Imaging considerations in tetralogy of Fallot: A comprehensive review

Table 3 Key computed tomography angiography reporting elements in pre-operative tetralogy of Fallot

Parameter
Situs	Solitus/ambiguous
Cardiac position	Levocardia/mesocardiac/dextrocardia
VSD	Size
	Site	Perimembranous/muscular
	Aortic override	50% or > 50%
ASD	Present/absent
Status of the main pulmonary artery	Atresia/stenosis
	Site of stenosis	Infundibular/valvular/supravalvular
	Pulmonary valve	Present/absent
Status of branch pulmonary arteries	Confluent/isolated
	Size	Good-sized/small-sized (Mcgoon ratio and Nakata index1)
Collateral vessels	PDA	Size and opacification
		Presence of proximal/distal end stenosis
	Aortopulmonary collaterals	Origin (DTA/aortic arch branches, etc.)
		Calibre (major/small); o’clock position, course and supply
Aortic arch	Side	Right/Left
	Branching pattern	Left: Normal; bovine; aberrant right subclavian artery; truncus bicaroticus; direct origin of the vertebral artery
		Right: Mirror image; independent origin of the vertebral artery; aberrant left subclavian artery
Coronary artery	Origin	Separate sinuses/common sinus/LAD originating from RCA
	Course	Course anterior to RVOT; inter-arterial course; hypertrophied conus branch of RCA coursing anterior to the infundibulum

¹McGoon ratio is calculated by dividing the sum of diameters of right and left pulmonary arteries by the diameter of the descending aorta at the level of the diaphragm. The Nakata index is obtained from the sum of areas of right and left pulmonary arteries, divided by the body surface area.

VSD: Ventricular septal defect; ASD: Atrial septal defect; PDA: Patent ductus arteriosus; DTA: Descending thoracic aorta; RCA: Right coronary artery; LAD: Left anterior descending artery; RVOT: Right ventricular outflow tract.