后循环短暂性脑缺血发作的CT灌注和CT血管成像应用研究

Application of CT Perfusion Imaging and CT Angiography in Posterior Circulative Transient Ischemic Attack

目的探讨CT灌注(computerized tomography perfusion,CTP)联合CT血管造影(computerized tomography angiography,CTA)检查在后循环短暂性脑缺血发作患者中的应用价值,并对后循环短暂性脑缺血发作的病因、发病机制进行研究。方法对50例后循环短暂性脑缺血发作患者进行CTP、CTA检查,测定脑干、小脑局部平均通过时间(mean transmit time,MTT)、脑血流量(cerebral blood flow,CBF)及脑血容量(cerebral blood volume,CBV)灌注参数,获得相应参数图,进行兴趣区与对侧镜像区域参数的比较。结果 (1)39例患者CT灌注成像发现与临床症状相对应的灌注异常区,阳性率为78%;(2)比较灌注异常区与对侧正常对照区平均MTT、平均CBF及平均CBV,患侧MTT较健侧明显延长,患侧CBF明显低于健侧,两者差异具有统计学意义(P<0.05);(3)50例患者中有40例(80%)CTA显示椎基底动脉异常,其相应供血区CTP异常者34例(85%);10例CTA未发现血管异常患者中,CTP异常者5例(50%),两者差异具有统计学意义。结论 CTP能够反映后循环TIA患者的脑灌注状态,CTA可以直观准确地评价相应供血血管的病变情况,后循环的低灌注是后循环TIA的主要发病机制,椎基底动脉狭窄是后循环TIA的主要病因。二者联合应用为后循环TIA的病因、发病机制及诊断提供了直接客观的影像学依据。

Objective Using the computerized tomography perfusion imaging （CTP） conbined with computerized tomography angiography（CTA） to observe the changes of regional cerebral blood flow and blood - supply artery, to study the value of CTP and CTA in posterior circulative TIA and further explore the etiological factors andpathogenesis of posterior circulative TIA. Methods Fifty patients with, which clinical symptoms displayed mainly dizziness was enrolled into the study randomly. These patients were underwent CTA and CTP. The mean transmit time（MTT）, cerebral blood flow（CBF）and cerebral blood volume（CBV）in the region of in- terests（ROIs）between the two sides of the patient were analyzed, and the relationship with CTA features and the etiological factors were discussed. Results （1）Thirty - nine of 50 patients（78 % ）with TIA were revealed abnor- mal perfusion regions corresponding to clinical symptom in CTP, of which there were 39 cases revealed abnormal perfusion regions on mean transmit time （MTT） maps, and 29 cases on cerebral blood flow（CBF） maps, only 10 on cerebral blood volume（CBV） maps. Other 11 cases showed normal results in CTP. 2. In 50 cases with TIA, the MTT of affected side（4.6 ± 1.3）s compared with that of the contralateral side （3.9 -± 0.9）s was significant- ly prolonged（P〈0.05） ;Also, the CBF of affected side （36.4 ± 13.26）ml/（100 g＇min） compared with that of the contralateral side （43.2 ± 14.95 ） ml/（ 100 g. min） was significantly different （ P 〈 0.05 ） ; And the difference of the CBV（P 〉0.05） was not statistically significant between the affected side （1.9 ± 0.7）ml/100 g and the contralateral side（2.0 ± 0.6） ml/100 g. （3）In 50 cases checked by CTA, there were 40 cases （80%） with ab- normal vascular. Among them 34（85 % ） eases were revealed perfusion abnormalities, which were matched with clinical symptoms. There were 5 cases （50%） with perfusion abnormalities but without convict vascular. Through statistical analysis, there was a significant difference betweenthem. It suggested that the positive rate of CTP were higher in the eases with convict vascular.Conclusion （1）MTT is the most sensitive and primary parameter in the diagnosis of posterior circulative TIA. （2）The application of CTP and CTA is important to study the etiology of posterior circulative TIA, which supports the hypoperfusion Theory is the pathogenesis mechanism of posterior circulative TIA. （3）CTP combined with CTA has a high sensitivity for the diagnosis of posterior circulative TIA, which provides noninvasive examination mean and allround objective support.