MRI scans may soon be able to gauge the risk of heart attack, according to researchers.
The main reason behind heart attacks is plaques made of immune cells and cholesterol that build up inside the coronary arteries, which feed the heart.
If a plaque ruptures, a clot can form, blocking blood flow with potentially catastrophic results.
Cameras can be sent into arteries to check the walls for plaques, but the probe itself could trigger cardiac arrest by rupturing a plaque.
An MRI scan can see inside the body without risk, but doesn't offer enough resolution to image artery walls directly.
However, Simon Robinson of Lantheus Medical Imaging in North Billerica, Massachusetts, and his colleagues found a way around this using gadolinium chelate, a substance that is already used to light up blood in MRI scans.
The researchers attached this 'contrast agent' to a molecule that binds to the protein elastin, which is found in artery walls.
When injected into the bloodstream of pigs, the resulting molecule binds to elastin throughout the thickness of the artery walls and lights them up in an MRI scan.
The plan is to image the arteries of people thought to be at risk of heart attack and check for a dangerous amount of thickening that would suggest the presence of plaques.
"If you've got a plaque developing, you'll see a brighter, thicker region," New Scientist quoted Robinson, as saying.
Patients with plaques could be given cholesterol-lowering drugs, such as statins, blood thinners that prevent a clot from forming if a plaque ruptures, or fitted with a stent to support artery walls and lower the risk that a plaque will burst.
The gadolinium chelate eventually detaches from the artery walls and is cleared by the kidneys.
Lantheus is conducting safety trials of the contrast agent and hopes to begin tests in humans early in 2010.
One possible obstacle is that some gadolinium-based contrast agents have previously been linked to kidney problems.