目的：探讨64层螺旋CT同序列分别行脑动脉、脑动静脉、脑静脉的成像方法和最佳扫描能量（kV）。方法在我院行减影脑血管成像研究患者共220例，按扫描仟伏值大小随机分为三组，A组（120kV ），共59例；B组（100kV ），共85例；C组（80kV），共76例。对整个头部平扫、动脉期和静脉期扫描（智能跟踪阈值70HU启动扫描），将动、静脉期数据减去平扫数据获得减影动脉期、减影动静脉期数据，静脉期数据减去动脉期数据获得减影静脉期数据。采用容积再现（VR）、最大密度投影（MIP）重建减影血管图像。测量A、B、C组减影后血管密度和翼内肌SD噪声（客观噪声），根据血管图像质量分为四级并分别记分。结果①血管密度：A、B、C三组患者血管组内比较减影动脉期动脉较静脉密度显著高，差异有统计学意义（P ＜0．05），减影动静脉期动脉和静脉密度相似，差异无统计学意义（P ＞0．05），减影静脉期动脉较静脉密度显著低，差异有统计学意义（ P ＜0．05）。三组减影动脉期、减影动静脉期和减影静脉期血管密度组间比较随能量降低密度升高，差异有统计学意义（ P ＜0．05）；②图像质量：A、B、C三组减影脑动脉全部有诊断价值，组间两两比较差异有统计学意义（ P ＜0．05）；三组减影动静脉全部有诊断价值，Ⅰ级图像以C组减影脑动静脉图像质量最高，BC组间两两比较差异无统计学意义（ P ＞0．05），AC和BC组间两两比较差异有统计学意义（ P ＜0．05）；三组减影脑静脉少数无诊断意义，Ⅰ级图像以B组最高，AC组间两两比较差异无统计学意义（ P ＞0．05），AB和BC组间两两比较差异有统计学意义（P＜0．05）；③辐射剂量和噪声：三组辐射剂量随能量的降低而明显下降，三组噪声随能量的降低而明显增加（P＜0．05）。结论64层螺旋C T同序列能分别脑动脉、脑动静脉和脑静脉成像，脑动脉、脑动静脉全部有诊断价值，仅脑静脉极少部分无诊断值，以100kV图像质量最好，100kV和80kV能量扫描使辐射剂量明显减少，值得临床大量推广应用。%Objective To study the method of 64-slice spiral CT for the cerebral arterious ,mixed cerebral arteriovenous and cerebral venous imaging respectively and the optimal scanning energy (kV) .Methods A total of 220 patients ,who underwent the cerebral subtraction angiography in our hospital ,were randomly divided into three groups according to the scanning kilovar value ,i .e .,Group A (120 kV) with 59 patients ,Group B (100 kV) with 85 patients ,and Group C (80 kV) with 76 patients .The whole head was subjected to plain scan ,arterial and venous phase scanning (starting scanning at 70 HU as intelligent tracking threshold) .Data from intravenous period minus the plian scaning data obtained subtrac-tion angiography data and the data from subtraction mixed arteriovenous arterial phase minus the arterial venous phase data obtained subtraction venous phase data .By use of the volume representation (VR) and maximum density projection (MIP) ,the image of subtraction blood vessels was reconstructed .The vascular density and wing the intrinsic SD (objec-tive noise) were measured in Group A ,B ,C .The noise and image quality were divided into four grades according to the blood vessels .Results ① Vascular density :In comparison to arterial blood vessels of patients in Group A ,B ,C ,the density in subtraction angiography artery was higher than that in venous phase ,with statistically significant difference ( P< 0 .05 ) , density in subtraction angiography arteriovenous mixed phase of arteries versus and veins was similar ,with no statistically significant difference ( P >0 .05) ,density in subtraction venous phase of artery versus vein was lower ,with statistically significant difference was ( P<0 .05) .The density in arterial ,mixed reduction stage ,arteri-ovenous vein stage was increased with the decreasing of energy in three groups ,with statistically significant difference ( P<0 .05);② Image quality :all cerebral arteries had diagnostic value ,with statistically significan difference among three groups ( P <0 .05);Mixed arteriovenous image in all three groups of subtraction angiography had diagnostic value .In levelⅠ image ,the mixed cerebral arteriovenous image quality in group C was supreme .There was no statistical signifi-cance between group B and C ( P >0 .05) .There were statistically significant differences between group A and C as well as between group B and C ( P <0 .05) .The subtraction angiography in minority had no sense of diagnosis in the three groups .The level Ⅰ image was the highest in group B .There was no statistical significant differences between group A and C groups ( P >0 .05) and there was statistically significant difference between group A and B as well as between group B and C ( P<0 .05);③ The radiation dose and noise :In the three groups ,the radiation dose was significantly de-creased with the decrease of energy ,but ,the noise was obviously increased with the decrease of energy ( P<0 .05) .Con-clusion One sequence of 64-slices spiral CT can be imaging for mixed cerebral arteries ,cerebral arteriovenous and cerebral vein .Cerebral arterious and mixed cerebral arteriovenous images all have diagnostic value .Only cerebral venous image has little diagnostic value .The image quality in 100 kV is best and the energy radiation dose for scan is significantly reduced in 100 kv and 80 kv ,which is wothy of applying in clinic .
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