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Papers by Jaakko Malmivuo

Research paper thumbnail of Study on the spatial resolution of EEG - effect of electrode density and measurement noise

The 26th Annual International Conference of the IEEE Engineering in Medicine and Biology Society

Research paper thumbnail of A multivariate ST/HR-analysis of the exercise ECG as a diagnostic method of the coronary artery disease

Research paper thumbnail of Optimization of ECG-leads with high regional aimed sensitivity for the detection of ischemic injury currents

Research paper thumbnail of Biomedical Engineering as a Career Resource: Part 1. Employment Situation after Graduation

Research paper thumbnail of Correction To (quote)Sensitivity Distributions Of EEG And MEG Measurements(quote)

Research paper thumbnail of ECG lead selection and reconstruction: application of model-based study to actual measurement datasets

Proceedings of the Second Joint 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society] [Engineering in Medicine and Biology

Research paper thumbnail of Computer-based data acquisition and analysis system for cardiac electrophysiological signals

Computers in Cardiology 1994

This study describes the main features of a microcomputer-based data acquisition and analysis sys... more This study describes the main features of a microcomputer-based data acquisition and analysis system of cardiac electrophysiological signals. The requirement set to the acquisition was to minimize the volume of stored data during the study. This was fulfilled by recording selectively only short, clinically relevant samples of the signal with several methods comprised from automatic recording triggered by the programmable

Research paper thumbnail of Estimation of ECG signal of closely separated bipolar electrodes using thorax models

The 26th Annual International Conference of the IEEE Engineering in Medicine and Biology Society

Research paper thumbnail of Effect of the skull on scalp potentials

Proceedings of the 2nd International Conference on Bioelectromagnetism (Cat. No.98TH8269)

The skull has low conductivity, which influences especially electroencephalographic (EEG) signals... more The skull has low conductivity, which influences especially electroencephalographic (EEG) signals recorded on the scalp, but also the magneto-encephalogram (MEG). Thus the information obtained from these signals can be prominently enhanced, if the effects of the skull can be taken into account. We have used both theoretical and experimental approaches to study these effects on EEG. Our experimental results suggest

Research paper thumbnail of The influence of electromagnetic interference and ionizing radiation on cardiac pacemakers

Strahlentherapie und Onkologie : Organ der Deutschen Röntgengesellschaft ... [et al], 1990

Adverse effects of the ionizing and non-ionizing electromagnetic fields on five pacemaker models ... more Adverse effects of the ionizing and non-ionizing electromagnetic fields on five pacemaker models have been tested. The study consisted of three parts: 1. measurement of magnetic fields in a radiotherapy room (microtron MM14), 2. the application of non-ionizing electromagnetic fields on pacemakers in a test laboratory (1...1000 microT, 10...10000 Hz), and 3. the application of ionizing radiation of different types of radiotherapy devices on the pacemakers. The magnetic field strength in the microtron treatment room was found to be under 7.5 microT, which is one order of magnitude lower than the tolerance level obtained for the pacemakers in the test laboratory. All the tested pacemakers tolerated the ionizing radiation dose levels (less than 60 Gy) which are used in the radiotherapy.

Research paper thumbnail of Software suite for finite difference method models

Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings, 2006

Research paper thumbnail of Measurement of noise and impedance of dry and wet textile electrodes, and textile electrodes with hydrogel

Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings, 2006

Research paper thumbnail of Analysing specificity of a bipolar EEG measurement

Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings, 2006

Research paper thumbnail of A Java-based multiplatform high performance 2D and 3D visualization engine for medical image data sets

Research paper thumbnail of Derivation of multichannel 12-lead ICG from independent data

Research paper thumbnail of Synthesized ECG Leads in Detection of Coronary Artery Disease

Research paper thumbnail of Computer modeling and lead field theory in the analysis and development of impedance cardiography

Research paper thumbnail of Segmentation of the pig head

Research paper thumbnail of The effect of lead selection on traditional and heart rate–adjusted ST segment analysis in the detection of coronary artery disease during exercise testing

