Biomedical subjects

A Prentza

Publications and source records attributed to A Prentza.

8 recordsLinked to original sources

PubMed2006

Classification algorithms for microcalcifications in mammograms (Review).

Early detection is the key to improve breast cancer prognosis. The only proven effective method of breast cancer early detection is mammography. An early sign of 30-50% of breast cancer is the appearance of clusters of fine, granular microcalcifications and 60-80% of breast carcinomas reveal microcalcification clusters upon histological examination. The high correlation between the appearance of the microcalcification clusters and diseases, proves that computer aided diagnosis (CAD) systems for automated classification of microcalcification clusters will be very useful and helpful for breast cancer control. The fuzzy nature of microcalcification, the low contrast and the low ability of distinguishing them from their surroundings make automated characterization of them extremely difficult. In this study, we give an overview of the currently available literature on characterization of malignant and benign microcalcifications. We compare and evaluate some of the classification algorithms on microcalcifications in mammograms used in various CAD systems, which are separated into categories according to the method in use. Neural networks are used in applications where only a few decisions are required concerning an amount of data. The k-nearest neighbour classifier distinguishes unknown patterns based on the similarity to known samples and the decision tree approach is much simpler than neural networks and does not need extensive knowledge of the probability distribution of the features.

Algorithms↗

PubMed2005

A feasibility study of a personalized, internet-based compliance system for chronic disease management.

This paper describes a feasibility study on an Internet-based compliance system to provide personalized care for patients suffering from chronic diseases. Relevant medical trials from three different European countries provided preliminary evidence of the feasibility of the system and its efficacy in helping patients to manage their diseases at home. The study discusses further improvements not only for the C-Monitor system, but also for other Internet-based health-care services.

Chronic Disease↗

PubMed2002

Computerised intrapartum diagnosis of fetal hypoxia based on fetal heart rate monitoring and fetal pulse oximetry recordings utilising wavelet analysis and neural networks.

OBJECTIVE: To develop a computerised system that will assist the early diagnosis of fetal hypoxia and to investigate the relationship between the fetal heart rate variability and the fetal pulse oximetry recordings. DESIGN: Retrospective off-line analysis of cardiotocogram and FSpO2 recordings. SETTING: The Maternity Unit of the 2nd Department of Obstetrics and Gynaecology, Aretaieion Hospital, University of Athens. POPULATION: Sixty-one women of more than 37 weeks of gestation were monitored throughout labour. METHODS: Multiresolution wavelet analysis was applied in each 10-minute period of second stage of labour focussing on long term variability changes in different frequency ranges and statistical analysis was performed in the associated 10-minute FSpO2 recordings. Self-organising map neural network was used to categorise the different 10-minute fetal heart rate patterns and the associated 10-minute FSpO2 recordings. MAIN OUTCOME MEASURES: Umbilical artery pH of < or = 7.20 and Apgar score at 5 minutes of < or = 7 formed the inclusion criteria of the risk group. RESULTS: After using k-means clustering algorithm, the two-dimensional output layer of the self-organising map neural network was divided into three distinct clusters. All the cases that mapped in cluster 3 belonged in the risk group except one. The sensitivity of the system was 83.3% and the specificity 97.9% for the detection of risk group cases. CONCLUSIONS: A relationship between the fetal heart rate variability in different frequency ranges and the time in which FSpO2 is less than 30% was noticed. Fetal pulse oximetry seems to be an important additional source of information. Computerised analysis of the fetal heart rate monitoring and pulse oximetry recordings is a promising technique in objective intrapartum diagnosis of fetal hypoxia. Further evaluation of this technique is mandatory to evaluate its efficacy and reliability in interpreting fetal heart rate recordings.

Adult↗

PubMed2001

Medical support system for continuation of care based on XML web technology.

In this paper, the implementation of an Internet-based telematic service for medical support is presented, which was developed and operated in pilot form within the INTRANET HEALTH CLINIC project--a 2-year project supported by the European Commission under the Health Telematics Programme. The aim of the application is to offer high quality care to users of health services over inexpensive communication pathways, using Internet-based, interactive communication tools, like remote access to medical records and transmission of multimedia information. The XML technology was employed to achieve customised views on patient data, according to the access rights of different user profiles. Strict security and access control policy were implemented to ensure secure transmission of medical data through the Internet. The system was designed to collaborate with existing clinical patient record systems and to be adjustable to different medical applications. Current implementations include the fields of Oncology, Lupus Erythrematosis, Obstetrics and Chronic Obstructive Pulmonary disease. The results of the pilot operation with oncological patients in Greece were encouraging, so that the refining of the system and its expansion to a large number of patients is already in progress.

