Published in:
01-06-2011 | Original Article
Improved cardiovascular flow quantification with time-resolved volumetric phase-contrast MRI
Published in: Pediatric Radiology | Issue 6/2011
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Background
Cardiovascular flow is commonly assessed with two-dimensional, phase-contrast MRI (2-D PC-MRI). However, scan prescription and acquisition over multiple planes is lengthy, often requires direct physician oversight and has inconsistent results. Time-resolved volumetric PC-MRI (4-D flow) may address these limitations.
Objective
We assess the degree of agreement and internal consistency between 2-D and 4-D flow quantification in our clinical population.
Materials and methods
Software enabling flow calculation from 4-D flow was developed in Java. With IRB approval and HIPAA compliance, 18 consecutive patients without shunts were identified who underwent both (1) conventional 2-D PC-MRI of the aorta and main pulmonary artery and (2) 4-D flow imaging. Aortic and pulmonary flow rates were assessed with both techniques.
Results
Both methods showed general agreement in flow rates (ρ: 0.87–0.90). Systemic and pulmonary arterial flow rates were well-correlated (ρ: 4-D 0.98–0.99, 2-D 0.93), but more closely matched with 4-D (P < 0.05, Brown-Forsythe). Pulmonary flow rates were lower than systemic rates for 2-D (P < 0.05, two-sample t-test). In a sub-analysis of patients without pulmonary or aortic regurgitation, 2-D showed improved correlation of flow rates while 4-D phase-contrast remained tightly correlated (ρ: 4-D 0.99–1.00, 2-D 0.99).
Conclusion
4-D PC-MRI demonstrates greater consistency than conventional 2-D PC-MRI for flow quantification.