Comparison of three-dimensional contrast-enhanced magnetic resonance angiography and axial radiographic angiography for diagnosing congenital stenoses in small pulmonary arteries

Accuracy of 3-dimensional contrast-enhanced magnetic resonance angiography (MRA) in diagnosing morphology of the branch pulmonary artery (PA) was evaluated in 73 patients (aged 7.2 +/- 6.4 years [mean +/- SD]) with various congenital heart diseases. The presence or absence of localized stenosis of branch PAs, PA diameter, and Nakata's PA index were determined on MRA and axial radiographic angiography, and the results were compared. Sensitivity, specificity, and overall accuracy in detecting branch PA stenoses were 92.7%, 96.2%, and 95.2%, respectively. Correlations between axial radiographic angiography and MRA were excellent in measuring PA diameter (r = 0.956, SEE = 1.49 mm, n = 139) as well as PA index (r = 0.839, SEE = 48.9, n = 37); both p < 0.0001. Bland-Altman plots showed a mean difference +/- SD for PA diameter of 0.17 +/- 1.51 mm and for PA index of 8.5 +/- 50.1. When the main right and left PAs were taken as the first generation, the most distal branches visible on MRA were the 4.7 +/- 0.7 generation with breath-holding (n = 23) and the 3.7 +/- 0.5 without breath-holding (n = 50), respectively (p < 0.0001). Both intra- and interobserver variabilities of MRA measurements were few (9.5 +/- 11.6% and 13.5 +/- 15.0%, respectively, n = 139). In conclusion, 3-dimensional contrast-enhanced MRA enables us to document branch PA morphology clearly in infants and adult patients with congenital cardiovascular defects.