Image quality assessment for machine learning tasks using meta-reinforcement learning

In this paper, we consider image quality assessment (IQA) as a measure of how images are amenable with respect to a given downstream task, or task amenability. When the task is performed using machine learning algorithms, such as a neural-network-based task predictor for image classification or segmentation, the performance of the task predictor provides an objective estimate of task amenability. In this work, we use an IQA controller to predict the task amenability which, itself being parameterised by neural networks, can be trained simultaneously with the task predictor. We further develop a meta-reinforcement learning framework to improve the adaptability for both IQA controllers and task predictors, such that they can be fine-tuned efficiently on new datasets or meta-tasks. We demonstrate the efficacy of the proposed task-specific, adaptable IQA approach, using two clinical applications for ultrasound-guided prostate intervention and pneumonia detection on X-ray images

Image quality assessment by overlapping task-specific and task-agnostic measures: application to prostate multiparametric MR images for cancer segmentation

Image quality assessment (IQA) in medical imaging can be used to ensure that downstream clinical tasks can be reliably performed. Quantifying the impact of an image on the specific target tasks, also named as task amenability, is needed. A task-specific IQA has recently been proposed to learn an image-amenability-predicting controller simultaneously with a target task predictor. This allows for the trained IQA controller to measure the impact an image has on the target task performance, when this task is performed using the predictor, e.g. segmentation and classification neural networks in modern clinical applications. In this work, we propose an extension to this task-specific IQA approach, by adding a task-agnostic IQA based on auto-encoding as the target task. Analysing the intersection between low-quality images, deemed by both the task-specific and task-agnostic IQA, may help to differentiate the underpinning factors that caused the poor target task performance. For example, common imaging artefacts may not adversely affect the target task, which would lead to a low task-agnostic quality and a high task-specific quality, whilst individual cases considered clinically challenging, which can not be improved by better imaging equipment or protocols, is likely to result in a high task-agnostic quality but a low task-specific quality. We first describe a flexible reward shaping strategy which allows for the adjustment of weighting between task-agnostic and task-specific quality scoring. Furthermore, we evaluate the proposed algorithm using a clinically challenging target task of prostate tumour segmentation on multiparametric magnetic resonance (mpMR) images, from 850 patients. The proposed reward shaping strategy, with appropriately weighted task-specific and task-agnostic qualities, successfully identified samples that need re-acquisition due to defected imaging process.Comment: Accepted for publication at the Journal of Machine Learning for Biomedical Imaging (MELBA) https://www.melba-journal.or

Prevalence and predictors of falls and dizziness in people younger and older than 80 years of age-A longitudinal cohort study.

The objectives were to investigate the prevalence and predictors for falls and dizziness among people younger and older than 80 years of age. The sample was drawn from the Swedish National study on Aging and Care (SNAC) and comprised 973 and 1273 subjects with data on the occurrence of falls and dizziness respectively at baseline. Follow-ups were made after 3- and 6-years. Data included socio-demographics, physical function, health complaints, cognition, quality of life and medications. The prevalence of falls was 16.5% in those under aged 80 and 31.7% in those 80+ years while dizziness was reported by 17.8% and 31.0% respectively. Predictors for falls in those under aged 80 were neuroleptics, dependency in personal activities of daily living (PADL), a history of falling, vision impairment and higher age, and in those 80+ years a history of falling, dependency in instrumental activities of daily living (IADL), fatigue and higher age. Factors predicting dizziness in those under aged 80 were a history of dizziness, feeling nervous and reduced grip strength and in those 80+ years a history of dizziness and of falling. Predictors for falls and dizziness differed according to age. Specific factors were identified in those under aged 80. In those 80+ years more general factors were identified implying the need for a comprehensive investigation to prevent falls. This longitudinal study also showed that falling and dizziness in many older people are persistent and therefore should be treated as chronic conditions

Open Problems on Central Simple Algebras

We provide a survey of past research and a list of open problems regarding central simple algebras and the Brauer group over a field, intended both for experts and for beginners.Comment: v2 has some small revisions to the text. Some items are re-numbered, compared to v

A multidisciplinary, multifactorial intervention program reduces postoperative falls and injuries after femoral neck fracture

INTRODUCTION: This study evaluates whether a postoperative multidisciplinary, intervention program, including systematic assessment and treatment of fall risk factors, active prevention, detection, and treatment of postoperative complications, could reduce inpatient falls and fall-related injuries after a femoral neck fracture. METHODS: A randomized, controlled trial at the orthopedic and geriatric departments at Umeå University Hospital, Sweden, included 199 patients with femoral neck fracture, aged  ≥70 years. RESULTS: Twelve patients fell 18 times in the intervention group compared with 26 patients suffering 60 falls in the control group. Only one patient with dementia fell in the intervention group compared with 11 in the control group. The crude postoperative fall incidence rate was 6.29/1,000 days in the intervention group vs 16.28/1,000 days in the control group. The incidence rate ratio was 0.38 [95% confidence interval (CI): 0.20 – 0.76, p = 0.006] for the total sample and 0.07 (95% CI: 0.01–0.57, p=0.013) among patients with dementia. There were no new fractures in the intervention group but four in the control group. CONCLUSION: A team applying comprehensive geriatric assessment and rehabilitation, including prevention, detection, and treatment of fall risk factors, can successfully prevent inpatient falls and injuries, even in patients with dementia

Does the Mediterranean diet predict longevity in the elderly? A Swedish perspective

