正常人3D-ASL脑血流灌注最佳标记后延迟时间分析

目的 分析动脉自旋标记（ASL）中延迟时间对正常人群大脑血流灌注值的影响，并探讨不同年龄段最佳标记后延迟时间（PLD）。方法 将84名健康志愿者分为青年（20~44岁）、中年（45~59岁）及老年组（60~80岁），分别行常规MR及3D-ASL灌注扫描，对每个年龄组分别采集三期PLD。采用基于Matlab平台的SPM分析灌注数据，提取全脑灰质、额叶、顶叶、枕叶、颞叶、边缘叶的脑血流量（CBF）值。各年龄组分别采用单因素方差分析、Scheffe两两比较分析不同延迟时间（1 025、1 525、2 525、3 025 ms）CBF值的差异。结果 青年组全脑灰质（P=0.011）、颞叶（P<0.001）、枕叶（P=0.013）及边缘叶（P<0.001）不同延迟时间CBF值差异有统计学意义，且1 025 ms及1 525 ms所得CBF均值较高；中年组全脑灰质（P=0.009）、额叶（P=0.008）、顶叶（P=0.019）、颞叶（P=0.002）、枕叶（P=0.001）、边缘叶（P=0.008）不同延迟时间CBF值差异均有统计学意义；老年组全脑灰质（P=0.026）、额叶（P=0.023）、颞叶（P=0.006）、枕叶（P<0.001）不同延迟时间CBF值差异均有统计学意义，且中年组、老年组均为1 525 ms及3 025 ms所得CBF值较高。结论 PLD是影响3D-ASL脑灌注值的一个重要参数，不同年龄段人群最佳PLD不同，青年组适合用较短PLD，1 525 ms是最佳PLD，中年组及老年组适合用较长PLD，3 025 ms是最佳PLD。

Optimal post label delay of 3D-ASL cerebral blood perfusion in normal people

Objective To analyze the effects of different post label delay (PLD) on the brain regional cerebral blood flow (CBF) of normal people, and to explore the most optimal PLD of each age group. Methods Eighty-four healthy volunteers were divided into youth group (20 to 44 years), the middle-aged group (45 to 59 years) and the elderly group (60 to 80 years). The MRI protocol included conventional MRI and 3D-ASL perfusion scanning. Three phase PLD were used in each group. Statistical parametric mapping based on Matlab was used to analyze the perfusion data and to extract a predefined set of standard ROIs, including whole brain gray matter, frontal lobe, parietal lobe, temporal lobe, occipital lobe, limbic lobe. Single factor analysis of variance was used to compare the CBF differences among different PLD, the further multiple comparisons were completed by Scheffe. Results In youth group, the CBF among different PLDs of global gray matter (P=0.011), temporal lobe (P<0.001), occipital lobe (P=0.013) and limbic lobe (P<0.001) had statistical significance, and the CBF value of 1 025 ms and 1 525 ms were higher than those of 2 525 ms. In middle-aged group, the CBF among different PLDs of global gray matter (P=0.009), frontal lobe (P=0.008), parietal lobe (P=0.019), temporal lobe (P=0.002), occipital lobe (P=0.001) and limbic lobe (P=0.008) had statistical significance. In elderly group, the CBF among different PLDs of global gray matter (P=0.026), frontal lobe (P=0.023), temporal lobe (P=0.006) and occipital lobe (P<0.001) had statistical significance. The CBF value of 1 525 ms and 3 025 ms were higher than those of 2 525 ms in middle-aged group as well as elderly group. Conclusion PLD is an important parameter of 3D-ASL, the most optimal PLD are different among each age group. The shorter PLD is suitable for the youth group, 1 525 ms is the best PLD. The longer PLD is suitable for the middle-aged group and elderly group, 3 025 ms is the best PLD.