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Independent cohort cross-validation of the real-time DISTq estimation of insulin sensitivity

COMPUTER MEthODS AND PROGRAMS IN BIOMEDICINE 2011年第2期102卷 94-104页

作者： Docherty, Paul D. Chase, J. Geoffrey Lotz, thomas F. Hann, Christopher E. Shaw, Geoffrey M. Berkeley, Juliet E. TeMorenga, Lisa Mann, Jim I. McAuley, Kirsten Univ Canterbury Dept Mech Engn Christchurch 8140 New Zealand Univ Otago Dept Med Christchurch Sch Med Christchurch New Zealand Univ Otago Edgar Natl Ctr Diabet Res Dunedin New Zealand

Insulin sensitivity (SI) is useful in the diagnosis, screening and treatment of diabetes. However, most current tests cannot provide an accurate, immediate or real-time estimate. the DISTq method does not require insulin or C-peptide assays like most SI tests, thus enabling real-time, low-cost SI estimation. the method uses a posteriori parameter estimations in the absence of insulin or C-peptide assays to simulate accurate, patient-specific, insulin concentrations that enable SI identification. Mathematical functions for the a posteriori parameter estimates were generated using data from 46 fully sampled DIST tests (glucose, insulin and C-peptide). SI values found using the DISTq from the 46 test pilot cohort and a second independent 218 test cohort correlated R = 0.890 and R = 0.825, respectively, to the fully sampled (including insulin and C-peptide assays) DIST SI metrics. When the a posteriori insulin estimation functions were derived using the second cohort, correlations for the pilot and second cohorts reduced to 0.765 and 0.818, respectively. these results show accurate SI estimation is possible in the absence of insulin or C-peptide assays using the proposed method. Such estimates may only need to be generated once and then used repeatedly in the future for isolated cohorts. the reduced correlation using the second cohort was due to this cohort's bias towards low SI insulin resistant subjects, limiting the data set's ability to generalise over a wider range. All the correlations remain high enough for the DISTq to be a useful test for a number of clinical applications. the unique real-time results can be generated within minutes of testing as no insulin and C-peptide assays are required and may enable new clinical applications. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

关键词： Insulin sensitivity test Diabetes risk assessment Physiological modelling

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Recurrence quantification analysis of sustained sub-maximal grip contractions in patients with various metabolic muscle disorders

Recurrence quantification analysis of sustained sub-maximal ...

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7th symposium on modelling and control in biomedical systems

作者： Li, Ke Hewson, David Snoussi, Hichem Duchene, Jacques Hogrel, Jean-Yves Univ Paris 06 Inst Myol UMR S974 CNRSINSERMU974UMR 7215GH Pitie Salpetriere F-75651 Paris 13 France Univ Technol Troyes Inst Charles Delaunay CNRS UMR 6279 F-10010 Troyes France Shandong Univ Sch Control Sci & Engn Jinan 250061 Peoples R China

Recurrence quantification analysis (RQA) was used to analyse force signals during sustained sub-maximal grip contraction (SSGC) of three types of patients suffering from a metabolic muscle disorder (glycogen storage disease type III (GSD III), glycogen storage disease type V (GSD V) and mitochondrial myopathies (MITO)) compared to control subjects. Recurrence plots (RP) of patients showed clear non-uniformity, in comparison to control subjects who displayed quasi-periodic patterns. Quantitative analysis of the RP showed significant differences between patients with metabolic disorders and the control group for four RQA parameters. the results showed that the SSGC signals of patients had decreased L-max, which indicated more chaotic patterns. In addition the deterministic component of the signals was less complex for patients than for controls. the differences of SSGC signal observed using RP and RQA were possibly related to the underlying changes in metabolism of muscle fibres due to the disease. Results of this study illustrate that the RQA technique is well suited to analyse sustained grip-force signals. (C) 2010 Elsevier Ltd. All rights reserved.