Dietary pattern analysis represents a useful improvement in the investigation of diet and health relationships. Particularly, the Mediterranean diet pattern has been associated with reduced mortality risk in several studies involving both younger and elderly population groups. In this research, relationships between dietary macronutrient composition, as well as the Mediterranean diet, and total mortality were assessed in 1,037 seventy-year-old subjects (540 females) information. Diet macronutrient composition was not associated with mortality, while a refined version of the modified Mediterranean diet index showed a significant inverse association (HR = 0.93, 95% CI: 0.89; 0.98). As expected, inactive subjects, smokers and those with a higher waist circumference had a higher mortality, while a reduced risk characterized married and more educated people. Sensitivity analyses (which confirmed our results) consisted of: exclusion of one food group at a time in the Mediterranean diet index, exclusion of early deaths, censoring at fixed follow-up time, adjusting for activities of daily living and main cardiovascular risk factors including weight/waist circumference changes at follow up. In conclusion, we can reasonably state that a higher adherence to a Mediterranean diet pattern, especially by consuming wholegrain cereals, foods rich in polyunsaturated fatty acids, and a limited amount of alcohol, predicts increased longevity in the elderly

For whom is a health-promoting intervention effective? Predictive factors for performing activities of daily living independently

BACKGROUND: Health-promoting interventions tailored to support older persons to remain in their homes, so-called "ageing in place" is important for supporting or improving their health. The health-promoting programme "Elderly Persons in the Risk Zone," (EPRZ) was set up for this purpose and has shown positive results for maintaining independence in activities of daily living for older persons 80 years and above at 1- and 2 year follow-ups. The aim of this study was to explore factors for maintaining independence in the EPRZ health-promoting programme.METHODS: Total of 459 participants in the original trial was included in the analysis; 345 in the programme arm and 114 in the control arm. Thirteen variables, including demographic, health, and programme-specific indicators, were chosen as predictors for independence of activities of daily living. Logistic regression was performed separately for participants in the health promotion programme and in the control arm.RESULTS: In the programme arm, being younger, living alone and self-rated lack of tiredness in performing mobility activities predicted a positive effect of independence in activities of daily living at 1-year follow-up (odds ratio [OR] 1.18, 1.73, 3.02) and 2-year, (OR 1.13, 2.01, 2.02). In the control arm, being less frail was the only predictor at 1-year follow up (OR 1.6 1.09, 2.4); no variables predicted the outcome at the 2-year follow-up.CONCLUSIONS: Older persons living alone - as a risk of ill health - should be especially recognized and offered an opportunity to participate in health-promoting programmes such as "Elderly Persons in the Risk Zone". Further, screening for subjective frailty could form an advantageous guiding principle to target the right population when deciding to whom health-promoting intervention should be offered.TRIAL REGISTRATION: The original clinical trial was registered at ClinicalTrials.gov. Identifier: NCT00877058 , April 6, 2009

Predicting ADL disability in community-dwelling elderly people using physical frailty indicators: a systematic review

<p>Abstract</p> <p>Background</p> <p>Disability in Activities of Daily Living (ADL) is an adverse outcome of frailty that places a burden on frail elderly people, care providers and the care system. Knowing which physical frailty indicators predict ADL disability is useful in identifying elderly people who might benefit from an intervention that prevents disability or increases functioning in daily life. The objective of this study was to systematically review the literature on the predictive value of physical frailty indicators on ADL disability in community-dwelling elderly people.</p> <p>Methods</p> <p>A systematic search was performed in 3 databases (PubMed, CINAHL, EMBASE) from January 1975 until April 2010. Prospective, longitudinal studies that assessed the predictive value of individual physical frailty indicators on ADL disability in community-dwelling elderly people aged 65 years and older were eligible for inclusion. Articles were reviewed by two independent reviewers who also assessed the quality of the included studies.</p> <p>Results</p> <p>After initial screening of 3081 titles, 360 abstracts were scrutinized, leaving 64 full text articles for final review. Eventually, 28 studies were included in the review. The methodological quality of these studies was rated by both reviewers on a scale from 0 to 27. All included studies were of high quality with a mean quality score of 22.5 (SD 1.6). Findings indicated that individual physical frailty indicators, such as weight loss, gait speed, grip strength, physical activity, balance, and lower extremity function are predictors of future ADL disability in community-dwelling elderly people.</p> <p>Conclusions</p> <p>This review shows that physical frailty indicators can predict ADL disability in community-dwelling elderly people. Slow gait speed and low physical activity/exercise seem to be the most powerful predictors followed by weight loss, lower extremity function, balance, muscle strength, and other indicators. These findings should be interpreted with caution because the data of the different studies could not be pooled due to large variations in operationalization of the indicators and ADL disability across the included studies. Nevertheless, our study suggests that monitoring physical frailty indicators in community-dwelling elderly people might be useful to identify elderly people who could benefit from disability prevention programs.</p

Influence of social support on cognitive function in the elderly

BACKGROUND: Social support is important in daily activities of the elderly. This study tests the hypothesis that there is an association between social support and cognitive function among the elderly in a community setting. METHODS: Face-to-face interviews were conducted in a cross-sectional stratified random sample of 4,993 elderly (≥65 years) city residents. Using multiple regression analysis, we investigated the influence of social support on cognitive function. RESULTS: 12% were over 80 years old. 53.28% were men. 67.14% were married. Higher Short Portable Mental Status Questionnaire (SPMSQ) scores (higher score means better cognitive function) were associated with strong social support, as measured by marital status and perceived positive support from friends. Lower cognitive function was associated with older and with female respondents. Only instrumental activities of daily living (IADL) were statistically and negatively related to SPMSQ. Lower functional status was associated with lower cognitive function. Elders with grade school educations had lower SPMSQ scores than did elders with high school educations. CONCLUSIONS: In Taiwan, higher cognitive function in community-living elderly was associated with increased social support. Life-style management should provide social activities for the elderly to promote a better quality of life