| 1. |
- Borrelli, P., et al.
(författare)
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Freely available convolutional neural network-based quantification of PET/CT lesions is associated with survival in patients with lung cancer
- 2022
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Ingår i: EJNMMI Physics. - : Springer Science and Business Media LLC. - 2197-7364. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Metabolic positron emission tomography/computed tomography (PET/CT) parameters describing tumour activity contain valuable prognostic information, but to perform the measurements manually leads to both intra- and inter-reader variability and is too time-consuming in clinical practice. The use of modern artificial intelligence-based methods offers new possibilities for automated and objective image analysis of PET/CT data. Purpose: We aimed to train a convolutional neural network (CNN) to segment and quantify tumour burden in [18F]-fluorodeoxyglucose (FDG) PET/CT images and to evaluate the association between CNN-based measurements and overall survival (OS) in patients with lung cancer. A secondary aim was to make the method available to other researchers. Methods: A total of 320 consecutive patients referred for FDG PET/CT due to suspected lung cancer were retrospectively selected for this study. Two nuclear medicine specialists manually segmented abnormal FDG uptake in all of the PET/CT studies. One-third of the patients were assigned to a test group. Survival data were collected for this group. The CNN was trained to segment lung tumours and thoracic lymph nodes. Total lesion glycolysis (TLG) was calculated from the CNN-based and manual segmentations. Associations between TLG and OS were investigated using a univariate Cox proportional hazards regression model. Results: The test group comprised 106 patients (median age, 76 years (IQR 61–79); n = 59 female). Both CNN-based TLG (hazard ratio 1.64, 95% confidence interval 1.21–2.21; p = 0.001) and manual TLG (hazard ratio 1.54, 95% confidence interval 1.14–2.07; p = 0.004) estimations were significantly associated with OS. Conclusion: Fully automated CNN-based TLG measurements of PET/CT data showed were significantly associated with OS in patients with lung cancer. This type of measurement may be of value for the management of future patients with lung cancer. The CNN is publicly available for research purposes. © 2022, The Author(s).
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| 2. |
- Teng, Fei, et al.
(författare)
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Multimedia Monitoring System of Obstructive Sleep Apnea via Deep Active Learning Model
- 2022
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Ingår i: IEEE Multimedia. - : IEEE. - 1070-986X .- 1941-0166. ; 29:3, s. 48-56
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Tidskriftsartikel (refereegranskat)abstract
- Obstructive Sleep Apnea (OSA) is one of the most common sleep-related breathing disorders. Nearly 1 billion people worldwide suffer from it, causing serious health effects and social burden. However, traditional monitoring systems often fall short in terms of cost and accessibility. In this article, we first propose a deep active learning model to detect OSA events from electrocardiogram (ECG). We then designed and developed a prototype of OSA monitoring system using ECG sensor and smartphone, in which our OSA detection algorithm is implemented and validated. Experiments show that we achieve accuracy of 92.15% while using 40% of labeled data, significantly reducing the cost of labeling and maximizing the performance. According to detection results and health-related multimedia signals, we provide OSA risk level and medical advice to users. We believe that the multimedia monitoring system can efficiently help diagnose OSA, which could lead to effective intervention strategies and better sleep care.
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| 3. |
- Lorentzen, Johnny, et al.
