青年人与老年人海马体积及形态的MR研究

The MRI study of hippocampal volume and shape in the youth and older

目的在区分海马标志点的基础上，测量青年人和老年人正常海马及其头、体、尾3个部位的体积、形态。方法选择正常青年人（年龄20～29岁，青年组）和老年人（60岁以上，老年组）志愿者各30名进行头部MR扫描，所得图像经后处理软件分析，确定较恒定、易辨认的解剖标志点后对海马进行分割。测量青年组和老年组海马的体积、平均扫描层面积及扫描层数，两组间以及青年组和老年组不同性别、不同侧别海马体积的比较采用独立样本t检验，并作海马的三维重建。结果60名受试者钩隐窝、脑室三角、钩顶等均能清晰显示。青年组和老年组不同性别间海马体积差异均无统计学意义。青年组左侧海马头部、体部、尾部及整体体积分别为（1250±174）、（653±115）、（372±116）、（2277±109）mm^3，右倾0分另1为（1255±147）、（657±129）、（386±105）、（2298±213）mm^3，左、右侧间差异均无统计学意义（t值分别为0．08、0．10、0．33、0．35，P值均〉0．05）。老年组左侧海马头部、体部、尾部及整体体积分别为（660±109）、（472±92）、（1814-73）、（1313±163）mm^3，右侧分别为（717±116）、（474±95）、（240±75）、（1432±171）mm^3，右侧海马尾部体积明显大于左侧，差异具有统计学意义（￡=2．21，P〈0．05）；其他部位左、右侧海马体积差异均无统计学意义（t值分别为1．39、0．06、1．95，P值均〉0．05）。青年组和老年组左侧海马头部、体部、尾部及整体体积差异均有统计学意义（t值分别为15．78、6．71、7．70、20．83，P值均〈0．05），右侧各部位差异也均有统计学意义（t值分别为15．76、6．26、6．15、17．36，P值均〈0．05）。老年组各部位体积明显小于青年组，其中以头部最为明显。青年组及老年组海马头部左侧层面积分别为（75±24）、（56±21）mm^3，右侧层面积分别为（73±22）、（58±19）mm^3，两组间差异均有统计学意义（t值分别为3．33、2．81，P值均〈0．01）。青年组及老年组左侧层数分别为（11．1±3．2）、（7．9±3．9）层，右侧层数分别为（11．5±3．7）、（8．2±3．1）层，两组间差异也均有统计学意义（t值分别为3．48、3．75，P值均〈0．05）。老年组的海马头部层数和层面积均小于青年组，呈短而窄的外形。结论根据海马标志点确认的原则，其所提出的标志点为海马形态体积的标准化测量提供了测量的基础，其所测的正常值有助于疾病的诊断或为某些疾病发病机制的研究提供基础。

Objective In the base of the landmarks of the hippocampus identified with neighborhood structures, to measure volumes and shape of normal older age group and youth group＇s hippocampus and hippocampal head, body, tail. Methods Thirty younger people（ age 20--29 years ,youth group） and thirty older people （above 60 years,older age group）were scanned by MR , anatomic landmarks were found, which were constancy and easy to be recognized for segmentation hippocampus. The hippocampal volumes, average areas and number of the hippocampal layer were measured, the interclass data of two groups, different gender and sides were compared with statistics methods of t test and the hippocampal model were made with the three-dimensional reconstruction. Results All landmarks of 60 subjects could be distinguished clearly, such as uncal recess, triangle of the lateral ventricle, uncal apex et al. The discrepancies of two groups＇ volumes of gender had not statistical significance. The youth groups＇ volumes of left hippocampus, head, body and tail were （ 1250 ± 174 ）, （653 ± 115 ）, （ 372 ± 116）, （2277 ± 109 ） mm3, and the right were （1255 ± 147 ）, （657 ± 129 ）, （386 ± 105 ）, （2298 ± 213 ）mm3. There was no statistical significance between left and right（t =0. 08,0. 10,0. 33,0. 35 ,P 〉0. 05）. The older age groups＇ volumes of left hippocampus, head, body and tail were （660 ± 109）, （472 ±92）, （ 181 ±73）, （ 1313 ± 163） mm3 ,and the fight were （ 717 ± 116 ）, （ 474 ± 95 ）, （ 240 ± 75 ）, （ 1432 ± 171 ） mm3. Older hippocampal volumes were obviously bigger in right tail than in left （t = 2. 21, P 〈 0.05 ） , and other parts had not statistical significance （ t = 1.39,0. 06, 1.95, P 〉 0.05 ）. There were manifest statistical significance between two groups＇ left volumes of hippocampus and each parts （t = 15.78,6. 71,7.70,20. 83,P 〈 0. 05 ） , and also right （t = 15.76, 6. 26,6. 15,17.36,P 〈 0.05 ）. The hippocampal volumes and its three parts were obviously smaller in older than youth, especially the hippocampal head. The left average areas of youth and older groups＇ were （75 ± 24 ）, （ 56 ± 21 ） mm2 and the right were （ 73 ± 22 ）, （ 58± 19 ）mm2. Both two groups had manifest statistical significance（t = 3.33,2. 81, P 〈 0. 01 ）. The number of layers of youth and older groups＇ were （ 11.1 ± 3.2）,（7.9 ±3.9）layers, and the right were （11.5 ±3.7）,（8.2 ±3.1）layers. Both two groups had manifest statistical significance （ t = 3.48,3.75, P 〈 0. 05 ）. The number of layers and average areas of hippocampal head were less in older than in youth group, and the shape of hippocampus become short and narrow. Conclusion According to the rule with landmarks that we selected, standardization measurement of the hippocampus may become possible and can be provided the basis of diagnosis and searching pathogenesis related to disease.