Table 1.

Transthoracic echocardiography and cardiovascular magnetic resonance imaging—relative merits and limitations.

	Echocardiography		Cardiovascular magnetic resonance
	Advantages	Limitations	Advantages	Limitations
Portability	Highly portable			Not portable—fixed systems
Ionisation	Non-ionising		Non-ionising
Image quality	Highly variable—from excellent to poor; dependent upon sonographer skills, intrinsic patient echo window factors and patient cooperation		More consistently excellent image quality	Image quality degraded by arrhythmia, poor breath-holding and motion
Speed of scanning	Rapid, tailored approach			Longer protocols relative to echo
Myocardial characterisation	Strain assessment allows good contractile function assessment		Range of tissue characterisation parameters that yield data regarding oedema, inflammation, extracellular volume and scarring (fibrosis/infarct)	Quantitative myocardial strain analysis not yet in clinical practise
Volumetric assessment	Variable depending on image quality for left ventricle	Limited for right ventricle	Excellent left and right ventricular volumetric assessment
Diastolic left ventricular assessment	Superior by echo			Not yet validated for clinical CMR use
Valve assessment	Superior characterisation of blood flow velocity and gradients		Superior assessment of valvular regurgitation volumes
Pulmonary pressure assessments	Quantitative approaches to pulmonary pressure estimates (PASP and PADP) in addition to visual assessment of septal motion and pulmonary artery diameter	Requires measurable TR jet	Qualitative assessment of septal motion and pulmonary artery calibre only	No quantitative measures
Temporal resolution	Superior temporal resolution			Inferior temporal resolution
Staff factors		Highly trained sonographers required		Highly trained radiographers required
Availability	Widely available			Availability limited to fixed locations in certain hospitals/medical facilities
Patient factors	Claustrophobia is not a concern			Unattractive to claustrophobic patients
	Can scan patients with orthopnoea			Patient must be able to lie flat for ≥40 min
	Patient can be scanned in echo lab or a portable machine taken to the bedside			Difficult logistics transporting critically unwell patients to the scanner
	Generally scanned in a semi-recumbent position; can also obtain at least some data if lying flat			Patients must be able to comfortably hold their breath while lying flat
	Kidney function not an issue with echo with or without echo contrast agents			Caution in patients with poor renal function if using gadolinium-based contrast, although lesser concerns with modern agents
Magnetic materials	No concern			Patients or equipment with ferromagnetic materials cannot enter the scanner room
Cost	Relatively cheap equipment			Much more expensive than echo systems
Infection control considerations		Close proximity of sonographer and patient	Distance between patient and radiographer

CMR, cardiac magnetic resonance; PASP, pulmonary artery systolic pressure; PADP, Pulmonary artery diastolic pressure; TR, tricuspid regurgitant.