(författare)
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Chloroanisoles may explain mold odor and represent a major indoor environment problem in Sweden
- 2016
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Ingår i: Indoor Air. - : Wiley-Blackwell. - 0905-6947 .- 1600-0668. ; 26:2, s. 207-218
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Tidskriftsartikel (refereegranskat)abstract
- Indoor mold odor is associated with adverse health effects, but the microbial volatiles underlying mold odor are poorly described. Here, chloroanisoles were studied as potential key players, being formed by microbial metabolism of chlorophenols in wood preservatives. Using a three-stage approach, we (i) investigated the occurrence of chloroanisoles in buildings with indoor air quality problems, (ii) estimated their frequency in Sweden, and (iii) evaluated the toxicological risk of observed chloroanisole concentrations. Analyses of 499 building materials revealed several chloroanisole congeners in various types of buildings from the 1950s to 1970s. Evaluation of Swedish records from this time period revealed three coinciding factors, namely an unprecedented nationwide building boom, national regulations promoting wood preservatives instead of moisture prevention, and use of chlorophenols in these preservatives. Chlorophenols were banned in 1978, yet analysis of 457 indoor air samples revealed several chloroanisole congeners, but at median air levels generally below 15ng/m(3). Our toxicological evaluation suggests that these concentrations are not detrimental to human health per se, but sufficiently high to cause malodor. Thereby, one may speculate that chloroanisoles in buildings contribute to adverse health effects by evoking odor which, enhanced by belief of the exposure being hazardous, induces stress-related and inflammatory symptoms.
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| 4. |
- Powell, Nelson, et al.
(författare)
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Patterns in pharyngeal airflow associated with sleep-disordered breathing
- 2011
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Ingår i: Sleep Medicine. - : Elsevier. - 1389-9457 .- 1878-5506. ; 12:10, s. 966-974
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To establish the feasibility of a noninvasive method to identify pharyngeal airflow characteristics in sleep-disordered breathing.Methods: Four patients with sleep-disordered breathing who underwent surgery or used positive airway pressure devices and four normal healthy controls were studied. Three-dimensional CT imaging and computational fluid dynamics modeling with standard steady-state numerical formulation were used to characterize pharyngeal airflow behavior in normals and pre-and post-treatment in patients. Dynamic flow simulations using an unsteady approach were performed in one patient.Results: The pre-treatment pharyngeal airway below the minimum cross-sectional area obstruction site showed airflow separation. This generated recirculation airflow regions and enhanced turbulence zones where vortices developed. This interaction induced large fluctuations in airflow variables and increased aerodynamic forces acting on the pharyngeal wall. At post-treatment, for the same volumetric flow rate, airflow field instabilities vanished and airflow characteristics improved. Mean maximum airflow velocity during inspiration reduced from 18.3 ± 5.7 m/s pre-treatment to 6.3 ± 4.5 m/s post-treatment (P = 0.002), leading to a reduction in maximum wall shear stress from 4.8 ± 1.7 Pa pre-treatment to 0.9 ± 1.0 Pa post-treatment (P = 0.01). The airway resistance improved from 4.3 ± 1.4 Pa/L/min at pre-treatment to 0.7 ± 0.7 Pa/L/min at post-treatment (P = 0.004). Post-treatment airflow characteristics were not different from normal controls (all P ⩾ 0.39).Conclusions: This study demonstrates that pharyngeal airflow variables may be derived from CT imaging and computational fluid dynamics modeling, resulting in high quality visualizations of airflow characteristics of axial velocity, static pressure, and wall shear stress in sleep-disordered breathing.
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| 5. |
- Rissler, Jenny, et al.
(författare)
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An experimental study on lung deposition of inhaled 2 μm particles in relation to lung characteristics and deposition models
- 2023
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Ingår i: Particle and Fibre Toxicology. - : BioMed Central Ltd. - 1743-8977. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- Background: The understanding of inhaled particle respiratory tract deposition is a key link to understand the health effects of particles or the efficiency for medical drug delivery via the lung. However, there are few experimental data on particle respiratory tract deposition, and the existing data deviates considerably when comparing results for particles > 1 μm. Methods: We designed an experimental set-up to measure deposition in the respiratory tract for particles > 1 μm, more specifically 2.3 μm, with careful consideration to minimise foreseen errors. We measured the deposition in seventeen healthy adults (21–68 years). The measurements were performed at tidal breathing, during three consecutive 5-minute periods while logging breathing patterns. Pulmonary function tests were performed, including the new airspace dimension assessment (AiDA) method measuring distal lung airspace radius (r AiDA). The lung characteristics and breathing variables were used in statistical models to investigate to what extent they can explain individual variations in measured deposited particle fraction. The measured particle deposition was compared to values predicted with whole lung models. Model calculations were made for each subject using measured variables as input (e.g., breathing pattern and functional residual capacity). Results: The measured fractional deposition for 2.3 μm particles was 0.60 ± 0.14, which is significantly higher than predicted by any of the models tested, ranging from 0.37 ± 0.08 to 0.53 ± 0.09. The multiple-path particle dosimetry (MPPD) model most closely predicted the measured deposition when using the new PNNL lung model. The individual variability in measured particle deposition was best explained by breathing pattern and distal airspace radius (r AiDA) at half inflation from AiDA. All models underestimated inter-subject variability even though the individual breathing pattern and functional residual capacity for each participant was used in the model. Conclusions: Whole lung models need to be tuned and improved to predict the respiratory tract particle deposition of micron-sized particles, and to capture individual variations – a variation that is known to be higher for aged and diseased lungs. Further, the results support the hypothesis that the AiDA method measures dimensions in the peripheral lung and that r AiDA, as measured by the AiDA, can be used to better understand the individual variation in the dose to healthy and diseased lungs.
