PET/CT > Artifacts & Pitfalls > Metallic Hardware

Metallic Hardware

There is intense activity in the left upper chest wall which correlates exactly in location with a metallic density pacemaker.

Because of the significantly higher density of metallic hardware compared to normal body tissues, the PET attenuation correction process “overcorrects” the PET images, essentially “adding in” activity to the tissues containing the hardware. This is because photons originating in these locations (if there were any) would be markedly attenuated by the metal. Of course, in the exact location of the hardware the artifactual activity “added in” does not pose a problem because it can be attributed to the hardware itself by close inspection of the CT data. However, the activity artifactually “added in” can include tissues closely approximated to hardware (such as muscles or lymph nodes) and this can pose a diagnostic dilemma. Therefore, the non-attenuation-corrected data should always be inspected in addition to the attenuation-corrected data. This will often elucidate whether there is any truly increased activity located within tissues adjacent to hardware. However, in some cases artifacts related to hardware preclude definitive evaluation of activity within adjacent tissues and other means of assessment are needed.

The non-attenuation-corrected data shown in the bottom row confirms that there is actually no increased activity in the left upper chest wall, as was apparent on the attenuation-corrected data shown in the top row. The attenuation correction process resulted in artifactually increased activity in the region of the metallic density pacemaker.

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