Restrictive and obstructive pulmonary diseases affect the general population globally. Thoracic inflammation is mostly diagnosed on anatomic imaging modalities, bronchoscopy, and histologic and microbiological evaluation. The spectrum of nonmalignant and noninfectious disease affecting lungs ranges from those affecting the interstitium to airspace and vasculature. The commonly encountered diseases include sarcoidosis and chronic obstructive pulmonary disease (COPD). Aortoarteritis, Wegener granulomatous arteritis, systemic lupus erythematosus (SLE), and Kikuchi disease are other less common diseases, affecting the thorax as part of generalized inflammatory process. In systemic inflammatory disorders, ¹⁸F-fluorodeoxyglucose (FDG)-PET/computed tomography (CT) functional molecular imaging serves 3 practical advantages compared with the conventional imaging modalities: (1) aiding in assessing entire body distribution of the disease in a single examination; (2) imaging the degree of inflammatory disease activity; and (3) assessing the whole-body metabolic burden of inflammation, which is useful both at initial diagnosis and in posttherapeutic scenarios. This article describes the role of PET/CT in the diagnosis and management of inflammatory diseases in the lungs and thorax and explores its potential for precision medicine.