Computerised Tomography (CT or CAT) scans are widely used in all fields of medicine and surgery. When doctors are considering treatment of a blood vessel, they need to get a detailed view of the inside of the vessel, so special dyes, called contrast agents, are injected to visualise the blood flow and find any abnormalities.

However, contrast dyes can cause complications, including allergy and kidney damage. Contrast dye injection also requires the insertion of a needle, longer scan time and additional radiation exposure.

The injection into the patient’s arm can be both uncomfortable and can result in the dye leaking out from the injection site to the tissues under the skin causing skin problems.

Reducing the use of contrast dye could have a positive impact on the environment and sustainability of healthcare. Radioactive contrast agents are a major component of pharmaceutical waste in hospital water systems. Although the long-term impact on health is yet to be defined, several European countries are actively seeking solutions to minimise wastewater contamination by radioactive contrast agents.

Professor Lee’s team has developed a method which uses AI to generate ‘contrast enhanced’ CT scans without using contrast dye. Although human eyes cannot tell the difference between blood flow and abnormalities such as blood clots, there are minute details in the scan that can be used to differentiate them.