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Visualizing Cardiac Blood Flow using Lagrangian Coherent Structures

by Johannes Ulén

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Abstract

The dynamics of cardiac blood flow is highly complex and not yet fully understood. Using three-dimensional, three-component, time-resolved phase contrast MRI (4D PC-MRI), new understanding of flow dynamics can be obtained. However, the three-dimensional time-resolved flow is too complex to visualize directly. Therefore a simplified view is needed.

In this thesis, Lagrangian Coherent Structures (LCS) are used to visualize blood flow. The idea behind LCS is to look at advection of particles in a time frame and mark particles which in some spatial direction have separated from their neighboring particles. The markings build up surfaces which divide the flow into regions with different flow dynamics. This division can be made with respect to the past or the future advection of blood particles.

A robust and automatic algorithm for extracting LCS is developed and tested. The algorithm is able to find and extract LCS in complex blood flow, giving new insight into the dynamics of blood flow in the human heart. LCS have previously not been used to visualize 4D PC-MRI measured flow.

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Last updated: 1970-01-01

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