64排螺旋CT透析自体动静脉瘘狭窄成像的技术初探

目的探讨64排螺旋CT在血液透析自体动静脉瘘狭窄中血管成像(CTA)的方法和体会。方法在让患者充分了解和愿意配合本检查后,使用64排螺旋CT。患者取俯卧位,患肢上举,高于头部,取健侧肘静脉穿刺,团注对比剂,最大不超过55 ml,流率4～5 ml/s。对比剂注射完毕后立即以相同流率注入20～30 ml生理盐水。CT扫描参数为:层厚0.625 mm,螺距为1.108,螺旋时间0.75 s/r,80 kV和120 mAs。采用自动管电流和Blous Track-ing扫描方式,对21例(男12例,女9例,中位年龄61岁)自体动静脉瘘狭窄的患者行CTA检查。在EBW工作站上采用1 mm层厚行矢、冠和轴位的重组,并进行三维的多平面重组(MPR),曲面重组(CPR),最大密度投影(MIP)和容积再现(VR)以最佳参数和角度显示自体动静脉瘘狭窄的状况。结果本组患者有20例(95%)获得了满意的CTA图像,即狭窄部位清晰可见,病变血管的范围、走行清楚。侧支循环血管清晰。本组21例均为血管超声所发现,其中10例被DSA或手术证实与CTA结果相同。结论要获得良好的自体动静脉瘘CT图像,需与患者良好的沟通,参数配置准确,恰当。其中对比剂的用量和扫描速度的快慢、扫描时间的长短,阈值的设定,为关键因素。

Preliminary Study On the Native Arteriovenous Fistula(AVF) Stenosis in Hemodialysis Patients with 64 slice Spiral CT Angiography

Objective To discuss the value of 64 slice spiral CT angiography in the evaluation of the native arteriovenous fistula(AVF) stenosis in hemodialysis patients.Methods Every patient had learned fully and cooperated to take CT angiography before scanning.21 hemodialysis patients(Male 12,Female 9,median age 61 years old) with AVF stenosis was detected by 64 slices spiral CT.Patients were positioned on prone position with their AVF arm extended above the head.The venous access was chosen in superficial vein of the contralaterial arm.The injection rate was 4-5 mL/s: maximum not more than 55 mL(2 mL/per BMI) of contrast agent was administered followed by a chase bolus of 30 mL of saline.The scanning protocol was a pitch of 1.108,acquision of 64×0.625 mm,rotation time of 0.75 second,80 kV and 120 mAs.Automated tube current modulation and bolus tracking technique was applied.Image reconstruction was derived from 1 mm slice thiickness in the axial,sagittal,and coronal orientations in EBW workstation.Additional MPR,CPR,MIP and VR 3D images were obtained as well.Results Interobserver agreement for good imaging quality was found in 20 patients(94%),the AVF could be clearly seen on CT imaging.The location and extent of arteriovenous lesions,collateral artery circulation could be observed clearly on the imaging.21 cases were detected by ultrasound for blood vessels,and the results of the CT angiography were confirmed by DSA or surgery in 10 cases.Conclusion Having a good communication with patient and selecting optimal scanning parameters are important for getting high quality CT imaging of AVF stenosis.The key points include the dose and injection rate of contract agent via venious,scanning parameters and threshold values.