well-known free software ImageJ. The mammographic systems under study are Hologic Selenia Value+ and Siemens Mammomat Inspiration PRIME and the ARTINIS EU DBT Test Set is used to perform QC sessions. IQWorks and OBJ_IQ softwares are used to investigate the consistence for NPS and MTF values while the plugins for analysis of the remaining parameters are directly derived from EUREF guidelines. The toolset allows full analysis of the parameters specified in european protocols, especially AEC steps and short term reproducibility, AEC long term reproducibility by SNR referred to 2D ROI and 3D voxel, SDNR, local dense area, image receptor response function, noise, image receptor homogeneity and stability based on 2D ROI and 3D voxel calculation, detector elements failure through text files analysis for visualization and comparison of bad pixel map, uncorrected defective detector elements, inter plate sensitivity variations, AGD from DICOM headers, MTF with edge and wire techniques, NPS from 2DFFDM images, NPS for full 3DDBT slices as well as by extraction. The toolset also evaluates distortions and tilt of the reconstructed 3DDBT planes. The sorting and renaming of a set of dicom images based on their acquisition time or slice position and the evaluation of homogeneity in every DBT focal plane (PV, variance, SNR variations) are also achievable.

278. Scatter correction software for grid-less acquisition in digital mammography – Statistical approach on a visual grading phantom study

Purpose The aim is to investigate the effect of lower radiation output on quality of reconstructed images using a grid-less acquisition-software based scatter correction algorithm versus conventional grid-mode in digital mammography. Methods 115 patient-equivalent images (CIRS mod. 020BR3D phantom) with breast thickness ranging from 10 to 60 mm was obtained with 2D (with grid) and PRIME (Progressive Reconstruction Intelligently Minimizing Exposure) algorithm on Siemens Mammomat Inspiration PRIME. Since PRIME algorithm directly produces images in ‘for presentation’ mode, than the quality assessment was not investigated through raw images derived parameters such SDNR and CNR, but applying score statistical analysis to the images having different type and size lesions at various depth within tissue equivalent and heterogeneous background. Statistical analysis on AGD values was derived from DICOM Header informations, as well as type of reconstruction algorithm and breast thickness. Scores for detectability of simulated lesions was recorded and analyzed using visual grading characteristic (VGC) analysis and ordinal logistic regression. Non parametric tests was performed between scores to assess their equivalence. Wilcoxon rank sum tests and multiple linear regression was also carried out on AGD. Results AGD shows significant differences (p Conclusions PRIME algorithm permits significant dose reduction without image quality loss in comparison to conventional grid-used acquisition mode in order to clinical dose optimization. Download : Download high-res image (166KB) Download : Download full-size image

P010] Radiation dose levels in digital mammography: A retrospective review in a South American imaging centre

Purpose To present results of a retrospective data analysis carried out at a large academic medical centre in South America and to establish a dose reference level (DRL) for digital mammography studies in the region. Methods All patients presenting for screening mammography between July 1 and December 30, 2017 at our imaging centre were reviewed in this study, for which the institutional review board granted approval and waived the requirement for informed consent. Technical parameters including breast compression force, compressed breast thickness, mean glandular dose (MGD), and the number of views needed for complete breast coverage were recorded and analysed. Results A total of 2492 images acquired from 623 patients with a Siemens Mammomat Inspiration digital mammography system were included. The MGD per examination was 2.88 ± 0.05 mGy, the average compressed breast thickness was 64.3 ± 0.5 mm, and the average compression force was 10.1 ± 0.4dN. Twelve percent of the cases required more than the four normal views to cover all breast tissue. When extra views were included, the MGD per subject was 3.85 ± 0.06 mGy. A DRL value of 1.64 mGy has been established by calculating the 95 th percentile of the average MGD for compressed thicknesses ranging from 55 mm to 64 mm. Conclusions Our results show that demographic factors including mean breast thickness and breast prosthesis affect MGD of patients in our region. Finally, our findings show a modest increase of radiation dose to the breast by digital mammography due to the average breast thickness of our patients.

New reconstruction algorithm for digital breast tomosynthesis: better image quality for humans and computers.

BackgroundThe image quality of digital breast tomosynthesis (DBT) volumes depends greatly on the reconstruction algorithm.PurposeTo compare two DBT reconstruction algorithms used by the Siemens Mammomat Inspiration system, filtered back projection (FBP), and FBP with iterative optimizations (EMPIRE), using qualitative analysis by human readers and detection performance of machine learning algorithms.Material and MethodsVisual grading analysis was performed by four readers specialized in breast imaging who scored 100 cases reconstructed with both algorithms (70 lesions). Scoring (5-point scale: 1 = poor to 5 = excellent quality) was performed on presence of noise and artifacts, visualization of skin-line and Cooper’s ligaments, contrast, and image quality, and, when present, lesion visibility. In parallel, a three-dimensional deep-learning convolutional neural network (3D-CNN) was trained (n = 259 patients, 51 positives with BI-RADS 3, 4, or 5 calcifications) and tested (n = 46 patients, nine positives), separately with FBP and EMPIRE volumes, to discriminate between samples with and without calcifications. The partial area under the receiver operating characteristic curve (pAUC) of each 3D-CNN was used for comparison.ResultsEMPIRE reconstructions showed better contrast (3.23 vs. 3.10, P = 0.010), image quality (3.22 vs. 3.03, P < 0.001), visibility of calcifications (3.53 vs. 3.37, P = 0.053, significant for one reader), and fewer artifacts (3.26 vs. 2.97, P < 0.001). The 3D-CNN-EMPIRE had better performance than 3D-CNN-FBP (pAUC-EMPIRE = 0.880 vs. pAUC-FBP = 0.857; P < 0.001).ConclusionThe new algorithm provides DBT volumes with better contrast and image quality, fewer artifacts, and improved visibility of calcifications for human observers, as well as improved detection performance with deep-learning algorithms.

