Highly accelerated 4D flow MRI with respiratory compensation and cardiac view sharing: a cross-sectional study of flow in the great vessels of pediatric congenital heart disease.

BACKGROUND

Conventional four-dimensional (4D) flow magnetic resonance imaging (MRI) is limited by long scan times, particularly in pediatric congenital heart disease (CHD) patients.

OBJECTIVE

This study evaluates accelerated 4D flow MRI incorporating respiratory compensation and cardiac view sharing in healthy adults and pediatric CHD patients.

MATERIALS AND

METHODS

Subjects underwent 5-min free-breathing protocol with a three-dimensional (3D) radial trajectory and compressed sensing reconstruction. The 4D flow MRI reconstruction pipeline was improved by respiratory soft-gating and cardiac view sharing. Flow in major thoracic vessels was compared with two-dimensional (2D) phase contrast MRI, the reference standard.

RESULTS

Fourteen pediatric CHD patients (median age: 13 years (interquartile range (IQR): 5)) and four healthy adult volunteers (median age: 26 years (IQR: 3)) were recruited. Soft-gating improved diaphragm sharpness and reduced respiratory-induced blur (image quality scores: healthy: 46.1 soft-gated vs. 47.2 non-gated; CHD: 47.8 soft-gated vs. 48.2 non-gated). View sharing reduced undersampling artifacts and enhanced the signal-to-noise ratio (SNR, healthy: +9.9%; CHD: +3.8%). In healthy adults, correlations with 2D phase contrast MRI were strong for mean flow (R2=0.94, slope=0.94±0.12, root mean square error (RMSE)=6.4 ml/s; bias=1.1±6.4 ml/s, P=0.45) and peak flow (R2=0.9, slope=0.86±0.13, RMSE=40.9 ml/s; bias=21.3±44.7 ml/s, P=0.04). Similarly, CHD patients showed a strong correlation for mean flow (R2=0.88, slope=0.93±0.09, RMSE=8.3 ml/s) and peak flow (R2=0.97, slope=0.98±0.03, RMSE=25.9 ml/s). Internal consistency for 4D flow MRI in CHD cases showed mean percent differences of 6.1% Main pulmonary artery=Left pulmonary artery+Right pulmonary artery and 6.5% Ascending aorta=Descending aorta+Superior vena cava.

CONCLUSION

The accelerated 4D flow MRI method provides robust flow quantification and visualization in pediatric CHD patients, strongly correlating with 2D phase contrast MRI and completing scans in 5 min for clinical use.