Search

Digital breast tomosynthesis (DBT) stands out as a highly robust screening technique capable of enhancing the rate at which breast cancer is detected. It also addresses certain limitations that are inherent to mammography. Nonetheless, the process of manually examining numerous DBT slices per case is notably time-intensive. To address this, computer-aided detection (CAD) systems based on deep learning have emerged, aiming to automatically identify breast tumors within DBT images. However, the current CAD systems are hindered by a variety of challenges. These challenges encompass the diversity observed in breast density, as well as the varied shapes, sizes, and locations of breast lesions. To counteract these limitations, we propose a novel method for detecting breast tumors within DBT images. This method relies on a potent dynamic ensemble technique, along with robust individual breast tumor detectors (IBTDs). The proposed dynamic ensemble technique utilizes a deep neural network to select the optimal IBTD for detecting breast tumors, based on the characteristics of the input DBT image. The developed individual breast tumor detectors hinge on resilient deep-learning architectures and inventive data augmentation methods. This study introduces two data augmentation strategies, namely channel replication and channel concatenation. These data augmentation methods are employed to surmount the scarcity of available data and to replicate diverse scenarios encompassing variations in breast density, as well as the shapes, sizes, and locations of breast lesions. This enhances the detection capabilities of each IBTD. The effectiveness of the proposed method is evaluated against two state-of-the-art ensemble techniques, namely non-maximum suppression (NMS) and weighted boxes fusion

Purpose: For 50 years now, SPIE Medical Imaging (MI) conferences have been the premier forum for disseminating and sharing new ideas, technologies, and concepts on the physics of MI. Approach: Our overarching objective is to demonstrate and highlight the major trajectories of imaging physics and how they are informed by the community and science present and presented at SPIE MI conferences from its inception to now. Results: These contributions range from the development of image science, image quality metrology, and image reconstruction to digital x-ray detectors that have revolutionized MI modalities including radiography, mammography, fluoroscopy, tomosynthesis, and computed tomography (CT). Recent advances in detector technology such as photon-counting detectors continue to enable new capabilities in MI. Conclusion: As we celebrate the past 50 years, we are also excited about what the next 50 years of SPIE MI will bring to the physics of MI., QC 20221205

ObjectivesTo analyse which mammographic and tumour characteristics led to concordant versus discordant recalls at blinded double reading to further optimise our breast cancer screening programme.MethodsWe included a consecutive series of 99,013 screening mammograms obtained between July 2013 and January 2015. All mammograms were double read in a blinded fashion. Discordant readings were routinely recalled without consensus or arbitration. During the 2-year follow-up, relevant data of the recalled women were collected. We compared mammographic characteristics, screening outcome and tumour characteristics between concordant and discordant recalls.ResultsThere were 2,543 concordant recalls (71.4%) and 997 discordant recalls (28.0%). The positive predictive value of a concordant recall was significantly higher (23.5% vs. 10.0%, p <0.001). The proportion of BI-RADS 0 was significantly higher in the discordant recall group (75.7% vs. 56.3%, p <0.001). Discordant recalls were more often an asymmetry or architectural distortion (21.8% vs. 13.2% and 9.3% vs. 6.5%, respectively, p <0.001). There were no differences in the distribution of DCIS and invasive cancers and tumour characteristics were comparable for the two groups, except for a more favourable tumour grade in the discordant recall group (54.7% vs. 39.9% grade I tumours, p = 0.022).ConclusionsScreen-detected cancers detected by a discordant reading show a more favourable tumour grade than cancers diagnosed after a concordant recall. The higher proportion of asymmetries and architectural distortions in this group provide a possible target for improving screening programmes by additional training of screening radiologists and the implementation of digital breast tomosynthesis.Key Points center dot With blinded double reading of screening mammograms, screen-detected cancers detected by a discordant reading show a more favourable tumour grade than cancers diagnosed after a concordant recall.center dot The pro

ProblemApproximately 75% of the breast cancer biopsies performed after recommendations from diagnostic mammography are benign, making it clear that specificity for diagnostic mammography still needs significant improvements. A novel three-compartment breast (3CB) composition technique developed by Laidevant et al. seeks to improve the specificity of diagnostic digital mammography, but it is prone to estimate incorrect compositional estimates for patient lesions. The focus of this thesis was to further develop this three-compartment technique for clinical applications in dual-energy X-ray imaging modalities. MethodsThree potential sources of error in the 3CB technique were studied: (1) attenuation coefficient differences in biological materials—for which 3CB is estimating compositional estimates—and their calibration equivalents, (2) nonuniformities in full-field digital mammography (FFDM) from X-ray source spectra, and (3) initial intensity I_0 differences between biological and calibration images. Initial developments for 3CB applications in digital breast tomosynthesis were also investigated, and these were in two areas: (1) dose measurements and estimates were made for high energy 3CB digital breast tomosynthesis (DBT) images and (2) derivation of potential variables of interest as predictors of breast thickness from raw DBT projections. Lastly, a novel technique for measuring body composition from 2D optical images to help monitor and maintain healthy body weight was investigated, which could potentially aid in monitoring adipose and muscular tissues to monitor and maintain a lean weight to reduce risk of cancer for postmenopausal women in low-resource settings.ResultsTo reduce error in the attenuation coefficient differences between biological and calibration materials, linear mappings were created using bovine and chicken phantoms. This linear mapping corrected negative 3CB compositional estimates in a population study. To reduce error in nonuniformities in FF

