1 University of Lübeck, Department of Radiology and Nuclear Medicine, University Hospital Schleswig-Holstein, Campus Lübeck, Germany. Electronic address: franz.wegner@uksh.de.
2 University of Giessen, Department of Internal Medicine and Rheumatology, Kerckhoff Clinic, Bad Nauheim, Germany.
3 Goethe University, Division of Rheumatology, University Hospital Frankfurt, Frankfurt am Main, Germany.