关键词： Muscle contraction Strength Metabolic muscle disorders Nonlinear analysis Chaos theory Recurrence quantification

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Development of a model-based clinical sepsis biomarker for critically ill patients

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COMPUTER MEthODS AND PROGRAMS IN BIOMEDICINE 2011年第2期102卷 149-155页

作者： Lin, Jessica Parente, Jacquelyn D. Chase, J. Geoffrey Shaw, Geoffrey M. Blakemore, Amy J. LeCompte, Aaron J. Pretty, Christopher Razak, Normy N. Lee, Dominic S. Hann, Christopher E. Wang, Sheng-Hui Univ Otago Christchurch Dept Med Christchurch New Zealand Univ Canterbury Dept Mech Engn Ctr Bioengn Christchurch 1 New Zealand Univ Canterbury Dept Math & Stat Christchurch 1 New Zealand

Sepsis occurs frequently in the intensive care unit (ICU) and is a leading cause of admission, mortality, and cost. Treatment guidelines recommend early intervention, however positive blood culture results may take up to 48 h. Insulin sensitivity (SO is known to decrease with worsening condition and could thus be used to aid diagnosis. Some glycemic control protocols are able to accurately identify insulin sensitivity in real-time. Hourly model-based insulin sensitivity S-1 values were calculated from glycemic control data of 36 patients with sepsis. the hourly S-1 is compared to the hourly sepsis score (ss) for these patients (ss = 0-4 for increasing severity). A multivariate clinical biomarker was also developed to maximize the discrimination between different ss groups. Receiver operator characteristic (ROC) curves for severe sepsis (ss >= 2) are created for both SI and the multivariate clinical biomarker. Insulin sensitivity as a sepsis biomarker for diagnosis of severe sepsis achieves a 50% sensitivity, 76% specificity, 4.8% positive predictive value (PPV), and 98.3% negative predictive value (NPV) at an SI cut-off value of 0.00013 L/mU/min. Multivariate clinical biomarker combining Si, temperature, heart rate, respiratory rate, blood pressure, and their respective hourly rates of change achieves 73% sensitivity, 80% specificity, 8.4% PPV, and 99.2% NPV. thus, the multivariate clinical biomarker provides an effective real-time negative predictive diagnostic for severe sepsis. Examination of both inter- and intra-patient statistical distribution of this biomarker and sepsis score shows potential avenues to improve the positive predictive value. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

关键词： Sepsis Insulin sensitivity Biomarker Diagnosis Receiver operator characteristic Glucose control Real-time clinical application

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Airway segmentation for low-contrast CT images from combined PET/CT scanners based on airway modelling and seed prediction

Airway segmentation for low-contrast CT images from combined...

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7th symposium on modelling and control in biomedical systems

作者： Wang, Xiuying Fang, Chaoqun Xia, Yong Feng, Dagan Univ Sydney Biomed & Multimedia Informat Technol BMIT Res Grp Sch Informat Technol Sydney NSW 2006 Australia Hong Kong Polytech Univ Ctr Multimedia Signal Proc Dept Elect & Informat Engn Hong Kong Hong Kong Peoples R China Royal Prince Alfred Hosp Dept PET & Nucl Med Sydney NSW 2050 Australia

Combined positron emission tomography (PET) and computed tomography (CT) scanning provides superior access to both functional information and the anatomical structures of the airway tree. However, due to the complex anatomical structures, limited image resolutions and partial volume effect (PVE), segmentation of airway trees from low-dose and low-contrast CT images from PET/CT scanning is a challenging task. Conventional airway segmentation algorithms usually produce less than satisfactory results. In this paper, we propose a novel region growing approach for automated airway tree segmentation in CT images from combined PET/CT scanners. In our approach, we employ prior anatomical knowledge of the airway to predict, extract, and validate the seeds of bronchi regions, and use those seeds to identify the airway branches that are not detectable by conventional 3D region growing. through analyzing the size of the bronchi in two successive slices, this approach allows airway seeds to grow sufficiently while avoiding leakages. Our method was compared to the traditional 3D region growing algorithm on 14 clinical thoracic PET/CT images. the experimental results demonstrate that the proposed technique is capable of retrieving considerably larger number of branches and providing more accurate airway segmentation. (C) 2010 Elsevier Ltd. All rights reserved.