Digital breast tomosynthesis (DBT) is a relatively new modality for breast imaging that can provide detailed assessment of dense tissue within the breast. In the domains of cancer diagnosis, radiogenomics, and resident education, it is important to accurately segment breast masses. However, breast mass segmentation is a very challenging task, since mass regions have low contrast difference between their neighboring tissues. Notably, the task might become more difficult in cases that were assigned BI-RADS 0 category since this category includes many lesions that are of low conspicuity and locations that were deemed to be overlapping normal tissue upon further imaging and were not sent to biopsy. Segmentation of such lesions is of particular importance in the domain of reader performance analysis and education. In this paper, we propose a novel deep learning-based method for segmentation of BI-RADS 0 lesions in DBT. The key components of our framework are an encoding path for local-to-global feature extraction, and a decoding patch to expand the images. To address the issue of limited training data, in the training stage, we propose to sample patches not only in mass regions but also in non-mass regions. We utilize a Dice-like loss function in the proposed network to alleviate the class-imbalance problem. The preliminary results on 40 subjects show promise of our method. In addition to quantitative evaluation of the method, we present a visualization of the results that demonstrate both the performance of the algorithm as well as the difficulty of the task at hand.

It has previously been shown that 2D spectral mammography can be used to discriminate between (likely benign) cystic and (potentially malignant) solid lesions in order to reduce unnecessary recalls in mammography. One limitation of the technique is, however, that the composition of overlapping tissue needs to be interpolated from a region surrounding the lesion. The purpose of this investigation was to demonstrate that lesion characterization can be done with spectral tomosynthesis, and to investigate whether the 3D information available in tomosynthesis can reduce the uncertainty from the interpolation of surrounding tissue. A phantom experiment was designed to simulate a cyst and a tumor, where the tumor was overlaid with a structure that made it mimic a cyst. In 2D, the two targets appeared similar in composition, whereas spectral tomosynthesis revealed the exact compositional difference. However, the loss of discrimination signal due to spread from the plane of interest was of the same strength as the reduction of anatomical noise. Results from a preliminary investigation on clinical tomosynthesis images of solid lesions yielded results that were consistent with the phantom experiments, but were still to some extent inconclusive. We conclude that lesion characterization is feasible in spectral tomosynthesis, but more data, as well as refinement of the calibration and discrimination algorithms, are needed to draw final conclusions about the benefit compared to 2D., QC 20170628

A look back at Skeletal Radiology in 2016 reveals a sizable number of publications that significantly advanced the state of knowledge about diseases of the musculoskeletal system. This review summarizes the content of some of the most intriguing papers of the year.

Rheumatoid arthritis (RA) is a systemic disease that is caused by autoimmunity. RA causes synovial proliferation, which may result in bone erosion and joint space narrowing in the affected joint. Tomosynthesis is a promising modality which may detect early bone lesions such as small bone erosion and slight joint space narrowing. Nevertheless, so far, the optimal reconstruction filter for detection of early bone lesions of fingers on tomosynthesis has not yet been known. Our purpose in this study was to determine an optimal reconstruction filter setting by using a bone phantom. We obtained images of a cylindrical phantom with holes simulating bone erosions (diameters of 0.6, 0.8, 1.0, 1.2, and 1.4 mm) and joint spaces by aligning two phantoms (space widths from 0.5 to 5.0 mm with 0.5 mm intervals), examining six reconstruction filters by using tomosynthesis. We carried out an accuracy test of the bone erosion size and joint space width, done by one radiological technologist, and a test to assess the visibility of bone erosion, done by five radiological technologists. No statistically significant difference was observed in the measured bone erosion size and joint space width among all of the reconstruction filters. In the visibility assessment test, reconstruction filters of Thickness+− and Thickness−− were among the best statistically in all characteristics except the signal-to-noise ratio. The Thickness+− and Thickness−− reconstruction filter may be optimal for evaluation of RA bone lesions of small joints in tomosynthesis.

