70kV管电压全脑CT灌注成像的可行性研究

Feasibility study of 70 kV whole brain CT perfusion imaging

目的 CT灌注成像目前已在临床上广泛应用,可定量评估脑血流状态,但其较高的辐射剂量一直受到关注。文中联合扫描方案改良,探讨70 k V管电压在全脑CT灌注成像(CT perfusion,CTP)中的可行性。方法将2014年10月至2015年3月期间于南京军区南京总医院疑诊为缺血性脑血管疾病或因眩晕症状就诊,并行CTP的患者60例以随机数字表法分成2组,每组30例。其中单数日采用80 k V、100 m As的扫描参数行CTP检查,扫描次数为21期者为80 k V组;双数日采用70 k V、120 m As的扫描参数行CTP检查,扫描次数为17期者为70 k V组。评估并比较2组间的灌注参数、主观图像质量评分及辐射剂量。结果 70 k V组尾状核头部、额叶白质及颞枕叶白质的血流量分别为(67.12±6.44)、(30.11±4.39)和(29.69±3.24)m L/(100 m L·min),血容量分别为(4.04±0.37)、(1.90±0.24)和(1.90±0.19)m L/100 g,平均通过时间分别为(3.74±0.64)、(4.79±0.98)和(5.35±1.09)s;与80 k V组同部位血流量(66.46±7.48)、(28.48±3.77)、(29.34±2.84)m L/(100 m L·min),血容量(3.99±0.47)、(1.82±0.23)、(1.82±0.26)m L/100 g,平均通过时间(3.54±0.47)、(4.54±0.89)、(4.95±1.18)s相比,差异无统计学意义(P>0.05);70 k V组血流量与血容量的灰白质对比度评分[(1.93±0.25)、(1.93±0.25)]高于80 k V组[(1.73±0.45)、(1.70±0.54)],差异有统计学意义(P<0.05),但2组总体主观图像质量的差异无统计学差异(P>0.05)。70k V组的辐射剂量较80 k V组降低37%(P<0.05)。结论结合扫描方案改良,70 k V管电压在全脑灌注成像具有可行性。与80 k V的CTP扫描方案相比,在保证图像质量的同时有效降低了辐射剂量,值得推广。

Objective Whole brain CT perfusion （CTP） is widely used in clinical practice for quantitative evaluation of cere- bral hemodynamic status, but the high radiation dose from the dynamic scanning has raised constant concerns. This study was to assess the feasibility of the whole brain CTP with lower kV （70 kV） and adaptive protocol. Methods Sixty patients suspected as ischemic cerebral vascular disease or accompanied with staggers from October 2014 to March 2015 were recruited in the present study. All the patients received the CTP examine and were randomly divided into two groups （ n = 30 for each ） ： 80 kV group, with traditional protocol of 22 scanning times ; and 70 kV group , with new protocol of 17 scanning times. The values of the perfusion parameter and subjective evaluation of the perfusion images were measured on the perfusion maps. Radiation dose was estimated. Results The perfusion parameters of cerebral blood flow （CBF） was 67.12±6.44,30. 11 ± 4.39 and 29.69 ± 3.24 mL/（ 100 mL·min）, cerebral blood volume （CBV） was 4.04 ± 0.37,1.90 ± 0.24, and 1.90 ± 0.19 mL/100 g, and mean transit time （MT＇F） was 3.74 ±0.64,4.79 ± 0.98 and 5.35± 1.09 s measured from the caudate nucleus, frontal white matter, and temporo-occipital white matter in the 70kV group. There was no significant difference in the perfusion parameters of CBF（66.46 ± 7.48,28.48 ±3.77,29.34 ±2.84 mL/（ 100 mL·min） ,CBV（3.99±0.47,1.82±0.23,1.82±0.26 mL/100 g）, and MTT（3.54 ± 0.47,4.54 ± 0.89,4.95 ±1.18 s ） in the 80 kV group（ P 〉 0.05 ）. Gray-white matter differentiation on the CBF and CBV maps was higher in the 70 kV group （ 1.93 ± 0.25, 1.93 ± 0.25 ） than in the 80kV group （ 1.73 ± 0.45, 1.70 ± 0.54） （ P 〈 0.05 ）, however, there was no significant difference for the overall subjective image quality between the two groups （ P 〉 0.05 ）. Radiation dose in the 70kV group was decreased by 37% compared with the 80kV group （ P 〈 0.05 ）. Conclusion Compared with 80 kV CTP, 70kV CTP is feasible ,which can obtain comparable image quality with lower radiation dose.