采用多回波采集T2^＊WI三维梯度回波序列测量兔脑损伤模型静脉血相位值及与神经功能损伤评分的相关性

Correlation between venous blood phase values detected by enhanced gradient echo T2 star weighted angiography sequence and neurological severity scale scores in mild and severe traumatic brain injury models of rabbits

目的探讨多回波采集T2^＊WI三维梯度回波（ESWAN）序列观察不同时期的轻重度兔脑损伤动物模型的静脉血相位值变化规律，并探寻其与神经功能损伤评分（NSS）相关性。方法选取51只新西兰白兔采用随机数字表法随机分为对照组（n=3）、轻度损伤组（n=24）与重度损伤组（n=24），分别于致伤前，致伤后1、6、12、24、48、72h及1、2周8个时相行常规MRI和ESWAN序列检查。并检测大脑内静脉（ICV）、双侧腹内侧静脉（VMV）、腹外侧静脉（VLV）、背侧矢状窦（DSS）、小脑引流静脉之背侧小脑静脉（DCV）、脑干引流静脉之脑干背侧正中静脉属支（MDVB）的血液相位值变化（每亚组3只动物）。致伤后观察其行为学改变，并进行神经功能损伤评分（NSS）。各测量时间段轻、重度损伤组间不同测量血管静脉血相位值的比较选用两独立样本t检验。各损伤组不同测量血管静脉血相位值随时间变化的比较采用单因素方差分析，组内两两比较采用LSD．t检验。轻、重度损伤组间NSS评分的比较选用两独立样本t检验。轻重度损伤组各测量血管静脉血相位值与NSS评分的相关性分析采用Spearman相关分析。结果兔脑损伤后，各组测量血管静脉血相位值均降低，多个时间点重度损伤组相位值低于轻度损伤组，差异具有统计学意义。静脉血相位值于损伤早期减低，至24—48h下降至最低，后逐渐恢复，其中以VMV、VLV、DSS及MDVB相位值减低较为显著（P〈0．05），ICV及DCV静脉血相位值变化亦呈相似趋势。轻、重度损伤组NSS评分分别为（15．5±3．1）和（33．2±6．5）分，差异具有统计学意义（t=3．543，P=0．001）。伤后6h，大部分静脉血相位值与NSS评分具有相关性（P〈0．05），伤后24—72h，各测量血管相位值均与NSS评分呈明显负相关性（P值均〈0．05），其中幕上静脉较幕下静脉、浅静脉较深静脉血液相位值更加准确与敏感。结论利用ESWAN序列检测脑外伤后静脉血相位值并以此反映静脉血氧饱和度水平是可行的，且可以有效评估颅脑损伤程度与患者临床症状，具有良好的临床应用前景。

Objective To explore the change of venous blood phase values detected by enhanced gradient echo T2 star weighted angiography （ESWAN）sequence in mild and severe traumatic brain injury （TBI） models of rabbits in diverse phases and investigate their association with neurological severity scale （NSS） scores. Methods Fifty-one New Zealand rabbits, which were randomly divided into control group （n=3） , mild injured group （n=24）, and severe injured group （n=24） by random digital table method, underwent routine MRI and ESWAN sequence at the time points of baseline, 1 h, 6 h, 12 h, 24 h, 48 h, 72 h, 1 week, and 2 weeks after injury （3 rabbits per subgroup）respectively. Blood phase values in veins of interest were recorded. Observation of behavior characteristics and abnormalities, followed by NSS, was executed post injury, and the correlation between venous blood phase values and NSS scores was statistically analyzed. Two independent-samples t-test was applied to compare venous blood phase values of diverse measured veins in each group separately at every time ponits. One-way ANOVA was used to analyze venous blood phase values varying over time of measured vessels in each injured group. Least significant difference t-test was applied to compare blood phase values within the subgroups with each other at each time point. NSS scores of mild and severe injured groups were compared by two independent-samples t-test. Correlations between venous blood phase values and NSS scores in each vein and group was analyzed with Spearman correlation analysis. Results Blood phase values in veins of interest presented an inclination of descending, which was more obvious in severe injured groups than in the mild. Change of venous blood phase values over time featured continuing reduction in earlier phases which reached to the minimum in 24-48h, and then increased gradually, especially in VMV, VLV, DSS, and MDVB （P〈0.05）. ICV and DCV also showed similar trend. Values of NSS scores in the two group were （15.5±3.1） and （33.2±6.5） respectively （t=3.543, P=0.001）. Blood phase values in most of the measured veins correlated with NSS scores （P〈0.05） after 6h post injury, especially significant during 24-72h among all the measured veins （P〈 0.05）. Higher accuracy and sensitivity were presented in the supratentorial or superficial veins compared with subtentorial or profound veins. Conclusions It is feasible to evaluate oxygen saturation of veins after TBI by measuring venous blood phase values on ESWAN images. The method is effective in the assessment of the degree of injury and clinical status, indicating a favorable application prospect.