[Resumen] Objetivos: El objetivo de esta revisión sistemática es determinar la efectividad de la tomosíntesis en el cribado de cáncer de mama comparándola con la mamografía digital convencional. Metodología: Se llevó a cabo una búsqueda bibliográfica de revisiones sistemáticas y artículos originales en las bases de datos de Medline, Embase, Dare, Cinahl y Scopus. Las variables de análisis escogidas fueron la tasa de detección de cáncer, la tasa de rellamadas y otras variables de interés en el diagnóstico como el valor predictivo positivo. Resultados: Se obtuvieron dos revisiones sistemáticas que apuntaban un posible beneficio en el uso de la tomosíntesis pero sin llegar a obtener resultados concluyentes para el screening. Los artículos originales seleccionados fueron nueve, dos grandes ensayos poblaciones europeos y siete estudios retrospectivos americanos. En seis de estos estudios se demostró un incremento en la tasa de detección de cáncer y una reducción en la tasa de rellamadas con el uso de la tomosíntesis. No obstante, los resultados son heterogéneos ya que el cribado es diferente según los países de estudio y ninguno de ellos realizó seguimiento de los cánceres de intervalo. Conclusiones: A pesar de la evidencia positiva para la tomosíntesis es necesario realizar más estudios prospectivos con adecuado seguimiento de las pacientes negativas e investigar la posibilidad de reducir la dosis de radiación., [Resumo] Obxectivos: O obxectivo desta revisión sistemática é determinar a efectividade da tomosíntese no cribado de cancro de mama comparándoa coa mamografía dixital convencional. Metodoloxía: Levouse a cabo unha busca bibliográfica de revisións sistemáticas e artigos orixinais nas bases de datos de Medline, Embase, Dare, Cinahl y Scopus. As variables de análise escollidas foron a taxa de detección de cancro, a taxa de rechamadas e outras variables de interese no diagnóstico como o valor preditivo positivo. Resultados: Obtivéronse dúas revisións sistemáticas que sinalaban un beneficio potencial no uso da tomosíntese pero sen chegar a obter resultados concluíntes no cribado. Os artigos orixinais seleccionados foron nove, dous grandes ensaios poblacionais europeos e sete estudos retrospectivos americanos. En seis destos estudos amosouse un aumento na taxa de detección de cancro e unha redución na taxa de rechamadas co uso da tomosíntese. Con todo, os resultados son heteroxéneos xa que o cribado é diferente segundo o país de estudo e ningún deles realizou o seguimento dos cancros de intervalo. Conclusións: A pesar da evidencia positiva para a tomosíntese é necesario realizar máis estudos prospectivos con adecuado seguimento das pacientes negativas e investigar a posibilidade de reducir a dose de radiación., [Abstract] Purpose: The aim of this review is to determine the tomosynthesis effectiveness in breast cancer screening and to compare it with conventional digital mammography. Methods: We carried out a literature search for systematic reviews and original items in the following databases: Medline, Embase, Dare, CINAHL and Scopus. We analyzed the following variables: cancer detection rate, recall rate and other variables of interest as positive predictive value. Results: We obtained two systematic reviews that pointed a potential benefit in using tomosynthesis but without conclusive results for screening. We selected nine original articles, two large European trials and seven American retrospective studies. Tomosynthesis showed an increase in cancer detection rate and a reduction in recall rate in six studies. However, the results are heterogeneous because screening was performed in different countries and none of them studied interval cancers. Conclusions: There is a positive evidence for the tomosynthesis. However further prospective studies are needed with adequate follow-up of negative patients and investigate the possible dose reduction.

Tomosynthesis is emerging as a next generation technology in mammography. Combined with photon-counting detectors with the ability for energy discrimination, a novel modality is enabled - spectral tomosynthesis. Further advantages of photon-counting detectors in the context of tomosynthesis include elimination of electronic noise, efficient scatter rejection (in some geometries) and no lag. Fourier-based linear-systems analysis is a well-established method for optimizing image quality in two-dimensional x-ray systems. The method has been successfully adapted to three-dimensional imaging, including tomosynthesis, but several areas need further investigation. This study focuses on two such areas: 1) Adaption of the methodology to photon-counting detectors, and 2) violation of the shift-invariance and stationarity assumptions in non-cylindrical geometries. We have developed a Fourier-based framework to study the image quality in a photon-counting tomosynthesis system, assuming locally linear, stationary, and shift-invariant system response. The framework includes a cascaded-systems model to propagate the modulation-transfer function (MTF) and noise-power spectrum (NPS) through the system. The model was validated by measurements of the MTF and NPS. High degrees of non-shift invariance and non-stationarity were observed, in particular for the depth resolution as the angle of incidence relative the reconstruction plane varied throughout the imaging volume. The largest effects on image quality in a given point in space were caused by interpolation from the inherent coordinate system of the x-rays to the coordinate system that was used for reconstruction. This study is part of our efforts to fully characterize the spectral tomosynthesis system, we intend to extend the model further to include the detective-quantum efficiency, observer modelling, and spectral effects., QC 20150706

Autologous fat grafting or lipomodeling is a newly-adopted technique that is gaining increasing popularity in the treatment of contour deformities following breast conservation therapy. Here, we describe the case of a 47-year-old woman with a prior history of breast cancer treated with a lumpectomy and radiation therapy. She underwent lipomodeling not only of her treated breast but also of the contralateral breast. She presented for her annual mammogram which was performed with digital breast tomosynthesis. On imaging, a space-occupying lesion of mixed density was seen, expanding the lumpectomy site. There was also subtle distortion in the contralateral, non-treated breast. This case aims to highlight the mammographic and tomosynthesis findings seen following lipomodeling that may present diagnostic challenges in this patient population.

