Information Technologies in Biomedicine, Volume 4

A survey of various laparoscopic liver surgery procedures is presented. First, depending on the tumor location, three patient positioning are discussed. Then, the resection procedures of benign and malignant lesions are presented. Pre- and intersurgical imaging techniques including 3D imaging and ultrasound procedures are often employed. Finally, the survival rate reported by various authors after nearly 15 years of experiences concludes the study.

Article presents methodology of computer aided destroying focal liver lesions using imaging navigation system. Methodology allows generation of personalized anatomical model of patient’s liver based on CAT screening with contract media of abdominal cavity, registration of edited anatomical model relative to real patient’s position on operation block, presentation of surgical tools position during treatment on the liver’s anatomical model and non-direct monitoring of ablation process of lesions. Liver anatomy model comprises organ’s and focal lesions’ surface and central lines of vascular structures in liver. Generation of personalized patient’s model has been verified based on anonymized abdominal cavity CAT with contrast media screening cases. The registration methodology has been evaluated on imaging data and patient from the Second Department of Clinical Radiology and the Chair and Department of General, Transplant and Liver Surgery at the Medical University of Warsaw after acceptance of the ethics committee of the Medical University of Warsaw.

This study presents the development of an image navigation system dedicated to assist a miniinvasive abdominal surgery. First, the system overview is discussed. Then, a development of a mesh model of abdominal structure is presented. Next, a system calibration including the component as well as patient registration is described.The evaluation of the system has been performed separately for each component. The accuracy of calibration as well as patient registration is reported. This yields the robustnes evaluation of the overall system.

In computer assisted surgery, the localizers can be used for tracking of an object in motion. In this paper, we propose a method for simulating the accuracy of such tracking mode for a specified efficiency of marker detection. From simulation, we obtain the relationship between marker detection efficiency and tracking precision, assuming linear interpolation of missing locations. We find, that for a typical design of the tracked tool, the marker recognition efficiency should be no less than 88% to keep the tracking precision at the level that is acceptable in computer assisted surgery. We use this criterion to determine a usable measurement volume of a physical prototype of optical localizer.

The aim of this paper was to analyze the spatial geometry of objects basing on ultrasound images recorded by free-hand probe. The data analysis consists of three phases: data recording, contour segmentation and triangulation. Several algorithms of segmentation have been tested to recognize the object’s contour. To analyze the efficiency of triangulation algorithms, the similarities of obtained 3D models to the reference CT-based 3D model were evaluated. For objective and quantitative evaluation of obtained models the Hausdorff’s distances were calculated for compared surfaces. The results revealed higher efficiency of greedy projection method than the 2D Delaunay’s Triangulation applied for projected set of points in step by step procedure for the same cloud of points obtained as the result of user controlled segmentation procedure. The free hand ultrasonography can be applied to measure the spatial tissue shape for virtual planning of surgery without radiation.

Accurate methods of hip joint centre (HJC) localization are necessary in gait analysis. It was shown that current methods could involve large mislocation errors, what affect both kinematics and kinetics. The purpose of present study was to compare three different HJC localization methods: predictive methods, functional calibration methods, and medical imaging analysis technique, as well as to assess of its effect on joint kinematic variables during gait on population of three able-bodied subjects. Significant deviations were observed for HJC determined with predictive method compared to ultrasound technique (44 ± 7 mm), resulted in errors propagating into calculated joint angles (mean 2.7°). While lower deviations observed for functional method comparing to ultrasound technique (mean 23 ± 6 mm) results in negligible joint angle differences (mean 0.6°.). Therefore, functional methods are highly recommended in the absence of imaging technique.

The paper presents the development of a radiological atlas employed in an abdomen patient specific model verification.

After a patient specific model introduction, the development of a radiological atlas is discussed.

Unprocessed database, containing DICOM images and radiological diagnosis presented. This database is processed manually to retrieve the required information. Organs and pathologies are determined and each study is tagged with specific labels, e.g. ‘liver normal’, ‘liver tumor’, ‘liver cancer’, ‘spleen normal’, ‘spleen absence’, etc. Selected structures are additionally segmented. Masks are stored as gold standard.

