Standardized Radiographic Evaluation of Human Donor Lungs During Ex Vivo Lung Perfusion Predicts Lung Injury and Lung Transplant Outcomes

Abstract

<h3>Purpose</h3> Ex vivo lung perfusion (EVLP) is increasingly used to evaluate marginal donor lungs for transplantation. A commonly used component of donor lung assessment during EVLP is a lung radiograph taken after 1h and 3h of perfusion. The purpose of our study was to systematically evaluate EVLP radiographic findings and define their association with observed lung injury and EVLP outcomes. <h3>Methods</h3> We retrospectively evaluated all EVLP cases from 2020-21 (n=113). Radiographs were scored by a thoracic radiologist blinded to donor lung outcome. Each ex vivo lung lobe was scored for five radiographic features (consolidation, infiltrates, atelectasis, nodules, and interstitial lines) on a scale of 0 to 3 by severity for a maximum radiographic lung score (RLS) of 18 per feature. The RLS was correlated with markers of lung injury (PaO₂/FiO₂ and edema) using Spearman's correlation. Logistic regression was used to generate receiver operating curves to derive the performance of RLS in predicting transplantation outcome following EVLP. <h3>Results</h3> Consolidation and infiltrates after 1h of EVLP were the most frequent findings (RLS 2.5±3.4 and 4.4±4.3). Interstitial lines were less frequent (RLS 1.76±3.53), with nodules and atelectasis being uncommon (RLS 0.60±1.30 and 0.41±0.65). At the first and third hours of perfusion, consolidation (r=-0.536 and -0.608, p<0.0001) and infiltrates (r=-0.492 and -0.616, p<0.0001) were inversely correlated with oxygenation (PaO₂/FiO₂), whereas interstitial lines were correlated with increased perfusate loss in the circuit reflecting increased edema (r=0.244, p=0.019, and r=0.309, p=0.0047). First-hour consolidation, infiltrates, atelectasis, nodules, and interstitial line RLS predicted the decision to transplant the lungs with area under the curve of 87%, 88%, 52%, 58%, and 56%, respectively. First- and third-hour RLS from all five features predicted the decision to transplant with an area under the curve of 90% and 88%, respectively, and when combined, the value increased to 92%. <h3>Conclusion</h3> Consolidation and infiltrates were the most frequent findings in lungs undergoing ex vivo lung perfusion. The Radiographic Lung Score (RLS) predicted the suitability of donor lungs for transplant. Radiographic ex vivo lung images provide key information for the clinical evaluation of donor lungs for transplantation.