The purpose of the project is to determine the potential of Digital Tomosynthesis (DTS) for quantitative analysis of vertebral bone quality and for predicting vertebral bone fragility. The current scope, as a proof of concept study, is to compare parameters derived from DTS to those measured from microCT and test their ability to predict in vitro vertebral strength by a set of destructive tests on vertebrae from human cadavers. We characterized the DTS system for its ability to resolve features, shapes and densities using a number of man-made reference materials. We have noted that a single best scan is obtained in a scan direction oblique to the major orientation of the structure of interest but multiple orthogonal scans can provide complementary information. We noted that zero angle view of the scans provides density information complementary to the structural information obtained through the synthesis of all views. By correlating DTS-based parameters of cancellous microstructure (fractal dimension, lacunarity, mean intercept length and line fraction deviation) to those derived from microCT (distribution properties of bone volume fraction, trabecular thickness, number and separation, and degree of anisotropy) and to bone stiffness estimated from large scale finite element analysis, we demonstrated that parameters of cancellous bone microstructure derived from DTS correlate with those derived from microCT and increase prediction accuracy of bone stiffness over bone mass alone. The importance of analysis volume and image pre-processing were assessed and determined to be important factors in correlational models between DTS-based parameters of cancellous microstructure and microCTbased stereology and finite element parameters., The original document contains color images.

Contrast-enhanced digital breast tomosynthesis (CE-DBT) is a novel x-ray imaging technique that produces a 3D representation of the breast vasculature via an intravenous contrast agent. CE-DBT offers a combination of excellent spatial resolution and accurate functional information, suggesting a strong potential role in disease prognostication. We have developed an innovative technique for obtaining dynamic contrast-enhanced (DCE) images with high spatial and temporal resolution. We have demonstrated, in proof-of-principle, that 4D DCE-DBT is technically feasible and that the derived data accurately measures vascular dynamics. Previous contrast-enhanced DBT systems produced images at 2-3 fixed time points. Our novel acquisition technique is capable of producing perfusion images at 30-60 time points for the same radiation dose. The method is compatible with both temporal and dual-energy subtraction methods. Reconstruction is performed using one full set of sequentially-acquired images; however, unlike conventional DBT, the starting angle (and hence measurement time point) is arbitrary in our method. The resulting 4D data set consists of many time-resolved 3D functional measurements of tumor perfusion, offering the potential for superior lesion characterization and hence diagnostic accuracy., The original document contains color images.

Stable operation of the new developed s-DBT scanner at 28kVp anode voltage and 38mA tube current was demonstrated with extended lifetime and good source-to-source consistency. For standard imaging protocol of 15 views, 14 degree, 100mAs dose, and 2x2 detector binning the projection resolution along scanning direction is increased from 4.0 lps/mm (at 10% MTF) in DBT to 5.1 lps/mm in s-DBT at magnification factor of 1.1. The improvement is more pronounced for faster scanning speed, wider angular coverage, and smaller detector pixel size. The scanning speed depends on the detector, the number of views, and the imaging dose. With 240ms detector readout time the s-DBT system scanning time is 6.3s for a 15-view, 100mAs scan regardless of the angular coverage. The scanning speed can be reduced to less than 4s when detectors become faster. Initial phantom studies showed good quality reconstructed images., The original document contains color images.

The purpose of the project is to determine the potential of Digital Tomosynthesis (DTS) for quantitative analysis of vertebral bone quality and for predicting vertebral bone fragility. The current scope, as a proof of concept study, is to compare parameters derived from DTS to those measured from microCT and test their ability to predict in vitro vertebral strength by a set of destructive tests on vertebrae from human cadavers. As of writing of this report, we characterized the DTS system for its ability to resolve features, shapes and densities using a number of man-made reference materials. We have noted that a single best scan is obtained in a scan direction oblique to the major orientation of the structure of interest but multiple orthogonal scans can provide complementary information. We noted that zero angle view of the scans provides density information complementary to the structural information obtained through the synthesis of all views. By correlating DTS-based parameters of cancellous microstructure (fractal dimension, lacunarity, mean intercept length and line fraction deviation) to those derived from microCT (distribution properties of bone volume fraction, trabecular thickness, number and separation, and degree of anisotropy) and to bone stiffness estimated from large scale finite element analysis, we demonstrated that parameters of cancellous bone microstructure derived from DTS correlate with those derived from microCT and increase prediction accuracy of bone stiffness over bone mass alone. As such, we produced strong evidence that the concept being explored, i.e., that quantitative analysis of bone quality using DTS is feasible. Current efforts are focused on i) examination of the information content that is represented in DTS parameters and the nature of the agreement and disagreement between microCT and DTS parameters in order to understand how predictive accuracy of DTS may be increased, and ii) mechanical testing of vertebral bodies.

