Rapid slice-to-volume four-dimensional flow in pediatric congenital heart disease: a feasibility study

Cardiovascular magnetic resonance (CMR) allows cardiac hemodynamic assessment in patients with congenital heart disease (CHD). However, conventional techniques are time-consuming and may require blood contrast agents. Slice-to-volume reconstruction (SVR) four-dimensional (4D) flow is an innovative imaging technique that may overcome these limitations. This study aimed to assess the feasibility of SVR 4D flow in pediatric CHD.

Patients with CHD (n=7, age=12.9±2.8years) underwent CMR with conventional two-dimensional (2D) phase-contrast magnetic resonance imaging (2D PCMRI) and SVR 4D flow. SVR 4D flow datasets were reconstructed from multi-slice 2D spiral PCMRI acquisitions, which were combined via slice-to-volume reconstruction. Mean flows in major thoracic vessels were measured and compared between the two techniques. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated for each participant and compared between imaging techniques.

Linear regression for SVR 4D flow against 2D PCMRI showed good agreement for mean flows (slope=1.03, intercept=-5.31 mL/s, r²=0.95). The SNR and CNR did not differ significantly between 2D PCMRI and SVR 4D flow data (SNR: p=0.85, CNR: p=0.90).

Our results suggest that SVR 4D flow CMR is a feasible 5-minute scan (relative to multiple 2D PCMRI prescriptions and scans) in pediatric patients with CHD. SVR 4D flow showed good agreement with 2D PCMRI for mean flow measurements. The advantages of SVR 4D flow support further research such as its comparison with conventional 4D flow.