中文摘要：

目的：比较不同扫描时长（时间点）对静息态低频振幅（ALFF）结果的影响。方法13例健康志愿者,采集10 min 10 s时长的静息态 fMRI 数据,平分成10段1 min 时长的静息态数据,比较扫描时长（1~10 min）对 ALFF 结果稳定性的影响。结果ALFF 的空间模式稳定地出现在各个时间段（1~10 min）；但随着扫描时长的延长,ALFF 空间分布范围和强度渐增强,扫描时长为1 min 时出现组内的统计学差异,扫描时长在5~10 min 时,能出现比较稳定的组内 ALFF 结果。结论ALFF 是一种比较稳定的指标,其结果显著受静息态扫描时长的影响,扫描时长在1~5 min 的情况下尤其应当慎重分析。

英文摘要：

Objective To examine the reliability and similarity of amplitude of low-frequency fluctuation （ALFF）for different scan duration.Methods 10 min 10 s resting state fMRI data acquired from 13 healthy volunteers separately were divided into 10 pieces of the same length.The reliability and similarity of ALFF were assessed for each scan length （1-10 min）.Results Spatial maps of ALFF steadily appeared in each time period （1-10 min）;but during the time evolution,both spatial distribution and extent of ALFF increased gradually.At only one minute,there were detectable statistical differences within the group.When the time ran-ging from 5 to 10 min,relatively stable ALFF results in the group achieved.Conclusion ALFF is a relatively stable index,it can be easily affected by scan duration.In the case of 1-5 min,it should be carefully analyzed and interpretated particularly.