In tomosynthesis, a 3D image of the breast is generated from multiple x-ray projections. Although prior authors have modeled image quality in tomosynthesis, their work is limited in approximating the incident angle as normal to the detector. This research studies the consequences of carefully modeling the incident angle. From first principles, an analytical model of the transfer functions for oblique incidence is derived in individual projections. The anisotropy of the transfer functions over the detector area is then demonstrated, and a technique for optimizing detector thickness at various incident angles is developed. In addition to modeling the effect of non-normal incidence on transfer functions, it is shown that oblique incidence yields subpixel translational shifts in the image of the object with each projection angle. By calculating the reconstruction of a high frequency sine input, the potential for super-resolution (i.e., sub-pixel resolution) is established from this property. Superresolution is demonstrated in experimental images of bar patterns and select clinical examples of microcalcifications. The feasibility of super-resolution is also verified in a broad range of multi-planar reconstructions. Finally, from the analytical modeling of the sine input, the scan time which optimizes modulation in the reconstruction is calculated in systems with patient motion., The original document contains color images.

Purpose: To investigate whether readers' experience affects performance in a study comparing 2D digital mammography (2D) with 2-view (CC and MLO) or 1-view (MLO) tomosynthesis. Materials and Methods: One-hundred-thirty 2D cases were collected from screening assessment and referral clinics; 64 of the cases had verified abnormalities and the remaining were confirmed normal. Two-view tomosynthesis images were obtained from the same patients. Ten accredited readers (5 with ≥ 10 years experience in mammography and 5 with < 10 years) classified the cases in terms of malignancy (rate 0-5), and recall (yes/no), for both modalities. A second experiment was performed with the same cases, with 10 other readers (again 5 experienced / 5 less experienced), but using 2D and 1-view tomosynthesis as the two modalities. The multi-reader-multi-case ROC method was applied and the significance of diagnostic accuracy difference of 2D vs tomosynthesis was calculated, as a function of experience and for each experiment. Recall rate (RR) on malignant and benign cases was also calculated, along with reading time. Results: No significant difference was reached between 2D and 2-view tomosynthesis for experienced readers (pvalue= 0.25); for less experienced readers the p-value was significant (0.03). No significant difference was found between 2D and 1-view tomosynthesis, independent of readers' experience. RR for benign cases decreased for tomosynthesis (for booth 1- and 2-view), independent of experience. Average reading time per case was 79 s (range 65- 91 s) and 134 s (range 119-158 s) for experienced readers; 56 s (range 46-67 s) and 115s (range 97-142 s) for nonexperienced, for 2D and 2-view tomosynthesis respectively. Reading time was 74 s (range 43-98 s) and 99 s (range 73- 117 s) for experienced readers; 74 s (range 62-85 s) and 94 s (range 82-137 s) for non-experienced, for 2D and 1-view tomosynthesis respectively. Conclusions: For experienced readers, there is no evidence of impro, QC 20160509

Digital breast tomosynthesis (DBT) is a new technology for breast cancer screening that promises to complement mammography or supersede it to become the standard for breast imaging. DBT involves taking multiple images in order to synthesize a new image that represents a slice through the breast volume -- hence the term tomosynthesis. The primary advantage of this paradigm is that it can reduce the amount of overlapping anatomy in the data, leading to improved visualization of potentially-cancerous findings. The difficulty in DBT is quantifying the advantages of the technology and determining the optimal conditions for its clinical use. This dissertation describes a virtual trial framework for assessing and optimizing DBT technology for the specific task of detecting small, low-contrast masses in the breast. It addresses each component of the imaging chain to some degree, from the patients/phantoms to the imaging hardware to the model observers used to measure signal detectability. The main focus, however, is on quantifying tradeoffs between three key parameters that affect image quality: (1) scan angle, (2) number of projections, and (3) exposure. We show that in low-density breast phantoms, detectability generally increases with both scan angle and number of projections in the anatomical-variability-limited (high-exposure) regime. We also investigate how breast density affects the optimal DBT scan parameters. We show task-specific results that support using an adaptive paradigm in DBT, where the imaging system reconfigures itself in response to information about the patient's breast density. The virtual framework described in this dissertation provides a platform for further investigations of image quality in 3D breast imaging.

