Ashraf et al selected people with lung nodules from the Danish Lung Cancer Screening Trial, referring them for PET. Having a suspicious PET scan, or a volume-doubling time (VDT) of < 1 year, each separately had a sensitivity of 71% and a specificity of 91% for lung cancer. Combining PET data with VDT improved sensitivity to 90% with a specificity of 82%. Nodules with discordant PET/VDT were malignant 57% of the time (n=8 of 14). Gold standard was stability after 2 years (negative) or pathology (positive); 54 nodules were analyzed. The VDTs were performed by cool software analyzing nodules on scans at least 3 months apart. Thorax 2011;66:315-319.