The efficacy of short acquisition time using 18F-FDG total-body PET/CT for the identification of pediatric epileptic foci

Abstract

Background: ¹⁸F-FDG positron emission tomography (PET) plays a crucial part in the evaluation for pediatric epileptic patients prior to therapy. Short-term scanning holds significant importance, especially for pediatrics epileptic individuals who exhibited involuntary movements. The aim was to evaluate the effects of short acquisition time on image quality and lesion detectability in pediatric epileptic patients using total-body (TB) PET/CT. A total of 25 pediatric patients who underwent TB PET/CT using uEXPLORER scanner with an ¹⁸F-FDG administered dose of 3.7 MBq/kg and an acquisition time of 600 s were retrospectively enrolled. Short acquisition times (60 s, 150 and 300 s) were simulated by truncating PET data in list mode to reduce count density. Subjective image quality was scored on a 5-point scale. Regions of interest analysis of suspected epileptogenic zones (EZs), corresponding locations contralateral to EZs, and healthy cerebellar cortex were used to compare the semi-quantitative uptake indices of short-time images and then were compared with 600 s images. The comparison of EZs detectability based on time-dependent PET images was performed.

Results: Our study demonstrated that a short acquisition time of 150 s is sufficient to maintain subjective image quality and lesion significance. Statistical analysis revealed no significant difference in subjective PET image quality between imaging at 300 s and 150 s (P > 0.05). The overall impression scores of image quality and lesion conspicuity in G60s were both greater than 3 (overall quality, 3.21 ± 0.46; lesion conspicuity, 4.08 ± 0.74). As acquisition time decreased, the changes of SUVmax and SD in the cerebellar cortex gradually increased (P < 0.01). There was no significant difference in asymmetry index (AI) difference between the groups and the AIs of EZs were > 15% in all groups. In 26 EZs of 25 patients, the lesion detection rate was still 100% when the time was reduced to 60 s.

Conclusions: This study proposed that TB PET/CT acquisition time could be reduced to 60 s with acceptable lesion detectability. Furthermore, it was suggested that a 150 s acquisition time would be sufficient to achieve diagnostic performance and image quality for children with epilepsy.

Keywords: Diagnostic performance; Epileptogenic zone; Fast acquisition; Pediatric; Total-body PET/CT.

Fig. 1

¹⁸F-FDG PET image of an 11-year-old female patient weighing 43 kg, who had been diagnosed with gangliocytoma by pathology, was reconstructed into brain axial views of 600, 300, 150 and 60 s (a–d). The overall image scores for the groups of 600, 300, 150, and 60 s were 5, 5, 4, and 3, respectively. (e) Histopathology finding of the patient, characterized by a mixed population of neoplastic glial cells and dysplastic neurons

Fig. 2

Box plots showing the change of ipsilateral cerebellar SUVmax, SD, and AI of EZs. The change of each index was calculated as the difference between G300 s, G150 s and G60 s of each patient and G600 s, respectively. (a) The SUVmax in the ipsilateral cerebellar cortex gradually increased as acquisition time decreased. G60 s-G600 s and G150 s-G600 s were significantly higher than G300 s-G600 s (P < 0.05). (b) The uptake of SD in the ipsilateral cerebellar cortex significantly increased as acquisition time decreased (P < 0.05). (c) There was no significant difference in AI difference between the groups with shortened acquisition time. The differences between G300 s-G600 s and G150 s-G600 s, G300 s-G600 s and G60 s-G600 s and G150 s-G600 s and G60 s-G600 s were not significant (P < 0.05 and Bonferroni correction). The difference in AI between the two time points was marked as ∆AI

Fig. 3

¹⁸F-FDG PET image of a 3-year-old female patient weighting 12.8 kg with a diagnosis of focal cortical dysplasia (FCD) by biopsy was reconstructed into brain axial views of 600, 300, 150 and 60 s (a–d). As the acquisition time was reduced to 60 s, the lesion was still identifiable. (e) Histopathology finding of the patient, characterized by architectural dysplasia and dysmorphic neurons

Fig. 4

A 5-year-old man diagnosed with FCD IIId with Rasmussen encephalitis by pathology. The images showed lesions in left cerebral hemisphere for the group 60–600 s (a–d). Diffuse hypometabolism and focal hypermetabolism were observed in the left cerebral hemisphere, and the lesion detectability was visible from 600 s to 60 s. (e) Pathological image showed neuron degeneration and necrosis with astrocytic hyperplasia