Congenital heart defects are the most frequent manifestation of congenital diseases (8 per 1000 live births). Imaging modalities play an increasing role in their diagnosis, follow-up, and pre/post-surgery check-up. Echocardiography usually provides a first line diagnosis, but Coronary CT Angiography (CCTA) also demonstrated its usefulness whenever accurate modelling of anatomic structures is required.

CCTA is well defined for adult patients. This is not the case for paediatric population, which rises two main difficulties:

• The use of ionising radiation in young subjects involves a very radio-sensitive population, potentially subject to multiple exams during their follow up.
• Technical issues related to young patients: No breath-holding, uncontrolled movements during acquisition, very high heart rates (making ECG gating more complex) and very small structures.

These conditions usually result in a deteriorated image quality or in radiation dose increase (retrospective gating). These two outcomes are not acceptable for both, clinician and patient.

In this study, investigators make the hypothesis that despite difficult conditions stated above, ultra-low dose acquisitions may results in diagnostic quality acquisition, thanks to state of art CT technologies combined with acquisition parameters specially designed for that purpose.

Investigators aim to demonstrate feasibility and performances of such exams.

Fifty paediatric patients are to be enrolled in this study. All these patients were prescribed a coronary angiography CT as part of their follow up for a known or suspected coronary artery anomaly.

Computed Tomography acquisitions are performed on a Revolution CT (GE Healthcare) using a wide detector aperture (160 mm), last generation of iterative reconstruction algorithm and specific reconstruction software reducing cardiac motion artefacts. A rotation time of 0.28 sec is used, with a slice thickness of 0.625 mm and a 0.625 mm reconstruction interval. The acquisition is ECG-gated (prospective) with kV and mAs depending on BMI, heart rate and heart rate variability of patients.

Inclusion Criteria:

• Patients from 0 to 18 years old
• Known or suspected coronary artery anomalies
• CCTA prescribed for regular follow up of the pathology
• No-objection of parents/legal representative of the patient
• Covered by social security

Patients from 0 to 18 years old with known or suspected coronay artery anomalies