Tien Tuan DAO is a research scientist in biomedical and computer science fields. He received the Engineer Diploma and the Master degree in Computer Science in 2005 at the University of Cantho (Vietnam) and in 2006 at the University of Technology of Compiègne (UTC) (France) respectively. After receiving the PhD degree in Biomechanics and Bioengineering in 2009 at UTC, he pursued his research activities as a postdoctoral fellow at the same university until 2011.
His main research interests deal with:
Modeling of biomechanics systems (osteoarticular and musculoskeletal systems): characterization of biological tissues (cartilage and intervertebral disc) derived from conventional (MRI, CT) and advanced medical imagings techniques (high resolution MRI 7 Tesla, T2-mapping MRI, diffusion weighted and diffusion tensor MRI); computer-aided simulations using multi-bodies rigid dynamics (patient specific modeling and motion analysis) and finite element methods
Knowledge-based modeling in biomechanics: multidimensional and multimodal data, ontology, data mining, data fusion, computer-aided decision system, uncertainty modeling, semantic search engine, semantic web services
Clinical applications: orthopedic pediatric disorders (post polio, rotational abnormalities, clubfoot deformities, children with cerebral palsy) and low back pain
His scientific activities and professional affiliations concern:
Conference Reviewer: IEEE Engineering in Medicine and Biology Society (EMBS) International Conferences since 2008
Journal Reviewer: Computers in Biology and Medicine since 2010; IEEE Transactions on Biomedical Engineering since 2012
Program & Scientific Committee: 5th European Conference of the International Federation for Medical and Biological Engineering (EMBEC 2011, Session chair: Knowledge-based and expert systems), Fourth International Conference on the Development of Biomedical Engineering in Vietnam (BME4)
Dr. Tien-Tuan DAO was awarded Guy Denielou Prize for the Best Ph.D. Student in UTC in 2010. He also received AUF Master Scholarship for the Best Undergraduate Student in the AUF Computer Engineering Program at the University of CanTho in Vietnam in 2005.
Abstract: For patients with patterns ranging out of anthropometric standard values, patient-specific musculoskeletal modelling
becomes crucial for clinical diagnosis and follow-up. However, patient-specific modelling using imaging techniques and
motion capture systems is mainly subject to experimental errors. The aim of this study was to quantify these experimental
errors when performing a patient-specific musculoskeletal model. CT scan data were used to personalise the geometrical
model and its inertial properties for a post polio residual paralysis subject. After having performed a gait-based experimental
protocol, kinematics data were measured using a VICON motion capture system with six infrared cameras. The
musculoskeletal model was computed using a direct/inverse algorithm (LifeMod software). A first source of errors was
identified in the segmentation procedure in relation to the calculation of personalised inertial parameters. The second source
of errors was subject related, as it depended on the reproducibility of performing the same type of gait. The impact of
kinematics, kinetics and muscle forces resulting from the musculoskeletal modelling was quantified using relative errors and
the absolute root mean square error. Concerning the segmentation procedure, we found that the kinematics results were not
sensitive to the errors (relative error ,1%). However, a strong influence was noted on the kinetics results (deviation up to
71%). Furthermore, the reproducibility error showed a significant influence (relative mean error varying from 5 to 30%). The
present paper demonstrates that in patient-specific musculoskeletal modelling variations due to experimental errors derived
from imaging techniques and motion capture need to be both identified and quantified. Therefore, the paper can be used as a
guideline.
