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目的探讨多层螺旋 CT 颅颈联合动脉成像追踪触发技术的应用,以及准直与螺距的最佳匹配方案。方法 (1)19名志愿者进行同层动态增强扫描,以时间密度曲线峰值之前4 s 处对应CT 值的平均值作为触发技术的理论阈值。(2)40名志愿者按随机数字表随机分为 A 组(准直1.0mm,螺距1.750)和 B 组(准直2.5 mm,螺距0.625),评价三维血管质量,探讨准直与螺距的恰当匹配。统计方法采用成组设计的两样本均数 t 检验(双侧,α=0.05)。结果 (1)19例时间密度曲线峰值之前4 s处对应 CT 值的平均值为75 HU。(2)按照三维动脉质量评分标准,B 组对颈总动脉、颈内动脉、大脑中动脉、额顶升动脉、终末支的评分分别为(2.85±0.37)、(2.64±0.49)、(2.29±0.72)、(1.70±0.98)、(1.07±0.94)分,A 组分别为(2.40±0.50)、(2.31±0.47)、(2.70±0.57)、(2.35±0.75)、(1.96±0.89);B 组对颈总动脉和颈内动脉等大动脉的成像质量较佳,血管边缘光滑、锐利,A 组对大脑中动脉、额顶升动脉及终末支动脉等小动脉的细节显示清晰。A、B 两组间的三维动脉质量差异有统计学意义(P 值均<0.05)。结论 (1)追踪触发技术可更好地显示头颈部血管。对比剂注射流率3.5 ml/s 时,触发阈值为75 HU 的图像质量较佳。(2)颅颈联合 CT 血管造影采用准直1.0mm、螺距1.750优于准直2.5 mm、螺距0.625,这种匹配方式对小血管显示较佳。
Objective To explore the application of multi-slice spiral CT craniocerebral artery imaging tracking triggering technique and the best match between collimation and pitch. Methods (1) Twenty-nine volunteers underwent dynamic contrast-enhanced scanning. The theoretical threshold value of the average CT value at 4 s before the peak of the time density curve was used as the triggering threshold. (2) Forty volunteers were randomly divided into group A (alignment 1.0 mm, pitch 1.750) and group B (alignment 2.5 mm, pitch 0.625) according to a random number table to evaluate the quality of three-dimensional blood vessels and to explore the appropriate collimation and pitch match. Statistical methods were grouped by two-sample t-test (bilateral, α = 0.05). Results (1) The average value of corresponding CT values at 4 s before peak time of 19 time-density curves was 75 HU. (2) According to the standard of three-dimensional artery grading, the score of common carotid artery, internal carotid artery, middle cerebral artery, frontal artery and terminal branch in group B were (2.85 ± 0.37), (2.64 ± 0.49) and (2.70 ± 0.57), (2.35 ± 0.75), (1.96 ± 0.89), (1.70 ± 0.98) and (1.07 ± 0.94) ). In group B, the imaging quality of the common carotid artery and internal carotid artery was better, and the blood vessel margin was smooth and sharp. The detail of the arterioles of middle cerebral artery, frontal ascending artery and terminal artery were clearly displayed in group A. There was significant difference in the quality of 3D arteries between groups A and B (P <0.05). Conclusions (1) Tracking triggering technique can better show the head and neck blood vessels. Contrast injection rate of 3.5 ml / s, the trigger threshold of 75 HU image quality is better. (2) Craniotomy and CT angiography with alignment 1.0mm, pitch 1.750 better than collimation 2.5 mm, pitch 0.625, this matching method shows better for small blood vessels.