American Heart Journal, 1997

Several methods of heart rate-adjusted ST segment (ST/HR) analysis have been suggested to improve... more Several methods of heart rate-adjusted ST segment (ST/HR) analysis have been suggested to improve the diagnostic accuracy of exercise electrocardiography in the identification of coronary artery disease compared with traditional ST segment analysis. However, no comprehensive comparison of these methods on a lead-by-lead basis in all 12 electrocardographic leads has been reported. This article compares the diagnostic performance of ST/HR hysteresis, ST/HR index, ST segment depression 3 minutes after recovery from exercise, and ST segment depression at peak exercise in a study population of 128 patients with angiographically proved coronary artery disease and 189 patients with a low likelihood of the disease. The methods were determined in each lead of the Mason-Likar modification of the standard 12-lead exercise electrocardiogram for each patient. The ST/HR hysteresis, ST/HR index, ST segment depression 3 minutes after recovery from exercise, and ST segment depression at peak exercise achieved more than 85% area under the receiver-operating characteristic curve in nine, none, three, and one of the 12 standard leads, respectively. The diagnostic performance of ST/HR hysteresis was significantly superior in each lead, with the exception of leads a VL and V 1. Examination of individual leads in each study method revealed the high diagnostic performance of leads I and-aVR, indicating that the importance of these leads has been undervalued. In conclusion, the results indicate that when traditional ST segment analysis is used for the detection of coronary artery disease, more attention should be paid to the leads chosen for analysis, and lead-specific cut points should be applied. On the other hand, ST/HR hysteresis, which integrates the ST/HR depression of the exercise and recovery phases, seems to be relatively insensitive to the lead selection and significantly increases the diagnostic performance of exercise electrocardiography in the detection of coronary artery disease. (Am HeartJ 1997;134:488-94.) Traditional interpretation of exercise electrocardiography for the detection of coronary artery disease is based on a positive criterion of 0.10 mV ST segment depression at the end of exercise, irrespective of which electrocardiographic lead is observed. 1,2 This type of fixed cutpoint procedure does not account for the differences in the measurement sensitivity distribution between the leads. These differences were clinically observed in 1976 by Froelicher et ai., 3 who suggested that different cut points should be applied for the different Ieads. Several methods have been suggested to improve the

Research paper thumbnail of Simultaneous Measurement Of The Magnetic Heart Vector Components With The Uni Positional Lead System

Biomagnetism, 1981

ABSTRACT

Research paper thumbnail of Study on the spatial resolution of EEG - effect of electrode density and measurement noise

The 26th Annual International Conference of the IEEE Engineering in Medicine and Biology Society

Research paper thumbnail of A multivariate ST/HR-analysis of the exercise ECG as a diagnostic method of the coronary artery disease

Research paper thumbnail of Optimization of ECG-leads with high regional aimed sensitivity for the detection of ischemic injury currents

Research paper thumbnail of Biomedical Engineering as a Career Resource: Part 1. Employment Situation after Graduation

Research paper thumbnail of Correction To (quote)Sensitivity Distributions Of EEG And MEG Measurements(quote)

Research paper thumbnail of ECG lead selection and reconstruction: application of model-based study to actual measurement datasets

Proceedings of the Second Joint 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society] [Engineering in Medicine and Biology

Research paper thumbnail of Computer-based data acquisition and analysis system for cardiac electrophysiological signals

Computers in Cardiology 1994

This study describes the main features of a microcomputer-based data acquisition and analysis sys... more This study describes the main features of a microcomputer-based data acquisition and analysis system of cardiac electrophysiological signals. The requirement set to the acquisition was to minimize the volume of stored data during the study. This was fulfilled by recording selectively only short, clinically relevant samples of the signal with several methods comprised from automatic recording triggered by the programmable

Research paper thumbnail of Estimation of ECG signal of closely separated bipolar electrodes using thorax models

The 26th Annual International Conference of the IEEE Engineering in Medicine and Biology Society

Research paper thumbnail of Effect of the skull on scalp potentials

Proceedings of the 2nd International Conference on Bioelectromagnetism (Cat. No.98TH8269)

The skull has low conductivity, which influences especially electroencephalographic (EEG) signals... more The skull has low conductivity, which influences especially electroencephalographic (EEG) signals recorded on the scalp, but also the magneto-encephalogram (MEG). Thus the information obtained from these signals can be prominently enhanced, if the effects of the skull can be taken into account. We have used both theoretical and experimental approaches to study these effects on EEG. Our experimental results suggest

