Author(s): Meller J, Altenvoerde G, Munzel U, Jauho A, Behe M,
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Abstract Gallium-67 citrate is currently considered as the tracer of first choice in the diagnostic workup of fever of unknown origin (FUO). Fluorine-18 2'-deoxy-2-fluoro-D-glucose (FDG) has been shown to accumulate in malignant tumours but also in inflammatory processes. The aim of this study was to prospectively evaluate FDG imaging with a double-head coincidence camera (DHCC) in patients with FUO in comparison with planar and single-photon emission tomography (SPET) 67Ga citrate scanning. Twenty FUO patients underwent FDG imaging with a DHCC which included transaxial and longitudinal whole-body tomography. In 18 of these subjects, 67Ga citrate whole-body and SPET imaging was performed. The 67Ga citrate and FDG images were interpreted by two investigators, both blinded to the results of other diagnostic modalities. Forty percent (8/20) of the patients had infection, 25\% (5/20) had auto-immune diseases, 10\% (2/20) had neoplasms and 15\% (3/20) had other diseases. Fever remained unexplained in 10\% (2/20) of the patients. Of the 20 patients studied, FDG imaging was positive and essentially contributed to the final diagnosis in 11 (55\%). The sensitivity of transaxial FDG tomography in detecting the focus of fever was 84\% and the specificity, 86\%. Positive and negative predictive values were 92\% and 75\%, respectively. If the analysis was restricted to the 18 patients who were investigated both with 67Ga citrate and FDG, sensitivity was 81\% and specificity, 86\%. Positive and negative predictive values were 90\% and 75\%, respectively. The diagnostic accuracy of whole-body FDG tomography (again restricted to the aforementioned 18 patients) was lower (sensitivity, 36\%; specificity, 86\%; positive and negative predictive values, 80\% and 46\%, respectively). 67Ga citrate SPET yielded a sensitivity of 67\% in detecting the focus of fever and a specificity of 78\%. Positive and negative predictive values were 75\% and 70\%, respectively. A low sensitivity (45\%), but combined with a high specificity (100\%), was found in planar 67Ga imaging. Positive and negative predictive values were 100\% and 54\%, respectively. It is concluded that in the context of FUO, transaxial FDG tomography performed with a DHCC is superior to 67Ga citrate SPET. This seems to be the consequence of superior tracer kinetics of FDG compared with those of 67Ga citrate and of a better spatial resolution of a DHCC system compared with SPET imaging. In patients with FUO, FDG imaging with either dedicated PET or DHCC should be considered the procedure of choice.
This article was published in Eur J Nucl Med
and referenced in Internal Medicine: Open Access