PET/CT Scan as a Surrogate for Treatment Outcomes in Pulmonary Sarcoidosis

Abstract Background: One of the challenges in treating sarcoidosis is that there is currently no reliable modality to measure disease activity and prognosis. This study was conducted to determine if PET/CT scans could be used to evaluate clinical response to sarcoidosis treatment. Methods: In a retrospective cohort study, subjects with symptomatic pulmonary sarcoidosis followed by the University of Miami Sarcoidosis program from 2015 through 2018 were assessed. Inclusion criteria were subjects ≥18 years who had histologically-confirmed pulmonary sarcoidosis for ≥2 years. Subjects that had PET/CT scans completed prior to starting treatment and approximately one year later were enrolled. Demographics, circulatory blood biomarkers, subjective symptoms, and medications were recorded at baseline (T0) and a year later (T1). Results: Ten subjects with symptomatic pulmonary sarcoidosis were enrolled. All subjects had at least one organ affected by sarcoidosis and a highest of five organs involved (mean 2.75, SD 1.21). Mean serum angiotensin-converting enzyme (ACE) level was 56.0 U/L (SD 43.08), mean lysozyme was 7.78 µg/mL (SD 3.78), and mean C-reactive protein (CRP) was 0.73 mg/dL (SD 0.85) at T0. Further, mean number of positive lesions was 4.27 (SD 2.65) and mean highest SUV was 5.59 (SD 3.59), with a highest of 14.5 at T0. After one year of therapy, a significant improvement in measured outcomes was noted. Dyspnea was absent in all subjects at T1 and only 1 (10%) reported cough at T1. The mean ACE was 42.17 U/L (SD 20.24), mean lysozyme was 6.24 µg/mL (SD 0.80), and mean CRP was 1.67 mg/dL (SD 1.60) at T1. Furthermore, five (50%) subjects were receiving a reduced dose of their respective medication at T1. In terms of PET/CT findings, the mean number of positive lesions decreased at T1 to 1.73 (SD 2.87) and the mean highest SUV decreased to 2.18 (SD 3.3). Conclusion: PET/CT scans can be used as a surrogate modality to help guide treatments in those subjects affected by sarcoidosis, as shown by significant reductions in the involvement of multiple organs. Further studies with larger sample sizes are necessary to explore the potential PET/CT scans have to influence treatment outcomes in sarcoidosis.