Research paper thumbnail of The influence of electromagnetic interference and ionizing radiation on cardiac pacemakers

Strahlentherapie und Onkologie : Organ der Deutschen Röntgengesellschaft ... [et al], 1990

Adverse effects of the ionizing and non-ionizing electromagnetic fields on five pacemaker models ... more Adverse effects of the ionizing and non-ionizing electromagnetic fields on five pacemaker models have been tested. The study consisted of three parts: 1. measurement of magnetic fields in a radiotherapy room (microtron MM14), 2. the application of non-ionizing electromagnetic fields on pacemakers in a test laboratory (1...1000 microT, 10...10000 Hz), and 3. the application of ionizing radiation of different types of radiotherapy devices on the pacemakers. The magnetic field strength in the microtron treatment room was found to be under 7.5 microT, which is one order of magnitude lower than the tolerance level obtained for the pacemakers in the test laboratory. All the tested pacemakers tolerated the ionizing radiation dose levels (less than 60 Gy) which are used in the radiotherapy.

Research paper thumbnail of Software suite for finite difference method models

Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings, 2006

Research paper thumbnail of Measurement of noise and impedance of dry and wet textile electrodes, and textile electrodes with hydrogel

Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings, 2006

Research paper thumbnail of Analysing specificity of a bipolar EEG measurement

Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings, 2006

Research paper thumbnail of A Java-based multiplatform high performance 2D and 3D visualization engine for medical image data sets

Research paper thumbnail of Derivation of multichannel 12-lead ICG from independent data

Research paper thumbnail of Synthesized ECG Leads in Detection of Coronary Artery Disease

Research paper thumbnail of Computer modeling and lead field theory in the analysis and development of impedance cardiography

Research paper thumbnail of Segmentation of the pig head

Research paper thumbnail of The effect of lead selection on traditional and heart rate–adjusted ST segment analysis in the detection of coronary artery disease during exercise testing

American Heart Journal, 1997

Several methods of heart rate-adjusted ST segment (ST/HR) analysis have been suggested to improve... more Several methods of heart rate-adjusted ST segment (ST/HR) analysis have been suggested to improve the diagnostic accuracy of exercise electrocardiography in the identification of coronary artery disease compared with traditional ST segment analysis. However, no comprehensive comparison of these methods on a lead-by-lead basis in all 12 electrocardographic leads has been reported. This article compares the diagnostic performance of ST/HR hysteresis, ST/HR index, ST segment depression 3 minutes after recovery from exercise, and ST segment depression at peak exercise in a study population of 128 patients with angiographically proved coronary artery disease and 189 patients with a low likelihood of the disease. The methods were determined in each lead of the Mason-Likar modification of the standard 12-lead exercise electrocardiogram for each patient. The ST/HR hysteresis, ST/HR index, ST segment depression 3 minutes after recovery from exercise, and ST segment depression at peak exercise achieved more than 85% area under the receiver-operating characteristic curve in nine, none, three, and one of the 12 standard leads, respectively. The diagnostic performance of ST/HR hysteresis was significantly superior in each lead, with the exception of leads a VL and V 1. Examination of individual leads in each study method revealed the high diagnostic performance of leads I and-aVR, indicating that the importance of these leads has been undervalued. In conclusion, the results indicate that when traditional ST segment analysis is used for the detection of coronary artery disease, more attention should be paid to the leads chosen for analysis, and lead-specific cut points should be applied. On the other hand, ST/HR hysteresis, which integrates the ST/HR depression of the exercise and recovery phases, seems to be relatively insensitive to the lead selection and significantly increases the diagnostic performance of exercise electrocardiography in the detection of coronary artery disease. (Am HeartJ 1997;134:488-94.) Traditional interpretation of exercise electrocardiography for the detection of coronary artery disease is based on a positive criterion of 0.10 mV ST segment depression at the end of exercise, irrespective of which electrocardiographic lead is observed. 1,2 This type of fixed cutpoint procedure does not account for the differences in the measurement sensitivity distribution between the leads. These differences were clinically observed in 1976 by Froelicher et ai., 3 who suggested that different cut points should be applied for the different Ieads. Several methods have been suggested to improve the

Research paper thumbnail of Simultaneous Measurement Of The Magnetic Heart Vector Components With The Uni Positional Lead System

Biomagnetism, 1981

ABSTRACT