Usefulness of brain FDG PET/CT imaging in pediatric patients with suspected autoimmune encephalitis from a prospective study

Abstract

Purpose Early diagnosis and treatment are of paramount importance for pediatric patients with autoimmune encephalitis (AE). The aim is to evaluate the usefulness of FDG PET/CT in pediatric patients with suspected AE from a prospective study. Methods The prospective study was conducted over a period of 23.5 months from May 14, 2019, to April 30, 2021. All patients (< 18-year-old) were hospitalized at the department of pediatric neurology and met the criteria of clinical suspected AE. The children underwent the tests of blood samplings, CSF, EEG, MRI, and 18F-FDG PET/CT. The criteria for FDG PET/CT diagnosis of AE were large lobar hypometabolism with or without focal hypermetabolism found on PET/CT. The clinical final diagnosis of AE includes seropositive and seronegative AE based on the diagnostic criteria. Results One hundred four pediatric inpatients (57 boys, 47 girls) were included, of which 58 children were diagnosed with AE (seropositive, 16; seronegative, 42), 45 children were diagnosed with non-AE, and one boy remained indeterminate diagnosis. Large lobar hypometabolism was found in 61 children, of which 54 (88.5%) children were finally diagnosed with AE. The sensitivity, specificity, and accuracy of FDG PET/CT for diagnosis of AE were 93.1%, 84.4%, and 89.3%, respectively, with a positive predictive value of 88.5% and a negative predictive value of 90.5%. The most common involved with hypometabolism was the parietal lobe, followed by occipital and frontal lobes, finally the temporal lobe on PET/CT in children with AE. Conclusion Brain FDG PET/CT imaging has high specificity, sensitivity, and accuracy for diagnosis of AE in clinical suspected AE children. Trial registration. Clinical Trials.gov. NCT02969213. Registered 17 October 2016.

Immune‐mediated encephalitis

“…However the sensitivity in antibody negative autoimmune encephalitis was markedly lower at 68% with more heterogeneous abnormalities reported 5 . In a prospective study of 103 children with suspected autoimmune encephalitis, sensitivity and specificity of abnormality on PET imaging in predicting a diagnosis of autoimmune encephalitis were reported at 93% and 84% 6 . However, as abnormality on PET scan was used as a paraclinical marker to make the diagnosis of autoimmune encephalitis alongside either CSF abnormalities or a response to immune therapy, the validity of the final diagnosis in this study, and therefore the specificity of PET imaging in clinical syndromes of immune‐mediated encephalopathy, remains unclear.…”

Bridging the Divide: An Integrated Neurobio-Psycho-Social Approach to Treating Antibody Negative Inflammatory Encephalitis in a School-Aged Child

“…In situations where neurodiagnostic and inflammatory biomarkers are not active, emerging evidence has identified that using a fludeoxyglucose-18 (FDG) positron emission tomography/computed tomography (FDG-PET/CT) scan may be both sensitive and specific for revealing the biochemical effects of neuroinflammation on imaging. 55,56 Diagnosis of AE using inflammatory and neurodiagnostic biomarkers will change dramatically in the next decade. Antibody testing panels are becoming increasingly more comprehensive and include more and more pathogenic antibodies each year.…”

“…Although more data are needed, the presence of imaging abnormalities may be important for determining how aggressive clinicians should be with immunotherapy early in the disease course. In situations where neurodiagnostic and inflammatory biomarkers are not active, emerging evidence has identified that using a fludeoxyglucose-18 (FDG) positron emission tomography/computed tomography (FDG-PET/CT) scan may be both sensitive and specific for revealing the biochemical effects of neuroinflammation on imaging 55,56 …”

Role of FDG PET/CT in definitive and presumed autoimmune encephalitis

“…F-18 Fluorodeoxyglucose PET/CT (FDG-PET) has demonstrated metabolic alterations in cortical and subcortical regions in AIE [10,11]. Specific patterns have been reported for NMDARE and LGI1E [12].…”