(1) Understanding lung anatomy that radiologists need to know for chest CT imaging.(2) Understanding the CT imaging findings, differential diagnoses, and correlations between CT and pathology for each characteristic CT sign.

I. IntroductionII. AnatomyIII. Parenchymal signs-Halo sign-Reversed halo sign (atoll sign)-Air crescent sign-Meniscus sign-Mosaic attenuation pattern-Three-density pattern (headcheese sign)-Crazy-paving appearance-Galaxy sign-Comet tail sign-Popcorn calcification-Melting ice cube signIV. Airway signs-Air bronchogram sign-Signet ring sign, string of pearls sign, tram line sign-Tree-in-bud sign-Gloved finger sign-Frown sign-Saber-sheath tracheaV. Vascular signs-CT angiogram sign-Feeding vessel sign-Polo mint sign-Scimitar signVI. Pleural signs- Split pleura sign