Gallium scanning in children with fever of unknown origin

Update on Pediatric Nuclear Medicine in Acute Care

Various radiopharmaceuticals are available for imaging pediatric patients in the acute care setting. This article focuses on the common applications used on a pediatric patient in acute care. To confirm the clinical diagnosis of brain death, brain scintigraphy is considered accurate and has been favorably compared with other methods of detecting the presence or absence of cerebral blood flow. Ventilation-perfusion lung scans are easy and safe to perform with less radiation exposure than computed tomography pulmonary angiography and remain an appropriate procedure to perform on children with suspected pulmonary embolism as a first imaging test in a hemodynamically stable patient with no history of lung disease and normal chest radiograph. 99mTc-pertechnetate scintigraphy (Meckel's scan) is the best noninvasive procedure to establish the diagnosis of ectopic gastric mucosa in Meckel's diverticulum. 99mTcred blood cell scintigraphy generally is useful for assessing lower GI bleeding in patients from any cause. Hepatobiliary scintigraphy is the most accurate diagnostic imaging modality for acute cholecystitis. 99mTc-dimercaptosuccinic acid scintigraphy is the simplest, and the most reliable and sensitive method for the early diagnosis of focal or diffuse functional cortical damage. 99mTcmercaptoacetyltriglycine scintigraphy is used to evaluate for early and late complications of renal transplantation. Bone scintigraphy is a sensitive and noninvasive technique for diagnosis of bone disorders such as osteomyelitis and fracture. 18F-fluorodeoxyglucose-positron emission tomography could be valuable in the evaluation of fever of unknown origin in pediatric patients, with better sensitivity and significantly less radiation exposure than a gallium scan. Moving forward, further refinement of pediatric radiopharmaceutical administered activities, including dose reduction, greater radiopharmaceutical applications, and updated consensus guidelines is warranted, with the use of radionuclide imaging likely to increase.

FDG PET in Evaluation of Patients With Fever of Unknown Origin: AJR Expert Panel Narrative Review

Fever of unknown origin (FUO) is a diagnostic challenge, with its cause remaining undiagnosed in approximately half of patients. Nuclear medicine tests typically are performed after a negative or inconclusive initial workup. Gallium-67 citrate and labeled leukocytes were previous mainstays of radionuclide imaging for FUO, although they had limited diagnostic performance. FDG PET/CT has subsequently emerged as the nuclear medicine imaging test of choice, supported by a growing volume of evidence. A positive FDG PET/CT result contributes useful information by identifying potential causes of fever, localizing sites for further evaluation, and guiding further management; a negative result contributes useful information by excluding focal disease as the cause of fever and predicts a favorable prognosis. In 2021, CMS rescinded a prior national noncoverage determination for FDG PET for infection and inflammation, leading to increasing national utilization of FDG PET/CT for FUO workup. This article reviews the current status of the role of FDG PET/CT in the evaluation of patients with FUO. The literature reporting the diagnostic performance and yield of FDG PET/CT in FUO workup is summarized, with comparison with historically used nuclear medicine tests included. Attention is also given to the test's clinical impact; protocol, cost, and radiation considerations; and application in children.

Search of Unknown Fever Focus Using PET in Critically Ill Children With Complicated Underlying Diseases

OBJECTIVES

PET/CT with F-fluorodeoxyglucose can be used to image cellular metabolism and has been used for evaluating fever of unknown origin in adults. However, there are limited studies about the role of F-fluorodeoxyglucose PET/CT in evaluation of fever of unknown origin in critically ill children, especially those presenting with complicated underlying diseases under treatment. Here, we report our preliminary experience using F-fluorodeoxyglucose PET/CT in this specific group of patients.

DESIGN

Retrospective observational study.

SETTING

PICUs of a university hospital.

