Acute and subacute non-infectious lung diseases: usefulness of HRCT for evaluation of activity especially in follow-up.

PURPOSE The purpose of this study was to survey the usefulness of high-resolution CT (HRCT) for the evaluation of activity in acute and subacute non-infectious diffuse infiltrative lung diseases before and after corticosteroid treatment. PATIENTS AND METHODS Sequential HRCT images and chest radiographs obtained before and after treatment were retrospectively evaluated in 33 patients with acute or subacute noninfectious diffuse infiltrative lung diseases. All these patients were histologically confirmed to have pulmonary Inflammation and to have responded to treatment with corticosteroid. Radiographic and CT scores were correlated with the degree of dyspnea and the results of arterial blood gas analysis using Spearman's rank-correlation coefficient. RESULTS On follow-up HRCT, the profusion score of areas with increased attenuation was significantly correlated with arterial oxygen tension (PaO2) (p=.003, r=-.53) and the alveolar-arterial oxygen tension difference (AaDO2) (p=.001, r=.57). No other correlation was found after treatment. Nodular and linear opacities were more commonly seen on follow-up chest radiographs and HRCT images than on initial ones. CONCLUSION HRCT is useful for the evaluation of disease activity in acute and subacute noninfectious infiltrative lung diseases before and after treatment if paying special attention to the profusion of ground-glass attenuation. Even if pretreatment HRCT has not been performed, posttreatment HRCT should be examined.