770 research outputs found
Inter country analysis of breast density classification using visual grading. Analysis of mammographic breast density using visual grading
Purpose: Disagreement in mammographic breast density (MBD) assessment can impact breast cancer risk stratification, choices of further breast cancer screening intervals and pathways. This study examines whether inter-country MBD expectations and assessment approaches are associated with differences in MBD assessment.
Methods: Twenty American Board of Radiology (ABR) examiners and 24 United Kingdom (UK) practitioners using the 4th edition BI-RADSĀ® lexicon assessed 40 mammogram cases of 20 women. Twenty-six Royal Australian and New Zealand College of Radiologists (RANZCR) registered radiologists also assessed the same cases. Inter-observer correlation and agreement were assessed using a Spearmanās correlation (Ļ) and weighted Kappa (Kw) respectively.
Results: Strong positive correlation was observed between the study cohorts on a binary scale (1ā2 vs. 3ā4) [ABR examiners and RANZCR radiologists (Ļ = 0.950); ABR examiners and UK practitioners (Ļ = 0.940); RANZCR radiologists and UK practitioners (Ļ = 0.958)]. ABR and RANZCR radiologists demonstrated slight agreement [Kw = 0.10; 95% CI = -1.13 - 0.43] while ABR and UK practitioners showed a fair agreement [Kw = 0.25; 95% CI = -0.42 - 0.61], and an almost perfect agreement was observed between RANZCR radiologists and UK practitioners [Kw = 0.95; 95% CI = 0.91 - 0.97].
Conclusion: Findings demonstrate wide international and inter-observer variability in MBD assessment. This level of variability underscores the need for automation and standardisation of MBD assessment.
Keywords: Breast density, inter-observer agreement, visual assessment methods
A self-directed learning intervention for radiographers rating mammographic breast density
Purpose: Subjective methods of mammographic breast density (MBD) assessment are prone to inter-reader variability. This work aims to assess the impact of a short self-directed experiential learning intervention on radiographersā reproducibility of MBD assessment.
Method: The study used two sets of images (test and learning intervention) containing left craniocaudal and left mediolateral oblique views. The test set had MBD ratings from VolparaTM and radiologists using the fourth edition Breast Imaging and Data Systems (BI-RADSĀ®). Seven radiographers rated the MBD of the test set before and after a self-directed learning intervention using the percentage descriptors in the fourth edition BI-RADSĀ® Atlas. The inter-reader agreement, agreement between radiographers and VolparaTM as well as radiologist, was assessed using a Weighted Kappa (Kw).
Results: Overall, radiographersā inter-reader agreement (Kw) was substantial (0.79; 95%CI: 0.70ā0.87) before the intervention and almost perfect (0.84; 95%CI: 0.77ā0.90) after the intervention. Before the intervention, radiographers demonstrated fair agreement with radiologists (0.24; 95%CI:-0.46ā0.61) and VolparaTM (0.24; 95% CI: -0.41ā0.59). A fair but slightly improved agreement was also observed between radiographers and radiologists (0.31; 95% CI: -0.33 - 0.64) as well as VolparaTM (0.28; 95% CI: -0.34- 0.61) after the intervention.
Conclusion: Findings demonstrate that a short duration self-directed experiential learning intervention reduces inter-reader differences in MBD classification, but has a negligible impact on improving the agreement between inexperienced and expert readers
Preliminary observations on the avifauna of Ikokoto Forest, Udzungwa Mountains, Tanzania
A study was conducted at c. 110 ha of Ikokoto forest using mist-netting and general field observations. Sixty-four species were recorded of which 61% were of conservation importance in terms of forest dependence. All species were found to belong to the familiar assembly of the large Udzungwa forests. Six species, the Green-throated Greenbul Andropadus fusciceps, Spot-throat Modulatrix stictigula, African Tailorbird Artisornis metopias, Black-lored Cisticola Cisticola nigriloris, Uhehe Fiscal Laniarius marwitzi and FĆ¼llebornās Black Boubou Laniarius fuelleborni detected are restricted range and one species Moreauās Sunbird Nectarinia moreaui is nearthreatened according to IUCN threat status. The presence of many species which are forest dependent in this tiny forest indicates that this site, though small in size and highly fragmented, retains significant conservation value for birds
A review of mammographic positioning image quality criteria for the craniocaudal projection
Detection of breast cancer is reliant on optimal breast positioning and the production of quality images. Two projections, the mediolateral (MLO) and craniocaudal (CC), are routinely performed. Determination of successful positioning and inclusion of all breast tissue is achieved through meeting stated image quality criteria. For the CC view, current image quality criteria are inconsistent. Absence of reliable anatomical markers, other than the nipple, further contribute to difficulties in assessing the quality of CC views.