Abstract: Knee osteoarthritis deals with the loss of cartilaginous substances. Biomaterial implant using mesenchymalstromal cells was usually used to perform cartilage regeneration.The biointegration and biofunctionality assessments of the used biomaterial implant on the injury sites require the longitudinal monitoring of the cartilage over times. The aim of this present study was to develop a characterization framework of the cartilage in knee osteoarthritis especially its morphological properties and contact areas derived from high-resolution magnetic resonance imaging (MRI) technique. Manual segmentation procedure was applied for extracting cartilage from surrounding biological tissues. Geometrical computing techniques were applied to calculate characterization properties of the rat cartilage. As clinical case study, curvature, thickness, volume and relative contact area properties of the rat cartilage in knee osteoarthritis were quantified on each knee full model and/or its region of interest (ROI) models.We found that the cartilage thickness and volume of three cartilage compartments decrease at the beginning (from 7 to 28 days). Tibial cartilage thickness increases at the end of the osteoarthritis process (from 28 to 56 days).This is due to the fact that the cartilage swelling occurred during osteoarthritis process. These findings were confirmed when observing cartilage curvature; we noted that there is an increasing curvature due to the incurvation effect of the cartilage during osteoarthritis process. The relative contact areas of three cartilage compartments increase slightly. However, the difference between control knees and osteoarthritis knees is significant. ROIs analyses of the thickness and curvature properties were also reported on the femoral and tibial cartilages.
Abstract:
The objective of this present study was to classify two types of spastic cerebral palsy pathology such as diplegia and hemiplegia with belief labels. The discrimination process aims to predict new issues of cerebral palsy in case of uncertain classification. The Belief theory was applied to perform uncertain and imprecise classification. Following data were provided by the Bois Larris Center: Clinical kinematics, kinetics, and muscle activity parameters of the cerebral palsy were acquired motion analysis, forces platforms and Electromyography (EMG) system. An extraction parameter process was developed to reveal significant characters from kinematics, kinetics, and EMG curves. A heuristics-based belief assignment method was developed to distribute the mass function of each subject based on theirs extracted parameters. Belief decision tree method was used to develop uncertain classification model. A preliminary clinical application of 10 subjects (5 diplegias and 5 hemiplegias) was performed. Significant kinematics and kinetics parameters of the cerebral palsy such as ground reaction forces, contact time between the ground and the foot, maximal tension muscle and EMG-based average rectified voltage of the muscles were reported and discussed. Preliminary clinical findings of cerebral palsy classification were addressed in order to help clinicians in their diagnosis, decision-makings, and communications. We showed that Belief formalism was a universal formalism to classify cerebral palsy subjects with belief level.
Abstract: The aim of this present study was to develop a patient specific 3D musculoskeletal model to post polio residual paralysis (PPRP) subject. This model allows the effects of the lower limbs orthosis on the gait kinematics and kinetics to be quantified objectively. CT scan data were used to personalize the geometrical model and its inertial properties. Gait-based experimental protocol based on Davidâs protocol was performed. Kinematics data were measured using VICON motion system with six infrared cameras. Ground reaction force and moments were acquired simultaneously using two AMTI forces platforms. A direct/inverse algorithm of BRB.LifeMod software was used to simulate healthy (standard model provided by LifeMod) and pathological gaits (PPRP). The comparison of healthy and PPRP subjects was carried out. The biomechanics effects of the orthosis device were studied on simulated joint angles and torques, muscle force, and experimental ground reaction forces. The results showed that the orthosis device reduces the amplitude of movement of PPRP subject. It increases the ground contact time of the PPRP subject. However, a strategy of compensation exhibits a greater joint angle of the PPRP subject. Moreover, PPRP subject supports greater joint torques and lower muscle force due to the blocked knee joint device. The biomechanic effects of the lower limb orthosis helps to prevent long-term the injuries and damages of the biological structures involved of the PPRP paralysis. Furthermore, the personalization of the inertial properties of segmental bodies was taken in account to improve the accuracy of the patient specific biomechanics modelling.
