Black Hole Artifact Over L4

Case Description:

This Hologic lumbar spine DXA scan shows a black hole-type artifact over L4. Items like lead bullets and tantalum clips show up as “black”on Hologic scans. The accompanying radiograph shows the clips over L4. L4 is omitted because of overlying artifacts.
Black hole artifacts occur with dense metals such as lead and tantalum on a Hologic scan. Other metals, like stainless steel, don’t produce black hole artifacts. Presumably there is complete attenuation of both Kev peaks so the difference is zero, making the image appear black. Lead bullets are measured as having high bone mineral content (BMC) and appear black in the dual-energy mode on the Hologic scanner and blue as artifact on GE Healthcare scanners. Black hole artifacts over bone are handled differently between Hologic and General Electric. With the Hologic scanner, when a dense artifact overlies bone, the BMC associated with that artifact is excluded, but the bone area is not altered. Consequently, the bone mineral density (BMD) of the affected vertebra, and of L1-4 is decreased. The GE scanners exclude both the associated BMC and area covered by the artifact, thereby minimizing the impact on BMD. Dense artifacts in the soft tissue do not significantly affect BMD on either manufacturer’s densitometer on phantom experiments., however, further experiments need to be done to verify this finding.

Credit:

Sarah L Morgan, MD, RD, CCD, The University of Alabama at Birmingham

References:

• Morgan, S.L., et al., Black hole artifacts-a new potential pitfall for DXA accuracy? J Clin Densitom, 2008. 11(2): p. 266-75.
• Morgan, S.L., et al., More on the black hole: tantalum, stainless steel, titanium, and lead J Clin Densitom, 2007. 10(2): p. S202-S203
• Morgan, S.L., et al., Effect of very dense artifacts on Hologic and General Electric bone densitometry results. . Arch Osteoporos 2020. 15(1): p. 77.

Click the Image to view DXA Atlas Sample Cases