Clinical utility of 18fluorodeoxyglucose positron emission tomography-computed tomography in rheumatology

Background: Several studies with 18fluorodeoxyglucose positron emission tomography with computed tomography (18FDG PET-CT) have indicated that 18fluorodeoxyglucose uptake in affected tissues reflects the disease activity. In addition, the usage of PET-CT for early detection, extent and monitoring of the treatment response has been reported. Methods: In this retrospective study, all 18FDG PET-CTs requested by rheumatologists were reviewed retrospectively. The clinical findings and scan findings were noted. Considering the final diagnosis made by the clinician as "gold standard", he sensitivity, specificity and positive were calculated. Results: Out of 48, 18FDG PET-CT requests, two were excluded (39 females, mean age - 39.22 ± 15.349). The indications included establishing diagnosis (n = 31 [67.4%]) and disease activity/extent (n = 15 [32.6%]). It contributed to the diagnosis in 9 (31%), when 18F FDG PETCT is used for establishing the diagnosis. It identified abnormalities in 14/15 when used for disease activity and active disease was identified in 10. Seventeen patients had a final diagnosis of fibromyalgia. Overall, 18FDG PET-CT had 100 sensitivity and NPV. The diagnostic accuracy was 56.52%. Conclusions: The 18FDG PET-CT has high diagnostic sensitivity and poor specificity in rheumatology practice with respect to establishing the diagnosis as well as to detect the extent and activity of disease.