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Introduction Immune-mediated interstitial pneumonitis may be treated with anti-CD20 therapy after failure of conventional therapies. However, clinical response is variable. It was hypothesized that autoreactive CD20-positive cells may play an important role in this variability. This prospective study aims to elucidate if imaging of CD20-positive cells in the lungs allows prediction of the response to anti-CD20 treatment. Methods Twenty-one patients with immune-mediated interstitial lung disease (ILD) with deteriorated pulmonary function received a dose of 1000 mg rituximab on day 1 and day 14 spiked with a tracer dose of radiolabeled [89Zr]-rituximab. PET/CT was performed on days 3 and 6. Standardized uptake values (SUV) were calculated as a measure for pulmonary CD20 expression. Based on pulmonary function tests (PFT), forced vital capacity (FVC), and diffusing capacity for carbon monoxide (DLCO), prior to and 6 months after treatment, patients were classified as responder (stable disease or improvement) or non-responder. Results Fifteen patients (71%) were classified as responder. Pulmonary [89Zr]-rituximab PET SUVmean was significantly correlated with the change in FVC and DLCO (K = 0.49 and 0.56, respectively) when using target-to-background ratios, but not when using SUVmean alone. [89Zr]-rituximab SUVmean was significantly higher in responders than in non-responders (0.35 SD 0.09 vs. 0.23 SD 0.06; P = 0.02). Conclusion Rituximab treatment was effective in the majority of patients. As a higher pulmonary uptake of [89Zr]-rituximab correlated with improvement of PFT and treatment outcome, [89Zr]-rituximab PET imaging may serve as a potential predictive biomarker for anti-CD20 therapy. Trial registration Clinicaltrials.gov identifier NCT02251964

The aim of this study was to investigate sensitivity of 67Ga imaging and 18F-FDG PET for sarcoidosis activity and their inter observer variability.Thirty-four newly diagnosed, histologically proven sarcoidosis patients were analyzed prospectively. (67)Ga imaging and (18)F-FDG PET were performed, the presence of pulmonary and extra pulmonary lesions was evaluated and inter observer variability of both techniques was assessed.Overall sensitivity to detect active sarcoidosis was 88% for (67)Ga imaging and 97% for (18)F-FDG PET. Although these results were not significantly different, 18F-FDG PET detected more lesions in the mediastinum (P0.05), hila (P0.05), lymph nodes (P0.001) and extra pulmonary regions in general (P0.001). Inter observer agreement was poor to moderate for (67)Ga imaging (kappa 0.19-0.59) and good to very good for (18)F-FDG PET (kappa 0.65-1.00).(18)F-FDG PET is more sensitive than (67)Ga imaging in the assessment of sarcoidosis activity with regard to the mediastinum, hila, lymph nodes and extra pulmonary lesions in general. Furthermore, (18)F-FDG PET demonstrates a very good inter observer agreement in contrast with (67)Ga imaging and (18)F-FDG PET is therefore the nuclear imaging technique of choice in sarcoidosis assessment.