Quantitative computed tomography assessment of graft-versus-host disease-related bronchiolitis obliterans in children: A pilot feasibility study

Objective: To suggest a simple method that can quantify air trapping from chest CT in children with graft-versus-host disease (GVHD)-related bronchiolitis obliterans (BO). Methods: This institutional review board-approved retrospective study included eight GVHD-related BO patients (age, 6 - 17 years) who underwent both 31 CTs of variable settings and pulmonary function tests (PFT). The attenuation values of lung parenchyma in normal (An) and air trapping (Aa) areas were obtained. Individualized threshold [(An + Aa)/2] and fixed threshold of -950 HU were set for air trapping quantification. Spearman correlation analysis and generalized linear mixed models were used for statistical analysis. Results: The mean value of individualized threshold was -830.2 ± 48.3 HU. The mean air trapping lung volume percentage with individualized threshold and -950 HU were 45.4 ± 18.9 % and 1.4 ± 1.9 %, respectively. The air trapping lung volume percentage with individualized threshold showed a significant negative correlation with the PFT of FEV1/FVC% in all data (γ = -0.795, P <.001) and in the correction of repetition (γ = -0.837, P =.010). Conclusions: We suggest a simple and individualized threshold attenuation setting method for air trapping quantification insusceptible to CT imaging protocols or respiratory phase control in children with GVHD-related BO. Key Points: • Simple and individualized threshold attenuation setting for air trapping quantification is possible. • Individualized threshold attenuation setting is insusceptible to CT imaging protocols or respiratory phase control. • CT air trapping quantification correlates with PFT of pulmonary obstruction.