Hippocampal vascularization patterns: A high-resolution 7 Tesla time-of-flight magnetic resonance angiography study

Considerable evidence suggests a close relationship between vascular and degenerative pathology in the human hippocampus. Due to the intrinsic fragility of its vascular network, the hippocampus appears less able to cope with hypoperfusion and anoxia than other cortical areas. Although hippocampal blood supply is generally provided by the collateral branches of the posterior cerebral artery (PCA) and the anterior choroidal artery (AChA), different vascularization patterns have been detected postmortem. To date, a methodology that enables the classification of individual hippocampal vascularization patterns in vivo has not been established. In this study, using high-resolution 7 Tesla time-of-flight angiography data (0.3 mm isotropic resolution) in young adults, we classified individual variability in hippocampal vascularization patterns involved in medial temporal lobe blood supply in vivo. A strong concordance between our classification and previous autopsy findings was found, along with interesting anatomical observations, such as the variable contribution of the AChA to hippocampal supply, the relationships between hippocampal and PCA patterns, and the different distribution patterns of the right and left hemispheres. The approach presented here for determining hippocampal vascularization patterns in vivo may provide new insights into not only the vulnerability of the hippocampus to vascular and neurodegenerative diseases but also hippocampal vascular plasticity after exercise training

Filtering the magnetohydrodynamic effect from 12-lead ECG signals using Independent Component Analysis

When recording an electrocardiogram (ECG) under the presence of the static magnetic feld of a magnetic resonance (MR) scanner, the ECG signal is disturbing by the magnetohydrodynamic (MHD) effect. Due to the MHD effect, the diagnostic information contained in the ECG signal is not accessible. This article copes with this problem by applying different Independent Component Analysis (ICA) algorithms to ECG signals corrupted by a simulated and real MHD effect. The applied ICA methods lead to significant errors in the resulting, filtered ECGs. Especially for the ECG signals with real MHD effect, a separation of the ECG and MHD components was not possible. © 2012 CCAL