Acute rejection diagnosed with computed tomography in a porcine experimental lung transplantation model

The role of computed tomography (CT) in the diagnosis of acute rejection was studied in an experimental lung transplantation model, with 15 left lung allotransplantations and six autotransplantations performed on piglets weighing 16-24 kg. There were 31 episodes of acute rejection. In the allotransplantation group the development of acute rejection was monitored 115 times with CT, transbronchial biopsy (TBB) and bronchoalveolar lavage (BAL). The stages of acute rejection were 1) ill-defined centrilobular micronodules or minimal patchy ground-glass opacities. 2) dense, small-nodular infiltration or extensive ground-glass opacities, and bronchial wall thickening. 3) lung volume loss and dense, patchy ground-glass opacities and 4) consolidation of the lung. In the autotransplantation group monitoring was done 42 times. After allotransplantation, TBB and BAL suggested rejection 60 times and infection 23 times. CT had 86.7% sensitivity and 85.6% specificity. During the first month these figures were, respectively, 71.4% and 84.2%. Rising histologic grade was associated with increasing stage of acute rejection on CT, which thus proved to be a sensitive and specific method for diagnosing acute rejection of lung transplant.