Search

In pulmonary angiography, the heartbeat creates artifacts that hinder extraction of blood vessel images in digital subtraction angiography. Remasking according to the cardiac phase of the angiogram may be effective but has yet to be automated. Here, automatic remasking was developed and assessed according to the cardiac phase from electrocardiographic information collected simultaneously with imaging. Manual remasking, fixed remasking, and our proposed automatic remasking were applied to 14 pulmonary angiography series from five participants with either chronic thromboembolic pulmonary hypertension or pulmonary arteriovenous malformation. The processing time and extent of artifacts from the heartbeat were compared. In addition, the peak signal-to-noise ratio (PSNR) was measured from differential images between mask image groups before the injection of the contrast medium to investigate optimal mask images. The mean time required for automatic remasking was 4.7 s/series, a significant reduction in processing time compared with the mean of 266 s/series for conventional manual processing. A visual comparison of the different approaches showed virtually no misregistration artifacts from the heartbeat in manual or automatic remasking according to cardiac phase. The results from measuring the PSNR for differential images between mask image groups also showed that smaller cardiac phase difference and time difference between two images ensure higher PSNR (p < 0.01). Automatic remasking according to the cardiac phase was fast and easy to implement and reduced misregistration artifacts from heartbeat. [ABSTRACT FROM AUTHOR]

Healthy aging is associated with structural and functional changes in the brain even in individuals who are free of neurodegenerative diseases. Using resting state functional magnetic resonance imaging data from a carefully selected cohort of participants, we examined cross sectional changes in the functional organization of several large-scale brain networks over the adult lifespan and its potential association with general cognitive performance. Converging results from multiple analyses at the voxel, node, and network levels showed widespread reorganization of functional brain networks with increasing age. Specifically, the primary processing (visual and sensorimotor) and visuospatial (dorsal attention) networks showed diminished network integrity, while the so-called core neurocognitive (executive control, salience, and default mode) and basal ganglia networks exhibited relatively preserved between-network connections. The visuospatial and precuneus networks also showed significantly more widespread increased connectivity with other networks. Graph analysis suggested that this reorganization progressed towards a more integrated network topology. General cognitive performance, assessed by Addenbrooke's Cognitive Examination-Revised total score, was positively correlated with between-network connectivity among the core neurocognitive and basal ganglia networks and the integrity of the primary processing and visuospatial networks. Mediation analyses further indicated that the observed association between aging and relative decline in cognitive performance could be mediated by changes in relevant functional connectivity measures. Overall, these findings provided further evidence supporting widespread age-related brain network reorganization and its potential association with general cognitive performance during healthy aging. [ABSTRACT FROM AUTHOR]