Use of 4D Flow Cardiac MRI Techniques in Congenital Heart Disease: Preliminary Experience and Comparison with Standard Phase Contrast Techniques

Introduction:

4D flow is a technique that allows simultaneous acquisition of all the flow data occurring throughout the cardiac cycle within the heart and great vessels, using a single sequence that takes approximately 5 minutes to acquire. Specifically this technique can be used to analyze differential flow, intracardiac shunt size, as well as more advanced physiological analysis, such as pulse wave velocity. This technique has not been extensively examined in the congenital heart disease population. We used a prototype 4D flow semi-automated software package (cvi⁴², Circle Cardiovascular Imaging, Inc., Calgary, AB, Canada, figure A) to assess aortic and pulmonary flows in patients with congenital heart disease, and compared the results with the standard Phase Contrast data.

Methods and results:

4D flow data was collected in 12 patients with congenital heart disease who underwent routine clinical cardiac MRI studies (4 with atrial septal defects, 4 with left sided heart disease, 3 S/P tetralogy of Fallot repair, and one S/P Scimitar syndrome repair). The net aortic and pulmonary flows, as well as the respective regurgitation fractions were recorded. The 4D flow data was compared with the “gold-standard” Phase Contrast flow data that was included in the clinical study report. Overall, there was good correlation for flow data between the two modalities (p≤0.008 for flows and regurgitation fractions, figures B and C), with modest agreement (R² = 0.15-0.63). The best agreement was for the pulmonary artery regurgitation fraction (R²=0.63).

Conclusions:

In this preliminary study of patients with congenital heart disease, 4D flow data correlated with standard Phase Contrast flow data. Agreement was modest, although this may be in part due to the small numbers. Further studies are warranted in order to better assess the role of this technique in congenital heart disease.