70kV颅脑CT灌注成像的可行性研究

Study on the Feasibility of Brain CT Perfusion with 70 kV Tube Voltage

目的探讨70 k V管电压技术对颅脑CT灌注参数及图像质量的可行性。方法 2013年10月-2014年2月拟行CT灌注检查的患者,按检查时间分为A、B两组。所有的患者采用西门子128层双源CT进行扫描。分别从每组中筛选出15例经CT检查无颅脑疾病患者的图像数据进行研究。在A、B两组患者的额叶室旁、尾状核、壳、丘脑、颞枕叶放置面积为80 mm2的感兴趣区进行测量,分别测量感兴趣区内脑血流量、脑血容量、平均通过时间。比较两组图像丘脑和额叶室旁脑白质的对比噪声比、信噪比。请2位高年资神经影像学诊断医生对两组患者的图像进行主观评分(5分=最好,1分=最差)。记录CT剂量指数、CT剂量长度乘积,计算出有效剂量来评价两组患者的辐射剂量。统计学方法采用独立样本t检验。结果两组患者感兴趣区内的灌注参数值差异无统计学意义(P>0.05)。两组患者图像质量主观评分和客观评价差异均无统计学意义(P>0.05)。B组患者的CT剂量指数、CT剂量长度乘积、有效剂量较A组患者均降低了35%。结论使用西门子第2代双源CT最新70 k V管电压技术行颅脑CT灌注检查,对颅脑灌注参数值和图像质量无明显影响,而且辐射剂量明显降低。

Objective To investigate the influence of 70 k V low-dose CT perfusion technique on brain CT perfusion parameter maps and image quality. Methods Retrospective analysis of all patients who underwent CT perfusion of brain between October 2013 and February 2014 was carried out. The patients were randomly divided into two groups according to different CT examination dose： group A（80 k V, 200 m As） and group B（70 k V, 200 m As）. All patients were scanned on a dual-source-CT（Siemens Definition Flash）. Fifteen normal subjects without brain diseases in each group were selected to be studied. Region of interest（ROI） with an area of 80 mm2 was placed in the nucleus, putamen, thalamus, periventricular white matter of the frontal lobe and temporo-occipital area, and the parameters in the ROI including cerebral blood flow, cerebral blood volume, mean transit time and time to peak were detected. The carrierto-noise ratio and signal-to-noise ratio of thalamus and periventricular white matter of the frontal lobe were contrasted. The image quality of perfusion was assessed by two senior radiologists using 5 point system for blind assessment（5=best, 1=worst）. The measurement of radiation dose was studied through effective dose, volume CT dose index（CTDIVOL） and dose length product（DLP）. Statistical analysis was performed by independent sample t test. Results There was no significant difference between group A and group B in brain CT perfusion parameters（P〉0.05）. There was no significant difference in image quality between the two groups in the objective and subjective assessment（P〉0.05）. In comparison with group A, the measured effective dose, CTDIVOL and DLP for group B decreased by 35%. ConclusionThere was no significant influence on the brain CT perfusion parameters and image quality using 70 k V tube voltage, and radiation dose is decreased obviously.