PATIENTS

Nineteen critically ill children (mean age, 5.7 yr old) with complicated underlying diseases requiring intensive care support underwent F-fluorodeoxyglucose PET/CT to evaluate fever of unknown origin. The median hospitalized stay was 34 days (range, 15-235 d) and fever of at least 7 days (mean, 21.6 d; range, 7-52 d). The PET scan was advocated after all routine microbiology, and conventional imaging showed negative or inconclusive results.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The F-fluorodeoxyglucose PET/CT findings (blinded to the final clinical diagnosis) were compared with final histopathology, culture, serology results, or follow-up imaging. A final diagnosis was made in 16 patients (84.2%). F-fluorodeoxyglucose PET/CT accurately localized the source of fever in 14 patients, confers to a sensitivity of 87.5% (14 of 16; 95% CI, 0.604-0.978). A false-positive scan in a patient led to subsequent unnecessary investigations. Two false-negative F-fluorodeoxyglucose PET/CT images were later attributed to relapse of underlying disease in the bone marrow and renal abscesses, respectively. In the other two patients where F-fluorodeoxyglucose PET/CT also showed negative findings, fever subsided shortly thereafter without treatment.

CONCLUSIONS

Our preliminary experience suggests that F-fluorodeoxyglucose PET/CT may be clinically beneficial in evaluating fever of unknown origin in children with complicated underlying diseases mandating intensive support in ICUs if usual investigative methods are unsuccessful. Further large prospective studies are needed to validate these findings.

Clinical approach to fever of unknown origin in children

BACKGROUND/PURPOSE

Fever of unknown origin (FUO) can be caused by many clinical conditions and remains a diagnostic challenge in clinical practice. The etiology of FUO varies markedly among different age groups, geographic areas, and seasons. A four-stage investigative protocol for FUO is widely applied in clinical practice. The aim of this study was to evaluate the usefulness of this four-stage protocol for identifying the etiology of FUO in children.

METHODS

We enrolled children younger than 18 years of age who were admitted to the Taichung Veterans General Hospital during the period from January 2006 to December 2014 with FUO persisting for more than 3 weeks. The four-stage FUO investigative guideline was used to evaluate the etiology of fever in all patients enrolled in the study.

RESULTS

The etiology of FUO was identified in 79 (84.9%) of the 93 patients enrolled in the study. The most common cause of FUO was infectious disease (37.6%), followed by malignancy (17.2%), miscellaneous disease (16.1%), and collagen vascular disease (14.0%). With respect to the four-stage survey of FUO, 36 of the 79 patients (45.6%) were identified in Stage 3, 28 patients (35.4%) in Stage 2, 13 patients (16.5%) in Stage 4, and only two patients (2.5%) in Stage 1.

CONCLUSION

A well-designed systemic review of the epidemiological information, medical history, physical examination, laboratory analysis, and adequate invasive procedures provide adequate data to identify the most common causes of FUO in children.

Clinical analysis of fever of unknown origin in children: A 10-year experience in a northern Taiwan medical center

BACKGROUND

Fever of unknown origin (FUO) was first described in 1961 as fever >38.3°C for at least 3 weeks with no apparent source after 1 week of investigations in the hospital. Infectious disease comprises the majority of cases (40-60%). There is no related research on FUO in children in Taiwan. The aim of this study is to determine the etiologies of FUO in children in Taiwan and to evaluate the relationship between the diagnosis and patient's demography and laboratory data.

METHODS

Children under 18 years old with fever >38.3°C for >2 weeks without apparent source after preliminary investigations at Taipei Veterans General Hospital during 2002-2012 were included. Fever duration, symptoms and signs, laboratory examinations, and final diagnosis were recorded. The distribution of etiologies and age, fever duration, laboratory examinations, and associated symptoms and signs were analyzed.

RESULTS

A total of 126 children were enrolled; 60 were girls and 66 were boys. The mean age was 6.7 years old. Infection accounted for 27.0% of cases, followed by undiagnosed cases (23.8%), miscellaneous etiologies (19.8%), malignancies (16.6%), and autoimmune disorders (12.7%). Epstein-Barr virus (EBV) and cytomegalovirus (CMV) were the most commonly found pathogens for infectious disease, and Kawasaki disease (KD) was the top cause of miscellaneous diagnosis.

CONCLUSIONS

Infectious disease remains the most common etiology. Careful history taking and physical examination are most crucial for making the diagnosis. Conservative treatment may be enough for most children with FUO, except for those suffering from malignancies.

