MRI测量正常人脑氧摄取分数

摘要

Objective To measure oxygen extraction fraction (OEF) of normal subjects using MR gradient-echo sampling of spin-echo (GESSE) sequence, and to compare OEF of gray and white matter of bilateral cerebral hemispheres, so as to elucidate the aging evolution of OEF in gray and white matter. Methods Totally 53 normal subjects were divided into young group (20-39 years, w=20), middle-aged group (40-59 years, n=20) and old group (≥60 years, n=13). All subjects underwent MR GESSE scanning on a 3. 0T MR scanner. Images were processed using Matlab 7. 6 software platform to calculate OEF. Six ROIs were drawn on cortical gray matter and white matter in centrum semiovale, respectively. Results There was no statistical difference of OEF values between gray and white matter of bilateral hemispheres in each group (all P>0. 05). OEF value of gray matter in young group (0. 32±0. 04) was lower than those in middle-aged group (0. 34±0. 05) and old group (0. 35±0. 05, both P<0. 05). There was a mild but significant positive correlation between age and OEF values of gray matter (r=0. 15, P = 0. 01). Averaged OEF value was 0. 34±0. 05 in the whole brain tissue. Conclusion Accurate estimates of OEF can be obtained with MR GESSE sequence. There was no statistical difference of OEF in gray and white matter. With age advancing, only OEF of gray matter increased mildly.%目的 利用MRI梯度回波采样自旋回波(GEssE)序列测量不同年龄段正常人脑的氧摄取分数(OEF),比较灰、白质OEF值及其随年龄变化规律.方法 将53名健康志愿者按年龄分为青年(20～39岁,20名)、中年(40～59岁,20名)、老年(60岁及以上,13名)组,均行GESSE序列扫描,应用Matlab 7.6软件对图像进行后处理.在双侧大脑半球皮层、半卵圆中心白质各设置6个ROI,测量其OEF值.结果 各年龄组内灰、白质OEF值在左、右大脑半球间差异无统计学意义(P均＞0.05)；双侧大脑半球灰、白质间()EF值无差异统计学意义(P均＞0.05).灰质OEF值在各年龄组间差异有统计学意义(P均＜0.05),青年组(0.32±0.04)小于中年组(0.34±0.05)、老年组(0.35±0.05).仅灰质OEF值与年龄呈弱相关(r＝0.15,P＝0.01).全脑OEF平均值为(0.34±0.05).结论 GESSE序列可以准确测量人脑OEF值,正常人脑灰、白质间OEF值差异无统计学意义,仅灰质OEF值随年龄增长而轻度升高.