Web service based network system is provided to permit PACS-driven retrieval of image data matching desired criteria. Image series as well as ground truth images may be retrieved for benchmark or model-development purposes. The database is evaluated.

The main method of skin cancer detection is direct examination of the skin by a trained professional. There is a shortage of dermatologists, a situation that could influence timely diagnosis and management of skin cancer. Teledermatology and teledermoscopy could overcome some of these barriers. To develop training programs we need to understand how dermatologists view digital skin images. Two dermatologists and 4 residents viewed 20 photographs and dermatoscopic images of benign and malignant lesions while eye position was recorded. They then completed an online training course and returned to repeat the cases. There were some differences in search and diagnoses although more as a function of experience than the online course. Further work is needed but we can characterize visual search in teledermatology settings.

A new web tool for distant diagnosing and learning on melanocytic skin lesions (

e-IMDLS

) was developed and tested. Currently, two separated versions of the system (Polish and English) are implemented and accessible by Internet. Here, the main features of the English version of

e-IMDLS

system are briefly discussed. Synthesis of digital images of selected skin lesions by the system is discussed; some possibilities and limitations of this algorithmic process are commented. Finally, the way of using the system by experienced dermatologists and/or family physicians is also described.

Bioelectrical activity of the female reproductive tract in different physiological and pathological states is vitally important in clinical practice. Telemetry allows for sending signals from the myometrium and other parts of the reproductive tract to computer system for further analysis. Telemetry system with incorporated decision support software presents telemedicine. Monica AN24 system lets us perform analysis of the uterine muscle contractions, fetal and maternal heart rate. Pregnant woman might constantly be monitored, even in the course of performing various tasks at home. Radiotelemetry enables wireless measurements of biological signals from freely moving conscious animals. The greatest advantage is that the experimental animals are neither stressed, nor are they bound in any way. No human presence is also necessary during recording of the data.

The early diagnosis of Alzheimer’s disease and mild cognitive impairment (MCI) may help reduce disability and enhance quality of life through early introduce of multimodal therapy. This study evaluated the utility of the telephone interview which was compared in the evaluation of cognitive function in 55 patients of geriatric hospital, with the classical methods of neuropsychological diagnosis. Data demonstrates that TICS can be used as a simple and accessible method for the observation and estimation of cognitive status on early stage of dementia. Widespread tele-diagnostics of early phases of dementia and other functional deficits of the brain, connected with its aging, stands a chance of becoming a standard in the assessment of health condition of the elderly population, and of contributing to quicker provision of medical and community care for them.

Aging society in developed countries forms new challenges for medical care. Ensuring well-being of the elderly and provide them support when required is of special concern. Nowadays, solutions in form of telecare centers and monitoring systems are able to estimate condition of the patient and provide necessary help accordingly. This paper addresses the problem of reviewing current state of the art by describing systems available commercially and presented in scientific papers as well as inference methods for condition assessment. Conclusions and problems to be taken into account while designing such systems are also pointed out.

The article deals with the accelerometer and gyroscope measurements and gravity vector components compensation. A part of work involves also design and realization of device serving for acceleration and angle rotation measurement. Within the work algorithm for gravity compensation was tested.

The paper presents a concept of an Ambient Assisted Living system for daily monitoring of the elderly. Description and testing of the prototype of a mobile data acquisition device for physical activity detection using inertial sensors is made. Testing has been performed on a mechanical test stand and a group of healthy individuals during normal walking. The purpose has been to assess the repeatability of acquired data. Obtained results are satisfactory and further development takes place.

The paper presents an advanced method of recognition of patient’s intention to move of multijoint hand prosthesis during the grasping and manipulating objects in a dexterous manner. The proposed method is based on a two-level multiclassifier system (MCS) with heterogeneous and homogeneous base classifiers dedicated to EMG and MMG biosignals and with combining mechanism using a dynamic ensemble selection scheme and probabilistic competence function. The performances of two MCSs with the proposed competence function and combining procedure were experimetally compared against three benchmark MCSs using real data concerning the recognition of six types of grasping movements. The systems developed achieved the highest classification accuracies demonstrating the potential of multiple classifier systems with multimodal biosignals for the control of bioprosthetic hand.

