Phase retrieval is vital for quantitative x-ray phase contrast imaging. This work presents an iterative method to simultaneously retrieve the x-ray absorption and phase images from a single x-ray ...exposure. The proposed approach uses the photon-counting detectors' energy-resolving capability in providing multiple spectrally resolved phase contrast images from a single x-ray exposure. The retrieval method is derived, presented, and experimentally tested with a multi-material phantom in an inline phase contrast imaging setup. By separating the contributions of photoelectric absorption and Compton scattering to the attenuation, the authors divide the phase contrast image into two portions, the attenuation map arises from photoelectric absorption and a pseudo phase contrast image generated by electron density. This way one can apply the Phase Attenuation Dualiby (PAD) algorithm and Fresnel propagation for the iteration. The retrieval results from the experimental images show that this iterative method is fast, accurate, robust against noise, and thus yields noticeable enhancement in contrast to noise ratios.
The objective of our study was to determine the ability of tomosynthesis (3D) to detect nonmalignant and malignant architectural distortion (AD) on 3D screening mammograms compared with digital ...mammography (2D) only and to correlate the 3D imaging features of nonmalignant and malignant AD with pathology findings.
For this single-institution retrospective study, screening mammography reports from October 1, 2012, to December 1, 2016, that included AD as a finding were reviewed. Associated additional imaging studies and pathology results were also reviewed.
Three-dimensional mammography showed statistically significant increased detection of both nonmalignant and malignant AD compared with 2D only (0.10% 24/24,902 examinations vs 0.01% 1/9470 examinations, p < 0.05; and 0.21% 52/24,902 examinations vs 0.07% 7/9470 examinations, p < 0.05, respectively). Higher percentages of nonmalignant AD (16%) were occult on ultrasound compared with malignant AD (3%). The pathologic diagnoses of nonmalignant AD included radial scar (42%), sclerosing adenosis (16%), stromal or dense fibrosis (16%), and other miscellaneous benign causes (25%). Morphologically, nonmalignant AD was more likely to show symmetric or spoke-wheel spiculation appearance (58% vs 2%, p < 0.05) and central lucency (25% vs 0%, p < 0.05) than malignant AD, whereas malignant AD was more likely to show asymmetric spiculation (98% vs 42%, p < 0.05) and central mass 60% vs 0%, p < 0.05) than nonmalignant AD.
Malignant AD and nonmalignant AD are more readily detected by 3D mammography than 2D mammography. Three-dimensional imaging features of AD can help to distinguish nonmalignant types in which symmetric or spoke-wheel spiculation with central lucency are more often seen and are more often occult on ultrasound.
Contrast-enhanced mammography (CEM) is an emerging breast imaging technology with promise for breast cancer screening, diagnosis, and procedural guidance. However, best uses of CEM in comparison with ...other breast imaging modalities such as tomosynthesis, ultrasound, and MRI remain inconclusive in many clinical settings. This review article summarizes recent peer-reviewed literature, emphasizing retrospective reviews, prospective clinical trials, and meta-analyses published from 2020 to 2023. The intent of this article is to supplement prior comprehensive reviews and summarize the current state-of-the-art of CEM.
In this study of 42,760 asymptomatic women, the overall diagnostic accuracy of digital and film mammography as a means of screening for breast cancer was similar, but the former method was better ...among women under the age of 50 years, women with radiographically dense breasts, and premenopausal or perimenopausal women.
In 42,760 asymptomatic women, the overall diagnostic accuracy of digital and film mammography was similar, but digital mammography was better among women under 50 years, women with radiographically dense breasts, and premenopausal or perimenopausal women.
There is now general agreement that screening mammography reduces the rate of death from breast cancer among women who are 40 years of age or older.
1
,
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Meta-analyses of eight large, randomized trials found a reduction in the mortality rate of 16 to 35 percent among women 50 to 69 years of age who were assigned to screening mammography,
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whereas women who were 40 to 49 years of age at entry had a smaller but significant reduction of 15 to 20 percent.
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–
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The smaller benefit of screening in younger women is probably due to a lower incidence of breast . . .
To retrospectively compare the accuracy of digital versus film mammography in population subgroups of the Digital Mammographic Imaging Screening Trial (DMIST) defined by combinations of age, ...menopausal status, and breast density, by using either biopsy results or follow-up information as the reference standard.
DMIST included women who underwent both digital and film screening mammography. Institutional review board approval at all participating sites and informed consent from all participating women in compliance with HIPAA was obtained for DMIST and this retrospective analysis. Areas under the receiver operating characteristic curve (AUCs) for each modality were compared within each subgroup evaluated (age < 50 vs 50-64 vs >or= 65 years, dense vs nondense breasts at mammography, and pre- or perimenopausal vs postmenopausal status for the two younger age cohorts 10 new subgroups in toto) while controlling for multiple comparisons (P < .002 indicated a significant difference). All DMIST cancers were evaluated with respect to mammographic detection method (digital vs film vs both vs neither), mammographic lesion type (mass, calcifications, or other), digital machine type, mammographic and pathologic size and diagnosis, existence of prior mammographic study at time of interpretation, months since prior mammographic study, and compressed breast thickness.
