KEYWORDS: Electroencephalography, Heart, Brain, Chest, Statistical analysis, Linear filtering, Modulation, Electronic filtering, Sensors, Process control
To search for possible interactions between the autonomic heart control and the brain activity we have evaluated the relation between heart rate variability (HRV) and the alpha and beta EEG band power dynamics. The experiments consisted in the alteration of HRV induced by respiratory rhythm changes. Modifications in the time series of the spectral density in each band {causally related to the HRV{ were recognized in the central and occipital regions using a Granger causality approach. The number of subjects and distribution of channels in which there was a causal relation changed with the different tasks assigned to the subjects and the analyzed bands. The causal relation between HRV and beta power series was observed in at least one channel, in eight out of nine subjects for a resting condition. On the other hand, in the HRV and alpha power series analysis the change in distribution was less pronounced, and detected in a smaller number of subjects. The results suggest that the HRV may be associated with the spectral band power time series dynamics, and this relationship is altered by the respiration.
During the first trimester of pregnancy fetal health assessment is especially important. In the clinical practice, the gestational sac (GS) volume estimation is manually done using a tedious procedure which is prone to physicians' subjectivity. The method proposed in this paper consists on a semiautomatic delimitation of the GS and a segmentation of its content with minimal expert intervention. It is based on spreading active contours (SAC), following a planimetric strategy to define the GS' edges. Additionally, an optimal thresholding method was used to separate solid matter and amniotic fluid. The comparison between manual GS segmentations and those obtained with the proposed SAC method, shows Dice similarities of 90% and a mean Hausdor distance of 5.63 ± 1.94 mm, while the correlation index between SAC and the clinical reference (VOCAL) is 0.997. However, with statistical tests (t-paired) a value of p < 0.05 was obtained, which suggests a difference in the measured volume by the compared methods. The proposed method (SAC) has shown to be reliable, besides of being easy to implement.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.