Brown fat uptake of 18F-FDG on dual time point PET/CT imaging

The aim of this report was to assess the changes in the 18F-fluorodeoxyglucose (18F-FDG) uptake of brown fats on integrated positron emission tomography/computed tomography (PET/CT) imaging. The patient presented with an enlargement of the neck lymph nodes, and was suspicious for tuberculous lymphadenitis. A whole body PET/CT imaging was performed, followed by a delayed imaging of the neck and thoracic regions. A visually increased 18F-FDG uptake was taken as a positive finding. A semi-quantitative evaluation was performed using a maximum standardised uptake value (SUVmax), with a cut-off value above 2.5. There were a number of 18F-FDG avid activity areas seen at the supraclavicular, mediastinal, paravertebral and perirenal regions. These are in keeping with the physiological 18F-FDG uptake in brown fat. The differences in SUVmax between the two images ranged from -20 percent to +20 percent. Based on our observations, dual time point imaging may not be a reliable method for assessing the 18F-FDG uptake of brown fat.

Whole Body Imaging Using 18-Fluorine Fluorodeoxyglucose (18F-FDG) Positron Emission Tomography/Computed Tomography (PET/CT) with or without Contrast Enhanced Computed Tomography (CT) in Dignosing Arteritis

Introduction: Takayasu's Arteritis and Horton's Arteritis are two rare cases of auto-immune complex diseases resulting in sterile inflammatory reactions affecting the wall of large and medium sized arteries. Various radiological and interventional methods employed are inconclusive and become diagnostic only when complications begin to set in. The new non-invasive hybrid Positron Emission Tomography Computed Tomography (PET/CT) using 18Florine-Fluorodeoxyglucose (18F-FDG) imaging technique could detect arteritis in an early clinical stage when routine conventional cross-sectional imaging was inconclusive. Method: Two cases from Klagenfurt Hospital, Austria and Milan General Hospital, Italy were compared with image acquisition being done in the respective hospitals. In Klagenfurt, PET/CT image acquisition was performed using intravenous contrast administration and in Milan, CT parameters were used as attenuation correction and anatomical correlation of PET images. Results: CT performed using both methods, with or without iodinated contrast media, were useful in detecting arteritis. Conclusion: It is concluded that PET/CT aside from being a useful tool in cancer imaging, is also useful for pyrexia of unknown origin. PET/CT should be employed early in managing this clinical condition where arteritis is a possible diagnosis.

18F-FDG positron emission tomography/computed tomography and the "underground map" appearance in imaging Horton's arteritis

A majority of the clinical use of positron emission tomography (PET)-computed tomography (CT) is related to cancer management. Its application in evaluating inflammatory diseases and pyrexia of unknown origin is becoming popular. We reviewed the fluorine-18-fluorodeoxyglucose PET-CT findings of an 80-year-old woman with nonspecific clinical presentation consisting of generalised malaise, moderately high fever and weight loss. Prior CT and magnetic resonance imaging were not helpful in providing a clinical diagnosis. The diagnosis was Horton's arteritis, and the patient responded well to high-dose steroids.