Parameter optimal selection during pediatric 18F-FDG PET/CT examination

Abstract

Objective Currently,pediatric 18F-FDG dose and acquisition durations are generally based on coarse extrapolation from adult guidelines.This study sought to determine whether shorter acquisition durations or a lower 18F-FDG injected activity could be used during pediatric 18F-FDG PET/CT examinations while maintaining diagnostic utility.Methods Thirty-six whole-body 18F-FDG PET/CT examinations were performed on 36 patients (weight,13-89 kg,(46.51±5.63) kg; age range,3-14 years old,(9.22±3.16) years old) with a weight-based injected activity (5.3 MBq/kg (0.144 mCi/kg)),fixed acquisition durations 180 S/FOV,VIP record acquisition mode using Discovery STE.For each examination,the Vip-mode data was truncated to form multiple datasets with shorter acquisition durations down to a minimum of 60 s/FOV (i.e.,60,80,100,120,140,160 s/FOV data were formed from single 180 s/FOV acquisition).168 image volumes were generated,randomized,and reviewed in a masked manner with corresponding CT image volumes by 6 radiologists.Overall,subjective adequacy and objective lesion detection accuracy by body region were evaluated.Results All examinations with maximum acquisition duration were graded as adequate and were used as the reference standard for detection accuracy.For patients more than 30 kg,when acquisition duration was more than 120 s/FOV,all PET/CT examinations were graded as adequate for clinical tasks,whereas,when acquisition duration was reduced to less than 120 s/FOV,lesion detection became less accurate.For patients less than 30 kg,lesion detection accuracy was perfect for acquisition times between 140 s/FOV and 180 s/FOV for all regions of the body.However,lesion detection became less accurate when imaging acquisition time was reduced less than 140 s/FOV.Conclusions When GE Discovery STE PET/CT was applied during pediatric PET/CT examination,using decreased acquisition times as a surrogate for 18F-FDG dose,18F-FDG dose can be reduced by approximately 33.33％ when patients weigh over 30 kg were scanned for 180 s/FOV.For patients less than 30 kg,18F-FDG dose can be reduced by approximately 22.22％ without losing diagnostic quality.Reduction of overall scan time potentially reduces motion artifacts,improves patient comfort,and decreases length of sedation.Alternatively,decreased 18F-FDG dose minimizes radiation risk. Key words: Pediatric PET/CT; Acquisition durations; 18F-FDG activity