The objective of this study is to detect Bronchiolitis Obliterans Syndrome (BOS) in an early stage using the outcome parameters generated by Functional Respiratory Imaging (FRI). Robust and automated segmentation algorithms will be developed for these parameters, focusing on quantitative computed tomography (CT) image analyses to provide the physician a more sensitive diagnostics tool. The evolution of BOS over time will be monitored using non-rigid image registration methods.

Inclusion Criteria:

• Male or female patient ≥ 18 years old
• Written informed consent obtained
• Patient who had undergone a lung transplant a year ago or more.
• Female patient of childbearing potential who confirm that a contraception method was used at least 14 days before visit 1 and will continue to use a contraception method during the study
• The patient must be able to perform the lung monitoring at home.

Exclusion Criteria:

• Pregnant or lactating female
• Known history of or active airways or anastomotic complications requiring intervention such as stenting or dilation