Within the project entitled ”The diagnostic system supporting the healing process of burn and chronic wounds” funded by The Polish National Centre of Research and Development the diagnostic system and device for recording thermal images/videos was created. The paper concerns the description of the prototype of the device registering encircling thermograms and video images.

The novelty consists in using 3D thermal imaging techniques in the analysis of circumferential burns, for which 2D thermography is insufficient. Developed instrument records thermograms, both radial and longitudinal, alongside the scanned object, which allows recording of temperature field on large body surfaces with improved measuring accuracy as compared with classic 2D thermograms.

This paper presents a preliminary study of prototype application supporting monitoring of healing process of burn and chronic wounds. Application has been designed in the client-server architecture that allows you to: adding new patients, looking for patients according their data, presentation of infrared burn wound map section. Course of patient’s healing process is represented in the form of history of patient’s medical visits which consists of: infrared images of burnt places, desciription of Computed Tomography (CT) screening i ultrasound screening, and results of microbiological and histopatological test. The presentation of a burn wound section includes: histogram presentation, selection of regions of interest by thresholding, imposition of colour masks on a thresholded section, manually selecting the region of interest by imposing a polygonal curve, slice and regions of interest descriptions. A prototype has been tested on a synthetic test images and anonymized pictures of pilot sample of test patients.

The surgery is a branch of medicine, that is integrally connected to wounds. Despite using sterile tools and compliance with aseptic rolls, some of the surgery wounds become infected. In clinical practice there is a lack of cheap, objective methods and tools for quantitative definition and estimation of the surgery wound healing progress. This paper presents preliminary results of Active Dynamic Thermography (ADT) parametric imaging of sternum surgery wounds. The study was performed in the Clinics of Cardio Surgery at the Medical University of Gdańsk. The results are presented in the form of the simplified exponential parameters approximation of examined objects’ thermal response:

dT

norm

and

t

90_10

images.

The chapter begins with a necessary introduction describing the fundamental importance of music in human life. Sounds of nature and typical music created by humans according to accepted rules (that are also nature philosophy derivatives) are considered here. Nowadays, music is used to intentional change the psychophysical state of a human being. It would be relatively easy to indicate that music stimulates activities, it is much more complicated to select such types of sound stimulation, which would be useful for recreation - music therapy is meant here. Currently, the choice is rather heuristic than algorithmic.

For a holistic analysis a snapshot of formal methods known in psychology is provided, such as Faces Pain Scale, State - Trait Anxiety Inventory (to assess anxiety), Rating Anxiety in Dementia (effective studying the influence of quiet music), Relax Rating Scale (a simple instrument to assess the relaxation degree), and techniques commonly known as biomedical measurement such as ECG , HR, BP , EEG, EEG or temperature measurement.

For a holistic analysis a snapshot of formal methods known in psychology is provided, such as Faces Pain Scale, State - Trait Anxiety Inventory (to assess anxiety), Rating Anxiety in Dementia (effective studying the influence of quiet music), Relax Rating Scale (a simple instrument to assess the relaxation degree), and techniques commonly known as biomedical measurement such as ECG , HR, BP , EEG, EEG or temperature measurement.

This article details our developed algorithm for eye tracking in low resolution video recordings, especially those with sub-VGA resolution and using lossy compression. The proposed method for eye tracking is an important step towards the successful detection of eye blink artifacts which result in false delta activity being recorded in EEG records. Once detected, we can automatically remove the erroneous delta activity during pre-processing of the EEG records and ultimately improve the precision of automated EEG analysis.

Eye movement data may be used for many various purposes. In most cases it is utilized to estimate a gaze point - that is a place where a person is looking at. Most devices registering eye movements, called eye trackers, return information about relative position of an eye, without information about a gaze point. To obtain this information, it is necessary to build a function that maps output from an eye tracker to horizontal and vertical coordinates of a gaze point. Usually eye movement is recorded when a user tracks a group of stimuli being a set of points displayed on a screen. The paper analyzes possible scenarios of such stimulus presentation and discuses an influence of usage of five different regression functions and two different head mounted eye trackers on the results.

