543 research outputs found
Using Active Shape Modeling Based on MRI to Study Morphologic and Pitch-Related Functional Changes Affecting Vocal Structures and the Airway
Copyright © 2013 The Voice Foundation. Published by Mosby, Inc. All rights reserved.Peer reviewedPostprin
Relationships Between Vocal Structures, the Airway, and Craniocervical Posture Investigated Using Magnetic Resonance Imaging
Peer reviewedPreprin
The Effects of Humming and Pitch on Craniofacial and Craniocervical Morphology Measured Using MRI
Peer reviewedPreprin
A longitudinal study of muscle rehabilitation in the lower leg after cast removal using Magnetic Resonance Imaging and strength assessment
Acknowledgements We thank the A&E nurses and plaster technicians for identifying suitable patients, the MRI radiographers for performing the scanning, Dr Scott Semple for invaluable help in some of the pilot studies and Mr E. C. Stevenson for constructing the footrest used in the scanner. We are very grateful to the dedicated patients themselves who gave considerable amounts of time to come in for scanning, exercise and assessment during the course of this study.Peer reviewedPublisher PD
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Improving Workflow Efficiency for Mammography Using Machine Learning.
OBJECTIVE: The aim of this study was to determine whether machine learning could reduce the number of mammograms the radiologist must read by using a machine-learning classifier to correctly identify normal mammograms and to select the uncertain and abnormal examinations for radiological interpretation. METHODS: Mammograms in a research data set from over 7,000 women who were recalled for assessment at six UK National Health Service Breast Screening Program centers were used. A convolutional neural network in conjunction with multitask learning was used to extract imaging features from mammograms that mimic the radiological assessment provided by a radiologist, the patient's nonimaging features, and pathology outcomes. A deep neural network was then used to concatenate and fuse multiple mammogram views to predict both a diagnosis and a recommendation of whether or not additional radiological assessment was needed. RESULTS: Ten-fold cross-validation was used on 2,000 randomly selected patients from the data set; the remainder of the data set was used for convolutional neural network training. While maintaining an acceptable negative predictive value of 0.99, the proposed model was able to identify 34% (95% confidence interval, 25%-43%) and 91% (95% confidence interval: 88%-94%) of the negative mammograms for test sets with a cancer prevalence of 15% and 1%, respectively. CONCLUSION: Machine learning was leveraged to successfully reduce the number of normal mammograms that radiologists need to read without degrading diagnostic accuracy
Cost-effectiveness and Benefit-to-Harm Ratio of Risk-Stratified Screening for Breast Cancer: A Life-Table Model.
IMPORTANCE: The age-based or "one-size-fits-all" breast screening approach does not take into account the individual variation in risk. Mammography screening reduces death from breast cancer at the cost of overdiagnosis. Identifying risk-stratified screening strategies with a more favorable ratio of overdiagnoses to breast cancer deaths prevented would improve the quality of life of women and save resources. OBJECTIVE: To assess the benefit-to-harm ratio and the cost-effectiveness of risk-stratified breast screening programs compared with a standard age-based screening program and no screening. DESIGN, SETTING, AND POPULATION: A life-table model was created of a hypothetical cohort of 364 500 women in the United Kingdom, aged 50 years, with follow-up to age 85 years, using (1) findings of the Independent UK Panel on Breast Cancer Screening and (2) risk distribution based on polygenic risk profile. The analysis was undertaken from the National Health Service perspective. INTERVENTIONS: The modeled interventions were (1) no screening, (2) age-based screening (mammography screening every 3 years from age 50 to 69 years), and (3) risk-stratified screening (a proportion of women aged 50 years with a risk score greater than a threshold risk were offered screening every 3 years until age 69 years) considering each percentile of the risk distribution. All analyses took place between July 2016 and September 2017. MAIN OUTCOMES AND MEASURES: Overdiagnoses, breast cancer deaths averted, quality-adjusted life-years (QALYs) gained, costs in British pounds, and net monetary benefit (NMB). Probabilistic sensitivity analyses were used to assess uncertainty around parameter estimates. Future costs and benefits were discounted at 3.5% per year. RESULTS: The risk-stratified analysis of this life-table model included a hypothetical cohort of 364 500 women followed up from age 50 to 85 years. As the risk threshold was lowered, the incremental cost of the program increased linearly, compared with no screening, with no additional QALYs gained below 35th percentile risk threshold. Of the 3 screening scenarios, the risk-stratified scenario with risk threshold at the 70th percentile had the highest NMB, at a willingness to pay of £20 000 (US 26 888) vs £537 985 (US $720 900) less, would have 26.7% vs 71.4% fewer overdiagnoses, and would avert 2.9% vs 9.6% fewer breast cancer deaths, respectively. CONCLUSIONS AND RELEVANCE: Not offering breast cancer screening to women at lower risk could improve the cost-effectiveness of the screening program, reduce overdiagnosis, and maintain the benefits of screening
Acute abdomen caused by bladder rupture attributable to neurogenic bladder dysfunction following a stroke: a case report.
INTRODUCTION: Spontaneous bladder rupture is a rare and serious event with high mortality. It is not often considered in the patient presenting with peritonitis. This often leads to delays in diagnosis. There are very few case reports of true spontaneous rupture in the literature. This is the first such reported case in which bladder rupture was attributable to neurogenic bladder dysfunction following a stroke. CASE PRESENTATION: We report the case of a 67-year-old Caucasian man who presented with lower abdominal pain and a peritonitic abdomen. He had a long-term urethral catheter because of urinary retention following a previous stroke. He was treated conservatively with antibiotics before a surgical opinion was sought. Exploratory laparotomy confirmed the diagnosis of spontaneous bladder rupture. After repair of the defect, he eventually made a full recovery. CONCLUSION: In this unusual case report, we describe an example of a serious event in which delays in diagnosis may lead to increased morbidity and mortality. To date, no unifying theory explaining why rupture occurs has been postulated. We conducted a thorough literature search to examine the etiological factors in other published cases. These etiological factors either increase intra-vesical pressure or decrease the strength of the bladder wall. We hope that by increasing awareness of these etiological factors, spontaneous bladder rupture may be diagnosed earlier and appropriate therapy started
A method for exploratory repeated-measures analysis applied to a breast-cancer screening study
When a model may be fitted separately to each individual statistical unit,
inspection of the point estimates may help the statistician to understand
between-individual variability and to identify possible relationships. However,
some information will be lost in such an approach because estimation
uncertainty is disregarded. We present a comparative method for exploratory
repeated-measures analysis to complement the point estimates that was motivated
by and is demonstrated by analysis of data from the CADET II breast-cancer
screening study. The approach helped to flag up some unusual reader behavior,
to assess differences in performance, and to identify potential random-effects
models for further analysis.Comment: Published in at http://dx.doi.org/10.1214/11-AOAS481 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Sporopollenin as a dilution agent in artificial diets for solitary bees
Nutritional studies often require precise control of nutrients via dilution of artificial diets with indigestible material, but such studies in bees are limited. Common diluents like cellulose typically result in total mortality of bee larvae, making quantitative studies difficult. We investigated potential alternative dietary dilution agents, sporopollenin (pollen exines) and agar. We reared Osmia bicornis larvae on pollen diluted with these substances, alongside undiluted controls. Sporopollenin neither prevented nor improved survival, suggesting it is a suitable diluent. Agar appeared marginally to increase survival and its suitability requires further research. Both substances reduced cocoon weight, and sporopollenin also prolonged development, suggesting processing costs. Determining the physiological mechanisms driving these responses requires further work. Our findings should facilitate studies involving nutritional manipulations for solitary bees
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