Table 3.

levels of recommendation of CMR/CCT in CHD

	Level 1	Level 2	Level 3
Definition	Cooperative Adolescent/adult patients with simple/moderate CHD that require additional cross-sectional imaging investigation	Cooperative patients with moderate/complex CHD candidate to longitudinal cross-sectional imaging evaluation	Uncooperative patients and complex CHD proposed for “optional” and technically difficult cross-sectional imaging investigation in potentially unsafe scanning condition
Refer to	Any center with cardiovascular imaging experience	Specialized center with experience in the diagnosis and treatment of CHD (Hub and Spoke)	Tertiary center with long-standing experience in the diagnosis and treatment of CHD (Hub)
General indication	Non-complex CHD in cooperative patients	Follow-up of CHD in adolescents and adults	Complex CHD pre/post-repair (e.g., univentricular heart Fontan, atrial switch, isomerism)
	Native or repaired Aortic Coarctation	Non-complex CHD in children	Fragile patients
	Anatomy of PVR, anatomy of Ao Arch	Conotruncal anomalies post-repair (TOF, TGA post arterial switch, Truncus…)	Anesthesiologic difficulties (Williams syndrome patients requiring anesthesia)
	Pulmonary vascular disorders anatomy of ASD, VSD	Post Ross intervention	Technical difficulties (highly specific sequences/protocols/facilities)
	CMR	Ebstein/tricuspid dysplasia
	Simple shunt quantification
	Semilunar valve regurgitation
	CT
	Airway/lungs anomalies
	Coronary anomalies*

Ao aortic ASD, atrial septal defect, AV artero-venous, CHD congenital heart disease, PVR pulmonary venous return, VSD ventricular septal defect, TOF Tetralogy of Fallot, TGA transposition of the great arteries. The choice of CMR versus CCT depends on the information required for patient's management and local availability. When both can provide the same information with no added risks (i.e., anesthesia), CMR is preferable

^*At least 64-rows or superior CT technology is required. Specific low-radiation dose CT equipment is highly preferable