Evaluating the Use of CT-Derived Lung Volumes in Donor-Recipient Lung Size Matching for Lung Transplantation in Patients With Interstitial Lung Disease and/or Idiopathic Pulmonary Fibrosis

Purpose: This study aims to assess the efficacy of current measurement strategies for lung sizing and the feasibility of future use of computed tomography (CT)-derived lung volumes to predict a donor-recipient lung size match during bilateral lung transplants. Methods: We reviewed the data of 62 patients who underwent bilateral lung transplantation for interstitial lung disease and/or idiopathic pulmonary fibrosis from 2018 to 2019. Data for recipients was retrieved from the department's transplant database and medical records, and the donor's data was retrieved from the DonorNet. The data included demographic data, lung heights, measured total lung capacity (TLC) from plethysmography for recipients and estimated TLC for donors, clinical data, and CT-derived lung volumes in both pre- and post-transplant recipients. The post-transplant CT-derived lung volume in recipients was used as a surrogate for donor lung CT volumes due to inadequate or poor donor CT data. Computed tomography–derived lung volumes were calculated using thresholding, region growing, and cutting techniques on Computer-Aided Design and Mimics (Materialise NV, Leuven, Belgium) programs. Preoperative CT-derived lung volumes in recipients were compared with the plethysmography TLC, Frustum Model, and donor-predicted TLC. The ratio of the recipient's pre-and postoperative CT-derived volumes, the ratio of preoperative CT-derived lung volume, and donor-estimated TLC were studied to detect a correlation with 1-year outcomes. Results: The recipient preoperative CT-derived volume correlated with the recipient preoperative plethysmography TLC (Pearson correlation coefficient [PCC] of 0.688) and with the recipient Frustum model volume (PCC of 0.593). The recipient postoperative CT-derived volume correlated with the recipient's postoperative plethysmography TLC (PCC of 0.651). There was no statistically significant correlation between recipients' CT-derived pre- or postoperative volume with donor-estimated TLC. The ratio of preoperative CT-derived volume to donor-estimated TLC correlated inversely with the length of ventilation (P value = .0031). The ratio of postoperative CT-derived volume to preoperative CT-derived volume correlated inversely with delayed sternal closure (P = .0039). No statistically significant correlations were found in evaluating outcomes related to lung oversizing in the recipient (defined as a postoperative to preoperative CT-derived lung volume ratio of >1.2). Conclusions: Generating CT-derived lung volumes is a valid and convenient method for evaluating lung volumes for transplantation in patients with ILD and/or IPF. Donor-estimated TLC should be interpreted carefully. Further studies should derive donor lung volumes from CT scans for a more accurate evaluation of lung size matching.