The paper concerns issues related to assistive technologies for disabled people. An interface which emulates a computer mouse, handled using eye blinks, is presented in the paper. A computer should be equipped with a low cost webcam to use the interface. Icons related to different directions of mouse cursor movements and real mouse buttons are sequentially presented to the user. An action corresponding to currently shown icon is performed when the user keeps his eyes closed for a specified period of time.

The interface is now used by a disabled girl with SMA (Spinal Muscular Atrophy). The part responsible for an analysis of an eyes behaviour was prepared as a dynamic linked library (DLL), so it can be used for other purposes.

This article describes a four-channel amplifier for human neurophysiologic electrical activity measurement. The advantage of the device, in combination with the developed software, lies in the real-time display of various human electrical signals such as ECG, EEG and EOG. Signal samples are stored in a binary file on the hard drive for further analysis. Combination of leads is changeable depending on the measurement type and characteristics thereof. Gain of individual leads is adjustable by digital potentiometers. The various types of measurement are presented in the article in order to verify device function.

The paper presents the preliminary results of the research aiming at the development of the Diagnostic Stroke Ontology. The described machine processable knowledge representation was designed for the applications supporting stroke diagnosis and management of stroke patients. Applied methodology of ontology development was methontology with subsequent activities: specifications of requirements, domain knowledge acquisition, conceptualization and formalization of conceptual model followed by evaluation. Presented in the article structure and content of Stroke Diagnostic Ontology (DStrokeOnto ontology) include salient ontology modules, classes in modules, relations between modules, main classes definition and details of ontology metrics and expressivity. The DStrokeOnto ontology is syntactically correct, model completeness and logical consistency was verified by two experts in neurology and brain anatomy (excluding sub-module of Imaging Procedure For Stroke - in progress) as good quality interface to CT-based system of computeraided stroke diagnosis.

Headache, medically known as cephalalgia, may have a wide range of symptoms and its types may be related and mixed. Its proper diagnosis is difficult and automatic diagnosis is usually rather imprecise, therefore, the problem is still the focus of intensive research. In the paper we propose headache diagnosis method which makes the decision on the basis of questionnaire only. It distinguished among 11 headache classes, which taxonomy is provided. The paper presents results of experiments which aim at selecting the best classification algorithm including several classical machine learning methods as well as ensemble approach. Results of experiments carried on dataset collected in University of Novi Sad confirm that the automatic classification system can gain high accuracy of classification for the problem under consideration.

Physiological shortening of atrioventricular (AV) delay with increasing of heart rate is well documented in healthy human beings. The specialized algorithms were developed that control the AV delay. The goal of our study is the assessment of the impact of varying heart rate on the optimal AV delay in paced patients. The SV values were assessed by the Impedance Cardiography (IC) and Penaz Plethyzmography (PP) at the same time for each patient. The statistical analysis has showed no statistically significant differences between results obtained simultaneously by both evaluation methods. Three types of AV optimal changes following pacing rate increase were found: 1. physiological (shorter), 2. neutral (no change), 3. atypical (longer).

This paper presents decision support system for estimation of patient’s general state with particular stress laid on cardiovascular and pulmonary diseases. It works in conjunction with a standard medical monitor, which provides input signals such as temperature, blood pressure, pulseoxymetry, ECG, ICG, etc. The signals are preprocessed and analysed by a set of algorithms, the core of which is based on Bayesian networks. As an output the system should give information about detected problems, possible future threats, possible causes and suggestions for further treatment. From the hardware point of view the system is implemented in DaVinci DM3730 embedded microprocessor. Use of the presented system might be especially important in places such as Accident Emergency Departments and Admission Rooms, where small medical team has to take care of many patients in various general conditions.

Electrohysterography measures a bioelectrical activity of a uterus. The methods which were published up to date still give inaccurate labour prediction/prediction of labour. This paper presents an application of multivariate sample entropy to differentiated 4-channels electrohysterographical signals. This nonlinear measure uses joint information from a multivariated signals. The obtained results confirm that a differentiation may improve sensitivity of a multivariate sample entropy on a uterine bioelectrical activity. It enables to recognize uterine contractions in labor with the sensitivity equaled too 87% and the specificity about 85%. These results should be verified in a prospective study.

