Primary graft dysfunction; possible evaluation by high resolution computed tomography, and suggestions for a scoring system.

We have reviewed and discussed current knowledge on existing scoring systems regarding high resolution computed tomography (HRCT) images for the assessment of primary graft dysfunction (PGD) after lung transplantation. Adult respiratory distress syndrome (ARDS) has been more widely studied and appears to have many morphological features similar to what is found in PGD, and might, therefore, be usefully extrapolated to PGD. Principles of HRCT, scoring systems based on HRCT and various terms describing PGD were reviewed and summarized. The sensitivity, inter-intra observer variability, and reproducibility of these systems were discussed. Lastly, the future perspectives for 64-multi-slice computed tomography (MSCT) in relation to PGD were discussed. Few studies on scoring systems of lung tissue by HRCT in ARDS patients and idiopathic pulmonary fibrosis (IPF) patients were found. Most studies were performed on patients with cystic fibrosis (CF). Sensitivity of HRCT for the detection of parenchymal changes is superior to other imaging methods. High levels of reproducibility are achievable amongst observers who score HRCT lung images. Development of standardized criteria that specify the inclusion/exclusion criteria of patients, pilot testing, and training investigators through review of disagreements, were possibilities suggested for decreasing inter/intra observer variability. Factors affecting the image attenuation (Hounsfield numbers) and thus, the reproducibility of CT densitometric measurements were of minimal influence. Studies have reported on how lung tissue images, derived by HRCT, can be scored and graded. There does not seem to be a golden standard for evaluating these images, which makes comparison between methods challenging. These scoring systems assess the presence, severity, and extent of parenchymal change in the lung. HRCT is considered relevant and superior in evaluating disease severity, disease progression, and in evaluating the effects of therapy regimes in the lung. It is, however, not clear to what extent these scoring methods may be implemented for grading PGD. Further efforts could be made to standardize scoring methods for lung tissue with regards to PGD.