“…MRI and CT showed poorer sensitivity to identify native pulmonary arteries in our patients, and whilst the numbers were too small to allow for a comprehensive comparison, falling acquisition times and the use of CT and MRI imaging without anaesthesia continue to increase their attractiveness in a clinical setting [ 6 , 20 , 21 ]. CT in particular has shown promising results for infants with aortopulmonary collaterals [ 22 ], with the potential for a reduced radiation burden in modern systems [ 23 ]. The potential advantage of cross-sectional imaging providing an initial “roadmap” for subsequent catheterisation was, however, not clearly demonstrated in our series: the mean radiation dose when catheterisation was performed without prior CT/MRI was 87 mGy cm 2 (median 78 mGy cm 2 , range 62–122 mGy cm 2 , n = 3), and 152 mGy cm 2 (median 150 mGy cm 2 , 47–338 mGy cm 2 , n = 10) when cross-sectional imaging was available; the mean anaesthetic time was 110 min (median 108 min, range 40–181 min) versus 86 min (median 99 min, range 40–119 min), respectively ( p = 0.38).…”