Interchangeable measure of pulmonary regurgitation in repaired tetralogy of Fallot: Comparison between serial cardiac CT and MRI.

PURPOSE: To identify an interchangeable pulmonary regurgitant measure in repaired tetralogy of Fallot by comparing pulmonary regurgitant volume and fraction between serial cardiac computed tomography (CT) and magnetic resonance imaging (MRI).

METHODS

A total of 40 patients (42 paired studies, age at CT examination: 18.6 ± 6.0 years) who underwent cardiac CT and MRI for the cardiac function assessment within 1 year were retrospectively evaluated. The pulmonary regurgitant volume and fraction quantified using CT volumetry were compared and correlated with the values quantified using phase-contrast imaging (reference standard). Furthermore, the degree of agreement between the methods was analyzed using Bland-Altman plot.

RESULTS

No statistically significant difference in the indexed pulmonary regurgitant volume was found between CT volumetry and phase-contrast imaging (p > 0.152). Compared with phase-contrast imaging, CT and MRI volumetry significantly underestimated the pulmonary regurgitant fraction (p = 0.001) and significantly overestimated the right ventricular stroke volume (p < 0.001). These parameters demonstrated high correlations between the two methods (R = 0.632-0.742, p < 0.001). With phase-contrast imaging as reference standard, the bias and 95 % limits of agreement in the indexed pulmonary regurgitant volume and fraction were 2.4 mL/m2 and -18.7 to 23.5 mL/m2 and -6.3 % and -26.5 to 14.0 %, respectively.

CONCLUSION

The indexed pulmonary regurgitant volume is an interchangeable measure of pulmonary regurgitation on serial cardiac CT and MRI enabling monitoring its severity in repaired tetralogy of Fallot.