用于儿科PET/CT检查的参数优化选择方法

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

目的 目前儿科β-2-[F]氟-2-脱氧-D-葡萄糖（18F-FDG）剂量和采集时间一般是按照成人的参数推算出来.本研究目的是对在不影响图像诊断质量的前提下,行儿科正电子发射型计算机断层显像（PET）/CT检查时,缩短采集时间或降低18F-FDG注射用量的可行性进行初步研究.方法 对36例患者（体质量为13～89 kg,平均体质量（46.51±5.63） kg;年龄3～14岁,平均年龄（9.22±3.16）岁）行36次全身18F-FDG PET/CT扫描,按照5.3 MBq/kg（0.14 mCi/kg）计算注射18F-FDG,采用VIP record采集模式,180 s/视野（FOV）;对于每次检查,VIP record记录的数据按照采集时间的减少（160、140、120、100、80、60 s/FOV的数据按照180 s/FOV的数据来模拟计算）,分别被缩减以形成不同采集时间下的图像.随机挑选168幅PET图像以及相对应的CT图像,通过6位影像学专家阅片,对全身存在的病灶进行分析,分别对颈部、胸部、腹部、骨等部位病灶的符合率进行对比,并对主观可信度以及客观准确度进行全面评估.结果 所有检查均以最大采集时间作为分级标准和检查准确度的参考标准.对于体质量＞30 kg的受检者,当采集时间＞120 s/FOV时,所有病灶均可以检测出来,采用120 s/FOV以下的参数进行采集时,病灶检测准确度会大大降低;对于体质量＜30 kg的受检者,当采集时间＞140s/FOV时,所有病灶均可以检测出来,采用140 s/FOV以下的参数进行采集时,病灶检测准确度会大大降低.结论 应用GE Discovery STE PET/CT行儿科检查时,采用减少18F-FDG用量替代减少采集时间,如果采用180s/FOV时,对于体质量＞30 kg的受检者,18F-FDG的用量可降低33.33％;对于体质量＜30 kg的受检者,18F-FDG的用量可降低22.22％,而且不会损失图像诊断质量.所需扫描全部时间的减少意味着可以减少运动伪影,提高受检者舒适度以及减少所需镇静的时间;另外,通过减少18F-FDG用量,还可降低受辐射的风险.

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.