Added Value of Digital Breast Tomosynthesis Combined with Digital Mammography According to Reader Agreement: Changes in BI-RADS Rate and Follow-Up Management

Background: The aim of this study was to evaluate the added value of digital breast tomosynthesis (DBT) when combined with digital mammography (DM) in BI-RADS assessment and follow-up management. Methods: From February 2014 to January 2015, 214 patients underwent DM and DBT, acquired with a Siemens Mammomat Inspiration unit. 2 expert readers independently reviewed the studies in 2 steps: DM and DM+DBT, according to BI-RADS rate. Patients with BI-RADS 0, 3, 4, and 5 were recalled for work-up. Inter-reader agreement for BI-RADS rate and work-up rate were evaluated using Cohen's kappa. Results: Inter-reader agreement (κ value) for BI-RADS classification was 0.58 for DM and 0.8 for DM+DBT. DM+DBT increased the number of BI-RADS 1, 2, 4, 5 and reduced the number of BI-RADS 0 and 3 for both readers compared to DM alone. Regarding work-up rate agreement, κ was poor for DM and substantial (0.7) for DM+DBT. DM+DBT also reduced the work-up rate for both Reader 1 and Reader 2. Conclusion: DM+DBT increased the number of negative and benign cases (BI-RADS 1 and 2) and suspicious and malignant cases (BI-RADS 4 and 5), while it reduced the number of BI-RADS 0 and 3. DM+DBT also improved inter-reader agreement and reduced the overall recall for additional imaging or short-interval follow-up.

Clinical performance of Siemens digital breast tomosynthesis versus standard supplementary mammography for the assessment of screen-detected soft-tissue abnormalities: a multi-reader study

To compare the diagnostic accuracy of standard screening images plus single-view digital breast tomosynthesis (DBT), using Siemens DBT equipment, with standard screening images plus supplementary mammographic views in non-calcific, screen-detected mammographic abnormalities. Participants were unselected women aged 50-69 years recalled within a population-based European breast screening programme for assessment of soft-tissue mammographic abnormalities. Supplementary mammographic views (SMVs) and DBT were performed in all cases. A range of equipment was used for screening and supplementary mammography, but all DBT examinations were performed using the Siemens Mammomat Inspiration. A retrospective multi-reader study including 238 cases for whom either histology or at least 2 years' follow-up was available was performed with eight suitably accredited UK breast screening personnel reading all cases under both conditions, with temporal separation. Readers were blinded to case outcomes and findings from other examinations. Diagnostic accuracy using receiver operating characteristic (ROC) analysis was compared between screening plus SMV images and screening plus DBT images. The study was powered to detect a 3% inferiority margin in diagnostic accuracy between methods. The final sample with complete data available for analysis included 195 benign cases (1,560 reads) and 35 malignant cases (280 reads). The DBT method yielded a slightly higher area under the curve (AUC) value than the SMV method (0.870 versus 0.857), but the difference was not statistically significant (p=0.4890), indicating that the methods have equivalent accuracy. Siemens DBT demonstrates equivalent diagnostic accuracy according to ROC curve analysis when used in place of SMVs in screen-detected soft-tissue mammographic abnormalities.

Radiation doses received by patients in digital mammography: A first investigation in Morocco

Introduction and objective Digital mammography is being introduced worldwide for breast cancer diagnosis and screening. While the technique is known to offer a good image quality–dose balance, its introduction in specific regions should be investigated. Present study focuses on the absorbed radiation dose, and more in particular on estimations of average glandular dose (AGD).The present work concerns a dosimetric study in digital mammography in Morocco. Materials and methods A dosimetric study was conducted in a Moroccan university hospital with system full-field digital mammography, Siemens Mammomat Inspiration. The average glandular dose of about hundred patients was calculated taking into account the entrance dose (tube output), half value layer and thickness of the compressed breast. Dose values were calculated with PMMA phantoms. Results The results showed that almost values were located below the achievable dose limit curve of the European Guidelines. For average thickness of 55 mm, the AGD is about 1.24 mGy for the Clinical–Caudal (CC) view and 1.32 mGy for the Mediolateral–Oblique (MLO) view with the same SD = 0.3. The results show also that the mean patients AGD is about 30% lower than that given by the PMMA. Conclusion The results show an increase in the average glandular dose as a function of breast thickness. Average and maximal doses are in line with values obtained in European studies. This study will now be performed in more Moroccan hospitals and the data obtained could be used to work at breast cancer screening in our country.

