Scanners which take three-dimensional pictures of the heart and its blood vessels could take the discomfort and risk out of diagnosing coronary artery disease.

Magnetic Resonance Imaging (MRI) technology is already widely used in hospitals, often to diagnose the extent of cancers by providing a detailed 3-D image of tumours.

But few use it to examine patients who are showing the symptoms of heart disease, relying instead on needle angiography.

This involves inserting a fine tube, usually into an artery at the groin, usually under local anaesthetic, and passing it all the way to the blood vessels surrounding the heart, where dye is injected which will show up on X-rays.

Researchers, writing in the Journal of the American Heart Association, say that angiography, which carries a small risk of excessive bleeding, heart attack and even stroke, is not necessary.

They say that MRI will cut the time, the discomfort and the danger experienced by heart patients, while still allowing cardiologists to make an accurate diagnosis.

Painless half hour of scanning

In addition, 20 to 30 minutes of MRI would cost the NHS less than one-quarter of the cost of an angiogram.

Angiography takes longer, and the patient requires three or four hours in hospital to recuperate following the procedure.

In the study, eight healthy adults and five patients with confirmed heart disease underwent the scanning test.

The network of arteries supplying the heart can narrow and harden

The researchers reported that the pictures they saw of the heart's arteries compared well with those obtained by angiography and X-ray.

Dr Warren Manning, co-director of the Beth Israel Deaconess Medical Center in Boston, where the study took place, said: "In about half an hour, you're done. It is likely that the technique will become the standard approach at many cardiac MRI centres because of its ease of use and high quality."

Although cardiac MRI has been tried before, by the same team in 1993, it failed because the technology involved required patients to hold their breath for up to 20 seconds to make the picture steady enough to be of use.

Dr Gregory Lip, a consultant cardiologist and reader in medicine at the Birmingham City Hospital, said that anything that reduced the small risks of angiography was to be welcomed.

But he added: "Not many places have got MRI scanners. At Birmingham, we are a major teaching hospital but we have only just got ours.

"I suspect it is going to be a little while before we get access to it."

The only common use in cardiology for MRI scanners, which cost millions of pounds each to install, is in the diagnosis of babies with congenital heart defects, where exact details of the layout of the tiny heart are vital to successful surgery.

One in a thousand suffer complications

The risks associated with angiography are currently thought to be about one in a thousand, with the most common complications being bleeding, infection.

But occasionally, a reaction to the dye used can send the artery into spasm, perhaps even triggering a heart attack, or dislodge a blood clot which then travels to the brain and causes a stroke.

Following angiography, doctors can treat narrowed arteries with drugs, angioplasty, in which a balloon is inserted into the artery and expanded to widen it, or, in more severe cases, by coronary artery bypass surgery.