[CT diagnosis of pulmonary infectious diseases].

Generally, the patient's inflammatory reaction is obvious, and the characteristic infiltrative shadow as pneumonia in the chest radiograph is recognized, no more imaging study is needed. However, when (1) radiographic finding is uncommon as a pneumonia; (2) antimicrobial drug treatment is ineffective; or (3) stenosis of central bronchi causing pneumonia by lung cancer and so on is suspicious, more precise imaging information of computed tomography (CT) is necessary. Recently, high resolution CT of lung disease as a new diagnostic method has been introduced, and diagnostic efficacy of CT has markedly advanced. Although the high resolution CT diagnosis based on the minute anatomy of the lung is also applied for the pulmonary infectious disease, their analysis and arrangement is not yet established since a large number of pathogens and various images exist. In reading CT films, it is necessary to consider patient's immune status. Infectiosity and size of the pathogen must be also considered. In this manuscript, CT imaging characteristics of lung infectious diseases are clarified by taking these points into account.