Evaluation of the technical performance of three different commercial digital breast tomosynthesis systems in the clinical environment

The aim of this work was to research and evaluate the performance of three different digital breast tomosynthesis (DBT) systems in the clinical environment (Siemens Mammomat Inspiration, Hologic Selenia Dimensions, and Fujifilm Amulet Innovality). The characterization included the study of the detector, the automatic exposure control, and the resolution of DBT projections and reconstructed planes.The modulation transfer function (MTF) of the DBT projections was measured with a 1mm thick steel edge, showing a strong anisotropy (30–40% lower MTF0.5 frequencies in the tube travel direction). The in-plane MTF0.5, measured with a 25μm tungsten wire, ranges from 1.3 to 1.8lp/mm in the tube-travel direction and between 2.4 and 3.7lp/mm in the chest wall–nipple. In the latter direction, the MTF peak shift is more emphasized for large angular range systems (2.0 versus 1.0lp/mm). In-depth resolution of the planes, via the full width at half maximum (FWHM) from the point spread function of a 25μm tungsten wire, is not only influenced by angular range and yields 1.3–4.6mm among systems. The artifact spread function from 1mm diameter tungsten beads depends mainly on angular range, yielding two tendencies whether large (FWHM is 4.5mm) or small (FWHM is 10mm) angular range is used. DBT delivers per scan a mean glandular dose between 1.4 and 2.7mGy for a 45mm thick polymethyl methacrylate (PMMA) block.In conclusion, we have identified and analysed specific metrics that can be used for quality assurance of DBT systems.

Avaliação da qualidade da imagem e da Dose Glandular Média em Mamografia Digital.

The most important reference for breast cancer diagnosis is still the mammography. Mammographic technology has evolved in such a way that we have digital systems nowadays. Thus, image generation quality control must evolve as well. In this work, we have evaluated digital image quality and entrance skin dose (ESD) for different breast thicknesses simulated by PMMA plates (one, two, three and four centimeters) for different target filter combinations, suggesting a protocol optimization to the mammographic automatic system.We have used CDMAM 3.4 phantom (a contrast detail phantom) and its software in order to analyze digital images from a Siemens Mammomat Inspiration mammographic equipment. It has been used three combinations of target-filter: Molybdenum Molybdenum, Molybdenum Rhodium, Tungsten Rhodium. Different peak tensions were tested to each configuration: 24 kVp, 26 kVp, 28 kVp and 30 kVp. Altogether 52 different configurations were tested. In order to measure ESD, we used Radcal’s 10x5–6M ionization chamber.Results show that automatic configuration does not offer an optimized process. Tungsten Rhodium was the best option for all breast thicknesses, once it offered the best relation between image quality and mean glandular dose. This result differs from literature which states that the Molybdenum Molybdenum combination is the best option for thin breasts.

TU-F-18C-02: Increasing Amorphous Selenium Thickness in Direct Conversion Flat-Panel Imagers for Contrast-Enhanced Dual-Energy Breast Imaging

Purpose: Contrast-enhanced (CE) breast imaging using iodinated contrast agents requires imaging with x-ray spectra at energies greater than those used in mammography. Optimizing amorphous selenium (a-Se) flat panel imagers (FPI) for this higher energy range may increase lesion conspicuity. Methods: We compare imaging performance of a conventional FPI with 200 μm a-Se conversion layer to a prototype FPI with 300 μm a-Se layer. Both detectors are evaluated in a Siemens MAMMOMAT Inspiration prototype digital breast tomosynthesis (DBT) system using low-energy (W/Rh 28 kVp) and high-energy (W/Cu 49 kVp) x-ray spectra. Detectability of iodinated lesions in dual-energy images is evaluated using an iodine contrast phantom. Effects of beam obliquity are investigated in projection and reconstructed images using different reconstruction methods. The ideal observer signal-to-noise ratio is used as a figure-of-merit to predict the optimal a-Se thickness for CE lesion detectability without compromising conventional full-field digital mammography (FFDM) and DBT performance. Results: Increasing a-Se thickness from 200 μm to 300 μm preserves imaging performance at typical mammographic energies (e.g. W/Rh 28 kVp), and improves the detective quantum efficiency (DQE) for high energy (W/Cu 49 kVp) by 30%. While the more penetrating high-energy x-ray photons increase geometric blur due to beam obliquity in the FPI with thicker a-Se layer, the effect on lesion detectability in FBP reconstructions is negligible due to the reconstruction filters employed. Ideal observer SNR for CE objects shows improvements in in-plane detectability with increasing a-Se thicknesses, though small lesion detectability begins to degrade in oblique projections for a-Se thickness above 500 μm. Conclusion: Increasing a-Se thickness in direct conversion FPI from 200 μm to 300 μm improves lesion detectability in CE breast imaging with virtually no cost to conventional FFDM and DBT. This work was partially supported by a research grant from Siemens Healthcare.