低管电压联合自动毫安秒调节技术在肺动脉 CT 成像中的应用

Application of low voltage with CARE dose 4D in the computed tomography pulmonary angiography（CTPA）

目的：评估低管电压联合自动毫安秒调制技术肺动脉 CT 成像的图像质量及辐射剂量差异，探讨其应用的可行性。方法将临床怀疑肺动脉栓塞需行 CTPA 检查的92例患者（体质量指数为20～30 kg／m^2），用随机数字表法分为研究组（A 组，80 kV）和对照组（B 组，100 kV）各46例，其中 A 组男女各23例，由放射科高年资医师双盲5分制评价图像质量，测量两组样本肺主动脉、右肺动脉、右下肺动脉后基底段、竖脊肌的 CT值和标准方差（SD），记录 CT 容积剂量指数（CT Dose Index of volume，CTDIvol），计算相应感兴趣区的信噪比（Signal Noise Ratio，SNR），比较其差异。对 A 组按性别分类，比较其辐射剂量的差异。结果A 组肺动脉内的 CT 值（510．27±115．45）HU 高于 B 组（413．32±100．38）HU，差异有统计学意义（t ＝10．367，P ＝0．000）， A 组 SD（50．06±11．67）HU 也高于 B 组（35．21±11．94）HU，差异有统计学意义（t ＝8．892，P ＝0．000）；A 组肺动脉感兴趣区的 SNR（12．36±3．90）低于 B 组（14．03±4．46），差异有统计学意义（t ＝－5．238，P ＝0.001），A 组1 mm 轴位图像主观评分（4．20±0．29）低于 B 组（4．91±0．36），差异有统计学意义（t ＝－20．23，P ＝0．000），但5 mm 冠状面 MPR 及20 mm 冠状面最大密度投影（MIP）差异均无统计学意义（均 P ＞0．05）；A 组 CTDIvol（2．03±0．39）mGy 低于 B 组（5．04±1．02）mGy，差异有统计学意义（P ＜0．05）；在 A 组其辐射剂量平均值男性为（2．05±0．39）mGy，女性（2．01±0．38）mGy，差异无统计学意义（t ＝－0．300，P ＞0.05）。结论对于 BMI 体质量指数为20～30 kg／m^2患者，80 kV 管电压 CTPA 图像质量接近100 kV 图像质量，辐射剂量可以降低约50％以上。

Objective To assess the feasibility of low voltage with CARE dose 4D computed tomography pul-monary angiography（CTPA）by using image quality and radiation dosage.Methods 92 patients with clinically sus-pected pulmonary embolism（BMI：20 ~30kg/m^2）were randomly divided into two groups（group A：n =46,80kV;groups B：n =46,100kV）,the male and female of group A were equal to the number.Image quality score（given blind-ly by two senior radiologists ranged from 1 to 5 points）.The CT value and standard deviation（SD）were measured and recorded in common pulmonary artery trunk,the main right pulmonary arteries,right low lobar arteries,and erector muscle of spine,calculated the SNR of ROI.Average CT value,signal noise ratio（SNR）,CTDIvol,DLP were com-pared between the two groups.Used the CT dose index（CTDIvol）to compare radiation dosage between group A female and male.Results The agent average CT value and SD in arteries in group A [（510.27 ±115.45）HU,（50.06 ± 11.67）HU respectively]were higher than those in group B[（413.32 ±100.38）HU,（35.12 ±11.94）HU respective-ly],there were significant differences between the two groups（t =10.367,8.892,all P =0.000）,but the SNR of ROI was （12.36 ±3.90）,which was lower than （14.03 ±4.46）in group B,there was significant difference between the＆amp;nbsp;two groups（t =-5.238,P =0.001 ）.Image quality score of transverse ection（1mm）in group A was （4.20 ± 0.29）,which was lower than （4.91 ±0.36）in group B,there was significant difference（t =-20.23,P =0.000）, but there was no significant difference in coronal section（5mm）,coronal maximum intensity project（MIP）image and the capability of displaying the pulmonary artery branches（all P 〉0.05 ）.The CTDIvol in group A was （2.03 ± 0.39）mGy,which was greatly lower than （5.04 ±1.02）mGy in group B,there was significant difference （P 〈0.05）;but there was no significant difference between female and male in group A[male：（2.05 ±0.39）mGy;female：（2.01 ±0.38）mGy,t =-0.300,P 〉0.05].Conclusion Radiation dose can be decreased greatly（above 50%）in 80kV CTPA compared 100kV without compressing obviously the image quality for patients BMI 20 -30kg/m^2 ,and no significant difference between the group A（80kV）different gender radiation dosage.