Table 1. The relative strengths and limitations of the three main imaging modalities used for adults with congenital heart disease (ACHD).

	Echocardiography	MRI	CT
Methodological strengths	Real timePortableLocal velocity measurementsM-mode traces and 3DSuitable for operating theatre and during exerciseFree of ionising radiation	VersatileUnrestricted accessMultislice cine coverageBiventricular functionVolumetric flow measurementTissue characterisationDynamic angiographyFree of ionising radiation	Excellent spatial resolution3D visualisation and accessShort acquisition timeCalcium seen wellLumen generally seen within stents
Clinical strengths in ACHD	Applicable in almost all casesStrong for valve disease, jet velocities, septal defects and vegetations	Many applications, notably in aortic coarctation, Fallot's tetralogy, shunts, TGA and complex cases	Visualisation of coronary and collateral arteriesVisualisation of conduits and stentsVisualisation of associated lung pathology
Methodological limitations	Limited windows, angles and depth of accessNot suitable for volumetric flow measurement	Image slices are relatively thickAcquisition is relatively time consuming and expensivePacemakers are generally regarded as a contraindication	Ionising radiationNo flow measurementLimited cine visualisation
Clinical weaknesses in ACHD	Cannot usually access all parts of the RV, pulmonary arteries, pulmonary veins or aorta	Cannot reliably exclude patent foramen ovale or a small ASD, detect mobile vegetations in endocarditis or measure tricuspid regurgitation jet velocity for RV pressure estimation	Relatively limited functional information. Unsuitable for repeated follow-up studies because of radiation