Assessing the internal consistency of cardiac output measurements in phase contrast MRI by comparison to other systemic flows

Zielsetzung:

In cardiac magnetic resonance imaging (MRI) cardiac output measurements in the ascending aorta with phase contrast (PC) velocity encoding can be compromised e.g. by susceptibility artifacts. This study investigated, whether such cardiac output measurements can be internally validated by comparison to flow measurements in other systemic vessels.

Material und Methodik:

50 consecutive patients with clinical indication for pulmonary/aortic functional valve assessment were included. The systemic cardiac output was measured by 1.5 Tesla MRI with PC imaging in the proximal ascending aorta. In the same image sets the flows in the descending aorta, superior vena cava and right azygos vein were measured and combined for comparison (comparator flow). This comparison was done by Bland-Altman and regression analysis. Flows were calculated in L/min, and as index in relation to the body surface area in L/min/m2.

Ergebnisse:

The patients' cardiac output index (measured in the ascending aorta) ranged from 1.9 to 6.6 L/min/m2 (mean, 3.4 L/min/m2). The comparator flow correlated well to the cardiac output (r = 0.98). The 95%-limits of agreement of the comparator flow index versus the ascending aortic flow index ranged from -0.38 to 0.17 mL/min/m2, corresponding to flow index ratios of 0.89 to 1.05 (mean, 0.97).

Schlussfolgerungen:

PC-MRI measurements of the cardiac output in the ascending aorta can be well consistency-checked by comparison to the combined flow of the descending aorta, superior vena cava and right azygos vein.