The hazy humerus artifact - A potential cause for misdiagnosis on computed tomography of the chest.

Computed tomography of the chest may be occasionally performed with the arm in mid extended position, in patients unable to fully raise their arms overhead. In such patients, a combination of beam hardening, incomplete projection and subtle motion artifacts may result in an appearance of diffuse cortical thickening and irregularity of the humerus. We describe this appearance as the 'hazy humerus artifact'. Radiologists must be aware of this appearance in order to avoid a misdiagnosis. The artifact can be minimized by having the arm positioned non-parallel to the plane of the gantry.