Inflammation and primary graft dysfunction after lung transplantation: CT-PET findings

The leading cause of early mortality after lung transplantation is Primary graft dysfunction (PGD). We assessed the lung inflammation, inflation status and inhomogeneities after lung transplantation. Our purpose was to investigate the possible differences between patients who did or did not develop PGD.

We designed a prospective observational study enrolling patients who underwent a CT-PET study within 1 week after lung transplantation. Twenty-four patients (10 after double- and 14 after single-lung) were enrolled. Respiratory and hemodynamic data were collected before, during and after lung transplantation. Each patient underwent computed tomography-positron emission tomography (CT-PET) scan early after surgery. Broncho-alveolar lavage (BAL) fluid collection was performed to analyze inflammatory mediators.

The grafts showed a [18F]fluoro-2-deoxy-D-glucose ([18F]FDG) uptake rate of 26[18-33]*10-4 mLblood/mLtissue/min (reference values 11[7-15]*10-4). Three double- and six single-lung recipients developed PGD. The grafts of patients who developed PGD had similar [18F]FDG uptake than grafts of patients who did not (28[18-26]*10-4 versus 26[22-31]*10-4, P=0.79). Not-inflated tissue fraction was significantly higher (28[20-38]% versus 14[7-21]%, P=0.01) while well-inflated fraction was significantly lower (29[25-41]% versus 53[39-65]%, P<0.01). Inhomogeneity extent was higher in patients who developed PGD (23[18-26]% versus 14[10-20]%, P=0.01)The lung weight was 650[591-820]g versus 597[480-650]g (P=0.09)). BAL fluid analysis for inflammatory mediators did not detect a difference between the study groups.

Compared to healthy lungs, all the grafts showed increased [18F]FDG uptake rate, but there were no differences between patients who developed PGD and patients who did not. Of note, the PGD patients showed a worse inflation status of lungs and a higher inhomogeneity extent.