Clinical Usefulness of HRCT in Assessing the Severity of Pneumocystis jirovecii Pneumonia

The aim of this study was to investigate the clinical relevance of thoracic high-resolution computed tomography (HRCT) in evaluating the severity and outcome of Pneumocystis jirovecii pneumonia (PJP) in non-AIDS immunocompromised patients. We measured mean lung attenuation (MLA) and extent of increased attenuation (EIA) of PJP lesions on thoracic HRCT in 40 non-AIDS immunocompromised patients with PJP diagnosed by demonstration of the pathogens in cytological smears of bronchoalveolar lavage fluid. The MLA and EIA of PJP lesions on thoracic HRCT were used to investigate the severity of PJP. Clinically, the severity of PJP was determined by arterial oxygen tension/fraction of inspired oxygen concentration (PaO2/FiO2) ratio, acute physiology and chronic health evaluation (APACHE) II scores, the need of mechanical ventilation, and death. MLA highly correlated with EIA of PJP lesions (ρ = 0.906, P