64层螺旋CT血管造影颅底段颈内动脉和基底动脉腔内线样低密度影的形成原因及临床意义

Reasons and clinical significance of low density streaks in 64-slice spiral CT image of arteria carotis interna and arteria vertebralis

目的对64层螺旋CT轴位像上显示的颅底颈内动脉及基底动脉腔内线状低密度影形成的原因进行初步研究探讨,并结合文献分析其临床意义。方法采用64层螺旋CT对本科室2009年9月14日至2009年10月15日收治的270例非外伤患者行头颈部血管成像检查,在ADW 4.4后处理机上进行后处理后传入PACS系统,并将得到的颅底血管轴位图像也传入PACS系统,由2位后处理经验丰富的医师进行观察,统计基底动脉及颅底颈内动脉各段出现线样低密度影的例数并进行分析,且分别测量基底动脉末端CT值及颈内动脉海绵窦段管腔直径、基底动脉垂直走行处直径,得到的数据进行统计学分析。结果纳入研究的270例患者中,不存在血管腔内线样低密度影的40例,而存在的230例,占总研究人数的85%(230/270)。线样低密度影在横轴位上分为3型,Ⅰ型440根,表现为血管腔内1条线状低密度影;Ⅱ型64根,表现为血管腔内从中心发出2条线状低密度影到达血管壁,形如"鱼叉"状;Ⅲ型137根,表现为血管腔内线样低密度影呈星芒状分布。统计各部位存在线状低密度影的例数,基底动脉108根,颈内动脉虹吸部341根,颈动脉孔前23根,颈动脉孔143根,眼动脉段19根,颈动脉海绵窦段7根,基底动脉及颈内动脉虹吸部出现线样低密度影的概率最大。分别测量基底动脉末端CT值,不存在线样低密度影血管腔内的CT值(421.68±65.26)Hu比存在其的CT值(390.81±73.78)Hu高(P=0.014)。将不存在线样低密度影与存在线样低密度影的血管腔直径进行分析,基底动脉不存在线样低密度影的血管腔比存在的血管腔管径小,而左侧颈内动脉不存在线样低密度影的血管比存在的血管管径大(P<0.01),右侧则无明显区别(P>0.05)。结论血管腔内线样低密度影的影像与血管腔内CT值、血管解剖因素及伪影的影响有关,与血管管径无明显关系,对外伤性血管损伤合并内膜瓣形成的鉴别诊断有重要的临床意义。

Objective To explore the reason of the streaks in low density in arteria carotis interna and arteria vertebralis of the skull base which are manifestationed by 64-multislice spiral computed tomography（MSCT）,and investigate the clinical values of the display.Methods CT angiography（CTA） was performed in 270 non-trauma patients admitted in our hospital from September 14 to October 15,2009 by a GE LightSpeed 64-slice MSCT scanner.Postprocessing images were obtained by ADW 4.4,then transmitted with the row date to a picture archiving and communication system（PACS）.The number of arteria basilaris and arteria carotis interna having streaks in low density in the lumen of blood vessel were calculated,and the computerized tomography value and the diameters of arteria carotis interna and arteria basilaris were measured and statistically analyzed.Results There were 40 patients having no streak in low density,and 230 patients having such streaks（85%）.The streaks in low density were divided into 3 types according to what were displayed in cross shaft images.Type I was 440 strips which displayed one streak in low density in lumen of blood vessel,type II was 64 strips with two streaks in low density（like ＂harpoon＂）,and type Ⅲ was 137 strips with three streaks in low density（like ＂stellate＂）.As for the location of streaks in low density,there were 108 strips in arteria basilaris,341 strips in arteria carotis interna siphonage,23 strips in segment anterior to carotid foramen,143 strips in carotid foramen,19 strips in arteria ophthalmica,and 7 strips in cavernous internal carotid artery,Our data showed that streaks in low density were more common in the arteria basilaris and arteria carotis interna siphonage.The CT value of the blood vessel with streak in low density（421.68±65.26 Hu） were higher than that having no streak（390.81±73.78 Hu）.The diameter of arteria basilaris having no streak in low density was smaller than that of the vessel having.But for the arteria carotis interna,the diameter of left vessel having no streak was larger than that of the vessel having（P0.01）.However,there was no significance for the right arteria carotis interna（P0.05）.Conclusion The streak in low density in the MSCT image has a relationship with CT value of blood vessel,blood anatomy and artifact,but has no relationship with blood vessel diameter.It has a very considerable significance in identifying the endomembrane laceration.