IEEE journal of biomedical and health informatics
-
IEEE J Biomed Health Inform · May 2014
A novel MRI tracer-based method for measuring water diffusion in the extracellular space of the rat brain.
We proposed a novel MRI tracer-based method for the determination of water diffusion in the brain extracellular space (ECS). The measuring system was validated in 32 Sprague Dawley rats. The rats were randomly divided into four groups with different injection sites: 1) caudate nucleus (Cn.); 2) thalamus (T.); 3) cortex (Cor.); and 4) substantia nigra (Sn.). ⋯ No statistical difference was demonstrated among D∗(Cn), D∗(T.), and D∗(Cor). with an average D∗ values of (3.28 ± 0.88) × 10(-4) mm(2)·s(-1)( F = 0.18, P > 0.05). By using the tracer-based MRI method, the local diffusion parameters of the brain ECS can be quantitatively measured. The different distribution territories and clearance rates of the tracer in four brain areas indicated that the brain ECS is a physiologically partitioned system.
-
IEEE J Biomed Health Inform · May 2014
Detection of respiratory arousals using photoplethysmography (PPG) signal in sleep apnea patients.
Respiratory events during sleep induce cortical arousals and manifest changes in autonomic markers in sleep disorder breathing (SDB). Finger photoplethysmography (PPG) has been shown to be a reliable method of determining sympathetic activation. We hypothesize that changes in PPG signals are sufficient to predict the occurrence of respiratory-event-related cortical arousal. ⋯ The results showed an accuracy of 84.68%, 85.15%, 86.93%, and 50.79% with a false rate of 21.80%, 55.41%, 64.78%, and 50.79% at PC(thresh) = 25% or PPI, PWA, Area , and PWA + Area features, respectively. This indicates that combining PWA and Area features reduced the false positive rate without much affecting the sensitivity of the arousal detection system. In conclusion, the PPG-based respiratory arousal detection model is a simple and promising alternative to the conventional electroencephalogram (EEG)-based respiratory arousal detection system.