We have designed a mammography system that for the first time combines photon-counting spectral imaging with tomosynthesis. The present study is a comprehensive physical evaluation of the system; tomosynthesis, spectral imaging, and the combination of both are compared using an ideal-observer model that takes anatomical noise into account. Predictions of signal and noise transfer through the system are verified by contrast measurements on a tissue phantom and 3D measurements of MTF and NPS. Clinical images acquired with the system are discussed in view of the model predictions., QC 20110927

Tomosynthesis is an emerging technique with potential to replace mammography, since it gives 3D information at a relatively small increase in dose and cost. We present an analytical singular-value decomposition of a tomosynthesis system, which provides the measurement component of any given object. The method is demonstrated on an example object. The measurement component can be used as a reconstruction of the object, and can also be utilized in future observer studies of tomosynthesis image quality., QC 20101213

One major deficiency of standard mammography that limits its accuracy in detecting breast cancer is the camouflaging effect of overlapping structures in the projection images. To minimize this effect, we proposed Multi-plane Correlation Imaging (MCI) technique. In this technique, multiple radiographic images of the breast are obtained from different angles in rapid succession. Angular information is used to identify and positively reinforce the lesion signals between different projections. In this research work, a theoretical foundation based on mathematical observer model was laid out to model the diagnostic process in MCI. Using this model, a framework was developed to optimize data acquisition in MCI to maximize its diagnostic performance. The framework was then validated using a new CADe processor. Furthermore, it was extended to optimize tomosynthesis and to compare its performance with MCI. The results revealed that the peak performance for MCI at dose levels of single-view mammography was achieved at 15 - 17 projections spanning an angular arc of ~45 deg, the widest angle tested in this study. An average angular separation of ~2.75 deg was found to be optimum. Overall, performance of optimized MCI exceeded that of standard mammography by 18% and that of tomosynthesis by 8%. MCI may thus prove to be potentially more accurate, and cost- and dose- effective breast imaging technique., The original document contains color images.

The goal of this research is to obtain systematic understandings of the effects of various physical factors that are important in breast tomosynthesis imaging and to develop techniques for effectively dealing with their effects and for reducing radiation dose. During the second year of the project we have achieved fruitful results based upon the progress made in our first year of the project. Specifically, we have further investigated the performance of the total-variation (TV) based algorithm under different data conditions and different constraint parameters. Furthermore, we have also proposed and investigated a new tomosynthesis imaging method with non-planar trajectories for yielding more data information with the same amount of imaging dose. We have also simulated the scatter in tomosynthesis breast imaging by convolving the ideal projection data with angular dependent scatter kernel., The original document contains color images.

We present data on a first prototype for photon counting tomosynthesis imaging of small children, which we call photoncounting tomosynthesis (PCT). A photon counting detector can completely eliminate electronic noise, which makes it ideal for tomosynthesis because of the low dose in each projection. Another advantage is that the detector allows for energy sensitivity in later versions, which will further lower the radiation dose. In-plane resolution is high and has been measured to be 5lp/mm, at least 4 times better than in CT, while the depth resolution was significantly lower than typical CT resolution. The image SNR decreased from 30 to 10 for a detail of 10 mm depth in increasing thickness of PMMA from 10 to 80 mm. The air kerma measured for PCT was 5.2 mGy, which leads to an organ dose to the brain of approximately 0.7 mGy. This dose is 96 % lower than a typical CT dose. PCT can be appealing for pediatric imaging since young children have an increased sensitivity to radiation induced cancers. We have acquired post mortem images of a newborn with the new device and with a state-of-the-art CT and compared the diagnostic information and dose levels of the two modalities. The results are promising but more work is needed to provide input to a next generation prototype that would be suitable for clinical trials., QC 20120307

We present the first evaluation of a recently developed silicon-strip detector for photon-counting dual-energy breast tomosynthesis. The detector is well suited for tomosynthesis with high dose efficiency and intrinsic scatter rejection. A method was developed for measuring the spatial resolution of a system based on the detector in terms of the three-dimensional modulation transfer function (MTF). The measurements agreed well with theoretical expectations, and it was seen that depth resolution was won at the cost of a slightly decreased lateral resolution. This may be a justifiable trade-off as clinical images acquired with the system indicate improved conspicuity of breast lesions. The photon-counting detector enables dual-energy subtraction imaging with electronic spectrumsplitting. This improved the detectability of iodine in phantom measurements, and the detector was found to be stable over typical clinical acquisition times. A model of the energy resolution showed that further improvements are witn reach by optimization of the detector., QC 20120215

One major deficiency of standard mammography is the camouflaging effect of overlapping structures in the projection images that limits the rendering of breast cancer. To minimize this effect, we proposed Multi-plane Correlation Imaging (MCI) technique. In this technique, multiple radiographic images of the breast are obtained from different angles. Angular information is used to identify and positively reinforce the lesion signals between different projections. In this phase of the study, we conducted a feasibility study of MCI using a mathematical model-based framework. Clinical utility of MCI was tested using a task that modeled clinical practice on clinically-realistic backgrounds of mastectomy specimens. The technique was then optimized to obtain maximum diagnostic information. Furthermore, a CADe based operator that takes advantage of the MCI configuration was developed. Results revealed that the peak performance for MCI at dose levels of one- and two-view mammography was achieved at 15 ? 17 projections spanning an angular arc of ~45o, the widest angle tested in this study. Performance of optimized MCI exceeded that of standard mammography by 18%. Overall, MCI may prove to be potentially more accurate, and cost-and dose-effective., The original document contains color images.

