Indications for Cardiac Imaging Flashcards
What are indications for cardiac imaging?
Symptoms (chest pain, palpitations, shortness of breath, dizziness, loss of consciousness)
Planning treatment
Risk stratification
Population and family screening
Follow up in patients established heart conditions
Reassurance
What is an echocardiogram?
Ultrasound waves transmitted via probe ‘pizoelectric crystals’
Pass through the skin and reflect off different structures in the heart.
Images produced
What can be seen on an echocardiogram?
- Heart muscle (systole, diastole)
- Valves
- Blood flow
- Turbluence
- Pericardium
- Fluid around the heart
- Blood vessels (aorta, pulmonary veins, vena cava)
What is a cardiac MRI?
Most of the human body is made up of water
At the centre of each hydrogen atom is an even smaller particle, called a proton.
In a magnetic field the protons line up in the same direction.
Short bursts ofradio waves knock the protons out of alignment. When the radio waves are turned off, the protons realign. This sends outradio signals, which arepicked up by receivers.
This allows characterisation between the various types of tissue in the body, because the protons in different types of tissue realign at different speeds and produce distinct signals.
What are three MRI contraindications?
Most pacemakers defibrillators unless MRI conditional
Pumps (insulin)
Foreign bodies in the eye
What can be seen using cardiac MRI as apposed to echocardiogram?
- Atrial and ventricular volumes, wall thickness and mass.
- Better visualisation of the right heart.
- Size of the great vessels.
- Late gadolinium enhancement (cardiomyopathy, viability)
- Blood flow in the great vessels.
- Non invasively quantify coronary blood flow in assessment of coronary artery disease.
The majority of cardiac MRI exams use what?
Intravenous gadolinium-based contrast agents (GBCAs) to improve visualization of the heart muscle and blood flow.
When should contract enhanced cardiac MRI not be used?
With those who are pregnant or lactating, to those with severe renal impairment, or to those who have had previous anaphylaxis
Different patterns of gadolinium enhancement occur and this is useful for what?
To differentiate between various conditions that may overlap e.g. myocarditis overlaps with several conditions
What is a Cardiac Computed tomography?
This uses a powerful X-ray machine to produce images of your heart and its blood vessels.
What can be seen using a cardiac CT?
This looks at the arteries that supply blood to your heart.
Why should caution be taken when using cardiac CT?
High radiation dose, ideally avoid in young.
Should not give contrast to those with severe renal impairment or to those who have had previous anaphylaxis
What is a Positron emission tomography (PET Scan)?
A PET scan uses a radioactive drug tracer FDG (intravenous).
The tracer collects in areas of your body that have higher levels of chemical activity. On a PET scan, these areas show up as bright spots.
Images are taken before and after injection of the tracer for comparison.
Can be combined with CT/MRI
Standard PET radation dose from sun over 3 years.
What can be seen using PET?
- Areas of diseased muscle (e.g. sarcoid)
- Coronary artery disease
- Viability
When should caution be taken with PET Scan?
Avoid prolonged close contact with pregnant women, babies or young children for a few hours after scan
