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Machine learning applications in healthcare
Blekinge Institute of Technology, Faculty of Engineering, Department of Health.ORCID iD: 0000-0002-6752-017X
2020 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Healthcare is an important and high cost sector that involves many decision-making tasks based on the analysis of data, from its primary activities up till management itself. A technology that can be useful in an environment as data-intensive as healthcare is machine learning. This thesis investigates the application of machine learning in healthcare contexts as an applied health technology (AHT). AHT refers to application of scientific methods for the development of interventions targeting practical problems related to health and healthcare.

The two research contexts in this thesis regard two pivotal activities in the healthcare systems: diagnosis and prognosis. The diagnosis research context regards the age assessment of the young individuals, which aims to address the drawbacks in the bone age assessment research, investigating new age assessment methods. The prognosis research context regards the prognosis of dementia, which aims to investigate prognostic estimates for older individuals who came to develop the dementia disorder, in a time frame of 10 years. Machine learning applications were shown to be useful in both research contexts.

In the diagnosis research context, study I summarized the state of the art evidence in the area of bone age assessment with the use of machine learning, identifying both automated and non-automated approaches for age assessment. Study II investigated a non-automated approach based on the radiologists' assessment and study III investigated an automated approach based on deep learning. Both studies used magnetic resonance imaging. The results showed that the radiologists' assessment as input was not precise enough for the estimation of age. However, the deep learning method was able to extract more useful features from the images and provided better diagnostic performance for the age assessment.

In the research context of prognosis, study IV conducted a review on the relevant evidence in on the prognosis of dementia with machine learning techniques, identifying a focus on the research on neuroimaging studies dedicated to validating biomarkers for pharmaceutical research. Study V proposed a multifactorial decision tree approach for the prognosis of dementia in older individuals as to their development or not of dementia in 10 years. Achieving consistent performance results, it provided an interpretable prognostic model identifying possible modifiable and non-modifiable risk factors and possible patient subgroups of importance for the dementia research.

Place, publisher, year, edition, pages
Karlskrona: Blekinge Tekniska Högskola, 2020. , p. 202
Series
Blekinge Institute of Technology Doctoral Dissertation Series, ISSN 1653-2090 ; 6
Keywords [en]
Machine learning, Healthcare, Diagnosis, Prognosis, Age assessment, Bone age assessment, Dementia, Applied health technology
National Category
Other Medical Sciences
Research subject
Applied Health Technology
Identifiers
URN: urn:nbn:se:bth-19513ISBN: 978-91-7295-405-2 (print)OAI: oai:DiVA.org:bth-19513DiVA, id: diva2:1433037
Public defence
2020-09-16, 14:00
Opponent
Supervisors
Available from: 2020-05-29 Created: 2020-05-28 Last updated: 2021-01-27Bibliographically approved
List of papers
1. Bone age assessment with various machine learning techniques: A systematic literature review and meta-analysis
Open this publication in new window or tab >>Bone age assessment with various machine learning techniques: A systematic literature review and meta-analysis
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2019 (English)In: PLOS ONE, E-ISSN 1932-6203, Vol. 14, no 7, article id e0220242Article, review/survey (Refereed) Published
Abstract [en]