关键词： biomedical system Image segmentation Combined PET/CT scanner Airway segmentation Region growing

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Tight glycemic control in critical care - the leading role of insulin sensitivity and patient variability: A review and model-based analysis

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COMPUTER MEthODS AND PROGRAMS IN BIOMEDICINE 2011年第2期102卷 156-171页

作者： Chase, J. Geoffrey Le Compte, Aaron J. Suhaimi, Fatanah Shaw, Geoffrey M. Lynn, Adrienne Lin, Jessica Pretty, Christopher G. Razak, Normy Parente, Jacquelyn D. Hann, Christopher E. Preiser, Jean-Charles Desaive, thomas Univ Canterbury Dept Mech Engn Ctr Bioengn Christchurch 1 New Zealand Univ Otago Sch Med Christchurch New Zealand Christchurch Hosp Dept Intens Care Christchurch New Zealand Christchurch Womens Hosp Neonatal Unit Christchurch New Zealand Univ Liege Ctr Hosp Univ Liege Dept Intens Care Med Liege Belgium Univ Liege Hemodynam Res Ctr Liege Belgium

Tight glycemic control (TGC) has emerged as a major research focus in critical care due to its potential to simultaneously reduce both mortality and costs. However, repeating initial successful TGC trials that reduced mortality and other outcomes has proven difficult with more failures than successes. Hence, there has been growing debate over the necessity of TGC, its goals, the risk of severe hypoglycemia, and target cohorts. this paper provides a review of TGC via new analyses of data from several clinical trials, including SPRINT, Glucontrol and a recent NICU study. It thus provides both a review of the problem and major background factors driving it, as well as a novel model-based analysis designed to examine these dynamics from a new perspective. Using these clinical results and analysis, the goal is to develop new insights that shed greater light on the leading factors that make TGC difficult and inconsistent, as well as the requirements they thus impose on the design and implementation of TGC protocols. A model-based analysis of insulin sensitivity using data from three different critical care units, comprising over 75,000 h of clinical data, is used to analyse variability in metabolic dynamics using a clinically validated model-based insulin sensitivity metric (S-I). Variation in S-I provides a new interpretation and explanation for the variable results seen (across cohorts and studies) in applying TGC. In particular, significant intra- and inter-patient variability in insulin resistance (1/S-I) is seen be a major confounder that makes TGC difficult over diverse cohorts, yielding variable results over many published studies and protocols. Further factors that exacerbate this variability in glycemic outcome are found to include measurement frequency and whether a protocol is blind to carbohydrate administration. (C) 2010 Published by Elsevier Ireland Ltd.

关键词： Critical care Glycemic control Variability Modeling Insulin sensitivity TGC ICU Mortality SPRINT Glucontrol Intensive insulin therapy IIT

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FRACTAL modelling AND ANALYSIS OF FLOW-FIELD IMAGES

FRACTAL MODELLING AND ANALYSIS OF FLOW-FIELD IMAGES

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7th IEEE International symposium on biomedical Imaging: From Nano to Macro

作者： Tafti, Pouya Dehghani Delgado-Gonzalo, Ricard Stalder, Aurelien F. Unser, Michael Ecole Polytech Fed Lausanne Biomed Imaging Grp Lausanne Switzerland Univ Hosp Freiburg Dept Diagnost Radiol Dept Phys Med Freiburg Germany Capital Med Univ Xuanwu Hosp Dept Radiol Beijing Peoples R China

ISBN: (纸本)9781424441266

We introduce stochastic models for flow fields with parameters that dictate the scale-dependent (self-similar) character of the field and control the balance between its rotational vs compressive behaviour. the development of our models is motivated by the availability of imaging modalities that measure flow vector fields (flow-sensitive MRI and Doppler ultrasound). To study such data, we formulate estimators of the model parameters, and use them to quantify the Hurst exponent and directional properties of synthetic and real-world flow fields (measured by means of phase-contrast MRI) in 3D.