The aim of this paper is to present the selected examples of possible applications of image of correlation coefficients matrix of EEG map series in the analysis of variation of the topography of the isopotential areas in EEG maps, and thus in the assessment of stationarity, spatio-temporal variability and trends of changes of bioelectric activity of the brain. The image of correlation coefficients matrix shows similiarity of all pairs of maps in a series. The choice of segmentation threshold of characteristic areas in images of the correlation coefficients matrix of EEG map series corresponding to the sequence similarity relationships in a series of maps was based on the results of research conducted on test series. Determining of the segmentation threshold value allowed for the presentation of research results of similar sequences in the examplary series of real EEG recordings. The obtained results consistent with the visual assessment of the similarity of the topographic distributions of isopotential areas in EEG maps form the basis for further research of usefulness of the analysis of the correlation coefficients matrix in the assessment of the dynamics of EEG mapping topography.

The paper describes the robust weighted averaging method applied to averaging of auditory brainstem responses. This type of signals is characterized with extremely low signal-to-noise ratio. Suppression of noise that contaminates this type of signals can be achieved with the use of the averaging technique. The auditory evoked potentials are timealigned and then the average template is determined. The weighted averaging operation can be regarded as special case of clustering. In this work the averaging process is formulated as the problem of certain criterion function minimization. The maximum likelihood estimator of location based on the generalized Cauchy distribution is used as the measure of dissimilarity function. The proposed methods performance is experimentally evaluated and compared to the reference methods in the presence of the artificial noise and in the case of real signals. The experiments show usefulness of the proposed method for robust weighted averaging of periodic signals, for instance the evoked potentials.

In this paper we propose a reproduction method of missing parts of an analysed signal. The analysed signal must meet one essential requirement: the signal should contain repetitive parts. The reproduction process is carried out in a phase-space. The phase space is created by applying the Taken’s theory to the analysed signal. In the proposed approach parts of the signal are reconstructed from a projective sub- space. The dimension of the projection sub-space is much lower than the phase-space dimension. An artificial generated signal is used in our numerical experiments. The median of a vicinity method is used as the reference method. The obtained results show advantages of the proposed approach.

In the paper a pronunciation error detection method has been presented, wchich is based on word structural features. A lowcomplexity classifier has been proposed, that is not concentrated on a limited base of error patterns, but is flexible enough to find unspecified mispronunciations. Two classification variants using Dynamic Time Warping (DTW) algorithm has been tested on speech corpus containing recordings of 30 people.

Present development of digital registration and methods of recorded voice processing are useful in detection of most pathologies and diseases of a human vocal tract. The recognition of the voice condition requires the creation of a model which is comprised of different acoustic parameters of speech signal. In this study a vector consisting of 31 parameters for analysing the speech signal was created. The speech parameters were extracted from time, frequency and cepstral domains. Using Principal Components Analysis the number of the parameters was reduced to 17. In order to validate the detection of the pathological voice signal, a tenfold cross-validation and confusion matrix were used. The goal and novelty of this work was the analysis of applicability of the parameters selectively used to assess the pathology.

The paper presents BPD (Bronchopulmonary Dysplasia) prediction for extremely premature infants after their first week of life. SVM (Support Vector Machine) and LR (Logit Regression) are used as classifiers. Data was collected thanks to the Neonatal Intensive Care Unit of The Department of Pediatrics at Jagiellonian University Medical College and includes 109 patients with birth weight less than or equal to 1500g. Fourteen different risk factor parameters were considered and all 2

14

combinations were analyzed. Classifier based on six feature LR model provides accuracy up to 82%, while SVM one turns out to be generally much worse, providing in best case scenario 80% of accuracy. In addition, the article discusses the influence of the model parameters selection on prediction quality.

Two commercially used noncontact tonometers: the Ocular Response Analyzer (ORA) and the Corvis ST (CST) are presented. The devices measures biomechanical properties of the cornea that are essential for better understanding of the optical and the geometrical properties of the cornea. Characteristic parameters for both ORA and Corvis ST are described. One of the main ORA parameter is corneal hysteresis (CH) which is supposed to represent the viscoelastic properties of the cornea. The main advantage of Corvis ST is a high-speed Scheimpflug camera capable of taking two-dimensional images of a cross-section of the cornea during its deformation, which can possibly give additional information about the biomechanical status of the cornea.