Thirty-three centers enrolled 49 528 women. Breast cancer status was determined for 42,760 women, the group included in this study. Pre- or perimenopausal women younger than 50 years who had dense breasts at film mammography comprised the only subgroup for which digital mammography was significantly better than film (AUCs, 0.79 vs 0.54; P = .0015). Breast Imaging Reporting and Data System-based sensitivity in this subgroup was 0.59 for digital and 0.27 for film mammography. AUCs were not significantly different in any of the other subgroups. For women aged 65 years or older with fatty breasts, the AUC showed a nonsignificant tendency toward film being better than digital mammography (AUCs, 0.88 vs 0.70; P = .0025).
Digital mammography performed significantly better than film for pre- and perimenopausal women younger than 50 years with dense breasts, but film tended nonsignificantly to perform better for women aged 65 years or older with fatty breasts.
Abstract
Background
One of the ecological impacts of exotic plant invasions may be alteration of the soil microbial community, which may cause changes to the diversity, richness and function of these ...communities. In order to explore to what extent invasive plants affect the soil microbial community, we performed a meta-analysis based on 46 scientific articles to document the effect of invasive plants on species richness and diversity of bacteria and fungi. We conducted our study across a range of invaded ecosystems including native communities, and evaluated biomass, richness and diversity. We use a random effects model to determine the increase or decrease in the values of the response variables in the presence of invasive plants.
Results
The results indicated that the response variable that changed with the invasion of plants was the diversity of bacteria. Bacterial diversity in the soil increases with the presence of invasive plants, specifically herbaceous plants producing allelopathic substances growing in forest ecosystems of temperate zones.
Conclusions
We provide evidence that invasive plants affect the soil biota differentially; however, it is important to consider more variables such as the N and C cycles, since these processes are mediated by soil biota and litter, and chemical compounds released by plants influence them. Changes in bacterial diversity have consequences for the nutrient cycle, enzymatic activity, mineralization rates and soil carbon and nitrogen content.
The purpose of this study was to test the hypothesis whether two-view wide-angle digital breast tomosynthesis (DBT) can replace full-field digital mammography (FFDM) for breast cancer detection.
In a ...multireader multicase study, bilateral two-view FFDM and bilateral two-view wide-angle DBT images were independently viewed for breast cancer detection in two reading sessions separated by more than 1 month. From a pool of 764 patients undergoing screening and diagnostic mammography, 330 patient-cases were selected. The endpoints were the mean ROC AUC for the reader per breast (breast level), ROC AUC per patient (subject level), noncancer recall rates, sensitivity, and specificity.
Twenty-nine of 31 readers performed better with DBT than FFDM regardless of breast density. There was a statistically significant improvement in readers' mean diagnostic accuracy with DBT. The subject-level AUC increased from 0.765 (standard error SE, 0.027) for FFDM to 0.835 (SE, 0.027) for DBT (
= 0.002). Breast-level AUC increased from 0.818 (SE, 0.019) for FFDM to 0.861 (SE, 0.019) for DBT (
= 0.011). The noncancer recall rate per patient was reduced by 19% with DBT (
< 0.001). Masses and architectural distortions were detected more with DBT (
< 0.001); calcifications trended lower (
= 0.136). Accuracy for detection of invasive cancers was significantly greater with DBT (
< 0.001).
Reader performance in breast cancer detection is significantly higher with wide-angle two-view DBT independent of FFDM, verifying the robustness of DBT as a sole view. However, results of perception studies in the vision sciences support the inclusion of an overview image.
Mammography is an effective imaging tool for detecting breast cancer at an early stage and is the only screening modality proved to reduce mortality from breast cancer. However, the overlap of ...tissues depicted on mammograms may create significant obstacles to the detection and diagnosis of abnormalities. Diagnostic testing initiated because of a questionable result at screening mammography frequently causes patients unnecessary anxiety and incurs increased medical costs. Breast tomosynthesis, a new tool that is based on the acquisition of three-dimensional digital image data, could help solve the problem of interpreting mammographic features produced by tissue overlap. Although the technology has not yet been approved by the Food and Drug Administration, breast tomosynthesis has the potential to help reduce recall rates, improve the selection of patients for biopsy, and increase cancer detection rates, especially in patients with dense breasts. Supplemental material available at radiographics.rsnajnls.org/cgi/content/full/27/S231/DC1.
Phase-sensitive x-ray imaging continues to attract research for its ability to visualize weakly absorbing details like those often encountered in biology and medicine. We have developed and assembled ...the first inline-based high-energy phase sensitive breast tomosynthesis (PBT) system, which is currently undergoing patient imaging testing at a clinical site. The PBT system consists of a microfocus polychromatic x-ray source and a direct conversion-based flat panel detector coated with a 1 mm thick amorphous selenium layer allowing a high detective quantum efficiency at high energies. The PBT system scans a compressed breast over 15° with 9 angular projection views. The high-energy scan parameters are carefully selected to ensure similar or lower mean glandular dose levels to the clinical standard of care systems. Phase retrieval and data binning are applied to the phase contrast angular projection views and a filtered back-projection algorithm is used to reconstruct the final images. This article reports the distributions of radiation dose versus thickness of the compressed breasts at 59 and 89 kV and sample PBT images acquired from 3 patients. Preliminary PBT images demonstrate the feasibility of this new imaging modality to acquire breast images at lower radiation dose as compared to the clinical digital breast tomosynthesis system with enhanced lesion characteristics (i.e. lesion spiculation and margins).
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