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Noninvasive cardiac flow assessment using high speed magnetic resonance fluid motion tracking.

Wong KK, Kelso RM, Worthley SG, Sanders P, Mazumdar J, Abbott D - PLoS ONE (2009)

Bottom Line: Cardiovascular diseases can be diagnosed by assessing abnormal flow behavior in the heart.We introduce, for the first time, a magnetic resonance imaging-based diagnostic that produces sectional flow maps of cardiac chambers, and presents cardiac analysis based on the flow information.Application of intensity flow tracking based on their non-uniform signal concentrations provides a flow field map of the blood motion.

View Article: PubMed Central - PubMed

Affiliation: Centre for Biomedical Engineering and School of Electrical & Electronic Engineering, University of Adelaide, Adelaide, South Australia. kelvin.wong@adelaide.edu.au

ABSTRACT
Cardiovascular diseases can be diagnosed by assessing abnormal flow behavior in the heart. We introduce, for the first time, a magnetic resonance imaging-based diagnostic that produces sectional flow maps of cardiac chambers, and presents cardiac analysis based on the flow information. Using steady-state free precession magnetic resonance images of blood, we demonstrate intensity contrast between asynchronous and synchronous proton spins. Turbulent blood flow in cardiac chambers contains asynchronous blood proton spins whose concentration affects the signal intensities that are registered onto the magnetic resonance images. Application of intensity flow tracking based on their non-uniform signal concentrations provides a flow field map of the blood motion. We verify this theory in a patient with an atrial septal defect whose chamber blood flow vortices vary in speed of rotation before and after septal occlusion. Based on the measurement of cardiac flow vorticity in our implementation, we establish a relationship between atrial vorticity and septal defect. The developed system has the potential to be used as a prognostic and investigative tool for assessment of cardiac abnormalities, and can be exploited in parallel to examining myocardial defects using steady-state free precession magnetic resonance images of the heart.

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Related in: MedlinePlus

Histograms of vorticity maps for right atrial flow pre- and post-ASO.The histogram represents the distribution of vorticity values in a map. Statistical parameters used include means ω1, ω2 and standard deviations σ1, σ2 obtained from the histograms of the vorticity maps, with the subscripts 1 and 2 representing pre- and post-ASO conditions respectively. The mean is a gauge of the average angular velocity throughout the flow, and the standard deviation measures the variability of vorticity measures.
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pone-0005688-g005: Histograms of vorticity maps for right atrial flow pre- and post-ASO.The histogram represents the distribution of vorticity values in a map. Statistical parameters used include means ω1, ω2 and standard deviations σ1, σ2 obtained from the histograms of the vorticity maps, with the subscripts 1 and 2 representing pre- and post-ASO conditions respectively. The mean is a gauge of the average angular velocity throughout the flow, and the standard deviation measures the variability of vorticity measures.

Mentions: We show the mapping of vorticity component normal to the measurement planes, i.e. in the principal direction of the most significant planar flow rotation (Figs. 4 and 5). From these results, we observe that the septal occlusion produces two significant effects. The first one is that it leads to an increase in strength of a single dominant counter-clockwise vortex within the cardiac chamber. Secondly, it reduces the concentration of clockwise vortical regions at the same time. For the post-occlusion condition, a strong negative vorticity region exists adjacent to the chamber wall that has less curvature relative to the septum that is associated with flow of positive vorticity. This is due to the quick motion of blood parallel to the endocardium of a relatively motionless and flat chamber wall. Consistent with this effect, there is a broader distribution of absolute vorticity in the right atrium for the same patient and at the same cardiac phase after septal occlusion. This deduction can be supported using statistical properties of the vorticity distributions. We note the atrial enlargement pre-occlusion, which may in part explain the reduction on the strength of the vorticity concentrations before occlusion. Another possible cause of the differences between the pre-and post-occlusion cases is the presence of left-to-right shunting of blood that disrupts the normal dominant vortex to introduce vortices of a smaller scale (Movie S1).


