第3代双源计算机断层扫描全脑灌注成像优化扫描方案的可行性研究

Optimized scanning protocol for whole-brain perfusion by third generation dual-source computed tomography:a feasibility study

目的评估不同采样方式对全脑计算机断层扫描灌注成像(CTP)灌注参数和辐射剂量的影响,制定符合临床诊断要求的优化扫描方案。方法连续收集我院2016年11月至2017年6月接受全脑CTP检查的47例受检者,包括19例急性缺血性脑卒中(AIS)患者(AIS组)和28例有AIS症状但计算机断层扫描或CTP检查未见病灶者(无AIS组)。根据时间-密度曲线(TAC)得到4种采样方式:标准对照组(第1组);采样间隔3 s(第2组);以动脉TAC的上升点和下降点作为界点,扫描前期和后期采样间隔3 s,中间部分采样间隔1.5 s(第3组);动静脉TAC顶点之间采样间隔1.5 s,其余采样间隔3 s(第4组),分别定量测量所有患者的灌注参数,并进行图像质量主观分析及辐射剂量统计。结果 AIS组及无AIS组每例患者缺血区域和同一部位对侧脑实质共放置10个感兴趣区(ROI),分别获得灌注参数数据点总数为190和280。AIS组与无AIS组的血流量、血容量和平均通过时间(MTT)差异均有统计学意义(P均<0.01),但组间分析结果显示无论是在AIS患者还是在无AIS者中,第3组上述灌注参数与第1组相比差异均无统计学意义(P均>0.05)。Bland-Altman一致性分析显示,AIS患者和无AIS者的第3组与第1组之间血流量、血容量和MTT的一致性较好,且与第1组即标准对照组相比,第3组的主观评分佳、辐射剂量较低。以第3组扫描方案为基础,设立两种推荐扫描方案并进行验证,AIS患者和无AIS者两种推荐方案所得灌注参数均与第1组相关性较好(P均<0.01)。结论 "以动脉TAC的上升点和下降点作为界点,扫描前期和后期采样间隔3 s,中间部分采样间隔1.5 s"的方案与标准扫描方式有较好的一致性,且能有效降低辐射剂量,有望成为适用临床需求的全脑CTP扫描方案。

Objective To assess the influence of different time sampling modes on perfusion parameters and radiation dose of whole-brain computed tomography perfusion imaging(CTP),and to formulate an optimized scanning protocol for clinical diagnosis requirements.Methods Forty-seven consecutive patients,who underwent cerebral CTP scanning in our hospital between Nov.2016 and Jun.2017,were included in this study.Nineteen of them had acute ischemic stroke(AIS)and 28 had AIS symptoms,but no lesions were found by computed tomography or CTP.According to the time-attenuation curve,four scanning protocols were obtained:standard control group(group 1),sampling interval of 3s(group 2),sampling interval of 3 s in pre-ascending and pro-descending period,and sampling interval of 1.5 s in the intermediate period(group 3),and smapling interval of 1.5 s between the peak of artery and vein and other sampling interval of 3 s(group 4).The perfusion parameters of all subjects were quantitatively measured.Subjective image quality was analyzed and radiation dose was calculated.Results In AIS and non-AIS groups,a total of 10 region of interests were placed in the ischemic area and contralateral brain parenchyma of each patient,and the total numbers of data points of perfusion parameters were 190 and 280,respectively.There were significant differences in blood flow,blood volume and mean transit time(MTT)between the AIS group and non-AIS group(all P<0.01).However,inter-group analysis showed that there were no significant differences in the above perfusion parameters between group 3 and group 1 in both the AIS group and non-AIS group(all P>0.05).Bland-Altman consistency analysis showed that group 3 and group 1 had good consistency of blood flow,blood volume and MTT in both the AIS group and non-AIS group.Compared with group 1(standard control group),group 3 had better subjective score and lower radiation dose.Based on the sampling mode of group 3,2 recommended scanning protocols were established and validated.The perfusion parameters of the 2 recommended scanning protocols were well correlated with those of group 1 in AIS patients and non-AIS patients(all P<0.01).Conclusion The scanning protocol,in which sampling interval is 3 s in pre-ascending and pro-descending period and 1.5 s in intermediate period,is in good agreement with the standard scanning mode,and can reduce radiation dose.It may be a whole-brain CTP scanning protocol for the clinical settings.