Evaluation of FDG-PET/CT Use in Children with Suspected Infection or Inflammation

F18-FDG PET-CT Findings in Juvenile-Onset Polyarteritis Nodosa: A First Series and Literature Review

Objectives: To investigate the findings associated with juvenile polyarteritis nodosa (PAN) on F18-FluoroDeoxyglucose (FDG), positron emission tomography combined with computed tomography (PET-CT). Methods: Patients diagnosed with juvenile PAN (onset <18 years) who underwent a PET-CT at diagnosis (before therapy) were enrolled. PET-CT images were systematically analyzed to identify abnormal findings associated with PAN. In addition, a systematic literature review was performed to identify previously published cases. Results: Six patients with biopsy-confirmed PAN were identified (age at onset 10-17 years). PET-CT was abnormal in all patients. Patchy muscular and subcutaneous FDG uptake with a symmetric distribution in the lower limbs was present in 4/6 patients. Increased FDG uptake in large arteries was found in 1/6 patients. FDG-avid bone lesions were identified in 2/6; additional MRI and bone biopsy results were consistent with chronic non-infectious osteomyelitis (CNO). Unspecific inflammatory findings (medullar and lymphoid organs hypermetabolism) were present in 6/6; these were the only abnormalities present in 2/6 patients. We found this pattern of PET-CT muscular involvement to differ from juvenile dermatomyositis and septic emboli (n = 7 and 2 patients, respectively). In addition, we identified four previously published cases of juvenile PAN investigated with PET-CT: one with FDG-avid muscular and subcutaneous foci, one with increased uptake in large arteries, and two with nonspecific signs (lymphoid organs hypermetabolism). Conclusions: This is the first series of juvenile PAN investigated with PET-CT. Diffuse, patchy hypermetabolic foci in the muscular and subcutaneous tissue of the lower limbs were the most common findings. These features should lead to suspicion of PAN. Further research is needed to assess the diagnostic value of PET-CT in PAN.

Role of FDG PET/CT in bacteremia and fever of unknown origin: a pictorial overview of finding the culprit

18F fluorodeoxyglucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) has established itself as a critical diagnostic tool in the evaluation of patients with bacteremia and fever of unknown origin (FUO), particularly following futile conventional investigations. These conditions are often challenging due to diverse underlying etiologies, including infections, inflammatory conditions and malignancies. PET/CT has the advantage of being a whole-body imaging technique with high sensitivity for detecting areas of increased metabolism often associated with infection or inflammation. In bacteremia, [18F]FDG PET/CT can help identify metastatic infections, endocarditis, or abscesses which may be clinically silent and missed on conventional imaging. In FUO, it helps to identify underlying etiologies, directing treatment and management strategies. This review aims to describe the role of PET/CT imaging in these diverse clinical scenarios. Perspectives in the field, including novel equipment and tracers, will be briefly discussed.

[18F]FDG PET/CT for identifying the causes of fever of unknown origin (FUO)

Fever of unknown origin (FUO) continues to be a challenging diagnosis in clinical medicine. It has more than 200 known causes, including infections, autoimmune diseases, neoplasia, and other miscellaneous disorders. Despite the development of a wide range of diagnostic tools, a specific diagnostic algorithm for FUO is not yet available. However, [18F]FDG PET/CT, which yields information on cellular metabolism, in addition to details of organ anatomy, has been shown to be successful in the FUO investigation. This study highlights the uses of [18F]FDG PET/CT in diagnosing various causes of FUO. [18F]FDG PET/CT has been increasingly used to detect septic infections, sterile inflammatory processes, and malignancies, occupying a significant portion of the known causes of FUO. It has led to a more definitive identification of the etiology of FUO and accurate clinical management. However, more in-depth studies are crucial to understanding if [18F]FDG PET/CT can be used in the work-up of FUO.

