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Lexiscan Results
sjuncker posted:
I am 40 and had a nuclear stress test with Lexiscan this past week and need some clarification on the results. The nuclear conclusion states "Fixed defect anterior wall suggestive of breast attenuation artifact"- What does this mean? Also the impression states "probably normal rest and stress nuclear images with artifact". Again, what does this mean. The stress test was for cardiac clearance for shoulder surgery in a few weeks. Do I need to be concerned?
CardiostarUSA1 responded:

"Do I need to be concerned?"

Probably not.

An artifact is a false image, e.g., due to body habitus/anatomy or dense breast tissue.

Noteworthy, soft tissue attentuation can cause a false-positive (F-P) result/finding, indicating a problem when there really isn't one.

During a nuclear rest/stress test, in some individual's, soft tissue may/can cause a decreased (attenuation) radioactivity count in the heart muscle (myocardium).

That is, it affects the SPECT scanner's ability to properly read the amounts of IV administered (in the arm) radioisotope (e.g., newer higher-energy/lower radiation technetium-based radioisotopes Cardiolite, Myoview or much older non-technetium-based Thallium) that is taken up into the heart muscle.

Gated-SPECT (synced to an electrocardiogram, ECG/EKG) improves the diagnostic accuracy by aiding in differentiating attenuation artifacts (false images) from heart attacks (myocardial infarctions) in areas of fixed perfusion defects (FPDs).

If say a fixed anterior perfusion defect shows normal wall motion (kinesis) and thickening post-stress, it is most likely due to the breast's soft tissue attenuation aspects.

The basics

The two main concerns regarding a nuclear stress test involves an actual narrowing or scarring, i.e., the findings of reversible (ischemia) or non-reversible (fixed, permanent, scar tissue) perfusion (blood flow) defects.

After stress myocardial perfusion imaging (stress MPI, e.g., gated-SPECT scan with Cardiolite or Myoview), the patient's cardiologist may take some time to study the results of the scan before discussing the findings.

One can typically expect one of the following four results -


No perfusion defect after exercise or at rest

The heart muscle and blood flow to the heart muscle appear to be normal.


Perfusion defect after exercise, BUT NOT at rest (reversible defect)

There is some degree of blockage in a coronary artery that interferes with the blood flow to the heart muscle. In someone with significant heart disease, when the heart works hard, it does not get the blood supply and oxygen that it needs (a supply 'n demand mismatch).

At rest, however, the blood adequately reaches these areas or regions, e.g., ANTERIOR/ANTERO (front wall), POSTERIOR (back wall), INFERIOR (lower area/lower wall area), Septal/Septum (dividing wall) APICAL/APEX (bottom tip of the heart) and LATERAL (side wall).

The heart muscle has living cells/tissue in these areas. This indicates that clearing the blockage in the affected artery will be of benefit.


Perfusion defect AFTER exercise AND at rest (fixed defect)

There is one or more totally blocked coronary arteries and one has had damage done to the heart muscle because of a heart attack.

There is an area/areas of the heart muscle that has become scar tissue (scarring, scarred) because of the heart attack.

This area would not be able to make functional use of any oxygen even if blood flow to that area of the heart were completely restored.


Combined reversible and fixed defects

It is common for individuals with coronary artery disease to have different degrees of blockages in different arteries.

A heart attack has left a fixed defect in one area of the heart, but there is a reversible defect in another area of the heart due to a less severe blockage.

Take care,


WebMD member (since 8/99)



Be well-informed


Isotope/Nuclear Stress Test

SEE: Actual rest/stress images

Coronary artery anatomy



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