Diagnostic utility of fluorodeoxyglucose positron emission tomography/computed tomography in pyrexia of unknown origin

Abstract

Purpose of the Study:The present study was undertaken to evaluate the diagnostic utility of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) in patients presenting as pyrexia of unknown origin (PUO).Materials and Methods:Forty-seven patients (31 males and 16 females; mean age of 42.7 ± 19.96 years) presenting as PUO to the Department of Medicine at the All India Institute of Medical Sciences, New Delhi over a period of 2 years underwent F-18 FDG PET/CT. PET ⁄ CT was considered supportive when its results correlated with the final definitive diagnosis. Final diagnosis was made on the basis of combined evaluation of history, clinical findings, investigations, and response to treatment.Results:Thirty-five PET/CT studies (74.5%) were positive. However, only 18 (38.3%) were supportive of the final diagnosis. In three patients (6.4%), PET/CT was considered diagnostic as none of the other investigations including contrast-enhanced computed tomography of chest and abdomen, and directed tissue sampling could lead to the final diagnosis. All these three patients were diagnosed as aortoarteritis.Conclusion:Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography is an important emerging modality in the workup of PUO. It supported the final diagnosis in 38% of our patients and was diagnostic in 6.4% of patients. Thus, PET/CT should only be considered as second-line investigation for the diagnostic evaluation of PUO; especially in suspected noninfectious inflammatory disorders.

Diagnostic Value of 18F-FDG-PET/CT in Patients with FUO

“…The percentage of patients diagnosed with malignancies in our study was quite low (16%), similar to that observed in many previous studies [ 21 , 27 , 28 , 32 ], which could be explained by the widespread early use of cross-sectional imaging (ultrasound CT, MRI) resulting in a reduction of cases of malignancies presented as FUO. Non-Hodgkin’s lymphoma was the most common malignant cause of FUO in our study, as in previous studies [ 27 , 35 , 36 ].…”

“…18 F-FDG, as a non-specific indicator of increased glycolytic metabolism, is concentrated not only in infectious sites but also in NIID and in neoplasms, all being possible causes of FUO. Several studies support the use of 18 F-FDG-PET in the assessment of FUO [ 12 , 13 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 32 , 33 , 34 , 35 , 36 , 37 ]. Moreover, an abnormal 18 F-FDG-PET/CT scan, as part of a structured diagnostic protocol for FUO, has been shown to be among the significant predictors for reaching a diagnosis [ 32 ].…”

“…In the present study, NIID was the second leading cause of FUO (22%), with large-vessel vasculitis being the most common cause in this group of patients. The high diagnostic yield of 18 F-FDG-PET/CT in detecting active large-vessel vasculitis (LVV) has been convincingly shown [ 20 , 28 , 33 , 35 ], and the investigation of patients suspected for LVV is currently among the major non-oncological indications of 18 F-FDG-PET/CT [ 38 ].…”

“…Several studies indicate the potential contributory role of both 18 F-FDG-PET alone [ 12 , 13 , 20 , 21 , 22 , 23 ] and 18 F-FDG-PET/CT [ 24 , 25 , 26 , 27 , 28 ] in the management of patients of FUO. However, the representativeness of the populations studied may be questionable as in the majority of the Northwestern European studies NIID is the leading causes of FUO, whereas in those coming from Asia, infections are more common, with tuberculosis predominating.…”

Individualized management of pyrexia of unknown origin: Will fludeoxyglucose-positron emission tomography/computed tomography emerge as the imaging common-point in the algorithm?

“…[ 1 2 ] In a study in an Indian setting, the overall estimated rate was found to be 38%,[ 9 ] akin to the reported literature. The major advantage can be observed in investigating NIID,[ 6 7 8 9 10 11 12 ] which is in recent times one of the single most identifiable causes of PUO and relatively unaddressed by the morphological cross-sectional imaging modalities. Particularly in situations such as vasculitis, metabolic FDG-PET/CT demonstrates great promise not only from diagnosis but also from the treatment monitoring viewpoint.…”