A new type of MRI scan can predict the risk of having a stroke, researchers have said in a study.

The non-invasive technique, developed by scientists at the University of Oxford, predicts whether plaques in the carotid arteries are rich in cholesterol and therefore more likely to cause a stroke.

Carotid arteries supply the brain with blood. The rupture of fatty plaques can block them and possibly starve the brain of oxygen, causing potentially debilitating and life-threatening strokes.

A quarter of the more than 100,000 strokes in the UK each year are caused by carotid plaques.

Dr Luca Biasiolli, the co-author of the study, said: “When someone goes to hospital having suffered a minor stroke, it’s vital that doctors know whether the patient might be at risk of a further stroke, which could be fatal.

“Being able to quantify cholesterol in carotid plaques is a really exciting prospect, as this new MRI technique could help doctors to identify patients at higher risk of stroke and make more informed decisions on their treatments.”

The study, published in the journal JACC: Cardiovascular Imaging on Thursday, created a test that produces a quantitative result, whereas traditionally the risk of stroke is measured by the size of the plaque in the carotid artery. At present, if a plaque is deemed too big it is removed, but the researchers say fatty plaques that are not large yet have a high risk of rupturing can be missed.

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The scientists used the new MRI scan to measure the amount of cholesterol in the carotid plaques of 26 patients scheduled for surgery. After the plaques were surgically removed, the team looked at the actual cholesterol content in each plaque and found that the new technique was accurate – the more cholesterol they detected within the plaque, the greater the risk of a stroke. The same team confirmed and extended their findings in another study on 50 people published in PLOS ONE.

Prof Sir Nilesh Samani, medical director at the British Heart Foundation, which part-funded the study, said: “This exciting research opens up the possibility that in the future we may be able to more accurately identify people with carotid plaques that are likely to rupture and cause a stroke.

“These patients can then be treated earlier – for example, with surgery to remove the plaque – while others might be spared surgery altogether. More research is now necessary before this advance can come into routine clinical practice. However, if successful this technique has the promise to save lives.”