Master's Thesis - Studierstube Augmented Reality Project - Graz ...

Chapter 1
Introduction
Assessment of blood flow properties is crucial in the understanding and diagnosis of
many cardiovascular diseases. The Magnetic Resonance (MR) through-plane phase
contrast method provides a lot of useful information from flow through cross sections
or velocities in preferred directions. However, its usefulness in situations involving
complex fluid dynamics - as for example in the cardiac chambers - is limited, because
the main directions of flow are neither known nor constant in time. Conceptually the
easiest way to acquire three-dimensional blood flow data is to measure both throughplane
and in-plane velocity components via phase contrast sequences. Velocity vectors
are determined on each imaging plane: In the case of the combined through-plane and
in-plane measurement for each pixel.
This measurement method is already available [Reiter2006; ClincalMRI2006], but
the vast amount of data and its complex composition requires the development of tools
and methods for a clear representation aimed at physicians who may evaluate possible
vascular diseases or understand the human cardiovascular system in a better way. Highperformance
real time GPU accelerated visualization techniques help to investigate the
resulting four-dimensional datasets in this work. These methods are also applicable to
other kinds of flow data.
The problem we are dealing with is that radiologists and physicians can form mental
images of a certain structure from human anatomical images slices, but flow information
given in additional images is not perceptible in a similar way. The main problem with
flow sensitive sequences is that three dimensional flow data requires three additional
images for each measured slice image and that they have to be investigated in addition
to basic morphological data. For physicians this is not feasible. Flow is also changing
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