Transcatheter correction of sinus venosus defects (SVD) with covered stent has recently emerged, with promising results, as an alternative to surgery. Our aim was to assess the feasibility and diagnostic value of 4D flow MRI in patients who underwent transcatheter repair of SVD.

Since may 2023, we scanned 16 patients who underwent transcatheter repair of SVD with cardiac magnetic resonance (CMR) including a 4D Flow MR sequence, using a 1.5T magnet. For all patients, balanced steady-state free precession (bSSFP) cine images were obtained for evaluation of left and right ventricle (RV) volumes and function. Coronal ECG-gated 4D flow MR sequences were performed, with complete thoracic coverage.

Global objective was, by a visual and quantitative analysis, to detect abnormal flow patterns and location of persistent shunts (PS). Pulmonary-to-systemic flow ratios (Qp/Qs) and RV end-diastolic volume indexed (RVEDVi) were also measured.

CMR and 4D Flow MR were feasible and assessed global success of the procedure in all 16 patients. RVEDVi decreased in all patients. Average Qp/Qs was 1.24 (±0.33), with RVEDVi of 77mL/m² (±21).

Qp/Qs measured by catheterization, 4D Flow MR and RV/LV stroke volume ratio were well correlated.

Twelve out of 16 patients (75%) had no significant PS with Qp/Qs<1.5, including 8 patients without any PS at all. Four patients showed significant shunting with Qp/Qs>1.5.

PS visual analysis provided valuable insights into the understanding and the mechanism analysis of the PS.

We demonstrated the feasibility of 4D Flow MRI in all patients who had undergone transcatheter correction of SVD. 4D flow MRI accurately identified PS with comprehensive visualization of their location and mechanism, providing valuable information for their follow-up and to further discuss reintervention.

Qp/Qs ratio assessment using 4D Flow data showed good correlation compared to other functional measurements.