title: Correlation of spleen metabolism assessed by 18F-FDG PET with serum interleukin-2 receptor levels and other biomarkers in patients with untreated sarcoidosis.
abstract: BACKGROUND
  The objective of our study was to assess the possible relationship between splenic F-18-fluorodeoxyglucose (18F-FDG) uptake and other established biochemical markers of sarcoidosis activity.
  
  
  METHODS
  Thirty treatment-naive sarcoidosis patients were prospectively enrolled in this study. They underwent biochemical laboratory tests, including serum interleukin-2 receptor (sIL-2R), serum C-reactive protein, serum angiotensin-I converting enzyme, and 24-h urine calcium levels, and a whole-body combined 18F-FDG PET/computed tomography (PET/CT) scan as a part of an ongoing study at our institute. These biomarkers were statistically compared in these patients.
  
  
  RESULTS
  A statistically significant linear dependence was detected between sIL-2R and log-transformed spleen-average standard uptake value (SUV avg) (R2=0.488, P<0.0001) and log-transformed spleen-maximum standard uptake value (SUV max) (R2=0.490, P<0.0001). sIL-2R levels and splenic size correlated linearly (Pearson's r=0.373, P=0.042). Multivariate linear regression analysis revealed that this correlation remained significant after age and sex adjustment (β=0.001, SE=0.001, P=0.024). No statistically significant associations were detected between (a) any two serum biomarkers or (b) between spleen-SUV measurements and any serum biomarker other than sIL-2R.
  
  
  CONCLUSIONS
  Our analysis revealed an association between sIL-2R levels and spleen 18F-FDG uptake and size, whereas all other serum biomarkers were not significantly associated with each other or with PET 18F-FDG uptake. Our results suggest that splenic inflammation may be related to the systemic inflammatory response in sarcoidosis that may be associated with elevated sIL-2R levels.
authors.affiliation: aDepartment of Pulmonary Medicine, Division of Pulmonary and Critical Care Medicine, 401 Military and VA Hospital bDepartment of Nuclear Medicine, 251 General Airforce and VA Hospital cDepartment of Nuclear Medicine and PET/CT, Evangelismos Hospital dDepartment of Medicine, Medical Physics Laboratory Simulation Centre, University of Athens, Athens eDepartment of Respiratory Medicine, University of Thessaly, Larisa, Greece fDepartment of Medicine, Albany Medical College, Albany, New York, USA.
authors.forename: Alexandros
authors.initials: A
authors.lastname: Kalkanis
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Kalkanis
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Drougas
authors.forename: George D
authors.initials: GD
authors.lastname: Vavougios
authors.forename: Ioannis
authors.initials: I
authors.lastname: Datseris
authors.forename: Marc A
authors.initials: MA
authors.lastname: Judson
authors.forename: Evangelos
authors.initials: E
authors.lastname: Georgiou
mesh_terms: D000328:Adult; D001692:Biological Transport; D015415:Biomarkers / Q000097:blood; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D049268:Positron-Emission Tomography; D015375:Receptors, Interleukin-2 / Q000097:blood*; D012507:Sarcoidosis / Q000097:blood / Q000000981:diagnostic imaging* / Q000378:metabolism*; D013154:Spleen / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D015375:Receptors, Interleukin-2; D019788:Fluorodeoxyglucose F18