Venous dysfunction and neurodegenerative diseases

Quantitative measurement of geometrical and physiological properties of blood vessels in the retina may indicate early stages of brain and systemic diseases in an efficient and cost-effective way. Retinal vasculature is brain vasculature, and can be imaged easily at high resolution with optical fundus or OCT cameras. Breakdown of the blood-brain barrier, as in diabetes, leads to marked vascular changes, which can be signaled early. This is e.g. exploited in large screening programs for diabetes worldwide. We will discuss how typical quantitative imaging biomarkers are measured automatically, as curvature and tortuosity, width, arteriovenous ratio, bifurcation analysis, micro-bleeds, aneurysms and stenosis, angiogenesis, fractal dimension etc. For the enhancement, tracking and segmentation of the tiny vessels we exploit highly robust methods learned from modern insight in brain mechanisms of visual perception. Optical imaging techniques have revealed multi-scale and multiorientation columns in the visual cortex, which we model mathematically. The micro-vascular analysis can be done in 2D (retina) and 3D (brain, heart). Computer algorithms also enable quantitative analysis and smart interactive 3D visualization of functional imaging, such as 4D blood flow. Flow in larger vessels is still poorly understood. Modern graphics cards (‘game cards’) enable cheap and massively parallel renderings. We give examples of modern visualization techniques, inspired by brain connectivity visualization, of 3D/4D flow patterns in brain aneurysms, and aortic arch flow turbulence as an indicator for valve functioning. The message of the presentation is that quantitative analysis of micro-vasculature, and interactive 4D visualization of complex flow parameters in larger vessels is now clinically feasible and accessible. Venous dysfunction and neurodegenerative diseases Chih-Ping Chung MD PhD Taipei Veterans General Hospital, National Yang Ming University, Taipei, Taiwan Several neurodegenerative diseases such as Alzheimer’s disease (AD), Parkinson’s disease, normal pressure hydrocephalus, etc. have been reported associated with cerebral or/and extracranial venous abnormalities. The present lecture will focus on the current evidences linking venous abnormalities with AD and cerebral small vessel disease in the elderly, e.g. age-related white matter changes. Meanwhile, the relationship between jugular venous reflux (JVR) and multiple neuropsychological performances in patients of AD, results of our latest study, will be presented. At last, a discussion about the postulated mechanisms how venous drainage impairment lead to dysfunctions in AD will be provided. Blood storage within the intracranial space and its impact on cerebrospinal fluid dynamics Clive B Beggs , Simon J Shepherd , Pietro Cecconi 2 and Maria Marcella Lagana 2 1. Medical Biophysics Laboratory, University of Bradford, Bradford, BD7 1DP, UK 2. Fondazione Don Carlo Gnocchi ONLUS, IRCCS S. Maria Nascente. Milan, Italy Background: The volumetric changes that occur throughout the cardiac cycle (CC) in the various intracranial vascular compartments are poorly understood. Although blood entering/leaving the cranium is pulsatile, flow in the cerebral vascular bed is non-pulsatile [1], implying the transient storage of blood. Objective: To characterise the temporal changes in fluid volume that occur within the cranium throughout the CC. Methods: Neck MRI data were acquired from 14 healthy adults (age <35), using a 1.5 Tesla scanner. Arterial, venous and cerebrospinal fluid (CSF) flow rate data acquired at the C2/C3 level were standardized to 32 points over the CC. The relative changes in the intracranial arterial, venous and CSF volumes were calculated by: (i) integrating the respective flow rate signals to compute the instantaneous volumetric changes (ivc); (ii) mean centering the respective ivc signals; and (iii) cumulating the mean centered ivc signals to yield the fluid volumetric changes in the cranium throughout the CC. Results: The aggregated flow rate signals for all subjects are shown in Figure 1, while Figure 2 shows the relative changes in the intracranial arterial, venous and CSF volumes. A strong inverse relationship exists between the arterial and venous volumetric signals (r = -0.844, p<0.001). As the intracranial arterial blood volume decreases to a minimum during diastole, so blood is stored in the intracranial venous compartments. This coincides with the period when the intracranial CSF volume increases. Only when the intracranial CSF volume peaks and starts to decrease, is the venous blood stored in the cranium allowed to discharge. Conclusions: The behavior of the venous pulse is controlled by volumetric changes within the cranium in a process that is mediated by the CSF. This finding supports the hypothesis that CSF interacts with the cortical bridging veins to facilitate the storage of venous blood during diastole [2,3]. Figure 1. Aggregated fluid flow rates. Figure 2. Relative intracranial fluid volumes. References: [1] Bateman GA. Neuroradiology 2002, 44:740–748; [2] Luce JM, et al. J Appl Physiol 1982, 53:1496–1503; [3] Vignes JR, et al. J Neurosurg 2007, 107:1205–1210. Advances in Treatment Strategies of Extracranial Venous Disease Hector Ferral, MD Senior Clinical Educator NorthShore University HealthSystem Evanston, IL.