The purpose of this study was to investigate feasibility of computer-aided detection of masses and calcification clusters in breast tomosynthesis images and obtain reliable estimates of sensitivity and false positive rate on an independent test set. Automatic mass and calcification detection algorithms developed for film and digital mammography images were applied without any adaptation or retraining to tomosynthesis projection images. Test set contained 36 patients including 16 patients with 20 known malignant lesions, 4 of which were missed by the radiologists in conventional mammography images and found only in retrospect in tomosynthesis. Median filter was applied to tomosynthesis projection images. Detection algorithm yielded 80% sensitivity and 5.3 false positives per breast for calcification and mass detection algorithms combined. Out of 4 masses missed by radiologists in conventional mammography images, 2 were found by the mass detection algorithm in tomosynthesis images., The original document contains color images. All DTIC reproductions will be in black and white.

The goal of this research is to obtain systematic understandings of the effects of various physical factors that are important in breast tomosynthesis imaging and to develop techniques for effectively dealing with their effects and for reducing radiation dose. During the second year of the project we have achieved fruitful results based upon the progress made in our first year of the project. Specifically we have further investigated the performance of the total-variation (TV) based algorithm under different data conditions and different constraint parameters. Furthermore we have also proposed and investigated a new tomosynthesis imaging method with non-planar trajectories for yielding more data information with the same amount of imaging dose. We have also simulated the scatter in tomosynthesis breast imaging by convolving the ideal projection data with angular dependent scatter kernel.

It is well documented that breast cancer is frequently missed on mammograms, leading to delayed detection and potentially less successful treatment. Our studies show that approximately 32% of cancers can be detected early using mammograms. While current Computer-Assisted Detection (CAD) technology is designed to capture as many of these cancers as possible, it is not able to offer information specific enough to assist the radiologist in determining the best course of action once a suspicious region is identified. The use of additional clinically relevant information will help the radiologist determine the best course of treatment. Approximately 4.6 billion dollars was spent on breast biopsies in 2002, and only 10-30% of these biopsies resulted in the diagnosis of breast cancer. The use of all available sensor and patient history data in diagnosis will help to eliminate a significant number of these unnecessary biopsies. The technical objective of the Computer-Assisted Cancer Device project was to develop a platform technology that will allow for a significant improvement in the accuracy of interpreting mammograms through the use of Second Generation Computer-Assisted Detection (2nd Generation CAD) that is designed for using not only the current year's screening mammograms (as is common in 1st generation commercial CAD), but also any additional clinically relevant information (e.g., prior mammograms, other sensors like 3D ultrasound/MRI/IR, participant history information, etc.). Specifically, in this study, the authors added a 3-D breast ultrasound examination to the modalities already used in the clinical care of enrolled participants as additional input to the development of a CAD algorithm. Using additional sources of information will help move CAD technology from being a detection aid to becoming a diagnostic aid.

One of the major deficiencies of standard mammography is the camouflaging effect of overlapping structures in the projection images that limits the rendering of breast cancer. To minimize the effect of this limiting factor, we investigated the feasibility of Multi-plane Correlation Imaging (MCI) technique. In this technique, multiple radiographic images of the breast are obtained from different angles. Angular information is used to identify and positively reinforce the lesion signals between different projections. In the first stage of this study, we investigated the optimal geometry of acquisitions in MCI which yields superior diagnostic information. Towards this end, a LG CHO mathematical observer model was constructed to assess the detectability of a simulated mass embedded in the different angular projections acquired as part of MCI. Detectability performance on various angular projections were combined using three techniques to determine a final figure of merit as a measure of the system's performance. Lastly, different components of acquisitions such as the number of angular projections and the angular span of them were changed to investigate which one of the combinations maximizes the detectability performance., The original document contains color images.

Although considerable progress has been made for the breast tomosynthesis, there are still some issues should be addressed before it becomes suitable for routine clinical use: (1) development of accurate and efficient algorithms for reconstructing 3D breast images from tomosynthesis data, (2) the effect of various physical factors on image quality. During the first year of this research, we have implemented and investigated the TV-based algorithm for image reconstruction in breast tomosynthesis, and investigated the convergence property of the TV-based algorithm under different data conditions and different constraint parameters. We have also conducted numerical studies to investigate the image reconstruction by use of the TV-based algorithm and the existing EM and ART algorithms for different imaging configurations in breast tomosynthesis. Furthermore, we have investigated some physical factors such as cone-beam data noise and non-isotropic spatial resolution on tomosynthesis images., The original document contains color images.

An automated spot mammography technique was developed to improve the imaging of lesions within dense breast tissue. The initial goal was to build a device that would automatically detect suspicious regions in mammograms and immediately perform spot compression and collimation at that region to produce a second image that better distinguishes masses from overlapping tissues. Preliminary studies with a prototype device and breast simulating test objects showed promise, but spot compression didn't always separate the tissues as much as desired. The authors conceived an improved method that employs three-dimensional stereoscopic digital spot mammography acquisition and display for superior perception and characterization of masses. Automated detection of suspicious regions was evaluated by comparing regions in patients' mammograms selected by radiologists with those selected by a computer program. There was good agreement between the radiologists and the computer. A spot collimator to restrict the x-ray beam to the suspicious region for stereo spot image acquisition was designed, built, tested, and refined. Then preliminary studies were performed on a further evolution of the technique: utilizing tomosynthesis to reconstruct slices of the breast, with the eventual goal of developing automated spot tomosynthesis for enhanced sensitivity and specificity in breast cancer screening.

