Types of Nuclear Heart Scanning

There are two main types of nuclear heart scanning:

• Single positron emission computed tomography (SPECT)
• Cardiac positron emission tomography (PET)

SPECT is the most well-established and widely used type, while PET is newer. There are specific reasons for using each, which are discussed in the following paragraphs.

Single Positron Emission Computed Tomography

Cardiac SPECT is the most commonly used nuclear scanning test for diagnosing coronary artery disease (CAD). Combining SPECT with a cardiac stress test can show problems with blood flow to the heart that can be detected only when the heart is working hard and beating fast.

SPECT also is used to look for areas of damaged or dead heart muscle tissue, which may be due to a previous heart attack or other cause of injury.

SPECT also can show how well the heart's left ventricle pumps blood to the body. Weak pumping ability may be the result of heart attack, heart failure, and other causes.

The most commonly used tracers in SPECT are called thallium-201, technetium-99m sestamibi (Cardiolite^®), and technetium-99m tetrofosmin (Myoview™).

Positron Emission Tomography

PET uses different kinds of tracers than SPECT. PET can provide more detailed pictures of the heart. However, PET is newer and has some technical limits that make it less available than SPECT. Research into advances in both SPECT and PET is ongoing. Right now, there is no clear cut advantage of using one over the other in all situations.

PET can be used for the same purposes as SPECT—to diagnose CAD, check for damaged or dead heart muscle, and evaluate the heart's pumping strength.

PET takes a clearer picture through thick layers of tissue (such as abdominal or breast tissue). PET also is better than SPECT at showing whether CAD is affecting more than one of your heart's blood vessels. A PET scan also may be used if a SPECT scan wasn't able to produce good enough pictures.