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Nuclear Images

Nuclear imaging of the heart is a valuable diagnostic tool in detecting clogged arteries. This is especially true in people with angina but no apparent heart attack.

Two separate scans are usually compared, a resting scan and a scan which follows stressing of the heart. This stress can be accomplished with exercise or can be provoked with medications. If a person has normal circulation, all areas of the heart will receive adequate amounts of blood and there will no defects in the photon image.

If, however, there is a blockage, the part of heart supplied by that particular artery will not get enough blood to supply to meet its needs
(ischemia). Not only will they commonly get chest pain (angina), but also the nuclear imaging will show a defect in the area of the heart supplied by this artery. If the defect exists with stress and the resting scan is normal, this indicates a significantly blocked artery and an increased risk of having a heart attack. If the defect exists at both rest and with stress, it indicates an area of previous heart attack.

The addition of stress perfusion imaging can assist in differentiating true-positive from false-positive ST depression. The accuracy can be as high as 90 percent

Below is a normal nuclear perfusion scan of the heart. There is no ischemia and there is no scarring.


Image source: Clotbuster Archives.

To increase the accuracy of the stress test, it is commonly used in conjunction with an echocardiogram, a stress echocardiogram. Ultrasound pictures of the heart are taken a rest and with stress. If a particular segment of the heart stops moving with stress, it suggests a blocked artery to that area. The accuracy of stress echo can be as high as 85 to 90%.

Image source: Clotbuster Archives.

Above is a nuclear scan of the heart performed at rest and at maximum exertion.

The red color indictes blood flow through the coronary arteries.

The arrow points to an area of reduced blood flow to the front of the heart (ischemia).

Below is angiogram of the left coronary artery
which shows a 95 per cent blockage of the left anterior descending branch which supplies the front part of the heart. This lesion is responsible for the reduced coronary circulation.


Image source: Clotbuster Archives.