How does image quality affect radiologists' perceived ability for image interpretation and lesion detection in digital mammography?

OBJECTIVES: To study how radiologists' perceived ability to interpret digital mammography (DM) images is affected by decreases in image quality. METHODS: One view from 45 DM cases (including 30 cancers) was degraded to six levels each of two acquisition-related issues (lower spatial resolution and increased quantum noise) and three post-processing-related issues (lower and higher contrast and increased correlated noise) seen during clinical evaluation of DM systems. The images were shown to fifteen breast screening radiologists from five countries. Aware of lesion location, the radiologists selected the most-degraded mammogram (indexed from 1 (reference) to 7 (most degraded)) they still felt was acceptable for interpretation. The median selected index, per degradation type, was calculated separately for calcification and soft tissue (including normal) cases. Using the two-sided, non-parametric Mann-Whitney test, the median indices for each case and degradation type were compared. RESULTS: Radiologists were not tolerant to increases (medians: 1.5 (calcifications) and 2 (soft tissue)) or decreases (median: 2, for both types) in contrast, but were more tolerant to correlated noise (median: 3, for both types). Increases in quantum noise were tolerated more for calcifications than for soft tissue cases (medians: 3 vs. 4, p = 0.02). Spatial resolution losses were considered less acceptable for calcification detection than for soft tissue cases (medians: 3.5 vs. 5, p = 0.001). CONCLUSIONS: Perceived ability of radiologists for image interpretation in DM was affected not only by image acquisition-related issues but also by image post-processing issues, and some of those issues affected calcification cases more than soft tissue cases. KEY POINTS: • Lower spatial resolution and increased quantum noise affected the radiologists' perceived ability to interpret calcification cases more than soft tissue lesion or normal cases. • Post-acquisition image processing-related effects, not only image acquisition-related effects, also impact the perceived ability of radiologists to interpret images and detect lesions. • In addition to current practices, post-acquisition image processing-related effects need to also be considered during the testing and evaluation of digital mammography systems

Burnout and use of HIV services among health care workers in Lusaka District, Zambia: a cross-sectional study

BACKGROUND: Well-documented shortages of health care workers in sub-Saharan Africa are exacerbated by the increased human resource demands of rapidly expanding HIV care and treatment programmes. The successful continuation of existing programmes is threatened by health care worker burnout and HIV-related illness. METHODS: From March to June 2007, we studied occupational burnout and utilization of HIV services among health providers in the Lusaka public health sector. Providers from 13 public clinics were given a 36-item, self-administered questionnaire and invited for focus group discussions and key-informant interviews. RESULTS: Some 483 active clinical staff completed the questionnaire (84% response rate), 50 staff participated in six focus groups, and four individuals gave interviews. Focus group participants described burnout as feeling overworked, stressed and tired. In the survey, 51% reported occupational burnout. Risk factors were having another job (RR 1.4 95% CI 1.2-1.6) and knowing a co-worker who left in the last year (RR 1.6 95% CI 1.3-2.2). Reasons for co-worker attrition included: better pay (40%), feeling overworked or stressed (21%), moving away (16%), death (8%) and illness (5%). When asked about HIV testing, 370 of 456 (81%) reported having tested; 240 (50%) tested in the last year. In contrast, discussion groups perceived low testing rates. Both discussion groups and survey respondents identified confidentiality as the prime reason for not undergoing HIV testing. CONCLUSION: In Lusaka primary care clinics, overwork, illness and death were common reasons for attrition. Programmes to improve access, acceptability and confidentiality of health care services for clinical providers and to reduce workplace stress could substantially affect workforce stability

Novel genetic loci underlying human intracranial volume identified through genome-wide association

Intracranial volume reflects the maximally attained brain size during development, and remains stable with loss of tissue in late life. It is highly heritable, but the underlying genes remain largely undetermined. In a genome-wide association study of 32,438 adults, we discovered five novel loci for intracranial volume and confirmed two known signals. Four of the loci are also associated with adult human stature, but these remained associated with intracranial volume after adjusting for height. We found a high genetic correlation with child head circumference (ρgenetic=0.748), which indicated a similar genetic background and allowed for the identification of four additional loci through meta-analysis (Ncombined = 37,345). Variants for intracranial volume were also related to childhood and adult cognitive function, Parkinson’s disease, and enriched near genes involved in growth pathways including PI3K–AKT signaling. These findings identify biological underpinnings of intracranial volume and provide genetic support for theories on brain reserve and brain overgrowth

Novel genetic loci associated with hippocampal volume

The hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic underpinnings of hippocampal structure here we perform a genome-wide association study (GWAS) of 33,536 individuals and discover six independent loci significantly associated with hippocampal volume, four of them novel. Of the novel loci, three lie within genes (ASTN2, DPP4 and MAST4) and one is found 200 kb upstream of SHH. A hippocampal subfield analysis shows that a locus within the MSRB3 gene shows evidence of a localized effect along the dentate gyrus, subiculum, CA1 and fissure. Further, we show that genetic variants associated with decreased hippocampal volume are also associated with increased risk for Alzheimer's disease (rg =-0.155). Our findings suggest novel biological pathways through which human genetic variation influences hippocampal volume and risk for neuropsychiatric illness