Continuity of Patient Care↗

PubMed2000

Mobile Medical Data (MOMEDA)--a Personalized Medical Information System.

MOMEDA is a two-years project supported by the European Commission (Telematics Applications Programme of DGXIII--Health Care Sector). The main objectives of the project are the development of a compact personal information terminal for hospital and home care environments that could be used by patients and a demonstrator that allows the consulting physician to access electronic patient record data from outside the hospital, using a hand held companion device connected to GSM network. Special attention is paid to a Personalized Medical Information System (PMIS) which will allow patients to access customized disease-specific information material that will enable them to fully understand in a simple and constructive form what their medical problem is, what the planned procedures are, what lifestyle they should follow during and after their hospitalization, thus becoming more qualified partners in the recovery process. Considering the fact that in most cases informed and educated patients are usually satisfied patients when the treatment is finished, patient satisfaction can be also accomplished. The design considerations for the PMIS system are presented and the implementation is discussed.

Computer Security↗

PubMed2000

Intranet health clinic: Web-based medical support services employing XML.

In this paper, the implementation of an Internet-based telematic service for medical support is presented, which operates in pilot form within the INTRANET HEALTH CLINIC project--a two-year project supported by the European Commission under the Health Telematics Programme. The aim of the application is to offer high quality care to users of health services over inexpensive communication pathways, using Internet-based, interactive communication tools, like remote access to medical records and transmission of multimedia information. The XML technology was employed to achieve customised views on patient data, according to the access rights of different users. Strict security and access control policy were implemented to ensure secure transmission of medical data through the Internet. The system is designed to collaborate with existing clinical patient record systems and to be adjustable to different medical applications. Current pilot implementations are under clinical evaluation and include oncological patients (Greece), Lupus Erythrematosis (Canada), Obstetrics (Belgium) and Chronic Obstructive Pulmonary disease (Spain).

Computer Communication Networks↗

PubMed1997

Models of brachial to finger pulse wave distortion and pressure decrement.

OBJECTIVE: To model the pulse wave distortion and pressure decrement occurring between brachial and finger arteries. Distortion reversion and decrement correction were also our aims. METHODS: Brachial artery pressure was recorded intra-arterially and finger pressure was recorded non-invasively by the Finapres technique in 53 adult human subjects. Mean pressure was subtracted from each pressure waveform and Fourier analysis applied to the pulsations. A distortion model was estimated for each subject and averaged over the group. The average inverse model was applied to the full finger pressure waveform. The pressure decrement was modelled by multiple regression on finger systolic and diastolic levels. RESULTS: Waveform distortion could be described by a general, frequency dependent model having a resonance at 7.3 Hz. The general inverse model has an anti-resonance at this frequency. It converts finger to brachial pulsations thereby reducing average waveform distortion from 9.7 (s.d. 3.2) mmHg per sample for the finger pulse to 3.7 (1.7) mmHg for the converted pulse. Systolic and diastolic level differences between finger and brachial arterial pressures changed from -4 (15) and -8 (11) to +8 (14) and +8 (12) mmHg, respectively, after inverse modelling, with pulse pressures correct on average. The pressure decrement model reduced both the mean and the standard deviation of systolic and diastolic level differences to 0 (13) and 0 (8) mmHg. Diastolic differences were thus reduced most. CONCLUSION: Brachial to finger pulse wave distortion due to wave reflection in arteries is almost identical in all subjects and can be modelled by a single resonance. The pressure decrement due to flow in arteries is greatest for high pulse pressures superimposed on low means.

Adult↗

PubMed1995

Catheter-manometer system damped blood pressures detected by neural nets.

Degraded catheter-manometer systems cause distortion of blood pressure waveforms, often leading to erroneously resonant or damped waveforms, requiring waveforms quality control. We have tried multilayer perceptron back-propagation trained neural nets of varying architecture to detect damping on sets of normal and artificially damped brachial arterial pressure waves. A second-order digital simulation of a catheter-manometer system is used to cause waveform distortion. Each beat in the waveforms is represented by an 11 parameter input vector. From a group of normotensive or (borderline) hypertensive subjects, pressure waves are used to statistically test and train the neural nets. For each patient and category 5-10 waves are available. The best neural nets correctly classify about 75-85% of the individual beats as either adequate or damped. Using a single majority vote classification per subject per damped or adequate situation, the best neural nets correctly classify at least 16 of the 18 situations in nine test subjects (binomial P = 0.001). More importantly, these neural nets can always detect damping before clinically relevant parameters such as systolic pressure and computed stroke volume are reduced by more than 2%. Neural nets seem remarkably well adapted to solving such subtle problems as detecting a slight damping of arterial pressure waves before it affects waveforms to a clinically relevant degree.

Adult↗