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| 6. |
- Mihaescu, Mihai, 1976-, et al.
(författare)
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Computational Modeling of Upper Airway Before and After Adenotonsillectomy for Obstructive Sleep Apnea
- 2008
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Ingår i: The Laryngoscope. - 0023-852X .- 1531-4995. ; 118:2, s. 360-362
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Tidskriftsartikel (refereegranskat)abstract
- Adenotonsillectomy, the first-line surgical treatment for obstructive sleep apnea (OSA) in children, is successful in only 50% of obese children. Computational fluid dynamics tools, which have been applied to differentiate OSA patients from those without OSA based on the airway flow characteristics, can be potentially used to identify patients likely to benefit from surgical intervention. We present computational modeling of the upper airway before and after adenotonsillectomy in an obese female adolescent with OSA. The subject underwent upper airway imaging on a 1.5 Tesla magnetic resonance imaging (MRI) scanner, and three-dimensional airway models were constructed using airway boundary coordinates from cross-sectional MRI scans. Our results using computational simulations indicate that, in an obese child, the resolution of OSA after adenotonsillectomy is associated with changes in flow characteristics that result in decreased pressure differentials across the airway walls and thus lower compressive forces that predispose to airway collapse. Application of such findings to an obese child seeking surgical treatment for OSA can potentially lead to selection of the surgical procedure most likely to result in OSA resolution. Effective intervention for OSA in this high-risk group will result in reduction in morbidity and the public health concerns associated with OSA.
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| 7. |
- Mihaescu, Mihai, 1976-, et al.
(författare)
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Modeling Flow in a Compromised Pediatric Airway Breathing Air and Heliox
- 2008
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Ingår i: The Laryngoscope. - : Wiley, The Triological Society. - 0023-852X .- 1531-4995. ; 118:12, s. 2205-2211
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Tidskriftsartikel (refereegranskat)abstract
- Objectives/Hypothesis: The aim of this study was to perform computer simulations of flow within an accurate model of a pediatric airway with subglottic stenosis. It is believed that the airflow characteristics in a stenotic airway are strongly related to the sensation of dyspnea. Methodology: Computed tomography images through the respiratory tract of an infant with subglottic stenosis, were used to construct the three-dimensional geometry of the airway. By using computational fluid dynamics (CFD) modeling to capture airway flow patterns during inspiration and expiration, we obtained information pertaining to flow velocity, static airway wall pressure, pressure drop across the stenosis, and wall shear stress. These simulations were performed with both air and heliox. Results: Unlike air, heliox maintained laminar flow through the stenosis. The calculated pressure drop over stenosis was lower for the heliox flow, in contrast to the airflow case. This lead to an approximately 40% decrease in airway resistance when using heliox, and presumably causes a decrease in the level of effort required for breathing. Conclusions: CFD simulations offer a quantitative method of evaluating airway flow dynamics in patients with airway abnormalities. CFD modeling illustrated the flow features and quantified flow parameters within a pediatric airway with subglottic stenosis. Simulations with air and heliox conditions mirrored the known clinical benefits of heliox as compared with air. We anticipate that computer simulation models will ultimately allow a better understanding of changes in flow caused by specific medical and surgical interventions in patients with conditions associated with dyspnea.