The aim of this paper was to explore published international quality standards to identify and find the origin of any CC positioning criteria which might provide for quantitative assessment. The pectoralis major (pectoral) muscle was identified as a key posterior anatomical structure to establish optimum breast tissue inclusion on mammographic projections. It forms the first two of the three main CC metrics that are frequently reported 1. visualisation of the pectoral muscle, 2. measurement of the posterior nipple line (PNL) and 3. depiction of retroglandular fat.
This literature review explores the origin of the three metrics, and discusses three key publications, spanning 1992 to 1994, on which subsequent image quality standards have been based. The evidence base to support published CC metrics is sometimes not specified and more often the same set of publications are cited, most often without critical evaluation.
To conclude, there remains uncertainty if the metrics explored for the CC view support objective evaluation and reproducibility to confirm optimal breast positioning and quality images
The Crisis in Legal Education: Dabbling in Disaster Planning
The legal education crisis has already struck for many recent law school graduates, signaling potential disaster for law schools already struggling with their own economic challenges. Law schools have high fixed costs caused by competition between schools, the unchecked expansion of federal loan programs, a widely exploited information asymmetry about graduate employment outcomes, and a lack of financial discipline masquerading as innovation. As a result, tuition is up, jobs are down, and skepticism of the value of a J.D. has never been higher. If these trends do not reverse course, droves of students will continue to graduate with debt that greatly reduces their ability to fulfill the law school graduate\u27s traditional and important role in American society. The point at which the law school crisis becomes a disaster for legal education is debatable, but the importance of preparing for and forestalling this disaster is not. This Article serves two forward-looking purposes that stem from the premise that American legal education requires structural change to reduce the cost of obtaining a legal education. First, we set a framework for thinking about reforms to the method of delivering legal education. Second, we examine three blueprints for structural reform: one that has already been implemented and is ineffective, and two that set the discussion on the right track. These blueprints reject mere tinkering in favor of refocusing the attention of legal education stakeholders on the drastic structural changes needed to provide quality, affordable legal education. While we provide only a starting point for considering how the two new models could work in principle, they serve as an intellectual blueprint that can pave the way for new and better ideas about legal education. It is clear that cost reform is necessary, and it is likely that substantial reform is coming. The shape of this reform depends on who gets involved, who we hope include actors beyond those who have set legal education on a path toward disaster
Mapping the stability of spatial production in integrated crop and pasture systems: Towards zonal management that accounts for both yield and livestock-landscape interactions
Precision farming technologies are now widely applied within Australian cropping systems. However, the use of spatial monitoring technologies to investigate livestock and pasture interactions in mixed farming systems remains largely unexplored. Spatio-temporal patterns of grain yield and pasture biomass production were monitored over a four-year period on two Australian mixed farms, one in the south-west of Western Australia and the other in south-east Australia. A production stability index was calculated for two paddocks on each farm. An example is given here for one paddock from Western Australia. The stability index described here is unique in that it combines spatial and temporal variation across both cropping and pasture phases. Co-efficient of variation in yield was used as the threshold value for determining stability. Production in each stability zone was analysed statistically for consistency and correlation between the cropping and pasture phases. Results indicate that the stability index can be used in mixed farming systems to assist in management decisions and for the paddock described, spatial and temporal variation in production between crop and pasture phases was strongly correlated
Effective lifetime radiation risk for a number of national mammography screening programmes
Background and purpose: The performance of mammography screening programmes is focussed mainly on breast cancer detection rates. However, when the benefits and risks of mammography are considered, the risk of radiation-induced cancer is calculated for only the examined breast using Mean Glandular Dose (MGD). The risk from radiation during mammography is often described as low or minimal. This study aims to evaluate the effective lifetime risk from full field digital mammography (FFDM) for a number of national screening programmes.
Material and Methods: Using an ATOM phantom, radiation doses to multiple organs were measured during standard screening mammography. Sixteen FFDM machines were used and the effective lifetime risk was calculated across the female lifespan for each machine. Once the risks were calculated using the phantom, the total effective lifetime risk across 48 national screening programmes was then calculated; this assumed that all these programmes use FFDM for screening.
Results: Large differences exist in effective lifetime risk, varying from 42.21 [39.12 - 45.30] cases/106 (mean [95% CI]) in the Maltese screening programme to 1099.67 [1019.25 - 1180.09] cases/106 for high breast cancer risk women in the United States of America. These differences are mainly attributed to the commencement age of screening mammography and the time interval between successive screens.
Conclusions: Effective risk should be considered as an additional parameter for the assessment of screening mammography programme performance, especially for those programmes which recommend an early onset and more frequent screening mammography
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