基于灰度差分法的7.0 T及3.0 T MRI测量正常大鼠海马容积的对比研究

Contrast research on accurate measurement of hippocampal volume in normal rats based on the gray scale difference method by 7.0 T and 3.0 T magnetic resonance

目的 评价7.0 T MRI对正常大鼠海马结构及亚区容积的检测能力.方法 40只正常Wistar大鼠分别行7.0 T 和3.0 T MRI T2WI扫描,图像导入IMAGE J软件,利用灰度差分法辨识海马及亚区的解剖点,测得两种场强MRI海马及亚区层面积、容积并进行比较.结果 7.0 T MRI中,侧脑室、环池辨认率达100%（40/40）,腹侧海马裂与下托辨认率达95%（38/40）,丘脑外侧核、外侧膝状体背侧核辨认率达90%（36/40）.3.0 T MRI上只能清晰辨认双侧侧脑室及环池,不能分辨大鼠海马亚区结构.3.0 T MRI所测海马层面积左侧 （2.81±0.86） mm^2、右侧 （2.77±0.80）mm^2,容积左侧（56.36±5.98） mm^3、右侧（55.61±6.03 ）mm^3;7.0 T MRI所测海马层面积左侧（3.25±0.92） mm^2、右侧 （3.14±0.81）mm^2,容积左侧（64.29±7.13）mm^3、右侧（65.34±7.74）mm^3;两者比较差异均有统计学意义（P值均〈0.05）.7.0 T MRI所测海马CA1区层面积左侧为 （2.81±0.98） mm^2、右侧 （2.88±0.92） mm^2,容积左侧为（27.02±4.62）mm^3、右侧（27.64±4.13） mm^3;CA3和DG区合并计为CA3-DG区,其层面积左侧为 （4.21±1.21） mm^2、右侧 （4.19±1.40）mm^2,容积左侧为（38.73±4.17） mm^3、右侧（38.11±5.09） mm^3.结论 依据灰度差分法,大鼠海马7.0 T MRI能够准确辨认海马结构、亚区边界标志点,获得其较为可靠的容积大小,其相关数据可为此类研究提供参照和依据.

Objective To evaluate the ability of 7.0 T MRI in detecting volume of hippocampaus and hippocampal subregions in normal Wistar rats.Methods Forty normal Wistar rats were scanned with T2WI sequence by 7.0 T MR, images were imported into IMAGE J.Based on gray scale difference method which was used to identify the anatomical points of hippocampus and subareas, the volume of, hippocampaus and hippocampal subregions was calculated.Subsequently, the measured results were compared with data of 3.0 T MRI.Results In 7.0 T magnetic resonance images, the identification rate of lateral ventricle and cisterna ambiens was 100%（40/40）;the identification rate of ventral hippocampal fissure and subiculum was 95%（38/40）;the identification rate of nuclei lateralis thalami and dorsal lateral geniculate nucleus was 90%（36/40）.3.0 T images could only clearly identify the bilateral lateral ventricles and cisterna, but could not identify the hippocampal subregions in normal Wistar rats.Compared with the floor areas [left： （2.81±0.86） mm^2, right： （2.77±0.80） mm^2）] and volume of hippocampus [（left： （56.36±5.98） mm^3, right： （55.61±6.03） mm^3）] measured by 3.0 T magnetic resonance, the layer areas [left： （3.25±0.92） mm^2, right： （3.14±0.81） mm^2）] and hippocampal volume [（left： （64.29±7.13） mm^3, right： （65.34±7.74） mm^3）] measured by 7.0 T MRI were increased, the difference was significant （all P values〈0.05）.The layer areas of hippocampal CA1 measured by 7.0 T were left： （2.81±0.98） mm^2, right： （2.88±0.92） mm^2 ,the volume was left： （27.02±4.62） mm^3, right： （27.64±4.13） mm^3.The layer areas of hippocampal CA3-DG measured by 7.0 T were left： （4.21±1.21） mm^2, right： （4.19±1.40） mm^2, the volume was left： （38.73±4.17） mm^3, right： （38.11±5.09） mm^3.Conclusions Using gray scale difference method, the boundary markers of hippocampus and hippocampal subregions can be accurately detected on 7.0 T magnetic resonance images, and the relevant data could be referenced for such related researches.