New technique could allow for safer, more accurate heart scans

The T1 mapping technique (right) provides easier-to-interpret imagery than the existing MRI method (left)(Credit: Dr Alexander Liu/OCMR/University of Oxford)

A recenet study from researchers at the University of Oxford has looked at using a new technique to scan patients' hearts, without the need to inject a potentially dangerous substance. The method could significantly improve treatment, providing imagery that's much easier for doctors to understand.

At present, we use magnetic resonance imaging (MRI) to scan the heart, but the process requires the injection of two substances, and isn't without risk. First, a medication called Adenosine mimics the effects of exercise, while Gadolinium – a rare heavy metal – is used to create contrast in the resulting images, allowing doctors to pick out areas of tissue with decreased blood flow.

Images of the heart created with this method rely on a doctor's ability to interpret the areas of light and shade, and it's possible for even the most experienced medical practitioners to disagree about what they're seeing. Gadolinium can also be harmful to certain patients, such as those suffering from kidney failure, whose systems are unable to fully remove the substance after the scan.

A University of Oxford team had an idea for a better method, making use of a process known a T1 mapping to provide images that are easier to understand and don't require the use of Gadolinium. T1 is the time constant that describes the amount of time it takes for atoms that have been hit by magnetic fields or radio waves to return to their normal thermodynamic state.

While each individual measurement doesn't provide much information, by mapping the heart using the method, researchers are able to look for readings outside the normal ranges, indicating the presence of disease. Specifically, elevated T1 times indicate increased water levels, which is something found in numerous heart conditions, such as when an area of the heart is suffering from limited blood supply as a result of blocked arteries.

It takes just three minutes to image the heart with T1 measurements, after which scientists are able to create a color map of the organ, which is significantly easier to interpret than the monochrome MRI imagery. Overall, it could mark a big step forward in the field.

"T1 mapping allows us to look in finer detail at the heart in a non-invasive way, which has not been possible before," says the University of Oxford's Dr Stefan Piechnik. "We can now get results without Gadolinium, meaning we have a technique that is safer and quicker and can be used with more people."

The researchers plan to continue their work on the technique, and hope to develop it into a clinically proven method for widespread use.

The findings of the study were published in the journal Cardiovascular Imaging.

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