素食者与杂食者头部MR弹性成像对比研究

The comparative study of the brain MR elastography between Chinese vegetarians and omnivores

目的比较中国的素食者及杂食者脑组织的剪切模量是否存在差异。方法选择年龄与性别相匹配的素食者与杂食者各20名，其中素食志愿者均保持素食时间1～16年，平均8年。每名志愿者均行头部MR弹性成像（MRE）。通过局部频率估算法计算所有志愿者额叶及顶叶灰、白质等4个部位脑实质的剪切模量，以及素食者、杂食者4个部位脑实质的剪切模量，并评估剪切模量与素食时间及年龄是否存在相关性。应用随机区组的方差分析判断不同部位的脑实质间是否存在差异，应用独立样本的t检验判断素食者与杂食者脑实质间是否存在差异。结果所有志愿者均成功获取脑实质额叶白质、灰质及顶叶白质、灰质的剪切模量，分别为（26．8±6．4）、（12．7±2．8）、（19．4±3．6）、（10．5±2．8）kPa（1kPa=7．5mmHg），4个部位脑实质剪切模量差异有统计学意义（F=174．48，P〈0．05）。额叶白质的剪切模量最高，而顶叶灰质的剪切模量最低。不同区域剪切模量与年龄无相关性（r值分别为-0．06、-0．11、-0．16、0．15，P值均〉0．05）。素食者额、顶叶白质的剪切模量分别为（23．7±6．4）、（17．9±3．3）kPa，而杂食者额、顶叶白质的剪切模量分别为（29．9±4．8）、（20．8±3．3）kPa，2组间差异有统计学意义（t值分别为3．45、2．79，P值均〈0．05）；素食者额、顶叶灰质的剪切模量分别为（12．2±3．1）、（9．8±2．4）kPa，杂食者额、顶叶灰质的剪切模量分别为（13．1±2．6）、（11．1±3．1）kPa，2组间差异无统计学意义（t值分别为1．03、1．42，P值均〉0．05）。不同部位脑实质剪切模量与素食时间无相关性（r值分别为0．070、-0．003、-0．195、0．177，P值均〉0．05）。结论素食者脑实质剪切模量低于杂食者，膳食因素可能对脑实质的剪切模量产生影响。

Objective To compare the shear stiffness of brain of parenchyma in Chinese vegetarians and omnivores by MR elastography examination. Methods Twenty vegetarians and 20 omnivores were enrolled. They were matched with sex and age. Each vegetarian described himself or herself as a keeping vegetarian with more than 1 year of experience. Brain MRE examination was performed on each subject and the shear stiffness of brain parenchamy was measured by local frequency estimation （LFE） algorithm in four location（ white matter and gray matter in frontal and parietal lobe）. Randomized block ANOVA was used to analyze the shear stiffness of four locations. Meanwhile, the correlation between shear stiffness and age was analyzed. Independent sample t-test was used to compare the shear stiffness of two groups. The correlation between shear stiffness and vegetarian time was also analyzed. Results The shear stiffness in four locations was （26.8 ±6.4）,（12.7 ±2.8）,（19.4±3.6）,（10.5 ±2.8） kPa （1 kPa =7.5 mm Hg）. There was significant difference among the four locations （ F = 174. 48, P 〈0. 05 ）. The shear stiffness of white matter in frontal region is highest and the shear stiffness of grey matter in parietal region is lowest. There was no significant correlation between shear stiffness of brain parenehyma and age （ r = - 0. 06, - 0. 11, - 0. 16, 0. 15, P 〉 0. 05 ）. The shear stiffness of frontal white matter was significantly lower in the vegetarians than in the omnivores [ （23.7 ± 6. 4 ） and （ 29. 9 ± 4. 8 ） kPa, t = 3.45, P 〈 0. 05 ]. In parietal region the shear stiffness of white matter was also significantly lower in the vegetarians than in the omnivores[（17. 9 ± 3.3） and （20. 8 ±3.3） kPa,t =2. 79,P 〈0. 05]. The differences of shear stiffness in frontal and parietal gray matter were not statistically significant in the vegetarians and in the omnivores [ （ 12. 2 -± 3.1 ） and （13.1_±2.6） kPa,t=l. O3,P〉0.3;（9.8_±2.4） and （11.1_±3.1） kPa; t=l.42,P〉0.1]. There was no significant correlation between shear stiffness of brain parenchyma and vegetarian time （ r = 0. 070, -0.003, -0. 195,0. 177,P 〉0.05）. Conclusions Compared with omnivore＇s, the shear stiffness of brain parenchyma was lower in vegetarians. The shear stiffness of brain parenchyma may be affected by the diet.