Background The assessment of bone age and skeletal maturity and its comparison to chronological age is an important task in the medical environment for the diagnosis of pediatric endocrinology, orthodontics and orthopedic disorders, and legal environment in what concerns if an individual is a minor or not when there is a lack of documents. Being a time-consuming activity that can be prone to inter- and intra-rater variability, the use of methods which can automate it, like Machine Learning techniques, is of value. Objective The goal of this paper is to present the state of the art evidence, trends and gaps in the research related to bone age assessment studies that make use of Machine Learning techniques. Method A systematic literature review was carried out, starting with the writing of the protocol, followed by searches on three databases: Pubmed, Scopus and Web of Science to identify the relevant evidence related to bone age assessment using Machine Learning techniques. One round of backward snowballing was performed to find additional studies. A quality assessment was performed on the selected studies to check for bias and low quality studies, which were removed. Data was extracted from the included studies to build summary tables. Lastly, a meta-analysis was performed on the performances of the selected studies. Results 26 studies constituted the final set of included studies. Most of them proposed automatic systems for bone age assessment and investigated methods for bone age assessment based on hand and wrist radiographs. The samples used in the studies were mostly comprehensive or bordered the age of 18, and the data origin was in most of cases from United States and West Europe. Few studies explored ethnic differences. Conclusions There is a clear focus of the research on bone age assessment methods based on radiographs whilst other types of medical imaging without radiation exposure (e.g. magnetic resonance imaging) are not much explored in the literature. Also, socioeconomic and other aspects that could influence in bone age were not addressed in the literature. Finally, studies that make use of more than one region of interest for bone age assessment are scarce. Copyright: © 2019 Dallora et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Place, publisher, year, edition, pages
Public Library of Science, 2019
National Category
Other Medical Sciences not elsewhere specified
Identifiers
urn:nbn:se:bth-18620 (URN)10.1371/journal.pone.0220242 (DOI)000484977900073 ()2-s2.0-85069805545 (Scopus ID)
Note

open access

Available from: 2019-09-10 Created: 2019-09-10 Last updated: 2023-12-04Bibliographically approved
2. Chronological Age Assessment in Young Individuals Using Bone Age Assessment Staging and Nonradiological Aspects: Machine Learning Multifactorial Approach
Open this publication in new window or tab >>Chronological Age Assessment in Young Individuals Using Bone Age Assessment Staging and Nonradiological Aspects: Machine Learning Multifactorial Approach
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2020 (English)In: JMIR Medical Informatics, E-ISSN 2291-9694, Vol. 8, no 9, article id e18846Article in journal (Refereed) Published
Abstract [en]

Background: Bone age assessment (BAA) is used in numerous pediatric clinical settings, as well as in legal settings when entities need an estimate of chronological age (CA) when valid documents are lacking. The latter case presents itself as critical since the law is harsher for adults and granted rights along with imputability changes drastically if the individual is a minor. Traditional BAA methods suffer from drawbacks such as exposure of minors to radiation, do not consider factors that might affect the bone age and they mostly focus on a single region. Given the critical scenarios in which BAA can affect the lives of young individuals it is important to focus on the drawbacks of the traditional methods and investigate the potential of estimating CA through BAA.

Objective: This paper aims to investigate CA estimation through BAA in young individuals of 14 to 21 years with machine learning methods, addressing the drawbacks in the research using magnetic resonance imaging (MRI), assessment of multiple ROIs and other factors that may affect the bone age.

Methods: MRI examinations of the radius, distal tibia, proximal tibia, distal femur and calcaneus were carried out on 465 males and 473 females subjects (14-21 years). Measures of weight and height were taken from the subjects and a questionnaire was given for additional information (self-assessed Tanner Scale, physical activity level, parents' origin, type of residence during upbringing). Two pediatric radiologists assessed, independently, the MRI images as to their stage of bone development (blinded to age, gender and each other). All the gathered information was used in training machine learning models for chronological age estimation and minor versus adults classification (threshold of 18 years). Different machine learning methods were investigated.

Results: The minor versus adults classification produced accuracies of 90% and 84%, for male and female subjects, respectively, with high recalls for the classification of minors. The chronological age estimation for the eight age groups (14-21 years) achieved mean absolute errors of 0.95 years and 1.24 years for male and female subjects, respectively. However, for the latter lower error occurred only for the ages of 14 and 15.

Conclusions: This paper proposed to investigate the CA estimation through BAA using machine learning methods in two ways: minor versus adults classification and CA estimation in eight age groups (14-21 years), while addressing the drawbacks in the research on BAA. The first achieved good results, however, for the second case BAA showed not precise enough for the classification.

