Venous and arterial flow quantification are equally accurate and precise with parallel imaging compressed sensing 4D phase contrast MRI

Abstract

Purpose: To evaluate the precision and accuracy of parallel-imaging compressed-sensing 4D phase contrast (PICS-4DPC) magnetic resonance imaging (MRI) venous flow quantification in children with patients referred for cardiac MRI at our children's hospital.

Materials and methods: With Institutional Review Board (IRB) approval and Health Insurance Portability and Accountability Act (HIPAA) compliance, 22 consecutive patients without shunts underwent 4DPC as part of clinical cardiac MRI examinations. Flow measurements were obtained in the superior and inferior vena cava, ascending and descending aorta, and the pulmonary trunk. Conservation of flow to the upper, lower, and whole body was used as an internal physiologic control. The arterial and venous flow rates at each location were compared with paired t-tests and F-tests to assess relative accuracy and precision.

Results: Arterial and venous flow measurements were strongly correlated with the upper (ρ = 0.89), lower (ρ = 0.96), and whole body (ρ = 0.97); net aortic and pulmonary trunk flow rates were also tightly correlated (ρ = 0.97). There was no significant difference in the value or precision of arterial and venous flow measurements in upper, lower, or whole body, although there was a trend toward improved precision with lower velocity-encoding settings.

Conclusion: With PICS-4DPC MRI, the accuracy and precision of venous flow quantification are comparable to that of arterial flow quantification at velocity-encodings appropriate for arterial vessels.

Figure 1

(a) Superior vena cava, (b) inferior vena cava, (c) descending aorta, (d) ascending aorta and (e) pulmonary trunk flow rates were measured. The precision of flow utilizing a vein & an artery was then determined. This was done in pairs for the upper body (superior vena cava flow vs difference between ascending and descending aortic flow), lower body (inferior vena cava flow vs descending aortic flow) and whole body (sum of superior vena cava and inferior vena cava flow vs ascending aortic flow).

Figure 2

(a) Correlation, (b) Bland Altman Absolute comparison & (c) Bland Altman Relative/Percent Difference comparison of Arterial & Venous Flow Quantification by 4-D phase contrast MRI (x-axis represent mean and y-axis represent difference (units: L/min in absolute plot & relative percentage in relative plot)). The outer dashed lines indicate the limits of agreement. Lower limit of agreement represents the mean difference −1.96 standard deviations and upper limit of agreement represents the mean difference +1.96 standard deviations. AA= Ascending Aorta, DA= Descending Aorta after last arch vessel, PT= Pulmonary Trunk, SVC= Superior Vena Cava, IVC= Inferior Vena Cava

Figure 3

(a) Bland Altman Absolute comparison & (b) Bland Altman Relative/Percent Difference of high vencs (250 or above) population (n=10) and low vencs (200 & below) population (n=12) for arterial & venous flow quantification in upper body (x-axis represent mean and y-axis represent difference (units: L/min in absolute plot & relative percentage in relative plot)). The outer dashed lines indicate the limits of agreement. Lower limit of agreement represents the mean difference −1.96 standard deviations and upper limit of agreement represents the mean difference +1.96 standard deviations.