Abstract: A Computer-Aided Decision System (CADS) was developed in order to assess the abnormalities of the clubfeet deformities. Our system consists of four components: 1) a diagnosis-based ontology of the musculoskeletal system of the lower limbs 2) a database for collecting clinical observations of the clubfeet deformities, e.g. the birth classification 3) the decision tree method and a diagnosis algorithm in order to predict new issues 4) an interactive module for managing the interaction between patients, experts and the due CADS. The pathological decision tree of the relationships between different parameters concerning clubfoot (equinus, varus, medial derotation of the Calcaneo-MidForefoot Unit, supination, muscle function, and joint flexibility) was computed. Rule knowledge was deduced to classify the 3 grades of the clubfoot deformities (Moderate, Severe, Rigid). Our system was validated clinically with the real patient data obtained from the Infant Surgery Service in Robert Debre Hospital in Paris. The remote access into our system has been guaranteed through a dynamic Web-based interface. Our system was developed in order to allow a better assessment for improving the knowledge and thus the evaluation and treatment of clubfeet.
Abstract: Modelling is necessary to understand and evaluate the musculoskeletal system of the human body. Most of the developed models used anthropometrical and geometrical parameters of the bones and muscles from the literature. The aim of the present work was to study the sensitivity of anthropometrical (segment mass) and geometrical (physiologic cross-sectional area of the muscle) parameters on musculoskeletal model of the lower limbs for simulation of the gait. An inverse dynamic analysis was performed to activate the joints and muscles. Then a direct dynamic analysis was carried out with active joints and muscles. The influences of these parameters on the kinematics and kinetics simulation results were reported. The obtained results show an influence of these parameters on the simulation results (maximal relative error varying from 2 to 75%). These results suggest subject specific parameters to be considered
Abstract: Risk analysis of the pathologies concerning the musculoskeletal system of the lower limbs is an importance for medical diagnosis. During medical consultation, the clinicians identify a pathology and establish a diagnosis by the connexion between symptoms with his medical knowledges. The outcome is directly depending accuracy of the diagnosis and the indication of the therapy. To improve the efficiency of this procedure, we propose to construct predictive mathematical models based on three data mining methods: decision tree or artificial neural network or support vector machines. Our approach allowed to study the relationship between different pathological parameters concerning the musculoskeletal system of the lower limbs. A meta-database is developed for synchronizing input data with classification process. This database included geometrical, kinematical, morphological data and mechanical properties of the musculoskeletal system. As example, rotational abnormality (RA) pathology is studied to deduce its principal risks factors (defined as significant pathological parameters). The performance comparison of three data mining techniques on the RA instances is also reported. We found that decision tree performed better than others methods on the RA instances. Our mathematical approach permitted to apply evidence of the medical diagnostic gained from the scientific method to medical practice.
Abstract: A Computer-Aided Decision System (CADS) based on the diagnostic-based ontology is developed in order to provide and broadcast of the knowledge of the medical experts (medicine, surgeon, physiotherapist, etc) for the diagnosis and treatment of children deformities specifically the lower limbs. We proposed a new infrastructure of the CADS which consists of four components: a diagnostic-based ontology of the musculoskeletal system of the lower limbs, a biomechanics meta-database, a statistical classification based on data mining techniques, and an interactive module as Web-based module for managing the interaction between experts, patients and the CADS. As applications, the Rotational Abnormalities (RA) and the clubfoot deformity of the musculoskeletal system of the lower limbs were studied. The quality of the diagnosis and treatment will be improved through an evidence-based diagnostic, a conservative treatment, and a follow up process. The use of the diagnostic-based ontology in the diagnosis process is a new approach which could be of help to improve the diagnosis and subsequently the treatment. Moreover, CADS could be extended to other children deformities.
