Non-Invasive Qp/Qs ratio measurement with phase contrast MRI and echocardiography in patients with atrial septal defect: comparison with heart catheterization

Abstract

Background: The objective of this study was to determine whether the assessment of pulmonary and systemic flow in patients with isolated atrial septal defects obtained by velocity encoded phase contrast magnetic resonance imaging was comparable to those acquired by heart catheterization and echocardiography.Results:Study population comprised 32 patients with Atrial Septal Defect.. All the three tests i.e. PC-MRI, Echocardiography, oximetry were done in all the patients after an informed consent with an average time gap of less than 24 hours between each. The mean values of Qp Qs as measured by the three methods depicted good correlation among them with p value 0.0001. The Bland–Altman plots for the measurement of Qp and Qs shows good agreement between the three methods, with correlation coefficient for Qp 0.85 measured by oximetry vs Echo and 0.93 fpr oximetry vs MRI and those for Qs 0.82 and 0.71 respectively. Qp/Qs ratios measured by MRI vs echo and oximetry showed excellent agreement, Mean differences of Qp/Qs ratios between echo and oximetry, and oximetry and MRI was 0.18% and 0.24% respectively. Both Qp/Qs ratios strongly correlated with correlation coeffient of 0.77 for oximetry vs echo and 0.72 for oximetery vs MRI. The Bland–Altman plots also showed good agreement between the three methods.Conclusion:Qp, Qs and Qp/Qs obtained by noninvasive methods ie Echocardiography and PC-MRI correlates well with that obtained by invasive oximetry. PC-MRI is non invasive, safe, feasible, reliable and accurate in assessment of flow dynamics in patients with ASD and has good agreement with invasive oximetry.