An experimental framework for performing 3-D imaging of the breast has been developed. The framework is designed to allow testing of many different detectors and acquisition protocols. We have developed and characterized three detectors. The first is now obsolete. The second detector is an active matrix amorphous-selenium device, and third uses a phosphor screen or an XRII optically coupled to a CCD camera. The second device has excellent dose efficiency (DOE) and resolution, but is too slow to allow easy tomographic imaging. The third device again has excellent resolution, but lacks the dose efficiency of the flat panel detector. This detector does, however, have the temporal response needed to perform CT. We have performed extensive evaluations of the reconstruction methods. In particular, we have concentrated on stereomammography and addressed the issue of dose in stereomammography. We have shown that stereomammography is possible at approximately the same dose as conventional projection mammography. This work considered the effect of x-ray quantum noise. To extend this work to other 3-D imaging techniques, and to consider additional effects, such as visual disparity and depth perception, we developed an extensive 3-D computer simulation of the breast.

Initial investigations of the four proposed reconstruction methods have been delayed due to the sale of the original detector system by Thomas Jefferson University Hospital. An experimental framework for performing 3-D imaging of the breast has been developed. We have also developed and begun to characterize two detectors that will replace the detectors originally proposed for use in the grant. The first detector is an active matrix amorphous-selenium device, and second uses a phosphor screen optically coupled to a CCD camera. The first device has excellent dose efficiency (DQE) and resolution, but is too slow to allow easy tomographic imaging. The latter device again has excellent resolution, but lacks the dose efficiency of the flat panel detector. This detector does, however, have the temporal response needed to perform CT. Due to the sale of the equipment, it will be necessary to alter the original work plan. We will not be able to image surgical specimens, instead we will image mastectomy and cadaveric breast tissue.

Tomosynthesis holds the promise of detecting breast cancer earlier, at a smaller size, with fewer false-positive outcomes. Progress toward this goal has been steady. It has been slowed by the unanticipated need to include an articulating collimator for X-ray beam control. GECRD interpreted recent FDA guidance as requiring the design and installation of an articulating collimator. GECRD has designed and installed this subsystem. The feasibility automatic motorized tomosynthesis system has been delivered, installed and acceptance tested at MGH. A physics report on the imaging characteristics is complete. We are now in position to evaluate tomosynthesis in the clinical setting. This will permit an understanding of it's clinical potential, and if warranted, the design of a clinical trial.

This journal is published by Hindawi Publishing Corporation. It covers the research and development of biomedical imaging. The journal's website provides details of the journal and access to full text papers in PDF format. Print subscriptions are available.

The relevance of studying the incidence of breast cancer is a problem of modern health care due to a steady growth of morbidity, including those of malignant character. About 1 million new cases of breast cancer are detected yearly in the world, predicting growth in the number of cases by 2014 to 1.45 million. Currently, a certain progress has been made in the diagnosis of early forms of the disease through the introduction of modern technologies of beam diagnostics. The most effective among them is an X-rays examination. However, there is a number of unresolved problems in the differential diagnosis of non-palpable breast formations because of their early symptoms non-specificity. In this regard, new technologies are developed that can enhance these capabilities. Despite the widespread use of mammography, there is still a number of limitations. This is primarily due to the complexity of interpreting the images of mass lesions because of superimposed structural elements of breast tissue located in different planes. Breast tomosynthesis is a new technology that allows avoiding these disadvantages. Using a flat panel X-ray detector and rotating the tube in relation to the image receiver, we perform a series of low-dose exposures at different angles, converting further the received information into a series of tomograms.

The relevance of studying the incidence of breast cancer is a problem of modern health care due to a steady growth of morbidity, including those of malignant character. About 1 million new cases of breast cancer are detected yearly in the world, predicting growth in the number of cases by 2014 to 1.45 million. Currently, a certain progress has been made in the diagnosis of early forms of the disease through the introduction of modern technologies of beam diagnostics. The most effective among them is an X-rays examination. However, there is a number of unresolved problems in the differential diagnosis of non-palpable breast formations because of their early symptoms non-specificity. In this regard, new technologies are developed that can enhance these capabilities. Despite the widespread use of mammography, there is still a number of limitations. This is primarily due to the complexity of interpreting the images of mass lesions because of superimposed structural elements of breast tissue located in different planes. Breast tomosynthesis is a new technology that allows avoiding these disadvantages. Using a flat panel X-ray detector and rotating the tube in relation to the image receiver, we perform a series of low-dose exposures at different angles, converting further the received information into a series of tomograms.