This paper describes a new technique for presenting information based on given flow images. Using a multistep
first order differentiation technique, we are able to map in two dimensions, vorticity of fluid within a
region of investigation. We can then present the distribution of this property in space by means of a color
intensity map. In particular, the state of fluid rotation can be displayed using maps of vorticity flow values.
The framework that is implemented can also be used to quantify the vortices using statistical properties which
can be derived from such vorticity flow maps. To test our methodology, we have devised artificial vortical flow
fields using an analytical formulation of a single vortex. Reliability of vorticity measurement from our results
shows that the size of flow vector sampling and noise in flow field affect the generation of vorticity maps. Based
on histograms of these maps, we are able to establish an optimised configuration that computes vorticity fields
to approximate the ideal vortex statistically. The novel concept outlined in this study can be used to reduce
fluctuations of noise in a vorticity calculation based on imperfect flow information without excessive loss of its
features, and thereby improves the effectiveness of flow
Modelling of non-stationary cardiac structures is complicated by the complexity of their intrinsic and extrinsic
motion. The first known study of haemodynamics due to the beating of heart was made by Leonardo Da Vinci,
giving the idea of fluid-solid interaction by describing how vortices develop during cardiac structural interaction
with the blood. Heart morphology affects in changes of cardio dynamics during the systolic and diastolic
phrases. In a chamber of the heart, vortices are discovered to exist as the result of the unique morphological
changes of the cardiac chamber wall by using flow-imaging techniques such as phase contrast magnetic resonance
imaging. The first part of this paper attempts to quantify vortex characteristics by means of calculating
vorticity numerically and devising two dimensional vortical flow maps. The technique relies on determining
the properties of vorticity using a statistical quantification of the flow maps and comparison of these quantities
based on different scenarios. As the characteristics of our vorticity maps vary depending on the phase of a cardiac
cycle, there is a need for robust quantification method to analyse vorticity. In the second part of the paper,
the approach is then utilised for examining vortices within the human right atrium. Our study has shown that
a proper quantification of vorticity for the flow field can indicate the strength and number of vortices within a
heart chamber.
A recent development based on optical flow applied onto Fast Imaging in Steady State Free Precession (TrueFISP)
magnetic resonance imaging is able to deliver good estimation of the flow profile in the human heart chamber. The
examination of cardiac flow based on tracking of MR signals emitted by moving blood is able to give medical doctors
insight into the flow patterns within the human heart using standard MRI procedure without specifically subjecting the
patient to longer scan times using more dedicated scan protocols such as phase contrast MRI. Although MR fluid motion
estimation has its limitations in terms of accurate flow mapping, the use of a comparatively quick scan procedure and
computational post-processing gives satisfactory flow quantification and can assist in management of cardiac patients. In
this study, we present flow in the left atria of five human subjects using MR fluid motion tracking. The measured flow
shows that vortices exist within the atrium of heart. Although the scan is two-dimensional, we have produced multiple
slices of flow maps in a spatial direction to show that the vortex exist in a three-dimensional space.
This study describes an application based on the optical flow algorithm to construct a 2D velocity field plot. The
estimated velocity field is used to track the movement of blood in real time. This methodology has been applied
to medical images to quantify blood flow turbulence in the right atrium of the heart. Blood intensity fields that
are obtained from clinical MRI scan sequences can be analyzed using this method. Septal defects and other
heart diseases can be assessed for degrees of abnormality and post-surgical success can be evaluated. We have
developed this technique specifically for characterizing the turbulence generated due to such heart abnormalities.
The degree of turbulence and fluid shear stress can be determined from the measured flow field. The cardio
dynamics information that is based on flow analysis and visualization of blood offers potential for the detection
and quantification of myocardial malfunctioning.
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