Breast imaging /

Breast Imaging: The Requisites, 2nd Edition, by Debra Ikeda, MD, presents all of today₂s core knowledge about diagnostic imaging of the breast. Clinically oriented and easy to use, it shows you how to interpret the full range of imaging studies for the most accurate diagnoses. Updates include all-new digital mammography images throughout - new, full-color chapters on PET-CT imaging for high-risk patients and patients with breast disease - new images and data on MR imaging - and new ultrasound images, with an emphasis on ultrasound of normal structures. Compact yet authoritative, this work is an ideal reference for both board preparation and clinical practice. Focus on the essentials needed to pass the boards and ensure accurate diagnoses in clinical practice. Interpret the findings generated from each high-tech imaging modality used to image the breast, including digital mammography, MRI and MRI-guided procedures, ultrasound, and PET-CT imaging. Get outstanding visual guidance with more than 700 superb illustrations that demonstrate a full range of mammography approaches and findings. Grasp key information quickly with numerous outlines, tables, ''pearls, '' and boxed material for easy reference. Benefit from expert coverage of risk factors, image interpretation and workup, breast masses and calcifications, cancer and its treatment, silicone breast implants, the postoperative breast, clinical problems, invasive procedures, and much more.Breast Imaging: The Requisites, 2nd Edition, by Debra Ikeda, MD, presents all of today₂s core knowledge about diagnostic imaging of the breast. Clinically oriented and easy to use, it shows you how to interpret the full range of imaging studies for the most accurate diagnoses. Updates include all-new digital mammography images throughout - new, full-color chapters on PET-CT imaging for high-risk patients and patients with breast disease - new images and data on MR imaging - and new ultrasound images, with an emphasis on ultrasound of normal structures. Compact yet authoritative, this work is an ideal reference for both board preparation and clinical practice. Focus on the essentials needed to pass the boards and ensure accurate diagnoses in clinical practice. Interpret the findings generated from each high-tech imaging modality used to image the breast, including digital mammography, MRI and MRI-guided procedures, ultrasound, and PET-CT imaging. Get outstanding visual guidance with more than 700 superb illustrations that demonstrate a full range of mammography approaches and findings. Grasp key information quickly with numerous outlines, tables, ''pearls, '' and boxed material for easy reference. Benefit from expert coverage of risk factors, image interpretation and workup, breast masses and calcifications, cancer and its treatment, silicone breast implants, the postoperative breast, clinical problems, invasive procedures, and much more.Includes bibliographical references and index.Mammogram acquisition : screen-film and digital mammography, the Mammography Quality Standards Act, and computer-aided detection / Debra Ikeda and R. Edward Hendrick -- Mammogram interpretation / Debra Ikeda -- Mammographic analysis of breast calcifications / Debra Ikeda -- Mammographic and ultrasound analysis of breast masses / Debra Ikeda -- Breast ultrasound / Debra Ikeda -- Mammographic and ultrasound-guided breats biopsy procedures / Debra Ikeda -- Magnetic resonance imaging of breast cancer and MRI-guided breast biopsy / Debra Ikeda, Bruce L. Daniel -- Breast cancer treatment-related imaging and the postoperative breast / Debra Ikeda, Frederick M. Dirbas, Kathleen C. Horst -- Breast implants and the reconstructed breast / Debra Ikeda -- Clinical breast problems and unusual breast conditions / Debra Ikeda -- FDG-PET/CT and the evaluation of breast cancer / Debra Ikeda and Andrew Quon.Print version record.Elsevie

Realism of mammography tissue patches simulated using perlin noise:A forced choice reading study

Software breast phantoms are central to the optimization of breast imaging, where in many cases the use of real images would be inefficient - or impossible. Establishing the realism of such phantoms is critical. For this study, patches of simulated breast tissue with different composition - fatty, scattered, heterogenous and dense tissue - were generated using a method based on Perlin noise. The composition of the patches is controlled by numerical parameters derived from input by radiologists and medical physicists with experience of breast imaging. Separate Perlin noise-based methods were used to simulate skin pores, high-frequency noise (representing quantum and electronic noise) and ligaments and vascular structures. In a forced choice reading study, the realism of the simulated tissue patches compared to patches from real mammograms was determined. Patches of 200-500 pixels were extracted from radiolucent, linear, nodular or homogenous (10 per category) mammograms randomly selected from a previously acquired dataset. Eighteen simulated patches in the same size range were added. Four readers, two radiologists and two medical physicists were shown the images in random order and asked to rate them as real or simulated. All readers accepted a substantial fraction of simulated images as real, ranging from 22% to 72%. Only two readers showed a significant difference in the number of images rated real in the real and simulated groups, 22% vs 73% (P=.0003) and 33% vs 63% (P=.04), respectively. These results suggest that the method employed can create images that are almost indistinguishable from patches of real mammograms