Serial CT findings in paragonimus Infected dogs and Micro-CT findings of the worm cysts

Abstract

Abstract

Purpose: To investigate serial CT findings in P. westermani infected dogs and microscopic structures of the worm cyst using Micro-CT.

Materials and Methods: Fifteen dogs infected with P. westermani underwent serial contrast-enhanced CT scans at pre-infection, after 10 days of infection, and monthly thereafter until 6 months for radiologic-pathologic correlation. Three dogs were sacrificed at 1, 3 and 6 months. After fixation of the lungs, both multi-detector CT and Micro-CT were performed for the worm cysts.

Results: The initial findings were pleural effusion (26.7%) and/or subpleural ground-glass opacities (20%) or linear opacities (20%) at 10 days. At day 30, subpleural (100%) and peribronchial nodules (100%) appeared with pleural effusion (26.7%), pneumothorax (93.3%), and abdominal or chest wall air bubbles (93.3%). Cavitary change (6.7%) began to be seen at day 30 and with mediastinal lymphadenopathy (64.2%) and bronchial dilatation (50%) at day 60 on CT scan. Thereafter, subpleural ground-glass opacities and nodules with or without cavitary changes were persistently observed until day 180. After cavitary change of the nodules, migrating features of the subpleural or peribronchial nodules were seen in all serial CT scans. Micro-CT showed that the cyst wall contains dilated interconnected tubular structures which have communications with the cyst cavity and adjacent distal bronchus.

Conclusion: The CT findings of paragonimiasis depend on the stage of migration of the worms. The worm cyst can have numerous interconnected tubular channels within its own wall and these channels have connections with the cavity and adjacent distal bronchus.