关键词： vector fractional Brownian motion flow-sensitive MRI wavelets vector fields Hurst exponent curl divergence

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Multiscale Information modelling for Heart Morphogenesis

Multiscale Information Modelling for Heart Morphogenesis

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13th IMEKO TC1-TC7 Joint symposium Without Measurement No Science, Without Science No Measurement

作者： Abdulla, T. Imms, R. Schleich, J. M. Summers, R. Univ Loughborough Dept Elect & Elect Engn Loughborough Leics England Univ Rennes 1 LTSI Signal & Image Proc Lab Rennes France

Science is made feasible by the adoption of common systems of units. As research has become more data intensive, especially in the biomedical domain, it requires the adoption of a common system of information models, to make explicit the relationship between one set of data and another, regardless of format. this is being realised through the OBO Foundry to develop a suite of reference ontologies, and NCBO Bioportal to provide services to integrate biomedical resources and functionality to visualise and create mappings between ontology terms. biomedical experts tend to be focused at one level of spatial scale, be it biochemistry, cell biology, or anatomy. Likewise, the ontologies they use tend to be focused at a particular level of scale. there is increasing interest in a multiscale systems approach, which attempts to integrate between different levels of scale to gain understanding of emergent effects. this is a return to physiological medicine with a computational emphasis, exemplified by the worldwide Physiome initiative, and the European Union funded Network of Excellence in the Virtual Physiological Human. However, little work has been done on how information modelling itself may be tailored to a multiscale systems approach. We demonstrate how this can be done for the complex process of heart morphogenesis, which requires multiscale understanding in both time and spatial domains. Such an effort enables the integration of multiscale metrology.

关键词： Ontology

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7th IFAC symposium on Modeling and control in biomedical systems [including Biological systems] MCBMS'09 - Proceedings

7th IFAC Symposium on Modeling and Control in Biomedical Sys...

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7th IFAC symposium on modelling and control in biomedical systems (including Biological systems) MCBMS'09

ISBN: (纸本)9783902661494

the proceedings contain 75 papers. the topics discussed include: modeling the double peak phenomenon in pharmacokinetics;an in-silico analysis of the smart study of HIV infection;fatigue and non-fatigue mathematical muscle models during functional electrical stimulation of paralyzed muscle;lung movement determination in temporal sequences of MR images using HOUGH transform and interval arithmetics;model-based decision support system to improve diabetes care and management;SVM based follow-up system for brain tumor evolution from magnetic resonance images;a priori knowledge based frequencydomain quantification of magnetic resonance spectroscopy;model reduction for adaptation in surgery anaesthesia;a new general glucose homeostatic model using a proportional-integral-derivative controller;and respiratory mechanics monitoring during artificial ventilation: batch algorithms and their accuracy.

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FADEC control system for MPM 20 engine

FADEC control system for MPM 20 engine

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7th International symposium on Applied Machine Intelligence and Informatics

作者： Andoga, Rudolf Fozo, Ladislav Madarasz, Ladislav Povazan, Jozef Tech Univ Kosice Dep Cybernet & Artificial Intelligence Kosice Slovakia Tech Univ Kosice Dept Aviat Engn Kosice Slovakia

ISBN: (纸本)9781424438013

the article deals with full authority digital engine control (FADEC) systems and possibilities of application of concepts and methods of artificial intelligence in such control system. FADEC represents a framework where the most modem methods of artificial intelligence can be applied. this represents a great potential for increase of reliability, efficiency and overall quality of control of turbojet engines. We are trying to design and implement a FADEC control system for our small experimental turbojet engine MPM 20.

关键词： small turbojet engine analytic models experimental identification situational modelling situational control

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A Real-Time Extension of Creol for modelling biomedical Sensors

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7th International symposium on Formal Methods for Components and Objects

作者： Kyas, Marcel Johnsen, Einar Broch Free Univ Berlin Dept Comp Sci D-1000 Berlin Germany Univ Oslo Dept Informat N-0316 Oslo Norway

ISBN: (纸本)9783642041662

this paper presents work on object-oriented modelling of wireless biomedical sensors in order to analyse their behaviour. these sensors combine synchronous and asynchronous communication, hard and soft real-time requirements, and have limited resources in terms of memory and energy. Moreover, design decisions tend to influence the validity of other requirements;e.g., higher communication throughput increases energy requirements. A single language is proposed in which design concerns can be expressed and analysed. this language is an extension for real-time systems of Creol, a modelling language specifically designed for distributed, asynchronously communicating, active objects. the extension proposes language primitives to capture requirements on the progress of time and the progress of the system. We integrate the timing requirements and the underlying object-oriented modelling language in a timed denotational semantics. the controller of a biomedical sensor node is used to illustrate the approach, for which there are both hard real-time requirements imposed by taking sensor measurements and soft requirements imposed by the communication network.

关键词： Real time systems

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