Truncation artifacts appear as dark lines extending cranio-caudally along the patient. Because PET emission images are acquired over many minutes (25-40 min), patients are often unable to keep their arms above their head for the duration of the scan. The CT scanner has a relatively narrow axial field of view of only 50 cm and often the arms, shoulders, and hips lie outside the visualized area. Artifacts are produced at these sites because the CT attenuation correction reconstruction algorithm does not account for any attenuation of the CT x-rays by the tissues outside the field of view.

Possible limitations:

• Try to image the patient with the arms up over the head if possible.
• If unable to keep arms above the head, they can be secured to avoid movement over the abdomen.