Place, publisher, year, edition, pages
JMIR Publications Inc., 2020
Keywords
chronological age assessment, bone age, skeletal maturity, machine learning, magnetic resonance imaging, radius, distal tibia, proximal tibia, distal femur, calcaneus
National Category
Other Medical Sciences not elsewhere specified
Identifiers
urn:nbn:se:bth-19500 (URN)10.2196/18846 (DOI)000577388800006 ()2-s2.0-85097465282 (Scopus ID)
Funder
Swedish National Board of Health and Welfare
Note

open access

Available from: 2020-05-26 Created: 2020-05-26 Last updated: 2022-04-29Bibliographically approved
3. Age assessment of youth and young adults using magnetic resonance imaging of the knee: A deep learning approach
Open this publication in new window or tab >>Age assessment of youth and young adults using magnetic resonance imaging of the knee: A deep learning approach
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2019 (English)In: JMIR Medical Informatics, E-ISSN 2291-9694, Vol. 7, no 4, p. 419-436, article id e16291Article in journal (Refereed) Published
Abstract [en]

Background: Bone age assessment (BAA) is an important tool for diagnosis and in determining the time of treatment in a number of pediatric clinical scenarios, as well as in legal settings where it is used to estimate the chronological age of an individual where valid documents are lacking. Traditional methods for BAA suffer from drawbacks, such as exposing juveniles to radiation, intra- and interrater variability, and the time spent on the assessment. The employment of automated methods such as deep learning and the use of magnetic resonance imaging (MRI) can address these drawbacks and improve the assessment of age. Objective: The aim of this paper is to propose an automated approach for age assessment of youth and young adults in the age range when the length growth ceases and growth zones are closed (14-21 years of age) by employing deep learning using MRI of the knee. Methods: This study carried out MRI examinations of the knee of 402 volunteer subjects-221 males (55.0%) and 181 (45.0%) females-aged 14-21 years. The method comprised two convolutional neural network (CNN) models: the first one selected the most informative images of an MRI sequence, concerning age-assessment purposes; these were then used in the second module, which was responsible for the age estimation. Different CNN architectures were tested, both training from scratch and employing transfer learning. Results: The CNN architecture that provided the best results was GoogLeNet pretrained on the ImageNet database. The proposed method was able to assess the age of male subjects in the range of 14-20.5 years, with a mean absolute error (MAE) of 0.793 years, and of female subjects in the range of 14-19.5 years, with an MAE of 0.988 years. Regarding the classification of minors-with the threshold of 18 years of age-an accuracy of 98.1% for male subjects and 95.0% for female subjects was achieved. Conclusions: The proposed method was able to assess the age of youth and young adults from 14 to 20.5 years of age for male subjects and 14 to 19.5 years of age for female subjects in a fully automated manner, without the use of ionizing radiation, addressing the drawbacks of traditional methods. © 2019 Journal of Medical Internet Research. All rights reserved.

Place, publisher, year, edition, pages
JMIR PUBLICATIONS, 2019
Keywords
Age assessment, Bone age, Convolutional neural networks, Deep learning, Knee, Machine learning, Magnetic resonance imaging, Medical imaging, Skeletal maturity, Transfer learning, adolescent, adult, article, bone age determination, child, convolutional neural network, diagnostic imaging, employment, female, human, human experiment, juvenile, major clinical study, male, maturity, nuclear magnetic resonance imaging, transfer of learning, young adult
National Category
Radiology, Nuclear Medicine and Medical Imaging Orthopaedics
Identifiers
urn:nbn:se:bth-19085 (URN)10.2196/16291 (DOI)000510198100031 ()2-s2.0-85077013897 (Scopus ID)
Note

open access

Available from: 2020-01-09 Created: 2020-01-09 Last updated: 2022-05-25Bibliographically approved
4. Machine learning and microsimulation techniques on the prognosis of dementia: A systematic literature review
Open this publication in new window or tab >>Machine learning and microsimulation techniques on the prognosis of dementia: A systematic literature review
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2017 (English)In: PLOS ONE, E-ISSN 1932-6203, Vol. 12, no 6, article id e0179804Article in journal (Refereed) Published
Abstract [en]