The main aim of this work was evaluate the displacements and strains and stresses in components of bone-fixator system using Finite Element Method. The Taylor-type fixator was chosen for the analysis as a one of the most technically advanced and the biggest therapy opportunities giving external fixator. Through the possibility of full and free manipulation of bone fractures (possible displacements and rotations in three independent planes) it is used in complex fractures therapy, complicated bones deformation therapy, distraction osteogenesis and much more. The first step was preparation of Taylor-type fixator geometrical model which was developed on a basis of a real model. To carry out an analysis it was necessary to develop a tibia bone model in which the fracture crack of 1mm breadth was simulated. Next a grid for finite-element method calculations was generated for the geometrical models. Subsequently it was necessary to specify and set the edge conditions to reflect appropriately the phenomena taking place in the real system. The system was loaded with axial force in range 100-1500N. Calculations were realized for fixator made of 316L steel. On a basis of obtained result, the highest values of reduced stress were observed in the fixator frame, in elements connecting telescopic strut with holder constrained in fixator full ring. For load

F

> 1400N the yield stress of frame material was exceeding, what could cause its damage. In turn, stress in bone didn’t exceed its compression strength. The biomechanical analysis may form the basis for improving the geometry of analyzed fixator and optimising a selection of the mechanical properties of the material used to manufacture them.

Ultra high molecular weight polyethylene (UHMWPE) is used in medicine, mainly in the acetabulum and the sliding elements of endoprosthesis. Benefits, which have determined its use is primarily a very good tribological properties, toughness, durability, resistance to biological fluids and good mechanical properties. Unfortunately UHMWPE is not free from drawbacks, which mainly include the low resistance to frictional wear a low yield strength, the tendency to creep and aging. An important issue exposed in the literature, is the change of the polyethylene physical properties by ionizing radiation, which influences the degree of crystallinity, and consequently, a decrease in mechanical properties. Therefore, the aim of the study was to determine the influence of X-rays on mechanical properties of polyethylene used for acetabula of hip endoprosthesis. The originality of the paper consists in the fact that the tested material was irradiated with the true value of radiation doses to which the patients are exposed during clinical treatment after hip replacement, in order to check their safety. Test specimens were irradiated with different X-ray doses. In the course of the study the visual inspection of the polyethylene surface, density measurement (immersion test), static tensile and bending tests as well as hardness test were carried out. As the result of this study, no influence of ionizing radiation on the mechanical properties (hardness, Young’s modulus, tensile strength) of the tested material was observed.

The correct relationship between implant and tissue environment provides a properly prepared surface of a medical device. The combination of advantages of metal implants with the required biocompatibility is achieved through various methods of surface treatment such as: electrochemical polishing, chemical passivation, preparation of oxide coatings obtained with the sol-gel method. The relatively short history of use of silica layers in biomedical applications transfers into a small amount of literature relating to the electrochemical properties of these layers. Therefore, the authors proposed in the work forming a silica layer of the established technological parameters on surface of the 316L stainless steel. In order to determine the usefulness of this technology electrochemical impedance spectroscopy studies were performed. Furthermore, corrosion resistance tests by means of the potentiodynamic method were also carried out. The obtained results were the basis for optimization of technological conditions for deposition of silica layers on the 316L steel surface.

One of the ways to increase the hemocompatibility of surface of titanium and its alloys is to apply sol-gel method to form oxide films based on such elements as Ti or Si. However, the literature suggests existence of group of undefined phenomena associated with oxide layer formation on surfaces of metallic biomaterals in the presence of silicon. Therefore, the study involves development of conditions suitable for production of surface layers that have phisycal and chemical properties adequate for application in cardiovascular system. To assess the usefulness of proposed modifications, the Authors carried out electrochemical tests involving potentiodynamic and impedance measurements. The tests were performed in artificial serum in temperature T = 37±1°C in order to simulate real-life conditions. The obtained results show diverse properties of SiO

2

layer that depend on process parameters of its formation.