Cardiology Coding Alert

Understanding how a single-photon emission computed tomography (SPECT) scan is performed should give cardiology coders a more thorough knowledge of what to code and why.

SPECT scans are a noninvasive technique for creating clear, three-dimensional pictures of the heart using a radionuclide tracer. Cardiologists use the scan to evaluate blood flow to the heart and often to enable them to predict which patients are at risk for a heart attack. They can also assess the heart size and muscle function. In many cases, cardiac physicians use the scan results to determine if a patient should undergo cardiac catheterization.

During a SPECT scan, the cardiologist injects the patient with a specific radiopharmaceutical tracer (e.g., Cardiolite, Myoview) that will be absorbed by healthy heart tissue at a certain rate over a specific period of time. The presence of areas with decreased absorption could be an indication of heart disease. A healthy heart will absorb a specific amount of the tracer, which produces a clear image on the gamma cameras that are rotated around the patient's body. The cameras are used with a computer to record the tracer's distribution in the heart. If regions of the heart absorb abnormally low levels of the tracer element, the pictures will show a dark region there, which can reflect coronary blockages or a previous heart attack.

Although SPECT scans are frequently referred to as "thallium stress tests," physicians rarely use thallium as the only radionuclide tracer any more. They are much more likely to use a radiopharmaceutical that breaks down more quickly, such as sestamibi, or Cardiolite, which is a technetium-based agent. These are particularly helpful for women because they provide better images through thicker breast material.

Cardiologists perform the first SPECT scan at rest and then another after the patient exercises. If the patient cannot reach a certain level of exercise, the physician may induce cardiac stress using medications such as adenosine.

The stress images are aligned with the resting images, and the physician reads both scans simultaneously. He or she then gives a comparative analysis of the heart both at rest and stressed.