Differential diagnosis of phenotypes of chronic lung allograft dysfunction (CLAD) remains troublesome. We hypothesized that 18F-fluorodeoxyglucose positron emission tomography with computed tomography (18F-FDG PET/CT) may help in differential diagnosis of CLAD phenotypes, as it showed promising results regarding diagnosis and prognosis in interstitial lung diseases.
A monocentric, retrospective study was performed including all lung transplant recipients suffering from bronchiolitis obliterans syndrome (BOS) or restrictive allograft syndrome (RAS) who underwent 18F-FDG PET/CT scan, in comparison with stable lung transplant recipients. Maximum standardized uptake value (SUVmax) was associated with pulmonary function and survival. Proof-of-concept microCT and glucose transporter-1 staining served as morphologic validation for regions with different SUVmax.
Maximum standardized uptake value was higher in RAS (median, 2.6; n = 29) compared with BOS (median, 1.0; n = 15) and stable patients (median, 0.59; n = 8) (P < 0.0001). In RAS, high SUVmax was associated with worse survival after 18F-FDG PET/CT (P = 0.0004; hazard ratio, 1.82). Forced vital capacity at 18F-FDG PET/CT inversely correlated with SUVmax (R = −0.40, P = 0.03). MicroCT analysis revealed extensive fibrosis in regions of high SUVmax, with an increased number of glucose transporter-1–positive cells.
18F-fluorodeoxyglucose positron emission tomography with CT may noninvasively differentiate RAS from BOS. RAS patients with areas of increased lung metabolism have worse outcome, demonstrating the potential use of 18F-FDG PET/CT during follow-up after lung transplantation.
1 Leuven Lung Transplant Unit, Department of Chronic Diseases, Metabolism and Ageing, KU Leuven, Leuven, Belgium.
2 Nuclear Medicine and Molecular Imaging, University Hospital Leuven, Leuven, Belgium.
3 Department of Imaging and Pathology, KU Leuven, Leuven, Belgium.
Received 23 April 2018. Revision received 22 June 2018.
Accepted 14 July 2018.
S.E.V. is sponsored by a grant from the FWO (FWO12G8715N, 1500617N, 1515816N) and KU Leuven (C24/18/073). B.M.V. is funded by the KU Leuven (C24/050). R.V. is supported by a UZ Leuven starting grant (STG015/23) and FWO (12G8715N). G.M.V. is supported by the “Broere foundation.” O.G. is supported by the FWO (senior clinical investigator 1831817N).
The authors declare no conflicts of interest.
S.E.V., O.G., and R.V. participated in research design. S.E.V., O.G., K.E.G., R.V. participated in the writing of the article. S.E.V., O.G., K.E.G., B.M.V., D.E.V.R., G.M.V., R.V. participated in the performance of the research. E.K.V. and B.W. contributed new reagents or analytic tools S.E.V., O.G., and R.V. participated in data analysis.
Correspondence: Robin Vos, K U Leuven, Lung Transplantation Unit, 49 Herestraat, B-3000 Leuven, Belgium. (firstname.lastname@example.org).