Long axial field of view PET/CT in critically ill patients: lessons from a case report

The introduction of new long axial field of view (LAFOV) scanners is a major milestone in positron emission tomography/computed tomography (PET/CT) imaging. With these new systems a revolutionary reduction in scan time can be achieved, concurrently lowering tracer dose. Therefore, PET/CT has come within reach for groups of patients in whom PET/CT previously was undesirable. In this case report we discuss the procedure of a continuous bed motion (CBM) total-body [18F]FDG PET/CT scan in an intensive care patient. We emphasize the clinical and technical possibilities with this new camera system, a matched clinical protocol, and the added value of a dedicated team.

Advanced Imaging for Detection of Foci of Infection in Staphylococcus aureus Bacteremia- Can a Scan Save Lives?

Bloodstream infection or sepsis is a common cause of mortality globally. Staphylococcus aureus (S. aureus) is of particular concern, through its ability to seed metastatic infections in almost any organ after entering the bloodstream (S. aureus bacteraemia), often without localising signs. A positive blood culture for S. aureus bacteria should lead to immediate and urgent identification of the cause. Failure to detect a precise focus of infection is associated with higher mortality, sometimes despite appropriate antibiotics. This is likely due to the limited ability to effectively target therapy in occult lesions. Early detection of foci of metastatic S. aureus infection is therefore key for optimal diagnosis and subsequent therapeutic management. 18F-FDG-PET/CT and MRI offer us invaluable tools in the localisation of foci of S. aureus infection. Crucially, they may identify unexpected foci at previously unsuspected locations in the body, for example vertebral osteomyelitis in the absence of back pain. S. aureus bloodstream infections are further complicated by their microbiological recurrence; 18F-FDG-PET/CT provide a means of localising, thus enabling source control. More evidence is emerging as to the utility of 18F-FDG-PET/CT in this setting, perhaps even to the point of reducing mortality. 18 F-FDG-PET/MRI may have a similar impact. The available evidence demonstrates a need to investigate the impact of 18F-FDG-PET/CT and MRI scanning in clinical management and outcomes of S. aureus infection further in a randomised prospective clinical trial.

18 F-FDG PET/CT imaging for haemophilic arthropathy compared with clinical, radiological and power Doppler sonographic characteristics of 20 haemophilia patients

INTRODUCTION AND OBJECTIVES

Repeated joint bleeding in haemophilia patients may lead to haemophilic arthropathy with marked inflammation and synovitis. This study investigated the potential of ¹⁸ F-fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸ F-FDG PET/CT) as a novel diagnostic method for haemophilic arthropathy.

MATERIALS AND METHODS

We recruited 20 adult haemophilia patients who reported history of hemarthroses in the shoulder, elbow, hip, knee, or ankle joints. All joints were assessed by power Doppler ultrasonography and radiography, and graded by hyperaemia score and Pettersson score, respectively. Joint pain was evaluated by visual analogue score (VAS). Range of motion (ROM), Haemophilia Joint Health Score (HJHS) and annual joint bleeding rate (AJBR) were recorded. Finally, all participants had whole-body ¹⁸ F-FDG PET/CT, and maximum standardized uptake value (SUVmax) of the joints being studied was measured.

RESULTS

Thirteen patients had severe haemophilia, and seven had moderate haemophilia. The mean age was 36 years. PET SUVmax showed significant correlations with VAS, ROM, Pettersson score, hyperaemia score, HJHS score and AJBR in all large joints except hip. Joints with pain, hyperaemia and radiographic changes were found to have higher SUVmax than those without these features. Using Youden's index, the optimal cut-off value for early radiographical arthropathy was found to be between 1.9 and 2.0.

CONCLUSION

Our study indicates that ¹⁸ F-FDG PET/CT imaging correlated well with various conventional diagnostic techniques. It also demonstrated high sensitivity and specificity for early radiographic arthropathy. ¹⁸ F-FDG PET/CT imaging may quantitatively evaluate disease activity of most large joints in a single examination and help detect early haemophilic arthropathy.