中文摘要：

目的：评估宝石能谱CT在低kV及低剂量对比剂的条件下,门静脉成像的图像质量及技术的可行性。方法：纳入临床建议行CT门静脉成像（CT Portal Venography,CTPV）检查且BMI〈28 kg/m~2的患者40例,分为试验组（采用低电压及低剂量对比剂）和对照组（采用常规电压及常规剂量对比剂）各20例。应用GE公司Discovery CT750HD宝石能谱CT进行扫描。试验组扫描参数：80 k V,300 m A,对比剂为威视派克（270 mg I/mL）60 mL,图像重建采用50%滤波反投影重建（FBP）＋50%自适应统计迭代重建（ASIR）;对照组扫描参数：120 kV,300 m A,对比剂为欧乃派克（350 mg I/mL）90 mL,图像重建采用100%滤波反投影重建（FBP）。评价图像质量采用目测5分法,记录扫描容积CT剂量指数（CTDIvol）,剂量长度乘积（DLP）,测量并计算图像噪声（Image Noise,IN）及肝内、外门静脉的对比噪声比（Contrast to Noise Ratio,CNR）。并应用独立样本t检验比较2组间图像质量评分、噪声值、对比噪声比（CNR）。结果：试验组和对照组图像质量评分分别为（4.0±0.5）、（4.1±0.5）分,差异无统计学意义（t=0.805,P〉0.05）。试验组肝内噪声及肝外噪声分别为（21.2±2.1）HU、（21.6±2.3）HU,高于对照组（14.2±1.5）HU、（15.0±1.4）HU,差异有统计学意义（t值分别为11.993、11.091,P值均〈0.01）;试验组肝内CNR及肝外CNR分别为3.6±0.9、5.1±0.8,低于对照组5.4±1.0、6.9±1.1,差异有统计学意义（t值分别为5.231、4.261,P值均〈0.01）。试验组所接受辐射剂量容积剂量指数CTDIvol（4.7±0.2）mGy和剂量长度乘积DLP（132.7±6.2）mGy·cm均低于对照组CTDIvol（13.7±0.3）mGy和DLP（395.2±22.1）mGy·cm,差异均有统计学意义（t值分别为102.781、51.089,P值均〈0.01）。结论：低剂量、等渗低浓度对比剂CTPV技术明显减少碘对比剂用量和射线暴露,并且满足临床诊断的需要。

英文摘要：

Objective： To evaluate the image quality and feasibility with spectral CT using double low dose technique （low tube voltage and low concentration contrast agent） in CT portal venography （CTPV）. Methods： Forty patients with clinically suggested CTPV and BMI〈28 kg/m2 underwent CTPV with a spectral MDCT scanner （GE Discovery CT750 HD）. Forty patients were divided into two groups（group A： n=20, 80 kV, 300 mA, 60 mL 270 mg I/mL, 50 %FBP＋50 %ASIR; group B： n=20,120 kV, 300 mA, 90 ml 350mg I/mL, 100%FBP）. Image quality was assessed, using a five-point scoring scale. CTDIvol and DLP were stored, IN and CNI（ of intrahepatic and extrahepatic were stored and calculated. Image quality score, IN and CNR of intrahepatic and extrahepatic, CTDIvol and DLP were compared between the two groups using t-test Results＂ The image quality scores for two groups were 4.0± 0.5 and 4.1± 0.5, respectively. There was no statistical difference between two groups（t=-0.805, P〉0.05）. The IN of intrahepatic and extrahepatie in group A[（21.2± 2.1） HU,（21.6± 2.3）HU, respectively]were higher than those in group B[（14.2± 1.5）HU, （15.0± 1.4）HU, respectively], which was statistically significant（t=l 1.993, 11.091, respectively; P〈0.01 both）. The CNR ofintrahepatic and extrahepatic in group A（3.6±0.9, 5.1± 0.8, respectively）were lower than those in group B（5.4~ 1.0, 6.9＋ 1.1, respectively）, which was statistically significant（t=-5.231, 4.261, respectively; P〈0.01 both）. The CTDIvol [（4.7± 0.2）mGy] and DLP [（132.7± 6.2）mGy.cm] in group A were significantly lower than those in group B CTDIvol [（13.7± 0.3）mGy, DLP（395.2± 22.1）mGy. cm]. The difference between two groups was statistically significant（t= 102. 781, 51.089, respectively, P〈0.01 both）. Conclusions： Using low tube voltage and low concentration contrast agent in CTPV with spectral CT reduces radiation exposure and contrast media volume and can meet clinical diagnostic needs.