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| 8. |
- Mylavarapu, Goutham, et al.
(författare)
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Importance of paranasal sinuses in computational modeling of nasal airflow
- 2009
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Ingår i: 47th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition. - : AIAA. - 9781563479694 ; , s. 2009-0772-
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Konferensbidrag (refereegranskat)abstract
- This paper investigates the importance of including paranasal sinuses in the computational modeling of the nasal airflow. Three dimensional models of human nasal airway with and without including paranasal sinuses were reconstructed from Computed Tomography (CT) axial images of a subject with healthy nasal airway. The reconstruction process was performed using MIMICS® software program. The airway volume was discretized using TGRID® mesh generator. Steady Reynolds-Averaged Navier-Stokes (RANS) simulations were carried in both inspiratory and expiratory phases of respiratory cycle at a peak flow rate of 15 L/min in FLUENT®. The results show that the left and right nasal resistances change with less than 11% when paranasal sinuses are included in the computational model of the nasal airway. The flow into the sinuses is characterized by very low velocities during both inspiration and expiration conditions. The velocity distributions in the main nasal passage show small change predominantly in regions closer to the paranasal sinuses when compared to the model where sinuses were not included.
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| 9. |
- Wasserstrom, Sebastian, et al.
(författare)
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Model visualization : from micro to macro
- 2022
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Ingår i: 3D lung models for regenerating lung tissue. - 9780323908719 ; , s. 207-221
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Bokkapitel (refereegranskat)abstract
- Because of increasing demand, rapid development of in vitro and in vivo models to be used to study lung regeneration and lung repair has occurred during the last years. Even if imaging has always been an important tool in diagnosing disease and validating models, the current disease models, including three-dimensional (3D) lung models, put a higher demand on advanced imaging techniques. Moreover, choosing the most relevant technique for a specific question is not a trivial task, and the rapid development of new techniques has not made this task easier. Therefore the aim of this chapter is to provide an overview of different advanced imaging techniques that can be used to evaluate and validate 3D lung models, to provide a discussion on the current state of the art, and to list the pros and cons of the available techniques.
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| 10. |
- Bashir, Muwada Bashir Awad, et al.
(författare)
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Computational phenotyping of obstructive airway diseases: protocol for a systematic review
- 2022
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Ingår i: Systematic Reviews. - : Springer Nature. - 2046-4053. ; 11:1
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Forskningsöversikt (refereegranskat)abstract
- Background: Over the last decade, computational sciences have contributed immensely to characterization of phenotypes of airway diseases, but it is difficult to compare derived phenotypes across studies, perhaps as a result of the different decisions that fed into these phenotyping exercises. We aim to perform a systematic review of studies using computational approaches to phenotype obstructive airway diseases in children and adults.Methods and analysis: We will search PubMed, Embase, Scopus, Web of Science, and Google Scholar for papers published between 2010 and 2020. Conferences proceedings, reference list of included papers, and experts will form additional sources of literature. We will include observational epidemiological studies that used a computational approach to derive phenotypes of chronic airway diseases, whether in a general population or in a clinical setting. Two reviewers will independently screen the retrieved studies for eligibility, extract relevant data, and perform quality appraisal of included studies. A third reviewer will arbitrate any disagreements in these processes. Quality appraisal of the studies will be undertaken using the Effective Public Health Practice Project quality assessment tool. We will use summary tables to describe the included studies. We will narratively synthesize the generated evidence, providing critical assessment of the populations, variables, and computational approaches used in deriving the phenotypes across studiesConclusion: As progress continues to be made in the area of computational phenotyping of chronic obstructive airway diseases, this systematic review, the first on this topic, will provide the state of the art on the field and highlight important perspectives for future works.Ethics and dissemination: No ethical approval is needed for this work is based only on the published literature and does not involve collection of any primary or human data.
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