Abstract
White blood cells activated by either a pathogen or as part of a systemic inflammatory disease are characterized by high energy consumption and are therefore taking up the glucose analogue PET tracer FDG avidly. It is therefore not surprising that a steadily growing body of research and clinical reports now supports the use of FDG PET/CT to diagnose a wide range of patients with non-oncological diseases. However, using FDG PET/CT in patients with infectious or inflammatory diseases has some limitations and potential pitfalls that are not necessarily as pronounced in oncology FDG PET/CT. Some of these limitations are of a general nature and related to the laborious acquisition of PET images in patients that are often acutely ill, whereas others are more disease-specific and related to the particular metabolism in some of the organs most commonly affected by infections or inflammatory disease. Both inflammatory and infectious diseases are characterized by a more diffuse and less pathognomonic pattern of FDG uptake than oncology FDG PET/CT and the affected organs also typically have some physiological FDG uptake. In addition, patients referred to PET/CT with suspected infection or inflammation are rarely treatment naïve and may have received varying doses of antibiotics, corticosteroids or other immune-modulating drugs at the time of their examination. Combined, this results in a higher rate of false positive FDG findings and also in some cases a lower sensitivity to detect active disease. In this review, we therefore discuss the limitations and pitfalls of FDG PET/CT to diagnose infections and inflammation taking these issues into consideration. Our review encompasses the most commonly encountered inflammatory and infectious diseases in head and neck, in the cardiovascular system, in the abdominal organs and in the musculoskeletal system. Finally, new developments in the field of PET/CT that may help overcome some of these limitations are briefly highlighted.
Highlights
Because white blood cells and other inflammatory cells that are recruited to infected and inflamed tissue have a high glucose metabolism compared to other cells, many infectious and inflammatory diseases are often readily visible on FDGPET/CT
We have previously demonstrated that dynamic whole body (D-WB) is feasible in a clinical setting and it is possible that the technique will be of particular interest in for example, patients with inflammatory diseases such as suspected vasculitis.[83]
There are various caveats that need to be taken into account when performing FDG-positron emission tomography (PET)/CT and interpreting elevated FDG uptake
Summary
The use of nuclear imaging for diagnosing infectious and inflammatory diseases has yMedical Imaging Center, Departments of Radiology, Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen. In cancer patients with suspected infection, it can be challenging to distinguish pulmonary metastases from septic emboli, as both can feature multiple small FDG avid nodules.[57] due to the relatively low spatial resolution of 4 to 6 millimeters of FDG-PET/CT and partial volume effect, small lesions may not be detected.[58,59]. It may be difficult to distinguish infection from mildly elevated FDG uptake associated with degenerative changes, but the distinction can usually be made based on the exact localization of elevated FDG uptake (ie, intervertebral disc in case of spondylodiscitis) and clinical presentation.[76] Another important indication for performing FDG-PET/ CT can be suspected infection of osteosynthesis material. This would benefit the detection of smaller inflamed vessels such as in Kawasaki arteritis and potentially inflamed cranial vessels in large vessel vasculitis.[54,89] Lastly, it would enable dynamic imaging of (almost the) the whole body, depending on the length of the detector tube
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
