低管电压在冠状动脉和头颈部CT血管成像“一站式”扫描中的应用价值

Application value of “one-stop”scanning of coronary and head and neck CTA using low tube voltage

目的探讨正常体质量指数(BMI)(18kg/m^2≤BMI≤25kg/m^2)的患者在低管电压(80kVp)条件下行冠状动脉和头颈部CT血管成像(CTA)“一站式”扫描中的应用价值。方法回顾性分析80例临床已完成冠状动脉和头颈部CTA“一站式”扫描的正常体质量指数患者,按不同的扫描方法分为A、B两组,每组连续抽取40例。A组扫描参数:管电压80kV、冠状动脉CTA管电流550mA、头颈部CTA管电流500mA,B组扫描参数:管电压100kV、冠状动脉CTA管电流450mA、头颈部CTA管电流400mA。将两组图像质量进行主观评价和客观评价。比较两组图像的主观评分、冠状动脉和头颈部CTA主干分支血管图像的CT值、对比噪声比(CNR)、图像噪声(SD)和有效剂量。结果两组图像质量均满足诊断要求,且两组图像质量主观评分差异无统计学意义(P>0.05)。A组与B组冠状动脉各主干分支、头颈部血管主干分支(颈总动脉、颈内动脉)的CT值和头颈部CTA背景噪声(SD)值差异有统计学意义(t=4.737、6.552、3.359、2.165、2.685、4.617,P<0.05),A组与B组冠状动脉CTA背景噪声(SD)值、头颈部血管(大脑中动脉)的CT值和CNR差异无统计学意义(P>0.05)。A组冠状动脉CTA有效剂量(1.16±0.20)mSv较B组(2.37±0.77)mSv降低约51.1%,A组头颈部CTA有效剂量(0.37±0.03)mSv较B组(0.71±0.17)mSv降低约47.9%。结论采用低管电压在冠状动脉和头颈部CTA“一站式”扫描时,图像质量主观评价满足诊断要求,图像质量客观测量CNR值与常规扫描方法基本保持一致,而患者接受的有效剂量降低约50%。

Objective To investigate the value of “one-stop”scanning of coronary and head and neck CTA in patients with normal body mass index (18 kg/m^2 ≤ BMI ≤ 25 kg/m^2) using low tube voltage (80 kVp). Methods In a retrospective analysis 80 patients with normal body mass index who had completed “one-stop” scanning of coronary and head and neck CTA were divided into A and B groups according to different scanning method, and 40 consecutive cases were selected in each group. Scanning parameters of group A and group B were tube voltage 80 kV, coronary CTA tube current 550 mA, head and neck CTA tube current 500 mA, and tube voltage 100 kV, coronary CTA tube current 450 mA, head and neck CTA tube current 400 mA separately. Subjective evaluation and objective evaluation were performed on the image quality of the two groups. CT values of coronary artery and head and neck CTA trunk branch vessel, contrast-to-noise ratio (CNR), image noise (SD) and effective dose between the two groups were compared. Results The image quality of both groups met the diagnostic requirements, and there was no statistically significant difference in subjective scores between two groups (P>0.05). The CT values of coronary arteries, the main branches of the head and neck (the common carotid artery, the internal carotid artery) and SD of head and neck CTA were significantly different between two groups (t=4.737, 6.552, 3.359, 2.165, 2.685, 4.617, P<0.05). There was no statistically significant difference in SD of coronary CTA, CT values and CNR between head and neck vessels (middle cerebral artery) in group A and group B (P>0.05). The effective dose of coronary CTA in group A (1.16±0.20)mSv was reduced by 51.1% than that in group B (2.37±0.77)mSv. The effective dose of head and neck CTA in group A (0.37±0.03)mSv was reduced by 47.9% than that in group B (0.71±0.17)mSv. Conclusions The image quality with subjective evaluation met the diagnostic requirements when using a low-tube voltage for “one-stop” scanning of coronary and head and neck CTA. The CNR values were basically consistent with the conventional scanning method, and the patient effective dose was reduced by about 50%.