Noninvasive cardiac flow assessment using high speed magnetic resonance fluid motion tracking.

Wong KK, Kelso RM, Worthley SG, Sanders P, Mazumdar J, Abbott D - PLoS ONE (2009)

Histograms of vorticity maps for right atrial flow pre- and post-ASO.The histogram represents the distribution of vorticity values in a map. Statistical parameters used include means ω1, ω2 and standard deviations σ1, σ2 obtained from the histograms of the vorticity maps, with the subscripts 1 and 2 representing pre- and post-ASO conditions respectively. The mean is a gauge of the average angular velocity throughout the flow, and the standard deviation measures the variability of vorticity measures.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2682657&req=5

pone-0005688-g005: Histograms of vorticity maps for right atrial flow pre- and post-ASO.The histogram represents the distribution of vorticity values in a map. Statistical parameters used include means ω1, ω2 and standard deviations σ1, σ2 obtained from the histograms of the vorticity maps, with the subscripts 1 and 2 representing pre- and post-ASO conditions respectively. The mean is a gauge of the average angular velocity throughout the flow, and the standard deviation measures the variability of vorticity measures.
Mentions: We show the mapping of vorticity component normal to the measurement planes, i.e. in the principal direction of the most significant planar flow rotation (Figs. 4 and 5). From these results, we observe that the septal occlusion produces two significant effects. The first one is that it leads to an increase in strength of a single dominant counter-clockwise vortex within the cardiac chamber. Secondly, it reduces the concentration of clockwise vortical regions at the same time. For the post-occlusion condition, a strong negative vorticity region exists adjacent to the chamber wall that has less curvature relative to the septum that is associated with flow of positive vorticity. This is due to the quick motion of blood parallel to the endocardium of a relatively motionless and flat chamber wall. Consistent with this effect, there is a broader distribution of absolute vorticity in the right atrium for the same patient and at the same cardiac phase after septal occlusion. This deduction can be supported using statistical properties of the vorticity distributions. We note the atrial enlargement pre-occlusion, which may in part explain the reduction on the strength of the vorticity concentrations before occlusion. Another possible cause of the differences between the pre-and post-occlusion cases is the presence of left-to-right shunting of blood that disrupts the normal dominant vortex to introduce vortices of a smaller scale (Movie S1).

Bottom Line: Cardiovascular diseases can be diagnosed by assessing abnormal flow behavior in the heart.We introduce, for the first time, a magnetic resonance imaging-based diagnostic that produces sectional flow maps of cardiac chambers, and presents cardiac analysis based on the flow information.Application of intensity flow tracking based on their non-uniform signal concentrations provides a flow field map of the blood motion.

View Article: PubMed Central - PubMed

Affiliation: Centre for Biomedical Engineering and School of Electrical & Electronic Engineering, University of Adelaide, Adelaide, South Australia. kelvin.wong@adelaide.edu.au

ABSTRACT
Cardiovascular diseases can be diagnosed by assessing abnormal flow behavior in the heart. We introduce, for the first time, a magnetic resonance imaging-based diagnostic that produces sectional flow maps of cardiac chambers, and presents cardiac analysis based on the flow information. Using steady-state free precession magnetic resonance images of blood, we demonstrate intensity contrast between asynchronous and synchronous proton spins. Turbulent blood flow in cardiac chambers contains asynchronous blood proton spins whose concentration affects the signal intensities that are registered onto the magnetic resonance images. Application of intensity flow tracking based on their non-uniform signal concentrations provides a flow field map of the blood motion. We verify this theory in a patient with an atrial septal defect whose chamber blood flow vortices vary in speed of rotation before and after septal occlusion. Based on the measurement of cardiac flow vorticity in our implementation, we establish a relationship between atrial vorticity and septal defect. The developed system has the potential to be used as a prognostic and investigative tool for assessment of cardiac abnormalities, and can be exploited in parallel to examining myocardial defects using steady-state free precession magnetic resonance images of the heart.

Show MeSH
Related in: MedlinePlus