thallium false positive or artifact

I had a thallium test.  Showed reversible anterior ischemia.  Doctor said in his report "concerning", although he said I was at low risk for coronary disease.  Another doctor looked at the pictures and said it was possibly "breast artifact".  Six months later, I saw the first doctor for a followup. I had not had any other tests done in the interim, just the visit with the doctor who mentioned the breast artifact.  He then said in his report that the first test was a false positive.  I had no other tests done to follow up.  How is a thallium test determined to be a false positive?  Thank you.

[CCF CARDIO MD - DLB]

The usual way a thallium is determined to be a false positive is if a catheterization determines there is no significant coronary artery disease, but the thallium was abnormal. I suspect your doctors thought that you were at low risk for heart disease and the abnormality in the thallium pictures was due to breast tissue, and not coronary disease. However, without a catheterization, there is no way to be really sure about this. This is why I do not recommend doing stress tests in low risk patients, because now you and your doctors are left with uncertainty about whether you really have coronary artery disease or not.