Verena Knobloch

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An approach to efficiently measure three-dimensional velocity vector fields and turbulent kinetic energy of blood flow is presented. Multipoint phase-contrast imaging is used in combination with Bayesian analysis to map both mean and fluctuating velocities over a large dynamic range and for practically relevant signal-to-noise ratios. It is demonstrated(More)
While there is growing experimental evidence that cerebrospinal fluid (CSF) flow induced by the beating of ependymal cilia is an important factor for neuronal guidance, the respective contribution of vascular pulsation-driven macroscale oscillatory CSF flow remains unclear. This work uses computational fluid dynamics to elucidate the interplay between(More)
Wnt/β-catenin signaling induced by the Norrin/Frizzled-4 pathway has been shown to improve capillary repair following oxygen induced retinopathy (OIR) in the mouse, a model for retinopathy of prematurity. Here we investigated if treatment with the monovalent cation lithium that has been shown to augment Wnt/β-catenin signaling in vitro and in vivo has(More)
The objective of this work is to quantify age-related differences in the characteristics and coupling of cerebral arterial inflow and cerebrospinal fluid (CSF) dynamics. To this end, 3T phase-contrast magnetic resonance imaging blood and CSF flow data of eleven young (24 ± 3 years) and eleven elderly subjects (70 ± 5 years) with a comparable sex-ratio were(More)
Time-resolved three-dimensional flow measurements are limited by long acquisition times. Among the various acceleration techniques available, k-t methods have shown potential as they permit significant scan time reduction even with a single receive coil by exploiting spatiotemporal correlations. In this work, an extension of k-t principal component analysis(More)
PURPOSE To measure arterial, venous, and cerebrospinal fluid (CSF) velocities simultaneously by using Bayesian multipoint velocity-encoded magnetic resonance (MR) imaging and to compare interacquisition reproducibility relative to that of standard phase-contrast MR imaging for sequential measurements of arterial, venous, and CSF velocities. MATERIALS AND(More)
PURPOSE To validate Bayesian multipoint MR velocity encoding against particle tracking velocimetry for measuring velocity vector fields and fluctuating velocities in a realistic aortic model. METHODS An elastic cast of a human aortic arch equipped with an 80 or 64% stenotic section was driven by a pulsatile pump. Peak velocities and peak turbulent kinetic(More)
Background Three-dimensional Phase Contrast (PC) MRI has emerged as a promising non-invasive acquisition technique for assessing velocity vector fields of blood flow [1]. To address the limited sensitivity when velocities are much lower than the encoding velocity venc, three-point acquisition methods with a high venc and a low venc acquisition to unwrap the(More)
Background Diseased or artificial heart valves possibly lead to turbulent flow and regurgitation, both increasing the workload of the heart. Current measures for valve assessment, i.e. effective orifice area, only indirectly and partially correlate with the energy loss due to the valve [1]. Phase-Contrast MRI makes it possible to directly quantify these(More)
PURPOSE During inhalation anaesthesia, contaminations of the working environment be anaesthetic volatiles and nitrous oxide occur. The amount of leaking gases is influenced by leakages of the anaesthetic ventilator, by fresh-gas flows and by the effectivity of the scavenging system. Since 1st January 1996 new ventilators have to be equipped with scavenging(More)