“一键式”个体化低辐射剂量CT结肠造影的可行性

Feasibility of“One Key”Realizing Individualized Low Dose CT Colonography

目的探究在CT结肠造影(CTC)中应用自动管电压预设置技术行“一键式”个体化低剂量扫描方案的可行性。资料与方法前瞻性收集2021年10月—2022年6月于大连医科大学附属第一医院行CTC扫描的131例患者,均行俯卧位(A组)、仰卧位(B组)两次扫描。A组管电压采用120 kVp,应用30%自适应迭代重建(ASIR-V)图像;B组管电压使用自动管电压预设置模式,采用70%ASIR-V图像,其余参数均一致。记录体重指数、CT容积剂量指数(CTDIvol)和剂量长度乘积(DLP)。测量两组轴位图像相同层面肝脏和肠腔内空气(背景)均匀处的CT值和噪声值,计算信号噪声比和对比噪声比;由2位观察者采用5分法对两组图像质量进行评价并行一致性检验,比较两组图像质量及辐射剂量的差异。结果B组(体重指数:17.96~32.05 kg/m^(2))kVp预设值分布为70 kVp 4例、80 kVp 64例、100 kVp 61例、120 kVp 2例。A、B组CTDIvol、DLP分别为(5.57±0.13)mGy、(291.80±7.46)mGy·cm和(3.79±0.14)mGy、(189.70±7.48)mGy·cm,B组与A组相比,CTDIvol、DLP分别降低31.96%和34.99%(Z=9.931,P均<0.05)。B组图像肝脏和肠腔内空气CT值与A组差异无统计学意义(t=1.888、-1.218,P>0.05),B组图像噪声值低于A组,信噪比和对比噪声比均高于A组(t=-33.200、-41.617,16.083、57.748,P<0.05);两组图像质量主观评分一致性较好(Kappa=0.766~0.879,P>0.05)。结论在低剂量CTC扫描中应用自动管电压预设置技术,能够在保证图像质量的同时进一步降低患者辐射剂量,实现了“一键式”个体化低剂量CTC成像,具有重要临床应用价值。

Purpose To explore the feasibility of“one key”individualized low-dose CT colonography(CTC)via auto-prescription technique.Materials and Methods A total of 131 patients who underwent CTC examination were prospectively collected from October 2021 to June 2022 in the First Affiliated Hospital of Dalian Medical University.All patients were scanned twice in prone(group A)and supine positions(group B).The tube voltage in prone position was 120 kVp combined with 30%adaptive statistical iterative reconstruction-veo(ASIR-V).The tube voltage in supine position was in auto-prescription mode,combining with 70%ASIR-V.The rest scanning parameters were remained the same.The body mass index,volume CT dose index(CTDIvol)and dose length product(DLP)were recorded,respectively.The signal-to-noise ratio(SNR)and contrast noise ratio(CNR)were calculated by measuring the CT and standard deviation(SD)values of air of intestine(background)and liver parenchyma on axial images.Two observers used a 5-point scale to evaluate the image quality of the two groups,and the consistency test was performed to test the inter-observer consistency.The differences in image quality and radiation dose were compared between the two groups.Results The kVp value in group B(body mass index:17.96-32.05 kg/m^(2))were 70 kVp(4/131),80 kVp(64/131),100 kVp(61/131),120 kVp(2/131),respectively.Compared with group A[(5.57±0.13)mGy and(291.80±7.46)mGy·cm],the CTDIvol and DLP of group B[(3.79±0.14)mGy and(189.70±7.48)mGy·cm]decreased by 33.94%and 36.91%(Z=9.931,both P<0.05),respectively.There was no statistically significant difference in the liver and air CT value between group B and group A(t=1.888,-1.218,P>0.05),SD value of group B was significantly lower than that of group A,the SNR and CNR of group B were significantly higher than those of group A(t=-33.200,-41.617,16.083,57.748,all P<0.05).Conclusion Application of auto-prescription technique in low-dose CTC can further reduce the radiation dose with maintaining the image quality,and can realize“one-click”individualized low-dose CTC,which has important clinical application value.