Backgorund: The present study aimed to assess the feasibility of multidetector-row computed tomography (MDCT) for the evaluation of systemic-pulmonary collateral (SPC) arteries in children with congenital heart disease associated with reduced pulmonary blood flow. Methods: Forty-eight consecutive patients (mean age 9±5 months; range, 0–30 months) underwent MDCT angiography of the thorax with a 16–detector row scanner prior to cardiac catheterization and operation. Conventional angiographic findings were used as a gold standard for the detection of SPC vessels. Findings on CT angiograms, including CT scans, maximum intensity projections, and three-dimensional volume-rendered images, were used to evaluate depiction of SPC arteries. Quantification of measurements at the SPC artery diameter was evaluated independently on MDCT and conventional invasive angiography.Results: Among the 48 patients, 115 SPC arteries were identified with conventional angiography, and 94 SPC arteries were identified with MDCT. In 89 (77%) vessels, concordant findings were observed with both modalities, with adequate depiction in 53 vessels and suboptimal depiction in 36 vessels. In 26 (23%) vessels, MDCT was unable to identify SPC arteries. Further, CT-angiography resulted in the false-positive identification of vessels in 5 cases. There was an excellent correlation between MDCT- and conventional angiography-based measurement of SPC vessel diameter (R²=0.83), although a systematic overestimation was observed with MDCT (bias 0.19 ± 0.74 mm).Conclusions: This study demonstrates that MDCT is a potentially useful tool, which may have implications for planning percutaneous interventions and surgical repair in the future.