title: Fever of unknown origin: prospective comparison of diagnostic value of 18F-FDG PET and 111In-granulocyte scintigraphy.
abstract: The diagnostic work-up in patients with fever of unknown origin (FUO) is often challenging and frequently includes nuclear medicine procedures. Whereas a role for leucocyte or granulocyte scintigraphy in FUO is generally accepted, a possible role of fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) in these patients remains to be established. To study this, we compared prospectively, on a head-to-head basis, the diagnostic value of FDG-PET and indium-111 granulocyte scintigraphy in patients with FUO. Nineteen patients with FUO underwent both FDG-PET and (111)In-granulocyte scintigraphy within 1 week. FDG-PET scans and granulocyte scintigrams were reviewed by different doctors who were blinded to the result of the other investigation. The diagnostic values of FDG-PET and granulocyte scintigraphy were evaluated with regard to identification of a focal infectious/inflammatory or malignant cause of FUO. The sensitivity of granulocyte scintigraphy and FDG-PET were 71% [95% confidence interval (CI): 37-85%] and 50% (CI: 16-84%), respectively. The specificity of granulocyte scintigraphy was 92% (71-100%), which was significantly higher than that of FDG-PET, at 46% (34-62%). Positive and negative predictive values for granulocyte scintigraphy were both 85%. Positive and negative predictive values for FDG-PET were 30% and 67%, respectively. (111)In-granulocyte scintigraphy has a superior diagnostic performance compared to FDG-PET for detection of a localised infectious/inflammatory or neoplastic cause of FUO. The poorer performance of FDG-PET is in particular attributable to a high percentage of false positive scans, leading to low specificity.
authors.affiliation: Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen, Denmark. kjaer@mfi.ku.dk
authors.forename: Andreas
authors.initials: A
authors.lastname: Kjaer
authors.forename: Anne-Mette
authors.initials: AM
authors.lastname: Lebech
authors.forename: Annika
authors.initials: A
authors.lastname: Eigtved
authors.forename: Liselotte
authors.initials: L
authors.lastname: Højgaard
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005335:Fever of Unknown Origin / Q000097:blood / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000209:etiology*; D019788:Fluorodeoxyglucose F18; D006098:Granulocytes / Q000000981:diagnostic imaging*; D006801:Humans; D007205:Indium Radioisotopes; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D007205:Indium Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18