Abstract: We focus here on the Multi-Period Renewal equipment Problem (MPRP) and present an heuristic
to solve realistic instances. The problem of renewal equipment planning is encountered in different
real-life situations, especially when one needs to manage a set of equipments by determining their
replacement date given a budget over a horizon time. Another important parameter is maintaining
a good general state of them. Hence, the renewal planning has to be determined for a horizon time
T, and we are interested in a general case where equipments can be replaced several times during
the time horizon. A direct way to model this situation gives rise to a quadratic mathematical
programing problem, which is quite hard to solve at optimum, especially given the large number of
equipments, (several thousands). We tackle the problem through an heuristic relied on the âSliding
Windowâ idea. That is, we consider the problem for a reduced number of years (time window), and
make it sliding forward until the entire horizon time is covered.We begin with a simplified case, that
is, the renewal of each equipment is done at most once during the horizon time. This will constitute
the main brick of the sliding window heuristic. We begin with the mathematical formulation, and
discuss two multiperiod budgeting strategies. The second one is particularly interesting as it leads
us to a particular multi-period knapsack problem (for more information on knapsack problems
the reader is referred to [1, 2]). In literature there are a few works dealing with some multiperiod
variants of knapsack problems, but, to the best of our knowledge, there are no studies directly
concerned with the problem considered in this paper. More specifically, in [3] the author deals
with the simple multiperiod knapsack problem and more recently in [4], the authors study the
multiperiod multiple-choice knapsack problem.
Abstract: A new approach is presented to understand the impact of pathologies of the musculo-skeletal system on the gait in Biomechanics. Usually models used in Biomechanics are based on rigid or deformable models. These models are used to understand the mechanism of the joint or the gait and diagnose the pathologies. Most of the models cannot simulate pathologies as simplified assumptions are performed. Our approach of modeling is based on the models abstracts. Our aim is to build an extensible ontology in the biomechanics field, named OSMMI--Ontology of the musculo-skeletal system of the lower limbs. Four principal objectives are to be addressed. The first objective is to formalize the studies concerning the lower limbs of the human body. The second objective is to build an expert system to diagnose the pathologies concerning the lower limbs and especially gait (rotational abnormalities, cerebral palsy, internally rotated gait, crouch gait). The third objective is to help to model the new problems based on accumulated knowledges and the last objective is to prepare the elements for the development of the semantic Web in Biomechanics. Firstly, the context of research is presented, then the methods used to create our ontology. Preliminary results of modeling and applications will be addressed.
Abstract: Understanding of the mechanical behavior of the human body is a challenge to take appropriate medical decisions (e.g. the patient's diagnosis or treatment). To solve this problem, First, a dynamic model of the musculoskeletal system of the lower limbs has been developed. A sensitivity analysis of the anthropometrical and geometrical parameters of the bones and muscles was performed with literature data. The computational results showed strong variations of kinematics and kinetics parameters function of the selected input data. All these findings suggest the development of patient specific musculoskeletal models using medical imaging technique for individualized geometrical parameters of the subjects. As clinical application, two personalized models were developed (a healthy subject with normal gait and a subject with gait disorders (Polio pathology)). This study showed the importance of personalized modeling to evaluate and design the Polio lower limb orthoses. The limitations and perspectives of the biomechanical models were presented in real clinical context. Second, a new class of model was proposed as meta-model (Computer-Aided Decision System) combining knowledge-based engineering methods to diagnose and guide the clinical treatment of the disorders of the musculoskeletal system of the lower limbs. The ontology, the data mining, the belief theory and the articial intelligence were applied to develop our meta-model. The crossing of these methods allowed us to develop a generic, flexible and extensible system. Three clinical applications (rotational anomalies, clubfeet deformities, and cerebral palsy) were studied in the first version of our system. The results showed that our system is able to provide aids to clinicians in their medical decisions (e.g. a diagnosis or a treatment). Finally, the methodological confrontation of these two modeling approaches was carried out to highlight the strengths and also the weaknesses of each modeling approach.
Abstract: This thesis relates to the problem of equiment renewal. The objective was to propose an optimal renewal strategy for the replacement of equipment in a drinking water production company. The optimization of the renewal strategy leds to make the decision on what equipment must be replaced and when in terms of contract. First, a study of different techniques/methods in operations research was performed to select most suitable mathematical models and appropriate solving methods. Second, we presented the implementation of selected methods. Finally, computational results were compared with those of an available operational tool named "Renouv'Eau". Discussion and conclusions were done before the perspectives of this work.
