Near-infrared imaging method detects risk of heart attack and stroke

Near-IR light could selectively identify the rupture-prone deposits that commonly lead to blood clots, heart attacks, and strokes.

A team of researchers from the Warwick Manufacturing Group (WMG) at the University of Warwick (Coventry, West Midlands, England) and colleagues observed that when they used near-infrared (near-IR) light to visualize the fatty buildup found in arteries (atherosclerotic plaques), they could selectively identify the rupture-prone deposits that commonly lead to blood clots, heart attacks, and strokes.

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While some fatty deposits or plaques can remain stable for years, other high-risk cases develop complications, such as bleeding into the plaque, which leads to the formation of cracks and rupture of the fatty plaque. This can result in blockages in the blood vessels, causing a heart attack or stroke. Current imaging techniques are able to identify some characteristics of high-risk plaques, but none are generally accepted as reliable methods for selectively detecting the dangerous plaques.

Tara Schiller from the International Institute for Nanocomposites Manufacturing at WMG, along with colleagues from the Baker IDI Heart & Diabetes Institute and Monash University (both in Melbourne, Australia), have discovered that increasing the wavelength of the IR radiation currently used to detect atherosclerotic plaques in arteries to near-IR wavelengths allowed them to selectively identify plaques with internal bleeding, typically associated with high-risk deposits.

The plaques causing this fluorescence were identified using Raman spectroscopy. They are thought to be a mixture of heme products formed during the degradation of red blood cells. These products were only observed in the unstable plaques with internal bleeding and not observed in the more stable fatty deposits. This can improve selectivity when looking for high-risk deposits in patients, and could help doctors to identify the most at-risk patients.

After further investigation with clinical trials, the technique could be used to assess unstable fatty arterial plaques, and could be used to monitor the effectiveness of the drugs used to prevent heart attacks or strokes.

Full details of the work appear in the journal Nature Communications.

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