Research
4D cardiovascular magnetic resonance velocity mapping of alterations of right heart flow patterns and main pulmonary artery hemodynamics in tetralogy of Fallot
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* Corresponding author: Christopher J François cfrancois@uwhealth.org
1 Departments of Radiology, University of Wisconsin - Madison, School of Medicine and Public Health, 600 Highland Avenue, Madison, WI 53562
2 Departments of Pediatrics, University of Wisconsin - Madison, School of Medicine and Public Health, 600 Highland Avenue, Madison, WI 53562
3 Departments of Medical Physics, University of Wisconsin - Madison, School of Medicine and Public Health, 600 Highland Avenue, Madison, WI 53562
4 Departments of Biomedical Engineering, University of Wisconsin - Madison, School of Medicine and Public Health, 600 Highland Avenue, Madison, WI 53562
5 Departments of Medicine, University of Wisconsin - Madison, School of Medicine and Public Health, 600 Highland Avenue, Madison, WI 53562
6 Department of Radiology, University Hospital Schleswig-Holstein, Germany
Journal of Cardiovascular Magnetic Resonance 2012, 14:16 doi:10.1186/1532-429X-14-16
Published: 7 February 2012Abstract
Background
To assess changes in right heart flow and pulmonary artery hemodynamics in patients with repaired Tetralogy of Fallot (rTOF) we used whole heart, four dimensional (4D) velocity mapping (VM) cardiovascular magnetic resonance (CMR).
Methods
CMR studies were performed in 11 subjects with rTOF (5M/6F; 20.1 ± 12.4 years) and 10 normal volunteers (6M/4F; 34.2 ± 13.4 years) on clinical 1.5T and 3.0T MR scanners. 4D VM-CMR was performed using PC VIPR (Phase Contrast Vastly undersampled Isotropic Projection Reconstruction). Interactive streamline and particle trace visualizations of the superior and inferior vena cava (IVC and SVC, respectively), right atrium (RA), right ventricle (RV), and pulmonary artery (PA) were generated and reviewed by three experienced readers. Main PA net flow, retrograde flow, peak flow, time-to-peak flow, peak acceleration, resistance index and mean wall shear stress were quantified. Differences in flow patterns between the two groups were tested using Fisher's exact test. Differences in quantitative parameters were analyzed with the Kruskal-Wallis rank sum test.
Results
4D VM-CMR was successfully performed in all volunteers and subjects with TOF. Right heart flow patterns in rTOF subjects were characterized by (a) greater SVC/IVC flow during diastole than systole, (b) increased vortical flow patterns in the RA and in the RV during diastole, and (c) increased helical or vortical flow features in the PA's. Differences in main PA retrograde flow, resistance index, peak flow, time-to-peak flow, peak acceleration and mean wall shear stress were statistically significant.
Conclusions
Whole heart 4D VM-CMR with PC VIPR enables detection of both normal and abnormal right heart flow patterns, which may allow for comprehensive studies to evaluate interdependencies of post-surgically altered geometries and hemodynamics.