PET imaging with [11C](R)-PK11195, a specific radioligand for translocator protein (18 kDa) (TSPO, formerly known as the peripheral-type benzodiazepine receptor, PBR), has been used to assess activation of macrophages in inflammatory animal models and COPD patients [11]–[13]. Here, TSPO is linked to chronic obstructive pulmonary disease.