Answer
It is an ultrasound-enhancing agent made from gas-filled microspheres; the echocardiogram does not use ionising radiation.
Sources for this answer
- OPTISON 0.19 mg/ml dispersion for injection — Current selected SmPCemc · Summary of Product Characteristics
- NHSNHS · NHS medicine guidance
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.