FIGURE 2. (A) Example of respiratory artifact that can be seen on PET/CT images obtained when patients breathe quietly. Moderate-sized "cold" area (above liver) was curvilinear and resulted from mismatch of top of liver on PET (free tidal breathing) (B) and CT (more full inspiration in this case). Cold area was actually part of liver, not lung. (Image courtesy of M. Olman).