Abstract
Atrial septum defects (ASDs), ventricular septum defects (VSDs) and patent ductus arteriosus (PDA) are the most common adult congenital heart defects. The degree of left-to-right shunting as assessed by the ratio of flow in the pulmonary (Qp) and systemic circulation (Qs) is crucial in the management of these conditions. This study compared phase-contrast cine magnetic resonance imaging (PC-MRI), ...
Abstract
Atrial septum defects (ASDs), ventricular septum defects (VSDs) and patent ductus arteriosus (PDA) are the most common adult congenital heart defects. The degree of left-to-right shunting as assessed by the ratio of flow in the pulmonary (Qp) and systemic circulation (Qs) is crucial in the management of these conditions. This study compared phase-contrast cine magnetic resonance imaging (PC-MRI), a non-invasive imaging technique, with invasive oximetry for the measurement of shunt volumes during cardiac catheterisation in adults with left-to-right shunting. Both invasive oximetry and shunt quantification by PC-MRI (1.5 T scanner; Sonata, Siemens Medical Solutions) were performed on 21 patients with left-to-right shunting (14 ASD, 5 VSD, 2 PDA) and data on Qp/Qs ratios and left-to-right shunt fraction compared. Mean Qp/Qs ratios assessed by PC-MRl and oximetry were 2.10 +/- 0.76 and 1.96 +/- 0.77, respectively (p = 0.37). Mean shunt fraction was 46.3 +/- 19.6% when calculated by PC-MRl and 42.3 +/- 20.1% when obtained by oximetry (p = 0.12). There was a strong correlation of Qp/Qs ratios and shunt fraction between both methods (r = 0.61, p < 0.01 and r = 0.84, p < 0.0001, respectively). The two methods had a good agreement according to Bland and Altman plots with a small but non-significant overestimation of Qp/Qs-ratios and shunt fraction by PC-MRI. On receiver operating characteristic analysis, the sensitivity and specificity of PC-MRl to detect an oximetry-derived Qp/Qs ratio of >= 1.5:1 were 93% and 100% at a PC-MRl threshold of a Qp/Qs ratio >= 1.75:1 (area under curve (AUC) = 0.99). Quantification of left-to-right shunting can be performed reliably and accurately by PC-MRl and the data obtained by this method correlate closely to those from invasive oximetry.
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