摘要目的 利用MR定量磁敏感图(QSM)对不同年龄正常人脑铁含量进行测量,观察其随年龄的变化趋势.方法 利用3.0T MR成像系统,对63名健康右利手志愿者行常规MRI和磁敏感加权成像(SWI)序列扫描,获得正常颅脑SWI未滤波相位图和幅度图,利用磁敏感图像成像与相位伪影消障工具(SMART)后处理软件对未滤波相位图和幅度图进行处理得到QSM,利用SPIN软件手工绘出磁敏感图中双侧额叶白质及灰质核团(尾状核、苍白球、壳核、背侧丘脑、红核、黑质及齿状核)的ROI,测量ROI的磁敏感值,并与Hallgren和Sourander对尸体脑组织染色所得铁含量的结果进行线性相关分析,观察两者的一致性.采用秩和检验比较不同侧别和性别间额叶白质及灰质核团间的磁敏感值的差异.利用Spearman相关分析其与年龄的相关性.结果 63名健康志愿者额叶白质、尾状核、苍白球、壳核、背侧丘脑、黑质、红核及齿状核磁敏感值的中位数(范围)分别为-12.81(-31.56,8.72)、39.27 (22.35,75.13)、93.99 (19.19,158.75)、29.16(4.11,81.53)、2.91(-27.80,27.95)、83.14 (38.57,185.79)、63.49(13.83,142.09)、63.30(36.78,128.53)ppb(×10-9),与Hallgren和Sourander的结果具有很高的一致性(r=0.91,P＜0.05).苍白球的磁敏感值最高,其次为黑质;额叶白质的磁敏感值最低.右侧尾状核、黑质、红核及齿状核的磁敏感值高于左侧,差异有统计学意义(Z值分别-3.18、-4.44、-3.70、-2.64,P值均＜0.05).男性左右侧苍白球磁敏感值与女性差异有统计学意义(Z值分别为-2.27、-2.42,P值均＜0.05).双侧尾状核、壳核、红核、齿状核磁敏感值均与年龄具有相关性(r值为0.30～0.49,P值均＜0.05).结论 QSM能清晰显示脑内核团;QSM能较准确评估脑内的铁含量,与组织病理学结果评估脑内铁含量具有较高一致性;双侧尾状核、壳核、红核、齿状核的铁含量随年龄的变化具有增加的趋势.

abstractsObjective To evaluate the distribution and age-related changes of brain iron content in healthy people using MR quantitative susceptibility mapping (QSM).Methods Sixty three healthy right-handed volunteers underwent the routine MRI and SWI scan to get SWI-unfiltered phase images and magnitude images.QSM were reconstructed from the SWI-unfiltered phase images and magnitude images using SMART software.The regions of interest at the bilateral frontal white matter and nuclei (caudate nuclews,globus pallidus,putamen,substantia nigra,dorsal thalamus,red nucleus and dental nucleus) were drawn manually,and the susceptibility was measured.The linear correlation between the susceptibility and iron concentration cited from Hallgren and Sourander's post-mortem brain study was calculated.Wilcoxon test were applied to calculate the difference between the bilateral frontal white matter and bilateral nuclei.The correlation of age with susceptibility of bilateral frontal white matter and bilateral nuclei were analyzed by Spearman correlation analysis.Results The median susceptibility (extent) of frontal white matter,caudate nucleus,globus pallidus,putamen,dorsal thalamus,substantia nigra,red nucleus and dentate nucleus of 63 healthy people were-12.81 (-31.56,8.72),39.27 (22.35,75.13),93.99 (19.19,158.75),29.16 (4.11,81.53),2.91 (-27.80,27.95),83.14 (38.57,185.79),63.49 (13.83,142.09),63.30 (36.78,128.53) ppb (× 10-9),respectively.There was high consistency with Hallgren and Sourander's study (r=0.91,P＜0.05).The susceptibility of globus pallidus was the highest,followed by substantia nigra.The least susceptibility was seen in the frontal white matter.The susceptibility of right caudate nucleus,substantia nigra,red nucleus and dental nucleus was higher than that of left side (Z value was-3.18,-4.44,-3.70 and-2.64,respectively,P＜0.05).The susceptibility of bilateral globus pallidus of the male was significantly different from that of the female (Z value was-2.27 and-2.42,respectively,P＜0.05).There was positive correlation between age and the susceptibility of bilateral caudate nucleus,putamen,red nucleus and dental nucleus (r value was 0.30 to 0.49,P＜0.05).Conclusions QSM based on the SWI-unfiltered phase and magnitude images can clearly display the cerebral nuclei and evaluate the brain iron content accurately,which is consistent with the histopathological results.Iron content of bilateral caudate nucleus,putamen,red nucleus and dental nucleus increase with aging.