Discrepency between 2D and 4D flow MRI in the assessement of pulmonary regurgitation in grown up congenital heart disease

ALATTAR Y; GENCER U; SOULAT G; KARCENTY C; CRAIEM D; PASCANER A; LADOUCEUR M; ISERIN L; MOUSSEAUX, E

Florida

Conferencia; SCMR 23rd annual scientific session; 2020

Society of cardiovascular magnetic resonance

Background- 2D phase contrast (2D flow) MRI is the reference method for the quantification of pulmonary regurgitation (PR) in grown up congenital heart disease (GUCH), helping in the decision to undergo pulmonary valve replacement (PVR). 4D flow can be an alternative method with the advantage to position the measurement section  retrospectively, however validation against a reference standard is still lacking.The purpose of this study was to compare 2D and 4D flow in the PR quantification using the degree of right ventricular (RV) remodeling after PVR as the reference standard.Methods- PR was assessed in 30 adult patients with a pulmonary valve disease (22 with a repaired tetralogy of Fallot) using both 4D and 2D flow with retrospective ECG gating. Quantification of PR in 4D flow was done by using an in-house software. Based on clinical standard of care, a second MRI was performed in all patients during the follow up, 22 of them had a PVR. The initial estimate of PR was compared using the post-operative decrease of end diastolic volume (EDV) and stroke volume (SV) as reference.Results-2D and 4D flow pulmonary regurgitant volume (PRvol) and regurgitant fraction (PRF) were well correlated but significantly different in the overall cohort (r=0.90, mean difference= -14 ± 12.5 ml; and r=0.72, mean difference=-15 ± 13% respectively; all p< 0.0001). As expected, no significant changes in RV volumes in the group who did not undergo PVR were observed in contrast to the significant decrease obtained in the group who underwent PVR. Correlation between PRvol or PRF estimation and post-Surgical RV EDV decrease was higher with 4D flow measurements (r=0.80, and r= 70, for PRvol and PRF respectively, all p< 0.0001) than with those obtained with 2D flow (r=0.72, p< 0.0001 for PRvol and r=0.36, p=NS for PRF). Similar results were found if post-surgical RV SV decrease was used as the reference ( r=0.83 and r=0.82 for 4D flow PRvol and PRF respectively, all p< 0.0001 versus r=0.73 , p< 0.0001 and r=0.42, p=NS for 2D flow PRvol and PRF respectively).Conclusion- Significant difference in PRvol and PRF can be obtained between 2D and 4D flow measurements. 4D flow was found more accurate than 2D flow in PR quantification