自适应性统计迭代重建（ASIR）算法结合双低技术在头颈CTA中的应用研究

摘要

Objective To evaluate the feasibility of using low-concentration contrast agent(Visipaque 270 mg I/ml)and low tube voltage in head and neck CT angiography(CTA).Methods Forty patients(22 men and 18 women;average age 48.7ys;average body mass index 23.9±3.7kg/m2)with suspected cerebrovascular disease were randomly assigned to two groups for head and neck CTA. Twenty patients were injected intravenously with 370 mg I/ml of Iopamidol and 20 patients with 270 mg I/ml of Visipaque.Images of the Iopamidol group were obtained with 120 kVp and filtered back projection reconstruction whereas images of the Visipaque group were acquired with 80 kVp and ASiR reconstruction.The CT values and standard deviation of intracranial arteries and image noise on the corona radiata were measured to calculate contrast-noise-ratio(CNR)and signal-noise-ratio(SNR).The CT dose index volume (CTDIvol)and dose-length product(DLP)were recorded.Two readers scored the image quality on volume rendering(VR)images on a scale of 1 to 5 and the scores between the two groups were compared.Results The mean CT values of the intracranial arteries, CNR,SNR with intravenous Visipaque were significantly higher than that with Iopamidol(P<0.001).The score of VR image quality of Visipaque(4.2)was significantly(P=0.001)higher than that of Iopamidol(3.7).The CTDIvol and DLP were significantly(P<0.001) decreased by 63.8%and 64%,respectively with Visipaque.Conclusions Contrast agent with low-iodine concentration using 80 kVp radiation tube voltage and ASiR reconstruction provides superior head and neck CTA image quality with 64%radiation dose reduction.%目的：探讨低浓度对比剂和低管电压在（GE Discovery CTHD 750 HD）头颈CTA的可行性。方法将40名拟行头颈CTA的患者随机分为A、B两组，每组20名。A组用370 mg I/ml对比剂、120 kVp及传统滤波反投影算法重建，B组用270 mg I/ml对比剂、80 kVp及ASiR进行图像重建。记录两组患者头颈血管各分支CT值、噪声值及背景CT值、噪声值、CT容积剂量指数（CTDIvol）剂量长度乘积（DLP），并计算和比较对比噪声比（CNR）、信噪比（SNR）。两位放射科医师采盲法对容积呈现（VR）图像质量进行评估（5分制）。结果 B组血管CT均值、CNR、SNR值及VR图像质量主观评分均高于A组（P＜0.05），而A组CTDIvol及DLP值高于B组。A、B两组的VR图像质量均能满足临床诊断要求。结论双低技术在应用ASiR重建算法的基础上进行头颈CTA扫描，在降低患者辐射剂量和碘单位时间注射剂量的同时，能保证VR图像质量。