We evaluated the effect of a reduced acquisition time for ¹⁸F-FDG PET studies of Alzheimer dementia (AD) and frontotemporal dementia (FTD) to derive a limit for reductions of acquisition time (improving patient compliance) and administered activity (lowering the radiation dose) with uncompromised diagnostic outcome. Methods: We included patients with a clinical diagnosis of AD (n = 13) or FTD (n = 12) who were examined with ¹⁸F-FDG PET/CT after injection of 210 ± 9 MBq of ¹⁸F-FDG. List-mode data were reconstructed over various time intervals simulating reduced acquisition times or administered activities. Volume-of-interest–based and voxelwise statistical analyses including group contrasts were performed for 15 different acquisition times ranging from 10 min to 2 s. In addition, masked visual reads were obtained from 3 readers independently for 7 different acquisition times down to 30 s, providing a diagnosis of either AD or FTD and the individual diagnostic certainty. Results: Regional mean uptake changed by less than 5% at a reduced acquisition time down to 1 min in all regions and patients except for the posterior cingulate cortex of 1 patient. Voxelwise group contrasts suggest a sufficient measurement time of only 2 min, for which the number of significant voxels decreased by merely 5% while maintaining their spatial pattern. In 450 visual reads at reduced times, no change in the original diagnosis was observed. The diagnostic certainty showed only a very slow and mild decline, with small effect sizes (Cohen’s d) of 0.3, at acquisition times of 3 and 2 min compared with the original results at 10 min. Conclusion: Statistical results at a region and voxel level, as well as single-subject visual reads, reveal a considerable potential to reduce the typical 10-min acquisition time (by a factor of 4) without compromising diagnostic quality. Conversely, our data suggest that for a given acquisition time of 10 min and a similar effect size, the administered activity may be reduced to 50 MBq, resulting in an effective dose of less than 1 mSv for the PET examination.

我们评估了^18个F-FDG PET研究减少阿尔茨海默氏痴呆（AD）和额颞痴呆（FTD）的获取时间的效果，从而得出了减少获取时间（改善患者依从性）和给药活动（降低放射剂量）的极限）的诊断结果。方法：我们纳入了临床诊断为AD（n = 13）或FTD（n = 12）的患者，他们在注射210±9 MBq的^18分后接受了¹⁸ F-FDG PET / CT检查F-FDG。在各种时间间隔上重建列表模式数据，以模拟减少的获取时间或管理的活动。基于兴趣量和体素的统计分析（包括组对比）在15分钟（从10分钟到2 s）内进行了不同的采集时间。此外，从3个阅读器分别获得了7次不同的采集时间（低至30 s）的掩盖视觉读取，可诊断AD或FTD并提供单独的诊断确定性。结果：在除1名患者的扣带后皮质以外的所有地区和患者中，在平均采集时间降低至1分钟的情况下，区域平均摄入量变化不到5％。体素组的对比表明只有2分钟的足够的测量时间，对于这种情况，重要体素的数量仅减少了5％，同时保持了其空间格局。在减少时间的450次视觉读取中，未观察到原始诊断的变化。诊断确定性仅显示出非常缓慢和轻微的下降，在3分钟和2分钟的采集时间上，与10分钟时的原始结果相比，效应大小（Cohen d）为0.3。结论：区域和体素水平的统计结果，以及单个对象的视觉读数，显示出在不影响诊断质量的前提下，减少10分钟典型采集时间（4倍）的巨大潜力。相反，我们的数据表明，对于给定的10分钟获取时间和相似的​​效应大小，所给予的活性可能会降低至50 MBq，从而导致PET检查的有效剂量小于1 mSv。