To investigate the CT features of early infection stage of thoracic and pulmonary paragonimiasis.

Medical records of 56 patients with thoracic and pulmonary paragonimiasis from January 2010 to June 2017 were collected, and the patients were diagnosed and treated at Yongjia County People's Hospital, and the results of laboratory examination and CT imaging features were analyzed retrospectively.

The absolute value of eosinophils in peripheral blood of 56 patients was (5.61 ± 3.18) × 10⁹/L, and the percentage of eosinophils was (35.90 ± 19.16)%, all of which increased to varying degrees. Forty-two patients had different degrees of pleural effusion and 52 cases with lung lesions. Lung lesions demonstrated one or several kinds of foci at the same time, randomly distributed in the lung field, mostly located in the sub-pleural lung tissue. There were 12 cases with pulmonary ground glass shadow, 4 cases with peribronchitis, 31 cases with pulmonary invasive lesions and 28 cases with pulmonary nodular/strip shadow. The size of most nodules were 0.5 - 1.0 cm, accompanied with halo sign.

The CT features of early infection stage of thoracic and pulmonary paragonimiasis are diverse. The size of 0.5 - 1.0 cm lung nodules with halo sign has certain characteristics in the diagnosis of paragonimiasis. Peribronchitis, infiltrative lesions, pleural effusion and increased peripheral blood eosinophil percentage can suggest diagnosis.

Paragonimiasis; Thoracic diseases; Tomography, X-ray computed