双能量CT头颅血管成像的影像质量、辐射剂量及初步临床应用

目的 探讨双源CT(DSCT)双能量技术头颅血管成像的初步临床应用价值.方法 选择41例临床怀疑有脑血管病变患者行双能量CTA(DECTA),另选择对照组41例患者行常规减影CTA.2名医师共同进行分析协商,评价两种方法颅底及颅内血管影像质量,计算辐射剂量,分析DECTA对41例患者的检查情况,选取经DSA证实的9例12个动脉瘤,测量动脉瘤的大小、瘤颈,并与DSA进行比较.DECTA和常规减影CTA血管影像质量的比较采用独立样本的非参数等级检验,辐射剂量的比较采用两个独立样本的t检验,DECTA和DSA显示动脉瘤的大小、瘤颈的比较采用配对t检验,DECTA和DSA测量动脉瘤颈、瘤长轴及瘤短轴的相关性采用Spearman相关分析.结果 颅内血管DECTA和常规减影CTA影像质量5分的病例分别占70.7%(29/41)、75.6%(31/41),差异无统计学意义(Z=-0.455,P=0.650),而颅底血管常规减影CTA总的影像质量优于DECTA(Z=-4.087,P=0.000),主要是岩段和虹吸段的影像质量较差;DECTA和常规CTA总辐射剂量分别为(396.54±17.43)、(1090.95±114.29)mGy·cm;DECTA所用总辐射剂量较常规减影CTA总辐射剂量降低了64%,差异有统计学意义(t=-38.52,P=0.000).41例临床怀疑有脑血管病变患者,DECTA检出19例患者有动脉瘤,2例动静脉畸形,3例烟雾病,17例阴性患者.9例动脉瘤患者(12个动脉瘤)、2例脑动静脉畸形、3例烟雾病和2例阴性患者行DSA或手术证实,诊断符合率达100%.DECTA检测动脉瘤颈、瘤长轴及瘤短轴分别为(2.90±1.61)、(5.23±1.68)及(3.83±1.69)mm,DSA检测动脉瘤颈、瘤长轴及瘤短轴分别为(2.95±1.71)、(5.10±1.60)及(3.83±1.65)mm.两者在动脉瘤大小、瘤径测量方面的差别无统计学意义(瘤颈、瘤长轴及短轴所对应的t值分别为-0.734、1.936及0.125,P值分别0.482、0.085及0.903);且两者测量之间有很好的相关性(瘤颈、瘤长轴及短轴的r值分别为0.964、0.976、0.973,P值均为0.000).结论 相对于常规减影CTA,颅内血管DECTA的图像质量没有明显下降,而颅底血管,尤其是岩段和虹吸段的影像质量较差.双源CT双能量CTA明显减少患者辐射剂量,有很高的诊断准确性,是一种较好的影像学检查手段.

Dual energy CT intracranial angiography: image quality, radiation dose and initial application results

Objective To assess the clinical value of dual-energy intracranial CT angiography (CTA).Methods Forty-one patients suspected of intracranial vascular diseases underwent dual-energy intracranial CT angiography, and 41 patients who underwent conventional subtraction CT were enrolled as the control group.Image quality of intracranial and skull base vessels and radiation dose between dual-energy CTA and conventional subtraction CTA were compared using two independent sample nonparametrie test and independent-samples t test, respectively.Prevalence and size of lesions detected by dual-energy CTA and digital subtraction CTA were compared using paired-samples t test and Spearman correlative analysis. Results The percentage of image quality scored 5 was 70.7% (29/41) for dual-energy CTA and 75.6% (31/41) for conventional subtraction CTA.There was no significant difference between the two groups(Z= -0.455, P=0.650).Image quality of vessels at the skull base in conventional subtraction CTA was superior to that in dual-energy CTA, especially for the petrosal and syphon segment (Z=-4.087, P= 0.000).Radiation exposure of dual energy CTA and conventional CTA were (396.54±17.43) and (1090.95±114.29) mGy · cm respectively.Radiation exposure was decreased by 64% (t=-38.52, P=0.000) by dual energy CTA compared with conventional subtraction CTA.Out of the 41 patients,19 patients were diagnosed as intracranial aneurysm, 2 patients as arteriovenous malformation (AVM), 3 patients with Moya-moya's disease, and the remaining 17 patients with negative results.Nine patients with intracranial aneurysm, 2 patients with AVM, 3 patients with Moya-moya's disease, and 2 patients with negative findings underwent DSA or operation, with concordant findings from both techniques.Diameter of aneurysm neck, long axis and minor axis by dual-energy CTA was (2.90±1.61), (5.23±1.68) and (3.83±1.69) nun, respectively; Diameter of aneurysm neck, long axis and minor axis by DSA was (2.95±1.71), (5.10±1.60) ,(3.83±1.65) nan,respectively.There was no significant difference for the diameters of aneurysm between dual energy CTA and DSA ((t=-0.734,1.936,0.12.5 respectively, P=0.482,0.085,0.903 respectively), and good correlation was found between diameter measurements using the two techniques(r=0.964,0.976,0.973, respectively, all P=0.000) Conclusions Compared with conventional subtraction CTA, dual energy CTA has good image quality for intracranial vessels; however, image quality of the skull base vessels is worse, especially for the petrosal and syphon segment.Dual energy CTA has decreased radiation dose and a high diagnostic accuracy, being a practical imaging madality for diagnosis of intracranial vascular lesions.