Functional imaging of infection: conventional nuclear medicine agents and the expanding role of 18-F-FDG PET

A growing body of literature suggests that 18-fluorine fluorodeoxyglucose positron emission tomography ((18)F-FDG PET), particularly when combined with CT, is a useful tool for the detection of infectious and inflammatory disease processes. This article will briefly review the data to date on the use of FDG PET in diagnosing musculoskeletal infections and fever of unknown origin, comparing it to conventional scintigraphic techniques in both adults and, when available, in children.

[Noninfectious febrile inflammatory syndromes in children: diagnosis and usefulness of diagnostic procedures]

OBJECTIVE

To determine the causes and to quantify the benefits obtained from further diagnostic investigations in children presenting with a non infectious inflammatory fever.

METHODS

The records of 62 children aged from two-months to 15 years (median: four years) admitted to a paediatric department between 1990 and 2000 for the evaluation of a fever associated to an inflammatory syndrome, defined as temperature over 38 degrees C with an increase of the erythrocyte sedimentation rate (ESR) more than 20 mm/h and/or a serum C-reactive protein level (CRP) > 20 mg/L, and excluding overt infectious diseases, were retrospectively reviewed.

RESULTS

Of these patients, 79% children (49 cases) had inflammatory systemic disease, 3.2% (two cases) had malignancy, and 17.8% (11 cases) had undiagnosed disorders. The most frequent disease was Kawasaki disease (22 children), especially in young children. Increase of ESR above 100 mm/h and of CRP above 100 mg/L was present in 59% of Kawasaki disease, 71% of idiopathic juvenile arthritis, 100% of malignancies and 7% of unknown diagnoses. Increase of ESR below 50 mm/h and of CRP below 50 mg/L was present in 75% of hemophagocytic syndromes and 46% of unknown diagnosis. The polymorphonuclear count, hepatic function evaluation, triglycerides levels, abdominal ultrasound, abdominal computed tomography, echocardiography, biopsies were useful diagnosis tools. Technetium scintigraphy was helpful only when abnormalities were found on physical examination.

CONCLUSION

The diagnosis of Kawasaki disease must be quickly suspected in febrile young children with inflammatory syndrome without infection. ESR and CRP values, abdominal ultrasound and echocardiography are helpful tools for the diagnostic procedure.

Clinical value of [(18)F]fluoro-deoxyglucose positron emission tomography for patients with fever of unknown origin

We describe the diagnostic contribution of [(18)F]fluoro-deoxyglucose (FDG) positron emission tomography (PET) scan in 58 consecutive cases of fever of unknown origin (FUO) and compare this new approach with gallium scintigraphy. This investigation was performed from March 1996 through October 1998 at Gasthuisberg University Hospital in Leuven, Belgium. A final diagnosis was established for 38 patients (64%). Forty-six FDG-PET scans (79%) were abnormal; 24 of these abnormal scans (41% of the total number of scans) were considered helpful in diagnosis, and 22 (38% of the total number) were considered noncontributory to the diagnosis. In a subgroup of 40 patients (69%), both FDG-PET and gallium scintigraphy were performed. FDG-PET scan and gallium scintigraphy were normal in 23% and 33% of these cases, respectively; helpful in diagnosis in 35% and 25%, respectively; and noncontributory in 42% each. All foci of abnormal gallium accumulation were also detected by use of an FDG-PET scan. We conclude that FDG-PET is a valuable second-step technique in patients with FUO because it yielded diagnostic information in 41% of the patients in whom the probability of a definite diagnosis was only 64%. FDG-PET scan compares favorably with gallium scintigraphy for this indication. Because of the quick results (within hours instead of days), FDG-PET scan may replace gallium scintigraphy as a radiopharmaceutical for the evaluation of patients with FUO.

Fever of unknown origin

The causes of fever in a child can vary from minor brief illnesses to life-threatening infectious, malignant, or autoimmune diseases. The physician often has to evaluate children with fevers of as yet undiagnosed cause lasting fewer than 2 weeks, in whom it is important to determine whether localizing findings are present. Fever without localizing signs and fevers complicating chronic disease and resulting from specific localized infection are considered in the sections concerning infectious causes, immunodeficiency diseases, and rheumatic diseases. The diagnostic and therapeutic approaches to the child with both prolonged fever and fever of unknown origin are then discussed, with emphasis on rheumatic diseases.