What does “Diaphragmatic attenuation artifact corrected with prone imaging is present” mean on a nuclear stress test report?

The diaphragm (sheet of muscle that separates the heart and the tummy structures) can sometimes obscure the bottom part of the heart during nuclear stress testing, and could potentially give rise to abnormal stress test result (a defect). This finding is more common in a man than a woman, in an overweight patient, and in certain imaging agents such as thallium.

When the technologist / interpreting physician sees such a potential defect, they would then perform “prone imaging” (scanning face down instead of face up). By performing this maneuver, the distance between the base of the heart and the diaphragm will increase and therefore the defect will potentially go away, telling the physician that the defect is caused by the diaphragm and not due to an abnormality in the heart.

As always, should there be any concern, one should talk to the ordering physician, in order to have query answered.