Diagnostic Value of Quantitative Lung Perfusion Single-photon Emission CT/CT for Chronic Lung Allograft Dysfunction in Patients After Bilateral Lung Transplantation

Background: Chronic lung allograft dysfunction (CLAD) is a major cause of late morbidity after lung transplantation, and spirometry lacks the ability to detect regional lung changes. Thus, in this study, we investigated whether quantitative perfusion single-photon emission CT/CT parameters can distinguish CLAD from non-CLAD lungs and how they relate to pulmonary function. Patients and Methods: This retrospective study included 80 lung transplant recipients who underwent SPECT/CT. Standardized uptake value (SUV) mean , total lung uptake (TLU), and percentage injected dose (%ID) were calculated, and group differences, receiver operating characteristic performance, and correlations with forced expiratory volume in 1 second, forced vital capacity, and total lung capacity were analyzed. Results: No significant difference was observed for SUV mean ( P = 0.250), whereas TLU and %ID were significantly lower in CLAD ( P < 0.0001). Area under the curve values were 0.56 (SUV mean ), 0.76 (TLU), and 0.78 (%ID). %ID showed the best accuracy (cutoff: 0.83; sensitivity: 65.0%; specificity: 83.8%). Conclusions: Volume-based metrics, especially %ID, serve as useful noninvasive indicators for the assessment of CLAD.