Background Dementia is a complex disorder characterized by poor outcomes for the patients and high costs of care. After decades of research little is known about its mechanisms. Having prognostic estimates about dementia can help researchers, patients and public entities in dealing with this disorder. Thus, health data, machine learning and microsimulation techniques could be employed in developing prognostic estimates for dementia. Objective The goal of this paper is to present evidence on the state of the art of studies investigating and the prognosis of dementia using machine learning and microsimulation techniques. Method To achieve our goal we carried out a systematic literature review, in which three large databases -Pubmed, Socups and Web of Science were searched to select studies that employed machine learning or microsimulation techniques for the prognosis of dementia. A single backward snowballing was done to identify further studies. A quality checklist was also employed to assess the quality of the evidence presented by the selected studies, and low quality studies were removed. Finally, data from the final set of studies were extracted in summary tables. Results In total 37 papers were included. The data summary results showed that the current research is focused on the investigation of the patients with mild cognitive impairment that will evolve to Alzheimer's disease, using machine learning techniques. Microsimulation studies were concerned with cost estimation and had a populational focus. Neuroimaging was the most commonly used variable. Conclusions Prediction of conversion from MCI to AD is the dominant theme in the selected studies. Most studies used ML techniques on Neuroimaging data. Only a few data sources have been recruited by most studies and the ADNI database is the one most commonly used. Only two studies have investigated the prediction of epidemiological aspects of Dementia using either ML or MS techniques. Finally, care should be taken when interpreting the reported accuracy of ML techniques, given studies' different contexts. © 2017 Dallora et al.This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Place, publisher, year, edition, pages
Public Library of Science, 2017
Keywords
Alzheimer disease, analytic method, artificial neural network, Bayesian Network, classification algorithm, comorbidity, DecisionTrees, disease course, human, k nearest neighbor, machine learning, microsimulation technique, mild cognitive impairment, population research, quality control, Review, support vector machine, systematic review
National Category
Geriatrics Computer Sciences
Identifiers
urn:nbn:se:bth-15017 (URN)10.1371/journal.pone.0179804 (DOI)000404608300049 ()2-s2.0-85021683292 (Scopus ID)
Note

Open access

Available from: 2017-08-23 Created: 2017-08-23 Last updated: 2023-12-04Bibliographically approved
5. A decision tree multifactorial approach for predicting dementia in a 10 years’ time
Open this publication in new window or tab >>A decision tree multifactorial approach for predicting dementia in a 10 years’ time
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Background: Dementia is a complex neurological disorder, to which little is known about its mechanisms and no therapeutic treatment was identified, to date, to revert or alleviate its symptoms. It affects the older adults population causing a progressive cognitive decline that can become severe enough to impair the individuals' independence and functioning. In this scenario, the prognosis research, directed to identify modifiable risk factors in order to delay or prevent its development, in a big enough time frame is substantially important.

Objective: This study investigates a decision tree multifactorial approach for the prognosis of dementia of individuals, not diagnosed with this disorder at baseline, and their development (or not) of dementia in a time frame of 10 years. 

Methods: This study retrieved data from the Swedish National Study on Aging and Care, which consisted of 726 subjects (313 males and 413 females), of which 91 presented a diagnosis of dementia at the 10-year study mark. A K-nearest neighbors multiple imputation method was employed to handle the missing data. A wrapper feature selection was employed to select the best features in a set of 75 variables, which considered factors related to demographic, social, lifestyle, medical history, biochemical test, physical examination, psychological assessment and diverse health instruments relevant to dementia evaluation. Lastly, a cost-sensitive decision tree approach was employed in order to build predictive models in an stratified nested cross-validation experimental setup.

Results: The proposed approach achieved an AUC of 0.745 and Recall of 0.722 for the 10-year prognosis of dementia. Our findings showed that most of the variables selected by the tree are related to modifiable risk factors, of which physical strength was an important factor across all ages of the sample. Also, there was a lack of variables related to the health instruments routinely used for the dementia diagnosis that might not be sensitive enough to predict dementia in a 10 years’ time.

Conclusions: The proposed model identified diverse modifiable factors, in a 10 years’ time from diagnosis, that could be investigated for possible interventions in order to delay or prevent the dementia onset. 

National Category
Other Medical Sciences not elsewhere specified
Identifiers
urn:nbn:se:bth-19499 (URN)
Note

This manuscript has not yet been submitted.

Available from: 2020-05-26 Created: 2020-05-26 Last updated: 2020-06-02Bibliographically approved

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